Увеличение и уменьшение изображения в Android ImageView

Сделайте два класса Java

Класс масштабирования

import android.content.Context;
import android.graphics.Canvas;
import android.graphics.drawable.Drawable;
import android.view.KeyEvent;
import android.view.View;
import android.widget.Button;
import android.widget.ImageButton;

public class Zoom extends View {

    private Drawable image;
    ImageButton img,img1;
    private int zoomControler=20;

    public Zoom(Context context){
            super(context);

            image=context.getResources().getDrawable(R.drawable.j);
            //image=context.getResources().getDrawable(R.drawable.icon);

            setFocusable(true);
    }

    @Override
    protected void onDraw(Canvas canvas) {
        super.onDraw(canvas);

        //here u can control the width and height of the images........ this line is very important
        image.setBounds((getWidth()/2)-zoomControler, (getHeight()/2)-zoomControler, (getWidth()/2)+zoomControler, (getHeight()/2)+zoomControler);
        image.draw(canvas);
    }

    @Override
    public boolean onKeyDown(int keyCode, KeyEvent event) {

            if(keyCode==KeyEvent.KEYCODE_DPAD_UP){
                    // zoom in
                    zoomControler+=10;
            }
            if(keyCode==KeyEvent.KEYCODE_DPAD_DOWN){
                    // zoom out
                    zoomControler-=10;
            }
            if(zoomControler<10){
                    zoomControler=10;
            }

            invalidate();
            return true;
    }
}

сделать второй класс

import android.app.Activity;
import android.os.Bundle;

public class Zoomexample extends Activity {
   /** Called when the activity is first created. */

   @Override
   public void onCreate(Bundle icicle) {
       super.onCreate(icicle);
       setContentView(new Zoom(this));
   }
}

Следуйте приведенному ниже классу, который используется для увеличения и уменьшения изображения для ImageView.

import android.app.Activity;
import android.graphics.Matrix;
import android.graphics.PointF;
import android.os.Bundle;
import android.util.Log;
import android.view.MotionEvent;
import android.view.View;
import android.view.View.OnTouchListener;
import android.widget.ImageView;

public class ZoomInZoomOut extends Activity implements OnTouchListener 
{
    private static final String TAG = "Touch";
    @SuppressWarnings("unused")
    private static final float MIN_ZOOM = 1f,MAX_ZOOM = 1f;

    // These matrices will be used to scale points of the image
    Matrix matrix = new Matrix();
    Matrix savedMatrix = new Matrix();

    // The 3 states (events) which the user is trying to perform
    static final int NONE = 0;
    static final int DRAG = 1;
    static final int ZOOM = 2;
    int mode = NONE;

    // these PointF objects are used to record the point(s) the user is touching
    PointF start = new PointF();
    PointF mid = new PointF();
    float oldDist = 1f;

    /** Called when the activity is first created. */
    @Override
    public void onCreate(Bundle savedInstanceState) 
    {
        super.onCreate(savedInstanceState);
        setContentView(R.layout.main);
        ImageView view = (ImageView) findViewById(R.id.imageView);
        view.setOnTouchListener(this);
    }

    @Override
    public boolean onTouch(View v, MotionEvent event) 
    {
        ImageView view = (ImageView) v;
        view.setScaleType(ImageView.ScaleType.MATRIX);
        float scale;

        dumpEvent(event);
        // Handle touch events here...

        switch (event.getAction() & MotionEvent.ACTION_MASK) 
        {
            case MotionEvent.ACTION_DOWN:   // first finger down only
                                                savedMatrix.set(matrix);
                                                start.set(event.getX(), event.getY());
                                                Log.d(TAG, "mode=DRAG"); // write to LogCat
                                                mode = DRAG;
                                                break;

            case MotionEvent.ACTION_UP: // first finger lifted

            case MotionEvent.ACTION_POINTER_UP: // second finger lifted

                                                mode = NONE;
                                                Log.d(TAG, "mode=NONE");
                                                break;

            case MotionEvent.ACTION_POINTER_DOWN: // first and second finger down

                                                oldDist = spacing(event);
                                                Log.d(TAG, "oldDist=" + oldDist);
                                                if (oldDist > 5f) {
                                                    savedMatrix.set(matrix);
                                                    midPoint(mid, event);
                                                    mode = ZOOM;
                                                    Log.d(TAG, "mode=ZOOM");
                                                }
                                                break;

            case MotionEvent.ACTION_MOVE:

                                                if (mode == DRAG) 
                                                { 
                                                    matrix.set(savedMatrix);
                                                    matrix.postTranslate(event.getX() - start.x, event.getY() - start.y); // create the transformation in the matrix  of points
                                                } 
                                                else if (mode == ZOOM) 
                                                { 
                                                    // pinch zooming
                                                    float newDist = spacing(event);
                                                    Log.d(TAG, "newDist=" + newDist);
                                                    if (newDist > 5f) 
                                                    {
                                                        matrix.set(savedMatrix);
                                                        scale = newDist / oldDist; // setting the scaling of the
                                                                                    // matrix...if scale > 1 means
                                                                                    // zoom in...if scale < 1 means
                                                                                    // zoom out
                                                        matrix.postScale(scale, scale, mid.x, mid.y);
                                                    }
                                                }
                                                break;
        }

        view.setImageMatrix(matrix); // display the transformation on screen

        return true; // indicate event was handled
    }

    /*
     * --------------------------------------------------------------------------
     * Method: spacing Parameters: MotionEvent Returns: float Description:
     * checks the spacing between the two fingers on touch
     * ----------------------------------------------------
     */

    private float spacing(MotionEvent event) 
    {
        float x = event.getX(0) - event.getX(1);
        float y = event.getY(0) - event.getY(1);
        return (float) Math.sqrt(x * x + y * y);
    }

    /*
     * --------------------------------------------------------------------------
     * Method: midPoint Parameters: PointF object, MotionEvent Returns: void
     * Description: calculates the midpoint between the two fingers
     * ------------------------------------------------------------
     */

    private void midPoint(PointF point, MotionEvent event) 
    {
        float x = event.getX(0) + event.getX(1);
        float y = event.getY(0) + event.getY(1);
        point.set(x / 2, y / 2);
    }

    /** Show an event in the LogCat view, for debugging */
    private void dumpEvent(MotionEvent event) 
    {
        String names[] = { "DOWN", "UP", "MOVE", "CANCEL", "OUTSIDE","POINTER_DOWN", "POINTER_UP", "7?", "8?", "9?" };
        StringBuilder sb = new StringBuilder();
        int action = event.getAction();
        int actionCode = action & MotionEvent.ACTION_MASK;
        sb.append("event ACTION_").append(names[actionCode]);

        if (actionCode == MotionEvent.ACTION_POINTER_DOWN || actionCode == MotionEvent.ACTION_POINTER_UP) 
        {
            sb.append("(pid ").append(action >> MotionEvent.ACTION_POINTER_ID_SHIFT);
            sb.append(")");
        }

        sb.append("[");
        for (int i = 0; i < event.getPointerCount(); i++) 
        {
            sb.append("#").append(i);
            sb.append("(pid ").append(event.getPointerId(i));
            sb.append(")=").append((int) event.getX(i));
            sb.append(",").append((int) event.getY(i));
            if (i + 1 < event.getPointerCount())
                sb.append(";");
        }

        sb.append("]");
        Log.d("Touch Events ---------", sb.toString());
    }
}

Все остальные реализации здесь имеют какой-то недостаток. так что я в основном перепутал их и придумал это.

Создайте собственное представление, подобное этому:

ZoomableImageView.java:

import android.content.Context;
import android.graphics.Bitmap;
import android.graphics.Matrix;
import android.graphics.PointF;
import android.util.AttributeSet;
import android.view.MotionEvent;
import android.view.ScaleGestureDetector;
import android.view.View;
import android.widget.ImageView;

public class ZoomableImageView extends ImageView
{
    Matrix matrix = new Matrix();

    static final int NONE = 0;
    static final int DRAG = 1;
    static final int ZOOM = 2;
    static final int CLICK = 3;
    int mode = NONE;

    PointF last = new PointF();
    PointF start = new PointF();
    float minScale = 1f;
    float maxScale = 4f;
    float[] m;

    float redundantXSpace, redundantYSpace;
    float width, height;
    float saveScale = 1f;
    float right, bottom, origWidth, origHeight, bmWidth, bmHeight;

    ScaleGestureDetector mScaleDetector;
    Context context;

    public ZoomableImageView(Context context, AttributeSet attr)
    {
        super(context, attr);
        super.setClickable(true);
        this.context = context;
        mScaleDetector = new ScaleGestureDetector(context, new ScaleListener());
        matrix.setTranslate(1f, 1f);
        m = new float[9];
        setImageMatrix(matrix);
        setScaleType(ScaleType.MATRIX);

        setOnTouchListener(new OnTouchListener()
        {

            @Override
            public boolean onTouch(View v, MotionEvent event)
            {
                mScaleDetector.onTouchEvent(event);

                matrix.getValues(m);
                float x = m[Matrix.MTRANS_X];
                float y = m[Matrix.MTRANS_Y];
                PointF curr = new PointF(event.getX(), event.getY());

                switch (event.getAction())
                {
                    //when one finger is touching
                    //set the mode to DRAG
                    case MotionEvent.ACTION_DOWN:
                        last.set(event.getX(), event.getY());
                        start.set(last);
                        mode = DRAG;
                        break;
                    //when two fingers are touching
                    //set the mode to ZOOM
                    case MotionEvent.ACTION_POINTER_DOWN:
                        last.set(event.getX(), event.getY());
                        start.set(last);
                        mode = ZOOM;
                        break;
                    //when a finger moves
                    //If mode is applicable move image
                    case MotionEvent.ACTION_MOVE:
                        //if the mode is ZOOM or
                        //if the mode is DRAG and already zoomed
                        if (mode == ZOOM || (mode == DRAG && saveScale > minScale))
                        {
                            float deltaX = curr.x - last.x;// x difference
                            float deltaY = curr.y - last.y;// y difference
                            float scaleWidth = Math.round(origWidth * saveScale);// width after applying current scale
                            float scaleHeight = Math.round(origHeight * saveScale);// height after applying current scale
                            //if scaleWidth is smaller than the views width
                            //in other words if the image width fits in the view
                            //limit left and right movement
                            if (scaleWidth < width)
                            {
                                deltaX = 0;
                                if (y + deltaY > 0)
                                    deltaY = -y;
                                else if (y + deltaY < -bottom)
                                    deltaY = -(y + bottom);
                            }
                            //if scaleHeight is smaller than the views height
                            //in other words if the image height fits in the view
                            //limit up and down movement
                            else if (scaleHeight < height)
                            {
                                deltaY = 0;
                                if (x + deltaX > 0)
                                    deltaX = -x;
                                else if (x + deltaX < -right)
                                    deltaX = -(x + right);
                            }
                            //if the image doesnt fit in the width or height
                            //limit both up and down and left and right
                            else
                            {
                                if (x + deltaX > 0)
                                    deltaX = -x;
                                else if (x + deltaX < -right)
                                    deltaX = -(x + right);

                                if (y + deltaY > 0)
                                    deltaY = -y;
                                else if (y + deltaY < -bottom)
                                    deltaY = -(y + bottom);
                            }
                            //move the image with the matrix
                            matrix.postTranslate(deltaX, deltaY);
                            //set the last touch location to the current
                            last.set(curr.x, curr.y);
                        }
                        break;
                    //first finger is lifted
                    case MotionEvent.ACTION_UP:
                        mode = NONE;
                        int xDiff = (int) Math.abs(curr.x - start.x);
                        int yDiff = (int) Math.abs(curr.y - start.y);
                        if (xDiff < CLICK && yDiff < CLICK)
                            performClick();
                        break;
                    // second finger is lifted
                    case MotionEvent.ACTION_POINTER_UP:
                        mode = NONE;
                        break;
                }
                setImageMatrix(matrix);
                invalidate();
                return true;
            }

        });
    }

    @Override
    public void setImageBitmap(Bitmap bm)
    {
        super.setImageBitmap(bm);
        bmWidth = bm.getWidth();
        bmHeight = bm.getHeight();
    }

    public void setMaxZoom(float x)
    {
        maxScale = x;
    }

    private class ScaleListener extends ScaleGestureDetector.SimpleOnScaleGestureListener
    {

        @Override
        public boolean onScaleBegin(ScaleGestureDetector detector)
        {
            mode = ZOOM;
            return true;
        }

        @Override
        public boolean onScale(ScaleGestureDetector detector)
        {
            float mScaleFactor = detector.getScaleFactor();
            float origScale = saveScale;
            saveScale *= mScaleFactor;
            if (saveScale > maxScale)
            {
                saveScale = maxScale;
                mScaleFactor = maxScale / origScale;
            }
            else if (saveScale < minScale)
            {
                saveScale = minScale;
                mScaleFactor = minScale / origScale;
            }
            right = width * saveScale - width - (2 * redundantXSpace * saveScale);
            bottom = height * saveScale - height - (2 * redundantYSpace * saveScale);
            if (origWidth * saveScale <= width || origHeight * saveScale <= height)
            {
                matrix.postScale(mScaleFactor, mScaleFactor, width / 2, height / 2);
                if (mScaleFactor < 1)
                {
                    matrix.getValues(m);
                    float x = m[Matrix.MTRANS_X];
                    float y = m[Matrix.MTRANS_Y];
                    if (mScaleFactor < 1)
                    {
                        if (Math.round(origWidth * saveScale) < width)
                        {
                            if (y < -bottom)
                                matrix.postTranslate(0, -(y + bottom));
                            else if (y > 0)
                                matrix.postTranslate(0, -y);
                        }
                        else
                        {
                            if (x < -right)
                                matrix.postTranslate(-(x + right), 0);
                            else if (x > 0)
                                matrix.postTranslate(-x, 0);
                        }
                    }
                }
            }
            else
            {
                matrix.postScale(mScaleFactor, mScaleFactor, detector.getFocusX(), detector.getFocusY());
                matrix.getValues(m);
                float x = m[Matrix.MTRANS_X];
                float y = m[Matrix.MTRANS_Y];
                if (mScaleFactor < 1) {
                    if (x < -right)
                        matrix.postTranslate(-(x + right), 0);
                    else if (x > 0)
                        matrix.postTranslate(-x, 0);
                    if (y < -bottom)
                        matrix.postTranslate(0, -(y + bottom));
                    else if (y > 0)
                        matrix.postTranslate(0, -y);
                }
            }
            return true;
        }
    }

    @Override
    protected void onMeasure (int widthMeasureSpec, int heightMeasureSpec)
    {
        super.onMeasure(widthMeasureSpec, heightMeasureSpec);
        width = MeasureSpec.getSize(widthMeasureSpec);
        height = MeasureSpec.getSize(heightMeasureSpec);
        //Fit to screen.
        float scale;
        float scaleX =  width / bmWidth;
        float scaleY = height / bmHeight;
        scale = Math.min(scaleX, scaleY);
        matrix.setScale(scale, scale);
        setImageMatrix(matrix);
        saveScale = 1f;

        // Center the image
        redundantYSpace = height - (scale * bmHeight) ;
        redundantXSpace = width - (scale * bmWidth);
        redundantYSpace /= 2;
        redundantXSpace /= 2;

        matrix.postTranslate(redundantXSpace, redundantYSpace);

        origWidth = width - 2 * redundantXSpace;
        origHeight = height - 2 * redundantYSpace;
        right = width * saveScale - width - (2 * redundantXSpace * saveScale);
        bottom = height * saveScale - height - (2 * redundantYSpace * saveScale);
        setImageMatrix(matrix);
    }
}

Затем добавьте изображение вот так:

ZoomableImageView touch = (ZoomableImageView)findViewById(R.id.IMAGEID);
touch.setImageBitmap(bitmap);

Добавьте такое представление в XML:

<PACKAGE.ZoomableImageView
android:id="@+id/IMAGEID"
android:layout_width="match_parent"
android:layout_height="match_parent"/>

Простой способ:

PhotoViewAttacher pAttacher;
pAttacher = new PhotoViewAttacher(Your_Image_View);
pAttacher.update();

Добавьте строку ниже в build.gradle:

compile 'com.commit451:PhotoView:1.2.4'

Я улучшил ответ, полученный из стека, для безупречного МАСШТАБА (два пальца) / ВРАЩЕНИЕ (два пальца) / перетаскивание (один палец).

// ============================ XML-код ==================

<?xml version="1.0" encoding="utf-8"?>
<LinearLayout
    xmlns:android="http://schemas.android.com/apk/res/android"
    xmlns:app="http://schemas.android.com/apk/res-auto"
    xmlns:tools="http://schemas.android.com/tools"
    android:layout_width="match_parent"
    android:layout_height="match_parent"
    tools:context="com.example.flochat.imageviewzoomforstack.MainActivity">

    <ImageView
        android:id="@+id/imageview_trash"
        android:layout_width="wrap_content"
        android:layout_height="wrap_content"
        android:src="@drawable/trash" />

</LinearLayout>

// ============================ Код Java ================== ========

public class MainActivity extends AppCompatActivity {

    ImageView photoview2;
    float[] lastEvent = null;
    float d = 0f;
    float newRot = 0f;
    private boolean isZoomAndRotate;
    private boolean isOutSide;
    private static final int NONE = 0;
    private static final int DRAG = 1;
    private static final int ZOOM = 2;
    private int mode = NONE;
    private PointF start = new PointF();
    private PointF mid = new PointF();
    float oldDist = 1f;
    private float xCoOrdinate, yCoOrdinate;

    @Override
    protected void onCreate(Bundle savedInstanceState) {
        super.onCreate(savedInstanceState);
        requestWindowFeature(Window.FEATURE_NO_TITLE);
        getWindow().setFlags(WindowManager.LayoutParams.FLAG_FULLSCREEN,
                WindowManager.LayoutParams.FLAG_FULLSCREEN);

        setContentView(R.layout.activity_main);

        photoview2 = findViewById(R.id.imageview_trash);

        photoview2.setOnTouchListener(new View.OnTouchListener() {
            @Override
            public boolean onTouch(View v, MotionEvent event) {
                ImageView view = (ImageView) v;
                view.bringToFront();
                viewTransformation(view, event);
                return true;
            }
        });
    }


    private void viewTransformation(View view, MotionEvent event) {
        switch (event.getAction() & MotionEvent.ACTION_MASK) {
            case MotionEvent.ACTION_DOWN:
            xCoOrdinate = view.getX() - event.getRawX();
            yCoOrdinate = view.getY() - event.getRawY();

                start.set(event.getX(), event.getY());
                isOutSide = false;
                mode = DRAG;
                lastEvent = null;
                break;
            case MotionEvent.ACTION_POINTER_DOWN:
                oldDist = spacing(event);
                if (oldDist > 10f) {
                    midPoint(mid, event);
                    mode = ZOOM;
                }

                lastEvent = new float[4];
                lastEvent[0] = event.getX(0);
                lastEvent[1] = event.getX(1);
                lastEvent[2] = event.getY(0);
                lastEvent[3] = event.getY(1);
                d = rotation(event);
                break;
            case MotionEvent.ACTION_UP:
                isZoomAndRotate = false;
                if (mode == DRAG) {
                    float x = event.getX();
                    float y = event.getY();
                }
            case MotionEvent.ACTION_OUTSIDE:
                isOutSide = true;
                mode = NONE;
                lastEvent = null;
            case MotionEvent.ACTION_POINTER_UP:
                mode = NONE;
                lastEvent = null;
                break;
            case MotionEvent.ACTION_MOVE:
                if (!isOutSide) {
                    if (mode == DRAG) {
                        isZoomAndRotate = false;
                        view.animate().x(event.getRawX() + xCoOrdinate).y(event.getRawY() + yCoOrdinate).setDuration(0).start();
                    }
                    if (mode == ZOOM && event.getPointerCount() == 2) {
                        float newDist1 = spacing(event);
                        if (newDist1 > 10f) {
                            float scale = newDist1 / oldDist * view.getScaleX();
                            view.setScaleX(scale);
                            view.setScaleY(scale);
                        }
                        if (lastEvent != null) {
                            newRot = rotation(event);
                            view.setRotation((float) (view.getRotation() + (newRot - d)));
                        }
                    }
                }
                break;
        }
    }

    private float rotation(MotionEvent event) {
        double delta_x = (event.getX(0) - event.getX(1));
        double delta_y = (event.getY(0) - event.getY(1));
        double radians = Math.atan2(delta_y, delta_x);
        return (float) Math.toDegrees(radians);
    }

    private float spacing(MotionEvent event) {
        float x = event.getX(0) - event.getX(1);
        float y = event.getY(0) - event.getY(1);
        return (int) Math.sqrt(x * x + y * y);
    }

    private void midPoint(PointF point, MotionEvent event) {
        float x = event.getX(0) + event.getX(1);
        float y = event.getY(0) + event.getY(1);
        point.set(x / 2, y / 2);
    }

}

// ======================== Просто передайте любое представление, которое вы хотите увеличить / повернуть / перетащить, в метод viewTransformation (). Очень подходит для масштабирования текста. Текст не пикселизируется.

Он старый, но может кому-то помочь.

Класс TouchImageView ниже поддерживает как увеличение / уменьшение масштаба, так и двойное нажатие.

import android.content.Context;
import android.graphics.Matrix;
import android.graphics.PointF;
import android.graphics.drawable.Drawable;
import android.util.AttributeSet;
import android.util.Log;
import android.view.GestureDetector;
import android.view.MotionEvent;
import android.view.ScaleGestureDetector;
import android.view.View;
import android.widget.ImageView;

public class TouchImageView extends ImageView implements GestureDetector.OnGestureListener, GestureDetector.OnDoubleTapListener {

    Matrix matrix;

    // We can be in one of these 3 states
    static final int NONE = 0;
    static final int DRAG = 1;
    static final int ZOOM = 2;
    int mode = NONE;

    // Remember some things for zooming
    PointF last = new PointF();
    PointF start = new PointF();
    float minScale = 1f;
    float maxScale = 3f;
    float[] m;

    int viewWidth, viewHeight;
    static final int CLICK = 3;
    float saveScale = 1f;
    protected float origWidth, origHeight;
    int oldMeasuredWidth, oldMeasuredHeight;

    ScaleGestureDetector mScaleDetector;

    Context context;

    public TouchImageView(Context context) {
        super(context);
        sharedConstructing(context);
    }

    public TouchImageView(Context context, AttributeSet attrs) {
        super(context, attrs);
        sharedConstructing(context);
    }

    GestureDetector mGestureDetector;

    private void sharedConstructing(Context context) {
        super.setClickable(true);
        this.context = context;
        mGestureDetector = new GestureDetector(context, this);
        mGestureDetector.setOnDoubleTapListener(this);

        mScaleDetector = new ScaleGestureDetector(context, new ScaleListener());
        matrix = new Matrix();
        m = new float[9];
        setImageMatrix(matrix);
        setScaleType(ScaleType.MATRIX);

        setOnTouchListener(new OnTouchListener() {

            @Override
            public boolean onTouch(View v, MotionEvent event) {
                mScaleDetector.onTouchEvent(event);
                mGestureDetector.onTouchEvent(event);

                PointF curr = new PointF(event.getX(), event.getY());

                switch (event.getAction()) {
                    case MotionEvent.ACTION_DOWN:
                        last.set(curr);
                        start.set(last);
                        mode = DRAG;
                        break;

                    case MotionEvent.ACTION_MOVE:
                        if (mode == DRAG) {
                            float deltaX = curr.x - last.x;
                            float deltaY = curr.y - last.y;
                            float fixTransX = getFixDragTrans(deltaX, viewWidth,
                                    origWidth * saveScale);
                            float fixTransY = getFixDragTrans(deltaY, viewHeight,
                                    origHeight * saveScale);
                            matrix.postTranslate(fixTransX, fixTransY);
                            fixTrans();
                            last.set(curr.x, curr.y);
                        }
                        break;

                    case MotionEvent.ACTION_UP:
                        mode = NONE;
                        int xDiff = (int) Math.abs(curr.x - start.x);
                        int yDiff = (int) Math.abs(curr.y - start.y);
                        if (xDiff < CLICK && yDiff < CLICK)
                            performClick();
                        break;

                    case MotionEvent.ACTION_POINTER_UP:
                        mode = NONE;
                        break;
                }

                setImageMatrix(matrix);
                invalidate();
                return true; // indicate event was handled
            }

        });
    }

    public void setMaxZoom(float x) {
        maxScale = x;
    }

    @Override
    public boolean onSingleTapConfirmed(MotionEvent e) {
        return false;
    }

    @Override
    public boolean onDoubleTap(MotionEvent e) {
        // Double tap is detected
        Log.i("MAIN_TAG", "Double tap detected");
        float origScale = saveScale;
        float mScaleFactor;

        if (saveScale == maxScale) {
            saveScale = minScale;
            mScaleFactor = minScale / origScale;
        } else {
            saveScale = maxScale;
            mScaleFactor = maxScale / origScale;
        }

        matrix.postScale(mScaleFactor, mScaleFactor, viewWidth / 2,
                viewHeight / 2);

        fixTrans();
        return false;
    }

    @Override
    public boolean onDoubleTapEvent(MotionEvent e) {
        return false;
    }

    @Override
    public boolean onDown(MotionEvent e) {
        return false;
    }

    @Override
    public void onShowPress(MotionEvent e) {

    }

    @Override
    public boolean onSingleTapUp(MotionEvent e) {
        return false;
    }

    @Override
    public boolean onScroll(MotionEvent e1, MotionEvent e2, float distanceX, float distanceY) {
        return false;
    }

    @Override
    public void onLongPress(MotionEvent e) {

    }

    @Override
    public boolean onFling(MotionEvent e1, MotionEvent e2, float velocityX, float velocityY) {
        return false;
    }

    private class ScaleListener extends
            ScaleGestureDetector.SimpleOnScaleGestureListener {
        @Override
        public boolean onScaleBegin(ScaleGestureDetector detector) {
            mode = ZOOM;
            return true;
        }

        @Override
        public boolean onScale(ScaleGestureDetector detector) {
            float mScaleFactor = detector.getScaleFactor();
            float origScale = saveScale;
            saveScale *= mScaleFactor;
            if (saveScale > maxScale) {
                saveScale = maxScale;
                mScaleFactor = maxScale / origScale;
            } else if (saveScale < minScale) {
                saveScale = minScale;
                mScaleFactor = minScale / origScale;
            }

            if (origWidth * saveScale <= viewWidth
                    || origHeight * saveScale <= viewHeight)
                matrix.postScale(mScaleFactor, mScaleFactor, viewWidth / 2,
                        viewHeight / 2);
            else
                matrix.postScale(mScaleFactor, mScaleFactor,
                        detector.getFocusX(), detector.getFocusY());

            fixTrans();
            return true;
        }
    }

    void fixTrans() {
        matrix.getValues(m);
        float transX = m[Matrix.MTRANS_X];
        float transY = m[Matrix.MTRANS_Y];

        float fixTransX = getFixTrans(transX, viewWidth, origWidth * saveScale);
        float fixTransY = getFixTrans(transY, viewHeight, origHeight
                * saveScale);

        if (fixTransX != 0 || fixTransY != 0)
            matrix.postTranslate(fixTransX, fixTransY);
    }

    float getFixTrans(float trans, float viewSize, float contentSize) {
        float minTrans, maxTrans;

        if (contentSize <= viewSize) {
            minTrans = 0;
            maxTrans = viewSize - contentSize;
        } else {
            minTrans = viewSize - contentSize;
            maxTrans = 0;
        }

        if (trans < minTrans)
            return -trans + minTrans;
        if (trans > maxTrans)
            return -trans + maxTrans;
        return 0;
    }

    float getFixDragTrans(float delta, float viewSize, float contentSize) {
        if (contentSize <= viewSize) {
            return 0;
        }
        return delta;
    }

    @Override
    protected void onMeasure(int widthMeasureSpec, int heightMeasureSpec) {
        super.onMeasure(widthMeasureSpec, heightMeasureSpec);
        viewWidth = MeasureSpec.getSize(widthMeasureSpec);
        viewHeight = MeasureSpec.getSize(heightMeasureSpec);

        //
        // Rescales image on rotation
        //
        if (oldMeasuredHeight == viewWidth && oldMeasuredHeight == viewHeight
                || viewWidth == 0 || viewHeight == 0)
            return;
        oldMeasuredHeight = viewHeight;
        oldMeasuredWidth = viewWidth;

        if (saveScale == 1) {
            // Fit to screen.
            float scale;

            Drawable drawable = getDrawable();
            if (drawable == null || drawable.getIntrinsicWidth() == 0
                    || drawable.getIntrinsicHeight() == 0)
                return;
            int bmWidth = drawable.getIntrinsicWidth();
            int bmHeight = drawable.getIntrinsicHeight();

            Log.d("bmSize", "bmWidth: " + bmWidth + " bmHeight : " + bmHeight);

            float scaleX = (float) viewWidth / (float) bmWidth;
            float scaleY = (float) viewHeight / (float) bmHeight;
            scale = Math.min(scaleX, scaleY);
            matrix.setScale(scale, scale);

            // Center the image
            float redundantYSpace = (float) viewHeight
                    - (scale * (float) bmHeight);
            float redundantXSpace = (float) viewWidth
                    - (scale * (float) bmWidth);
            redundantYSpace /= (float) 2;
            redundantXSpace /= (float) 2;

            matrix.postTranslate(redundantXSpace, redundantYSpace);

            origWidth = viewWidth - 2 * redundantXSpace;
            origHeight = viewHeight - 2 * redundantYSpace;
            setImageMatrix(matrix);
        }
        fixTrans();
    }
}

Использование: вы можете заменить свой ImageView на TouchImageView как в XML, так и в java.

1. Для XML

<?xml version="1.0" encoding="utf-8"?>
<com.example.android.myapp.TouchImageView 
    xmlns:android="http://schemas.android.com/apk/res/android"
    android:id="@+id/imViewedImage"
    android:layout_width="match_parent"
    android:layout_height="match_parent"
    android:clickable="true"
    android:focusable="true" />

2. Для Java

TouchImageView imViewedImage = findViewById(R.id.imViewedImage);

просто используйте этот класс: TouchImageView

Это еще одна реализация, основанная на коде, опубликованном Николасом Тайлером.

Исправлены следующие ошибки:

• Установка minScale на число меньше 1 теперь работает
• Вам не нужно использовать setImageBitmap() для установки изображения (вы можете использовать, например, setImageResource()
• Все конструкторы теперь работают правильно

В числе прочего убрано следующее:

• OnTouchListener не используется, в этом нет необходимости, потому что класс может просто реализовать метод onTouchEvent().

• Присваивание right = width * saveScale - width - (2 * redundantXSpace * saveScale); было упрощено до right = (originalBitmapWidth * saveScale) - width, что, на мой взгляд, гораздо менее запутанно.

• Некоторые переменные-члены удалены (из этого класса, вероятно, можно удалить больше состояний)

Это не идеально, но вот, пожалуйста:

import android.content.Context;
import android.graphics.Matrix;
import android.graphics.PointF;
import android.graphics.drawable.Drawable;
import android.util.AttributeSet;
import android.view.MotionEvent;
import android.view.ScaleGestureDetector;
import android.widget.ImageView;

/**
 * Created by alex on 23/02/16.
 * Based on code posted by Nicolas Tyler here:
 * https://stackoverflow.com/questions/6650398/android-imageview-zoom-in-and-zoom-out
 */
public class ZoomableImageView extends ImageView {

    private class ScaleListener extends ScaleGestureDetector.SimpleOnScaleGestureListener {

        @Override
        public boolean onScaleBegin(ScaleGestureDetector detector) {
            mode = ZOOM;
            return true;
        }

        @Override
        public boolean onScale(ScaleGestureDetector detector) {
            float scaleFactor = detector.getScaleFactor();
            float newScale = saveScale * scaleFactor;
            if (newScale < maxScale && newScale > minScale) {
                saveScale = newScale;
                float width = getWidth();
                float height = getHeight();
                right = (originalBitmapWidth * saveScale) - width;
                bottom = (originalBitmapHeight * saveScale) - height;

                float scaledBitmapWidth = originalBitmapWidth * saveScale;
                float scaledBitmapHeight = originalBitmapHeight * saveScale;

                if (scaledBitmapWidth <= width || scaledBitmapHeight <= height) {
                    matrix.postScale(scaleFactor, scaleFactor, width / 2, height / 2);
                } else {
                    matrix.postScale(scaleFactor, scaleFactor, detector.getFocusX(), detector.getFocusY());
                }
            }
            return true;
        }

    }

    static final int NONE = 0;
    static final int DRAG = 1;
    static final int ZOOM = 2;
    static final int CLICK = 3;

    private int mode = NONE;

    private Matrix matrix = new Matrix();

    private PointF last = new PointF();
    private PointF start = new PointF();
    private float minScale = 0.5f;
    private float maxScale = 4f;
    private float[] m;

    private float redundantXSpace, redundantYSpace;
    private float saveScale = 1f;
    private float right, bottom, originalBitmapWidth, originalBitmapHeight;

    private ScaleGestureDetector mScaleDetector;

    public ZoomableImageView(Context context) {
        super(context);
        init(context);
    }

    public ZoomableImageView(Context context, AttributeSet attrs) {
        super(context, attrs);
        init(context);
    }

    public ZoomableImageView(Context context, AttributeSet attrs, int defStyleAttr) {
        super(context, attrs, defStyleAttr);
        init(context);
    }

    private void init(Context context) {
        super.setClickable(true);
        mScaleDetector = new ScaleGestureDetector(context, new ScaleListener());
        m = new float[9];
        setImageMatrix(matrix);
        setScaleType(ScaleType.MATRIX);
    }

    @Override
    protected void onMeasure(int widthMeasureSpec, int heightMeasureSpec) {
        super.onMeasure(widthMeasureSpec, heightMeasureSpec);
        int bmHeight = getBmHeight();
        int bmWidth = getBmWidth();

        float width = getMeasuredWidth();
        float height = getMeasuredHeight();
        //Fit to screen.
        float scale = width > height ? height / bmHeight :  width / bmWidth;

        matrix.setScale(scale, scale);
        saveScale = 1f;

        originalBitmapWidth = scale * bmWidth;
        originalBitmapHeight = scale * bmHeight;

        // Center the image
        redundantYSpace = (height - originalBitmapHeight);
        redundantXSpace = (width - originalBitmapWidth);

        matrix.postTranslate(redundantXSpace / 2, redundantYSpace / 2);

        setImageMatrix(matrix);
    }

    @Override
    public boolean onTouchEvent(MotionEvent event) {
        mScaleDetector.onTouchEvent(event);

        matrix.getValues(m);
        float x = m[Matrix.MTRANS_X];
        float y = m[Matrix.MTRANS_Y];
        PointF curr = new PointF(event.getX(), event.getY());

        switch (event.getAction()) {
            //when one finger is touching
            //set the mode to DRAG
            case MotionEvent.ACTION_DOWN:
                last.set(event.getX(), event.getY());
                start.set(last);
                mode = DRAG;
                break;
            //when two fingers are touching
            //set the mode to ZOOM
            case MotionEvent.ACTION_POINTER_DOWN:
                last.set(event.getX(), event.getY());
                start.set(last);
                mode = ZOOM;
                break;
            //when a finger moves
            //If mode is applicable move image
            case MotionEvent.ACTION_MOVE:
                //if the mode is ZOOM or
                //if the mode is DRAG and already zoomed
                if (mode == ZOOM || (mode == DRAG && saveScale > minScale)) {
                    float deltaX = curr.x - last.x;// x difference
                    float deltaY = curr.y - last.y;// y difference
                    float scaleWidth = Math.round(originalBitmapWidth * saveScale);// width after applying current scale
                    float scaleHeight = Math.round(originalBitmapHeight * saveScale);// height after applying current scale

                    boolean limitX = false;
                    boolean limitY = false;

                    //if scaleWidth is smaller than the views width
                    //in other words if the image width fits in the view
                    //limit left and right movement
                    if (scaleWidth < getWidth() && scaleHeight < getHeight()) {
                        // don't do anything
                    }
                    else if (scaleWidth < getWidth()) {
                        deltaX = 0;
                        limitY = true;
                    }
                    //if scaleHeight is smaller than the views height
                    //in other words if the image height fits in the view
                    //limit up and down movement
                    else if (scaleHeight < getHeight()) {
                        deltaY = 0;
                        limitX = true;
                    }
                    //if the image doesnt fit in the width or height
                    //limit both up and down and left and right
                    else {
                        limitX = true;
                        limitY = true;
                    }

                    if (limitY) {
                        if (y + deltaY > 0) {
                            deltaY = -y;
                        } else  if (y + deltaY < -bottom) {
                            deltaY = -(y + bottom);
                        }

                    }

                    if (limitX) {
                        if (x + deltaX > 0) {
                            deltaX = -x;
                        } else if (x + deltaX < -right) {
                            deltaX = -(x + right);
                        }

                    }
                    //move the image with the matrix
                    matrix.postTranslate(deltaX, deltaY);
                    //set the last touch location to the current
                    last.set(curr.x, curr.y);
                }
                break;
            //first finger is lifted
            case MotionEvent.ACTION_UP:
                mode = NONE;
                int xDiff = (int) Math.abs(curr.x - start.x);
                int yDiff = (int) Math.abs(curr.y - start.y);
                if (xDiff < CLICK && yDiff < CLICK)
                    performClick();
                break;
            // second finger is lifted
            case MotionEvent.ACTION_POINTER_UP:
                mode = NONE;
                break;
        }
        setImageMatrix(matrix);
        invalidate();
        return true;
    }

    public void setMaxZoom(float x) {
        maxScale = x;
    }

    private int getBmWidth() {
        Drawable drawable = getDrawable();
        if (drawable != null) {
            return drawable.getIntrinsicWidth();
        }
        return 0;
    }

    private int getBmHeight() {
        Drawable drawable = getDrawable();
        if (drawable != null) {
            return drawable.getIntrinsicHeight();
        }
        return 0;
    }
}

Я сделал свой собственный просмотр изображений с помощью щипка для увеличения. Для кода Чирага Раваля нет ограничений, поэтому пользователь может перетащить изображение за пределы экрана.

Вот класс CustomImageView:

    public class CustomImageVIew extends ImageView implements OnTouchListener {


    private Matrix matrix = new Matrix();
    private Matrix savedMatrix = new Matrix();

    static final int NONE = 0;
    static final int DRAG = 1;
    static final int ZOOM = 2;

    private int mode = NONE;

    private PointF mStartPoint = new PointF();
    private PointF mMiddlePoint = new PointF();
    private Point mBitmapMiddlePoint = new Point();

    private float oldDist = 1f;
    private float matrixValues[] = {0f, 0f, 0f, 0f, 0f, 0f, 0f, 0f, 0f};
    private float scale;
    private float oldEventX = 0;
    private float oldEventY = 0;
    private float oldStartPointX = 0;
    private float oldStartPointY = 0;
    private int mViewWidth = -1;
    private int mViewHeight = -1;
    private int mBitmapWidth = -1;
    private int mBitmapHeight = -1;
    private boolean mDraggable = false;


    public CustomImageVIew(Context context) {
        this(context, null, 0);
    }

    public CustomImageVIew(Context context, AttributeSet attrs) {
        this(context, attrs, 0);
    }

    public CustomImageVIew(Context context, AttributeSet attrs, int defStyle) {
        super(context, attrs, defStyle);
        this.setOnTouchListener(this);
    }

    @Override
    public void onSizeChanged (int w, int h, int oldw, int oldh){
        super.onSizeChanged(w, h, oldw, oldh);
        mViewWidth = w;
        mViewHeight = h;
    }

    public void setBitmap(Bitmap bitmap){
        if(bitmap != null){
            setImageBitmap(bitmap);

            mBitmapWidth = bitmap.getWidth();
            mBitmapHeight = bitmap.getHeight();
            mBitmapMiddlePoint.x = (mViewWidth / 2) - (mBitmapWidth /  2);
            mBitmapMiddlePoint.y = (mViewHeight / 2) - (mBitmapHeight / 2);

            matrix.postTranslate(mBitmapMiddlePoint.x, mBitmapMiddlePoint.y);
            this.setImageMatrix(matrix);
        }
    }

    @Override
    public boolean onTouch(View v, MotionEvent event){
        switch (event.getAction() & MotionEvent.ACTION_MASK) {
        case MotionEvent.ACTION_DOWN:
            savedMatrix.set(matrix);
            mStartPoint.set(event.getX(), event.getY());
            mode = DRAG;
            break;
        case MotionEvent.ACTION_POINTER_DOWN:
            oldDist = spacing(event);
            if(oldDist > 10f){
                savedMatrix.set(matrix);
                midPoint(mMiddlePoint, event);
                mode = ZOOM;
            }
            break;
        case MotionEvent.ACTION_UP:
        case MotionEvent.ACTION_POINTER_UP:
            mode = NONE;
            break;
        case MotionEvent.ACTION_MOVE:
            if(mode == DRAG){
                drag(event);
            } else if(mode == ZOOM){
                zoom(event);
            } 
            break;
        }

        return true;
    }



   public void drag(MotionEvent event){
       matrix.getValues(matrixValues);

       float left = matrixValues[2];
       float top = matrixValues[5];
       float bottom = (top + (matrixValues[0] * mBitmapHeight)) - mViewHeight;
       float right = (left + (matrixValues[0] * mBitmapWidth)) -mViewWidth;

       float eventX = event.getX();
       float eventY = event.getY();
       float spacingX = eventX - mStartPoint.x;
       float spacingY = eventY - mStartPoint.y;
       float newPositionLeft = (left  < 0 ? spacingX : spacingX * -1) + left;
       float newPositionRight = (spacingX) + right;
       float newPositionTop = (top  < 0 ? spacingY : spacingY * -1) + top;
       float newPositionBottom = (spacingY) + bottom;
       boolean x = true;
       boolean y = true;

       if(newPositionRight < 0.0f || newPositionLeft > 0.0f){
           if(newPositionRight < 0.0f && newPositionLeft > 0.0f){
               x = false;
           } else{
               eventX = oldEventX;
               mStartPoint.x = oldStartPointX;
           }
       }
       if(newPositionBottom < 0.0f || newPositionTop > 0.0f){
           if(newPositionBottom < 0.0f && newPositionTop > 0.0f){
               y = false;
           } else{
               eventY = oldEventY;
               mStartPoint.y = oldStartPointY;
           }
       }

       if(mDraggable){
           matrix.set(savedMatrix);
           matrix.postTranslate(x? eventX - mStartPoint.x : 0, y? eventY - mStartPoint.y : 0);
           this.setImageMatrix(matrix);
           if(x)oldEventX = eventX;
           if(y)oldEventY = eventY;
           if(x)oldStartPointX = mStartPoint.x;
           if(y)oldStartPointY = mStartPoint.y;
       }

   }

   public void zoom(MotionEvent event){
       matrix.getValues(matrixValues);

       float newDist = spacing(event);
       float bitmapWidth = matrixValues[0] * mBitmapWidth;
       float bimtapHeight = matrixValues[0] * mBitmapHeight;
       boolean in = newDist > oldDist;

       if(!in && matrixValues[0] < 1){
           return;
       }
       if(bitmapWidth > mViewWidth || bimtapHeight > mViewHeight){
           mDraggable = true;
       } else{
           mDraggable = false;
       }

       float midX = (mViewWidth / 2);
       float midY = (mViewHeight / 2);

       matrix.set(savedMatrix);
       scale = newDist / oldDist;
       matrix.postScale(scale, scale, bitmapWidth > mViewWidth ? mMiddlePoint.x : midX, bimtapHeight > mViewHeight ? mMiddlePoint.y : midY); 

       this.setImageMatrix(matrix);


   }





    /** Determine the space between the first two fingers */
    private float spacing(MotionEvent event) {
        float x = event.getX(0) - event.getX(1);
        float y = event.getY(0) - event.getY(1);

        return (float)Math.sqrt(x * x + y * y);
    }

    /** Calculate the mid point of the first two fingers */
    private void midPoint(PointF point, MotionEvent event) {
        float x = event.getX(0) + event.getX(1);
        float y = event.getY(0) + event.getY(1);
        point.set(x / 2, y / 2);
    }


}

Вот как вы можете использовать это в своей деятельности:

CustomImageVIew mImageView = (CustomImageVIew)findViewById(R.id.customImageVIew1);
mImage.setBitmap(your bitmap);

И макет:

<your.package.name.CustomImageVIew
        android:id="@+id/customImageVIew1"
        android:layout_width="fill_parent"
        android:layout_height="fill_parent"
        android:layout_marginBottom="15dp"
        android:layout_marginLeft="15dp"
        android:layout_marginRight="15dp"
        android:layout_marginTop="15dp"
        android:layout_centerHorizontal="true"
        android:layout_centerVertical="true" 
        android:scaleType="matrix"/> // important

Я думаю, что ответ Чирага Равалса великолепен!

Единственное, что можно улучшить, - это переместить весь этот код в какой-нибудь класс, например:

PinchZoomImageView extends ImageView {...

и добавив туда начальную инициализацию матрицы изображений, чтобы предотвратить масштабирование после первого нажатия:

@Override
protected void onMeasure(int widthMeasureSpec, int heightMeasureSpec) {
    super.onMeasure(widthMeasureSpec, heightMeasureSpec);
    matrix = new Matrix(this.getImageMatrix());
}

Кстати, это исправит ошибку, упомянутую Мухаммадом Умаром и Базом.

P.S. Также может быть полезно иметь пределы максимального и минимального масштабирования. Например, максимальное масштабирование составляет 2X, а минимальное масштабирование является исходным масштабом, когда изображение подогнано к экрану:

static final int MAX_SCALE_FACTOR = 2;

@Override
protected void onMeasure(int widthMeasureSpec, int heightMeasureSpec) {
    super.onMeasure(widthMeasureSpec, heightMeasureSpec);

    // Getting initial Image matrix
    mViewMatrix = new Matrix(this.getImageMatrix());
    mMinScaleMatrix = new Matrix(mViewMatrix);
    float initialScale = getMatrixScale(mViewMatrix);


    if (initialScale < 1.0f) // Image is bigger than screen
        mMaxScale = MAX_SCALE_FACTOR;
    else
        mMaxScale = MAX_SCALE_FACTOR * initialScale;

    mMinScale = getMatrixScale(mMinScaleMatrix);
}


@Override
public boolean onTouch(View v, MotionEvent event) {
    ImageView view = (ImageView) v;
    // We set scale only after onMeasure was called and automatically fit image to screen
    if(!mWasScaleTypeSet) {
        view.setScaleType(ImageView.ScaleType.MATRIX);
        mWasScaleTypeSet = true;
    }

    float scale;

    dumpEvent(event);

    switch (event.getAction() & MotionEvent.ACTION_MASK) {
    case MotionEvent.ACTION_DOWN: // first finger down only
        mCurSavedMatrix.set(mViewMatrix);
        start.set(event.getX(), event.getY());
        mCurrentMode = DRAG;
        break;

    case MotionEvent.ACTION_UP: // first finger lifted
    case MotionEvent.ACTION_POINTER_UP: // second finger lifted
        mCurrentMode = NONE;

        float resScale = getMatrixScale(mViewMatrix);

        if (resScale > mMaxScale) {
            downscaleMatrix(resScale, mViewMatrix);
        } else if (resScale < mMinScale)
            mViewMatrix = new Matrix(mMinScaleMatrix);
        else if ((resScale - mMinScale) < 0.1f) // Don't allow user to drag picture outside in case of FIT TO WINDOW zoom
            mViewMatrix = new Matrix(mMinScaleMatrix);
        else
            break;

        break;

    case MotionEvent.ACTION_POINTER_DOWN: // first and second finger down
        mOldDist = spacing(event);
        Helper.LOGD(TAG, "oldDist=" + mOldDist);
        if (mOldDist > 5f) {
            mCurSavedMatrix.set(mViewMatrix);
            midPoint(mCurMidPoint, event);
            mCurrentMode = ZOOM;
            Helper.LOGD(TAG, "mode=ZOOM");
        }
        break;

    case MotionEvent.ACTION_MOVE:
        if (mCurrentMode == DRAG) {
            mViewMatrix.set(mCurSavedMatrix);
            mViewMatrix.postTranslate(event.getX() - start.x, event.getY() - start.y); // create the transformation in the matrix  of points
        } else if (mCurrentMode == ZOOM) {
            // pinch zooming
            float newDist = spacing(event);
            Helper.LOGD(TAG, "newDist=" + newDist);
            if (newDist > 1.f) {
                mViewMatrix.set(mCurSavedMatrix);
                scale = newDist / mOldDist; // setting the scaling of the
                                            // matrix...if scale > 1 means
                                            // zoom in...if scale < 1 means
                                            // zoom out
                mViewMatrix.postScale(scale, scale, mCurMidPoint.x, mCurMidPoint.y);
            }
        }
        break;
    }

    view.setImageMatrix(mViewMatrix); // display the transformation on screen

    return true; // indicate event was handled
}


////////////////////////////////////////////////////////////////////////////////////////////////////////////////////////
//////////////////////////////////////////////////// PRIVATE SECTION ///////////////////////////////////////////////////
////////////////////////////////////////////////////////////////////////////////////////////////////////////////////////
// These matrices will be used to scale points of the image
private Matrix mViewMatrix = new Matrix();
private Matrix mCurSavedMatrix = new Matrix();
// These PointF objects are used to record the point(s) the user is touching
private PointF start = new PointF();
private PointF mCurMidPoint = new PointF();
private float mOldDist = 1f;

private Matrix mMinScaleMatrix;
private float mMinScale;
private float mMaxScale;
float[] mTmpValues = new float[9];
private boolean mWasScaleTypeSet;


/**
 * Returns scale factor of the Matrix
 * @param matrix
 * @return
 */
private float getMatrixScale(Matrix matrix) {
    matrix.getValues(mTmpValues);
    return mTmpValues[Matrix.MSCALE_X];
}

/**
 * Downscales matrix with the scale to maximum allowed scale factor, but the same translations
 * @param scale
 * @param dist
 */
private void downscaleMatrix(float scale, Matrix dist) {
    float resScale = mMaxScale / scale;
    dist.postScale(resScale, resScale, mCurMidPoint.x, mCurMidPoint.y);
}

Я получил наиболее полезный ответ от @Nicolas Tyler, но у меня были проблемы с тем, как работают синтаксис и логика. Я также не хотел никакого альфа-пространства, а моя алгебра была ржавой! Через 3 дня я собрал свою собственную версию этого.

Мой ответ отличается от ответа @Nicolas Tyler следующим:

1. Различные имена переменных, которые, как я обнаружил, имеют больше смысла в контексте базового использования.

2. Этот класс изображений Pinch-Zoom НЕ показывает альфа-пространство и позволит вам увеличивать и уменьшать масштаб, но при этом не позволяет вам перемещать изображение сверху / снизу и открывать альфа-пространство.

3. Добавлены глубокие комментарии к разделу матриц, чтобы объяснить, что происходит с задействованной математикой.

4. Этот класс изображения также позволит вам передать resourceId, и он создаст из него растровое изображение.

5. Гораздо более простые алгоритмы масштабирования и трансляции и немного переменных.

6. Изменение изображения в нем приведет к его увеличению / уменьшению, так что новое изображение займет контейнер представления.

Здесь можно найти отличный справочник по алгебре: https://youtu.be/IiXB6tYtY4w?t=4m12s Это видео охватывает ядро ​​скалярных матриц и матриц трансляции (и поможет вам разобраться в материалах MTRANS_X и MTRANS_Y). Если у вас есть вопросы, задавайте, и я постараюсь ответить (но я НЕ эксперт по алгебре).

import android.content.Context;
import android.graphics.Bitmap;
import android.graphics.BitmapFactory;
import android.graphics.Matrix;
import android.graphics.PointF;
import android.view.MotionEvent;
import android.view.ScaleGestureDetector;
import android.view.View;
import android.widget.ImageView;

public class iImage extends ImageView
{
    static final int NONE_MODE = 0;
    static final int DRAG_MODE = 1;
    static final int ZOOM_MODE = 2;
    int _mode = NONE_MODE;

    Matrix _matrix = new Matrix();
    PointF _previousPoint = new PointF();
    PointF _startPoint = new PointF();
    float _currentScale = 1f;
    float _minScale = 1f;
    float _maxScale = 3f;
    float[] _arrayOf9Floats;
    float _bitmapWidth, _bitmapHeight,_displayWidth, _displayHeight;
    ScaleGestureDetector _scaleDetector;
    Context _context;

    public iImage(Context context)
    {
        super(context);
        super.setClickable(true);
        _context = context;
        _scaleDetector = new ScaleGestureDetector(context, new ScaleListener());
        _arrayOf9Floats = new float[9];
        setScaleType(ScaleType.MATRIX);
        setOnTouchListener(new OnTouchListener() {
            @Override
            public boolean onTouch(View v, MotionEvent event) {
                return handleTouch(v, event);
            }
        });
    }

    private boolean handleTouch(View v, MotionEvent event)
    {
        _scaleDetector.onTouchEvent(event);
        //Contrary to how this line looks, the matrix is not setting the values from the arrayOf9Floats, but rather taking the
        //matrix values and assigning them into the arrayOf9Floats. I extremely dislike this syntax and I think
        //it should have been written as _arrayOf9Floats = _matrix.getValues() but that's Android for you!!!
        _matrix.getValues(_arrayOf9Floats);

        //Look at https://youtu.be/IiXB6tYtY4w?t=4m12s , it shows scale, rotate, and translate matrices
        //If you look at the translate matrix, you'll see that the 3rd and 6th values are the values which represent x and y translations respectively
        //this corresponds to the 2nd and 5th values in the array and hence why the MTRANS_X and MTRANS_Y have the constants 2 and 5 respectively
        float xTranslate = _arrayOf9Floats[Matrix.MTRANS_X];
        float yTranslate = _arrayOf9Floats[Matrix.MTRANS_Y];
        PointF currentEventPoint = new PointF(event.getX(), event.getY());
        switch (event.getAction())
        {
            //First finger down only
            case MotionEvent.ACTION_DOWN:
                _previousPoint.set(event.getX(), event.getY());
                _startPoint.set(_previousPoint);
                _mode = DRAG_MODE;
                break;
            //Second finger down
            case MotionEvent.ACTION_POINTER_DOWN:
                _previousPoint.set(event.getX(), event.getY());
                _startPoint.set(_previousPoint);
                _mode = ZOOM_MODE;
                break;
            case MotionEvent.ACTION_MOVE:
                if (_mode == ZOOM_MODE || _mode == DRAG_MODE )
                {
                    float deltaX = currentEventPoint.x - _previousPoint.x;
                    float deltaY = currentEventPoint.y - _previousPoint.y;
                    //In matrix terms, going right is + and going left is +
                    //Moving the image right past 0 means it will show alpha space on the left so we dont want that
                    //Keep in mind this is a TOP LEFT pivot point, so we dont want the top left to be past 0 lest we have alpha space
                    if(xTranslate + deltaX > 0)
                    {
                        //get absolute of how much into the negative we would have gone
                        float excessDeltaX = Math.abs(xTranslate + deltaX);
                        //take that excess away from deltaX so X wont got less than 0 after the translation
                        deltaX = deltaX - excessDeltaX;
                    }

                    //Going left we dont want the negative value to be less than the negative width of the sprite, lest we get alpha space on the right
                    //The width is going to be the width of the bitmap * scale and we want the - of it because we are checking for left movement
                    //We also need to account for the width of the DISPLAY CONTAINER (i.e. _displayWidth) so that gets subtracted
                    //i.e. we want the max scroll width value
                    float maxScrollableWidth = _bitmapWidth * _currentScale - _displayWidth;
                    if(xTranslate + deltaX < -maxScrollableWidth)
                    {
                        //this forces the max possible translate to always match the - of maxScrollableWidth
                        deltaX = -maxScrollableWidth - xTranslate;
                    }

                    //repeat for Y
                    if(yTranslate + deltaY > 0)
                    {
                        float excessDeltaY = Math.abs(yTranslate + deltaY);
                        deltaY = deltaY - excessDeltaY;
                    }

                    float maxScrollableHeight = _bitmapHeight * _currentScale - _displayWidth;
                    if(yTranslate + deltaY < -maxScrollableHeight)
                    {
                        //this forces the max possible translate to always match the - of maxScrollableWidth
                        deltaY = -maxScrollableHeight - yTranslate;
                    }

                    _matrix.postTranslate(deltaX, deltaY);
                    _matrix.getValues(_arrayOf9Floats);
                    //System.out.println(_matrix);

                    _previousPoint.set(currentEventPoint.x, currentEventPoint.y);
                }
                break;
            case MotionEvent.ACTION_POINTER_UP:
                _mode = NONE_MODE;
                break;
        }
        setImageMatrix(_matrix);
        invalidate();
        return true;
    }

    @Override
    public void setImageBitmap(Bitmap bm)
    {
        super.setImageBitmap(bm);
        _bitmapWidth = bm.getWidth();
        _bitmapHeight = bm.getHeight();
        invalidate();
    }

    @Override
    public void setImageResource(int resid)
    {
        Bitmap bitmapImage = BitmapFactory.decodeResource(_context.getResources(), resid);
        setImageBitmap(bitmapImage);
    }

    private class ScaleListener extends ScaleGestureDetector.SimpleOnScaleGestureListener
    {

        @Override
        public boolean onScaleBegin(ScaleGestureDetector detector)
        {
            _mode = ZOOM_MODE;
            return true;
        }

        @Override
        public boolean onScale(ScaleGestureDetector detector)
        {
            float scaleFactor = detector.getScaleFactor();
            float originalScale = _currentScale;
            _currentScale *= scaleFactor;
            //Zoom in too much
            if (_currentScale > _maxScale) {
                _currentScale = _maxScale;
                scaleFactor = _maxScale / originalScale;
            }//Zoom out too much
            else if (_currentScale < _minScale) {
                _currentScale = _minScale;
                scaleFactor = _minScale / originalScale;
            }
           _matrix.postScale(scaleFactor,scaleFactor);

            return true;
        }
    }

    @Override
    protected void onMeasure (int widthMeasureSpec, int heightMeasureSpec)
    {
        super.onMeasure(widthMeasureSpec, heightMeasureSpec);
        _displayWidth = MeasureSpec.getSize(widthMeasureSpec);
        _displayHeight = MeasureSpec.getSize(heightMeasureSpec);
        adjustScale();
    }

    private void adjustScale()
    {
        //Fit to display bounds with NO alpha space
        float scale;
        float scaleX =  _displayWidth / _bitmapWidth;
        float scaleY = _displayHeight / _bitmapHeight;
        scale = Math.max(scaleX, scaleY);
        _matrix.setScale(scale, scale);
        setImageMatrix(_matrix);
        _currentScale = scale;
        _minScale = scale;
    }

    public void setMaxZoom(float maxZoom){_maxScale = maxZoom;}
    public void setMinZoom(float minZoom) {_minScale = minZoom;}
}

Этот код работает и реализует двойное касание для возврата к исходному размеру изображения.

1-й шаг - в макете xml поместите это:

<com.****.*****.TouchImageView
    android:id="@+id/action_infolinks_splash"
    android:layout_width="match_parent"
    android:layout_height="match_parent"
    android:src="@mipmap/myinfolinks_splash"
    android:layout_gravity="center"
    android:gravity="center"
    android:scaleType="fitCenter"
    android:contentDescription="@string/aboutSupport_description_image"/>

2-й шаг - Создайте файл (TouchImageView.java) с классом TouchImageView:

import android.content.Context;
import android.graphics.Bitmap;
import android.graphics.BitmapFactory;
import android.graphics.Matrix;
import android.graphics.PointF;
import android.util.AttributeSet;
import android.view.GestureDetector;
import android.view.MotionEvent;
import android.view.ScaleGestureDetector;
import android.view.View;
import android.widget.ImageView;

public class TouchImageView extends ImageView {

    Matrix matrix;

    // We can be in one of these 3 states
    static final int NONE = 0;
    static final int DRAG = 1;
    static final int ZOOM = 2;
    int mode = NONE;

    // Remember some things for zooming
    PointF last = new PointF();
    PointF start = new PointF();
    float minScale = 1f;
    float maxScale = 3f;
    float[] m;
    float redundantXSpace, redundantYSpace, origRedundantXSpace, origRedundantYSpace;

    int viewWidth, viewHeight;
    static final int CLICK = 3;
    static final float SAVE_SCALE = 1f;
    float saveScale = SAVE_SCALE;
    protected float origWidth, origHeight;
    int oldMeasuredWidth, oldMeasuredHeight;
    float origScale, bottom, origBottom, right, origRight;

    ScaleGestureDetector mScaleDetector;
    GestureDetector mGestureDetector;

    Context context;

    public TouchImageView(Context context) {
        super(context);
        sharedConstructing(context);
    }

    public TouchImageView(Context context, AttributeSet attrs) {
        super(context, attrs);
        sharedConstructing(context);
    }

    private void sharedConstructing(Context context) {
        super.setClickable(true);
        this.context = context;
        mScaleDetector = new ScaleGestureDetector(context, new ScaleListener());
        matrix = new Matrix();
        m = new float[9];
        setImageMatrix(matrix);
        setScaleType(ScaleType.MATRIX);

        setOnTouchListener(new OnTouchListener() {

            @Override
            public boolean onTouch(View v, MotionEvent event) {

                boolean onDoubleTapEvent = mGestureDetector.onTouchEvent(event);
                if (onDoubleTapEvent) {
                    // Reset Image to original scale values
                    mode = NONE;
                    bottom = origBottom;
                    right = origRight;
                    last = new PointF();
                    start = new PointF();
                    m = new float[9];
                    saveScale = SAVE_SCALE;
                    matrix = new Matrix();
                    matrix.setScale(origScale, origScale);
                    matrix.postTranslate(origRedundantXSpace, origRedundantYSpace);
                    setImageMatrix(matrix);
                    invalidate();
                    return true;
                }

                mScaleDetector.onTouchEvent(event);
                PointF curr = new PointF(event.getX(), event.getY());

                switch (event.getAction()) {
                    case MotionEvent.ACTION_DOWN:
                        last.set(curr);
                        start.set(last);
                        mode = DRAG;
                        break;

                    case MotionEvent.ACTION_MOVE:
                        if (mode == DRAG) {
                            float deltaX = curr.x - last.x;
                            float deltaY = curr.y - last.y;
                            float fixTransX = getFixDragTrans(deltaX, viewWidth, origWidth * saveScale);
                            float fixTransY = getFixDragTrans(deltaY, viewHeight, origHeight * saveScale);
                            matrix.postTranslate(fixTransX, fixTransY);
                            fixTrans();
                            last.set(curr.x, curr.y);
                        }
                        break;

                    case MotionEvent.ACTION_UP:
                        mode = NONE;
                        int xDiff = (int) Math.abs(curr.x - start.x);
                        int yDiff = (int) Math.abs(curr.y - start.y);
                        if (xDiff < CLICK && yDiff < CLICK) performClick();
                        break;

                    case MotionEvent.ACTION_POINTER_UP:
                        mode = NONE;
                        break;
                }

                setImageMatrix(matrix);
                invalidate();
                return true; // indicate event was handled
            }

        });

        mGestureDetector = new GestureDetector(context, new GestureDetector.SimpleOnGestureListener() {
            @Override
            public boolean onDoubleTapEvent(MotionEvent e) {
                return true;
            }
        });
    }

    public void setMaxZoom(float x) {
        maxScale = x;
    }

    private class ScaleListener extends ScaleGestureDetector.SimpleOnScaleGestureListener {
        @Override
        public boolean onScaleBegin(ScaleGestureDetector detector) {
            mode = ZOOM;
            return true;
        }

        @Override
        public boolean onScale(ScaleGestureDetector detector) {
            float mScaleFactor = detector.getScaleFactor();
            //float mScaleFactor = (float) Math.min(Math.max(.95f, detector.getScaleFactor()), 1.05);
            float origScale = saveScale;
            saveScale *= mScaleFactor;
            if (saveScale > maxScale) {
                saveScale = maxScale;
                mScaleFactor = maxScale / origScale;
            } else if (saveScale < minScale) {
                saveScale = minScale;
                mScaleFactor = minScale / origScale;
            }

            right = viewWidth * saveScale - viewWidth - (2 * redundantXSpace * saveScale);
            bottom = viewHeight * saveScale - viewHeight - (2 * redundantYSpace * saveScale);

            if (origWidth * saveScale <= viewWidth || origHeight * saveScale <= viewHeight)
                matrix.postScale(mScaleFactor, mScaleFactor, viewWidth / 2, viewHeight / 2);
            else
                matrix.postScale(mScaleFactor, mScaleFactor, detector.getFocusX(), detector.getFocusY());

            fixTrans();
            return true;
        }
    }

    void fixTrans() {
        matrix.getValues(m);
        float transX = m[Matrix.MTRANS_X];
        float transY = m[Matrix.MTRANS_Y];

        float fixTransX = getFixTrans(transX, viewWidth, origWidth * saveScale);
        float fixTransY = getFixTrans(transY, viewHeight, origHeight * saveScale);

        if (fixTransX != 0 || fixTransY != 0)
            matrix.postTranslate(fixTransX, fixTransY);
    }

    float getFixTrans(float trans, float viewSize, float contentSize) {
        float minTrans, maxTrans;

        if (contentSize <= viewSize) {
            minTrans = 0;
            maxTrans = viewSize - contentSize;
        } else {
            minTrans = viewSize - contentSize;
            maxTrans = 0;
        }

        if (trans < minTrans)
            return -trans + minTrans;
        if (trans > maxTrans)
            return -trans + maxTrans;
        return 0;
    }

    float getFixDragTrans(float delta, float viewSize, float contentSize) {
        if (contentSize <= viewSize) {
            return 0;
        }
        return delta;
    }

    @Override
    protected void onMeasure(int widthMeasureSpec, int heightMeasureSpec) {
        super.onMeasure(widthMeasureSpec, heightMeasureSpec);
        viewWidth = MeasureSpec.getSize(widthMeasureSpec);
        viewHeight = MeasureSpec.getSize(heightMeasureSpec);

        //
        // Rescales image on rotation
        //
        if (oldMeasuredHeight == viewWidth && oldMeasuredHeight == viewHeight || viewWidth == 0 || viewHeight == 0) return;

        oldMeasuredHeight = viewHeight;
        oldMeasuredWidth = viewWidth;

        if (saveScale == 1) {
            // Fit to screen.
            float scale;
            int bmWidth,bmHeight;

            Bitmap bm = BitmapFactory.decodeResource(context.getResources(), R.mipmap.myinfolinks_splash);
            bmWidth = bm.getWidth();
            bmHeight = bm.getHeight();

            int  w = bmWidth;
            int  h = bmHeight;
            viewWidth = resolveSize(w, widthMeasureSpec);
            viewHeight = resolveSize(h, heightMeasureSpec);

            float scaleX = (float) viewWidth / (float) bmWidth;
            float scaleY = (float) viewHeight / (float) bmHeight;
            scale = Math.min(scaleX, scaleY);
            matrix.setScale(scale, scale);
            saveScale = SAVE_SCALE;
            origScale = scale;

            // Center the image
            redundantYSpace = (float) viewHeight - (scale * (float) bmHeight);
            redundantXSpace = (float) viewWidth - (scale * (float) bmWidth);
            redundantYSpace /= (float) 2;
            redundantXSpace /= (float) 2;

            origRedundantXSpace = redundantXSpace;
            origRedundantYSpace = redundantYSpace;

            matrix.postTranslate(redundantXSpace, redundantYSpace);

            origWidth = viewWidth - 2 * redundantXSpace;
            origHeight = viewHeight - 2 * redundantYSpace;

            right = viewWidth * saveScale - viewWidth - (2 * redundantXSpace * saveScale);
            bottom = viewHeight * saveScale - viewHeight - (2 * redundantYSpace * saveScale);
            origRight = right;
            origBottom = bottom;

            setImageMatrix(matrix);
        }
        fixTrans();
    }
}

И, наконец, сделайте звонок в своей основной деятельности:

TouchImageView imgDisplay = (TouchImageView) messageView.findViewById(R.id.id_myImage);
imgDisplay.setMaxZoom(2f);
imgDisplay.setImageResource(R.drawable.myImage);

Я видел много кода, и после моих корректировок он работает. Наслаждаться!

Вы должны поместить изображение в веб-просмотр и работать с ним. Элементы управления увеличением / уменьшением доступны в веб-просмотре.

• http://xjaphx.wordpress.com/2011/09/18/using-webview-as-a-image-zoom-view-control/
• http://androidforums.com/android-lounge/121522-how-display-image-sdcard-webview.html

Шаг 1. Сначала вы добавляете зависимости в файл build.gradle (Module: app).

dependencies {

     implementation 'com.jsibbold:zoomage:1.2.0'

    }

Шаг 2. Затем создайте курс

ImageFullScreenFragment.java

public class ImageFullScreenFragment{

   private ZoomageView ImageZoomageView;

    @Override
    public View onCreateView(LayoutInflater inflater, ViewGroup container,
                             Bundle savedInstanceState) {
        // Inflate the layout for this fragment
        View view = null;

      try {
         view = inflater.inflate(R.layout.fragment_image_full_screen, container, false);
            ImageZoomageView = view.findViewById(R.id.imageViewImageFullScreen);
            ImageZoomageView.setImageResource(R.drawable.image);

         } catch (Exception e) {
             e.printStackTrace();
         }
    return view;

}

Шаг 3. Затем создайте XML-файл макета

fragment_image_full_screen.xml

<?xml version="1.0" encoding="utf-8"?>
<RelativeLayout xmlns:android="http://schemas.android.com/apk/res/android"
    xmlns:tools="http://schemas.android.com/tools"
    android:layout_width="match_parent"
    android:layout_height="match_parent"
    android:padding="8dp"
    xmlns:app="http://schemas.android.com/apk/res-auto">

    <com.jsibbold.zoomage.ZoomageView
        android:layout_width="match_parent"
        android:layout_height="match_parent"
        app:zoomage_restrictBounds="false"
        app:zoomage_animateOnReset="true"
        app:zoomage_autoResetMode="UNDER"
        app:zoomage_autoCenter="true"
        app:zoomage_zoomable="true"
        app:zoomage_translatable="true"
        app:zoomage_minScale="0.6"
        app:zoomage_maxScale="8"
        android:id="@+id/imageViewImageFullScreen"
        />

</RelativeLayout>

OutPut: -

Попробуйте следующее:

package com.example.nwssugeoinformationmobileapplication;
import android.os.Bundle;
import android.annotation.SuppressLint;
import android.app.Activity;
import android.content.Intent;
import android.util.FloatMath;
import android.util.Log;
import android.view.Menu;
import android.view.MenuInflater;
import android.view.MenuItem;
import android.view.MotionEvent;
import android.view.View.OnTouchListener;
import android.widget.TabHost;
import android.widget.TabHost.TabSpec;
import android.graphics.Matrix;
import android.graphics.PointF;
import android.graphics.RectF;
import android.graphics.drawable.Drawable;
import android.view.View;
import android.widget.ImageView;
public class MainActivity extends Activity implements  OnTouchListener {

    private static final String TAG = "Touch";
    Matrix matrix = new Matrix();
    Matrix savedMatrix = new Matrix();
    static final int NONE = 0;
    static final int DRAG = 1;
    static final int ZOOM = 2;
    int mode = NONE;
    PointF start = new PointF();
    PointF mid = new PointF();
    float oldDist = 1f;

    private ImageView view;
    private float[] matrixValues = new float[9];
    private float maxZoom;
    private float minZoom;
    private float height;
    private float width;
    private RectF viewRect;

    @Override
    protected void onCreate(Bundle savedInstanceState) {
        super.onCreate(savedInstanceState);
        setContentView(R.layout.activity_main);

        TabHost th = (TabHost) findViewById (R.id.tabhost);
        th.setup();

        TabSpec specs = th.newTabSpec("tag1");
        specs.setContent(R.id.tab1);
        specs.setIndicator("Map");
        th.addTab(specs);


        specs = th.newTabSpec("tag2");
        specs.setContent(R.id.tab2);
        specs.setIndicator("Search");
        th.addTab(specs);


        view = (ImageView) findViewById(R.id.imageView1);
        Drawable bitmap = getResources().getDrawable(R.drawable.map);
        view.setImageDrawable(bitmap);
        view.setOnTouchListener(this); 

        matrix.setTranslate(1f, 1f);
        view.setImageMatrix(matrix);



    } 



    @Override
    public void onWindowFocusChanged(boolean hasFocus) {
    super.onWindowFocusChanged(hasFocus);
    if(hasFocus){
    init();
            }
    }
    private void init() {
        maxZoom = 2;
        minZoom = 1f;
        height = view.getDrawable().getIntrinsicHeight();
        width = view.getDrawable().getIntrinsicWidth();
        viewRect = new RectF(0, 0, view.getWidth(), view.getHeight());
        }

    @Override
    public boolean onCreateOptionsMenu(Menu menu) {
        MenuInflater inflater = getMenuInflater();
        inflater.inflate(R.menu.menus, menu);
        return true; 
        }

    public boolean onOptionsItemSelected(MenuItem item) {

        if(item.getItemId()== R.id.item1){
            Log.d("Tracks", "Track Us was Clicked");

            startActivity(new Intent (MainActivity.this, Tracklocation.class ));
            }

        if(item.getItemId()== R.id.item2){
            Log.d("Updates", "Updates was Clicked");

            startActivity(new Intent (MainActivity.this, Updates.class ));
            }

        if(item.getItemId()== R.id.item3){
            Log.d("About Us", "About Us was Clicked");


            startActivity(new Intent (MainActivity.this, Horoscope.class ));
            }


        return super.onOptionsItemSelected(item);

     }


    @Override
    public boolean onTouch(View v, MotionEvent rawEvent) {
        ImageView view = (ImageView) v;
        view.setScaleType(ImageView.ScaleType.MATRIX);
        dumpEvent(rawEvent);
    // Handle touch events here...
    switch (rawEvent.getAction() & MotionEvent.ACTION_MASK) {
    case MotionEvent.ACTION_DOWN:
    savedMatrix.set(matrix);
    start.set(rawEvent.getX(), rawEvent.getY());
    Log.d(TAG, "mode=DRAG");
    mode = DRAG;
    break;
    case MotionEvent.ACTION_POINTER_DOWN:
    oldDist = spacing(rawEvent);
    Log.d(TAG, "oldDist=" + oldDist);
    if (oldDist > 10f) {
    savedMatrix.set(matrix);
    midPoint(mid, rawEvent);
    mode = ZOOM;
    Log.d(TAG, "mode=ZOOM");
    }
    break;
    case MotionEvent.ACTION_UP:
    case MotionEvent.ACTION_POINTER_UP:
    mode = NONE;
    Log.d(TAG, "mode=NONE");
    break;
    case MotionEvent.ACTION_MOVE:
    if (mode == DRAG) {
    matrix.set(savedMatrix);
    // limit pan
    matrix.getValues(matrixValues);
    float currentY = matrixValues[Matrix.MTRANS_Y];
    float currentX = matrixValues[Matrix.MTRANS_X];
    float currentScale = matrixValues[Matrix.MSCALE_X];
    float currentHeight = height * currentScale;
    float currentWidth = width * currentScale;
    float dx = rawEvent.getX() - start.x;
    float dy = rawEvent.getY() - start.y;
    float newX = currentX+dx;
    float newY = currentY+dy;
    RectF drawingRect = new RectF(newX, newY, newX+currentWidth, newY+currentHeight);
    float diffUp = Math.min(viewRect.bottom-drawingRect.bottom, viewRect.top-drawingRect.top);
    float diffDown = Math.max(viewRect.bottom-drawingRect.bottom, viewRect.top-drawingRect.top);
    float diffLeft = Math.min(viewRect.left-drawingRect.left, viewRect.right-drawingRect.right);
    float diffRight = Math.max(viewRect.left-drawingRect.left, viewRect.right-drawingRect.right);

    if(diffUp > 0 ){
    dy +=diffUp;
    }
    if(diffDown < 0){
    dy +=diffDown;
    }
    if( diffLeft> 0){
    dx += diffLeft;
    }
    if(diffRight < 0){
    dx += diffRight;
    }
    matrix.postTranslate(dx, dy);
    } else if (mode == ZOOM) {
    float newDist = spacing(rawEvent);
    Log.d(TAG, "newDist=" + newDist);
    if (newDist > 10f) {
    matrix.set(savedMatrix);
    float scale1 = newDist / oldDist;
    matrix.getValues(matrixValues);
    float currentScale = matrixValues[Matrix.MSCALE_X];
    // limit zoom
    if (scale1 * currentScale > maxZoom) {
    scale1 = maxZoom / currentScale;
    } else if (scale1 * currentScale < minZoom) {
    scale1 = minZoom / currentScale;
    }
    matrix.postScale(scale1, scale1, mid.x, mid.y);
    }
    }
    break;
    }
    view.setImageMatrix(matrix);
    return true; 
    }

    @SuppressWarnings("deprecation")
    private void dumpEvent(MotionEvent event) {
        String names[] = { "DOWN", "UP", "MOVE", "CANCEL", "OUTSIDE",
        "POINTER_DOWN", "POINTER_UP", "7?", "8?", "9?" };
        StringBuilder sb = new StringBuilder();
        int action = event.getAction();
        int actionCode = action & MotionEvent.ACTION_MASK;
        sb.append("event ACTION_").append(names[actionCode]);
        if (actionCode == MotionEvent.ACTION_POINTER_DOWN
        || actionCode == MotionEvent.ACTION_POINTER_UP) {
        sb.append("(pid ").append(
        action >> MotionEvent.ACTION_POINTER_ID_SHIFT);
        sb.append(")");
        }
        sb.append("[");
        for (int i = 0; i < event.getPointerCount(); i++) {
        sb.append("#").append(i);
        sb.append("(pid ").append(event.getPointerId(i));
        sb.append(")=").append((int) event.getX(i));
        sb.append(",").append((int) event.getY(i));
        if (i + 1 < event.getPointerCount())
        sb.append(";");
        }
        sb.append("]");
        Log.d(TAG, sb.toString());
        }
        /** Determine the space between the first two fingers */
        private float spacing(MotionEvent event) {
        float x = event.getX(0) - event.getX(1);
        float y = event.getY(0) - event.getY(1);
        return FloatMath.sqrt(x * x + y * y);
        }
        /** Calculate the mid point of the first two fingers */
        @SuppressLint("FloatMath")
        private void midPoint(PointF point, MotionEvent event) {
        float x = event.getX(0) + event.getX(1);
        float y = event.getY(0) + event.getY(1);
        point.set(x / 2, y / 2);
        }
}

Мне нужно было что-то подобное, но нужна была возможность легко получать размеры, а также перетаскивать. Я основал это на ответе @Nicolas Tyler и изменил его оттуда.

К функциям относятся увеличение / уменьшение масштабирования пальцем, длительное нажатие для вибрации / выделенное перетаскивание.

Чтобы использовать его, добавьте этот класс CustomZoomView в свой проект.

public class CustomZoomView extends View implements View.OnTouchListener, View.OnLongClickListener{


private Paint mPaint;

Vibrator v;

static final int NONE = 0;
static final int DRAG = 1;
static final int ZOOM = 2;
static final int MOVE = 3;

private int mode = NONE;

Rect src;
Rect mTempDst = new Rect();
Rect dst = new Rect();

Bitmap mBitmap;

private int mBitmapWidth = -1;
private int mBitmapHeight = -1;

private PointF mStartPoint = new PointF();
private PointF mMiddlePoint = new PointF();
private PointF mStartDragPoint = new PointF();
private PointF mMovePoint = new PointF();

private float oldDist = 1f;
private float scale;
private float oldEventX = 0;
private float oldEventY = 0;
private float oldStartPointX = 0;
private float oldStartPointY = 0;
private int mViewWidth = -1;
private int mViewHeight = -1;

private boolean mDraggable = false;


public CustomZoomView(Context context) {
    this(context, null, 0);

}

public CustomZoomView(Context context, AttributeSet attrs) {
    this(context, attrs, 0);
}

public CustomZoomView(Context context, AttributeSet attrs, int defStyle) {
    super(context, attrs, defStyle);
    this.setOnTouchListener(this);
    this.setOnLongClickListener(this);
    v = (Vibrator) context.getSystemService(Context.VIBRATOR_SERVICE);
    mPaint = new Paint();
    mPaint.setColorFilter(new PorterDuffColorFilter(Color.argb(100,255,255,255), PorterDuff.Mode.SRC_IN));
}

@Override
public void onSizeChanged(int w, int h, int oldw, int oldh) {
    super.onSizeChanged(w, h, oldw, oldh);
    mViewWidth = w;
    mViewHeight = h;
}

public void setBitmap(Bitmap bitmap) {
    if (bitmap != null) {

        src = new Rect();
        src.left = 0;
        src.top = 0;
        src.right = bitmap.getWidth();
        src.bottom = bitmap.getHeight();
        mBitmap = bitmap;

        mBitmapWidth = bitmap.getWidth() * 1;
        mBitmapHeight = bitmap.getHeight() * 1;

        dst = new Rect();
        dst.left = (mViewWidth / 2) - (mBitmapWidth / 2);
        dst.top = (mViewHeight / 2) - (mBitmapHeight / 2);
        dst.right = (mViewWidth / 2) + (mBitmapWidth / 2);
        dst.bottom = (mViewHeight / 2) + (mBitmapHeight / 2);

    }
}


@Override
public boolean onTouch(View v, MotionEvent event) {

    switch (event.getAction() & MotionEvent.ACTION_MASK) {
        case MotionEvent.ACTION_DOWN:
            mStartPoint.set(event.getX(), event.getY());
            mStartDragPoint.set(event.getX(), event.getY());
            mTempDst.set(dst.left, dst.top, dst.right, dst.bottom);
            mode = DRAG;
            break;
        case MotionEvent.ACTION_POINTER_DOWN:
            oldDist = spacing(event);
            if (oldDist > 10f) {
                midPoint(mMiddlePoint, event);
                mode = ZOOM;
            }
            break;
        case MotionEvent.ACTION_UP:
        case MotionEvent.ACTION_POINTER_UP:
            if (mode == ZOOM) {
                mBitmapWidth = dst.right - dst.left;
                mBitmapHeight = dst.bottom - dst.top;
            }
            mode = NONE;
            break;
        case MotionEvent.ACTION_MOVE:
            if (mode == DRAG) {
                mMovePoint.x = event.getX();
                mMovePoint.y = event.getY();
                drag(event);
            } else if (mode == ZOOM) {
                zoom(event);
            } else if (mode == MOVE) {
                move(event);
            }
            break;
    }

    return false;
}

public void move(MotionEvent event) {

    int xChange = (int) (event.getX() - mStartPoint.x);
    int yChange = (int) (event.getY() - mStartPoint.y);

    dst.left = mTempDst.left + (xChange);
    dst.top = mTempDst.top + (yChange);

    dst.right = mTempDst.right + (xChange);
    dst.bottom = mTempDst.bottom + (yChange);

    invalidate();
}


public void drag(MotionEvent event) {

    float eventX = event.getX();
    float eventY = event.getY();
    float spacingX = eventX - mStartDragPoint.x;
    float spacingY = eventY - mStartDragPoint.y;
    float newPositionLeft = (dst.left < 0 ? spacingX : spacingX * -1) + dst.left;
    float newPositionRight = (spacingX) + dst.right;
    float newPositionTop = (dst.top < 0 ? spacingY : spacingY * -1) + dst.top;
    float newPositionBottom = (spacingY) + dst.bottom;
    boolean x = true;
    boolean y = true;

    if (newPositionRight < 0.0f || newPositionLeft > 0.0f) {
        if (newPositionRight < 0.0f && newPositionLeft > 0.0f) {
            x = false;
        } else {
            eventX = oldEventX;
            mStartDragPoint.x = oldStartPointX;
        }
    }
    if (newPositionBottom < 0.0f || newPositionTop > 0.0f) {
        if (newPositionBottom < 0.0f && newPositionTop > 0.0f) {
            y = false;
        } else {
            eventY = oldEventY;
            mStartDragPoint.y = oldStartPointY;
        }
    }

    if (mDraggable) {
        if (x) oldEventX = eventX;
        if (y) oldEventY = eventY;
        if (x) oldStartPointX = mStartDragPoint.x;
        if (y) oldStartPointY = mStartDragPoint.y;
    }

}

public void zoom(MotionEvent event) {
    float newDist = spacing(event);
    boolean in = newDist > oldDist;

    if (!in && scale < .01f) {
        return;
    }

    scale = newDist / oldDist;

    int xChange = (int) ((mBitmapWidth * scale) / 2);
    int yChange = (int) ((mBitmapHeight * scale) / 2);

    if (xChange > 10 && yChange > 10) { //ADDED THIS TO KEEP IT FROM GOING INVERSE

    int xMidPoint = ((dst.right - dst.left) / 2) + dst.left;
    int yMidPoint = ((dst.bottom - dst.top) / 2) + dst.top;

    dst.left = (int) (float) (xMidPoint - xChange);
    dst.top = (int) (float) (yMidPoint - yChange);

    dst.right = (int) (float) (xMidPoint + xChange);
    dst.bottom = (int) (float) (yMidPoint + yChange);

    }

    invalidate();

}


/**
 * Determine the space between the first two fingers
 */
private float spacing(MotionEvent event) {
    float x = event.getX(0) - event.getX(1);
    float y = event.getY(0) - event.getY(1);

    return (float) Math.sqrt(x * x + y * y);
}

/**
 * Calculate the mid point of the first two fingers
 */
private void midPoint(PointF point, MotionEvent event) {
    float x = event.getX(0) + event.getX(1);
    float y = event.getY(0) + event.getY(1);
    point.set(x / 2, y / 2);
}


@Override
public boolean onLongClick(View view) {


    if (mode == DRAG) {
        if ((mStartPoint.x > dst.left && mStartPoint.x < dst.right) && (mStartPoint.y < dst.bottom && mStartPoint.y > dst.top)
                && (mMovePoint.x > dst.left && mMovePoint.x < dst.right) && (mMovePoint.y < dst.bottom && mMovePoint.y > dst.top)) {
            mode = MOVE;
            v.vibrate(500);
        }
    }
    return true;
}

@Override
protected void onDraw(Canvas canvas) {
    super.onDraw(canvas);
    if (mode == MOVE) {
        canvas.drawBitmap(mBitmap, src, dst, null);
        canvas.drawBitmap(mBitmap, src, dst, mPaint);
    } else {
        canvas.drawBitmap(mBitmap, src, dst, null);
    }

}
}

... затем добавьте это в свою деятельность

CustomZoomView customImageView = (CustomZoomView) findViewById(R.id.customZoomView);
customImageView.setBitmap(yourBitmap);

... и это, на ваш взгляд, в xml.

<your.package.name.CustomZoomView
   android:id="@+id/customZoomView"
   android:layout_width="fill_parent"
   android:layout_height="fill_parent"
   android:longClickable="true"/>

... и добавьте это в свой манифест

<uses-permission android:name="android.permission.VIBRATE"/>

Вот мое решение, оно основано на решении @ alexbirkett.

public class ZoomImageView extends ImageView {

// region . Static fields .

static final int NONE = 0;
static final int DRAG = 1;
static final int ZOOM = 2;
static final int CLICK = 3;

// endregion . Static fields .

// region . Fields .

private int mode = NONE;

private Matrix mMatrix = new Matrix();

private PointF mLastTouch = new PointF();
private PointF mStartTouch = new PointF();
private float minScale = 0.5f;
private float maxScale = 4f;
private float[] mCriticPoints;

private float mScale = 1f;
private float mRight;
private float mBottom;
private float mOriginalBitmapWidth;
private float mOriginalBitmapHeight;

private ScaleGestureDetector mScaleDetector;

//endregion . Fields .

// region . Ctor .
public ZoomImageView(Context context) {
    super(context);
    init(context);
}

public ZoomImageView(Context context, AttributeSet attrs) {
    super(context, attrs);
    init(context);
}

public ZoomImageView(Context context, AttributeSet attrs, int defStyleAttr) {
    super(context, attrs, defStyleAttr);
    init(context);
}

// endregion . Ctor .

// region . Overrider .

@Override
protected void onMeasure(int widthMeasureSpec, int heightMeasureSpec) {
    super.onMeasure(widthMeasureSpec, heightMeasureSpec);
    int bmHeight = getBmHeight();
    int bmWidth = getBmWidth();

    float width = getMeasuredWidth();
    float height = getMeasuredHeight();
    float scale = 1;

    // If image is bigger then display fit it to screen.
    if (width < bmWidth || height < bmHeight) {
        scale = width > height ? height / bmHeight : width / bmWidth;
    }

    mMatrix.setScale(scale, scale);
    mScale = 1f;

    mOriginalBitmapWidth = scale * bmWidth;
    mOriginalBitmapHeight = scale * bmHeight;

    // Center the image
    float redundantYSpace = (height - mOriginalBitmapHeight);
    float redundantXSpace = (width - mOriginalBitmapWidth);

    mMatrix.postTranslate(redundantXSpace / 2, redundantYSpace / 2);

    setImageMatrix(mMatrix);
}

@Override
public boolean onTouchEvent(MotionEvent event) {
    mScaleDetector.onTouchEvent(event);

    mMatrix.getValues(mCriticPoints);
    float translateX = mCriticPoints[Matrix.MTRANS_X];
    float trnslateY = mCriticPoints[Matrix.MTRANS_Y];
    PointF currentPoint = new PointF(event.getX(), event.getY());

    switch (event.getAction()) {
        //when one finger is touching
        //set the mode to DRAG
        case MotionEvent.ACTION_DOWN:
            mLastTouch.set(event.getX(), event.getY());
            mStartTouch.set(mLastTouch);
            mode = DRAG;
            break;
        //when two fingers are touching
        //set the mode to ZOOM
        case MotionEvent.ACTION_POINTER_DOWN:
            mLastTouch.set(event.getX(), event.getY());
            mStartTouch.set(mLastTouch);
            mode = ZOOM;
            break;
        //when a finger moves
        //If mode is applicable move image
        case MotionEvent.ACTION_MOVE:

            //if the mode is ZOOM or
            //if the mode is DRAG and already zoomed
            if (mode == ZOOM || (mode == DRAG && mScale > minScale)) {

                // region . Move  image.

                float deltaX = currentPoint.x - mLastTouch.x;// x difference
                float deltaY = currentPoint.y - mLastTouch.y;// y difference
                float scaleWidth = Math.round(mOriginalBitmapWidth * mScale);// width after applying current scale
                float scaleHeight = Math.round(mOriginalBitmapHeight * mScale);// height after applying current scale

                // Move image to lef or right if its width is bigger than display width
                if (scaleWidth > getWidth()) {
                    if (translateX + deltaX > 0) {
                        deltaX = -translateX;
                    } else if (translateX + deltaX < -mRight) {
                        deltaX = -(translateX + mRight);
                    }
                } else {
                    deltaX = 0;
                }
                // Move image to up or bottom if its height is bigger than display height
                if (scaleHeight > getHeight()) {
                    if (trnslateY + deltaY > 0) {
                        deltaY = -trnslateY;
                    } else if (trnslateY + deltaY < -mBottom) {
                        deltaY = -(trnslateY + mBottom);
                    }
                } else {
                    deltaY = 0;
                }

                //move the image with the matrix
                mMatrix.postTranslate(deltaX, deltaY);
                //set the last touch location to the current
                mLastTouch.set(currentPoint.x, currentPoint.y);

                // endregion . Move image .
            }
            break;
        //first finger is lifted
        case MotionEvent.ACTION_UP:
            mode = NONE;
            int xDiff = (int) Math.abs(currentPoint.x - mStartTouch.x);
            int yDiff = (int) Math.abs(currentPoint.y - mStartTouch.y);
            if (xDiff < CLICK && yDiff < CLICK)
                performClick();
            break;
        // second finger is lifted
        case MotionEvent.ACTION_POINTER_UP:
            mode = NONE;
            break;
    }
    setImageMatrix(mMatrix);
    invalidate();
    return true;
}

//endregion . Overrides .

// region . Privates .

private void init(Context context) {
    super.setClickable(true);
    mScaleDetector = new ScaleGestureDetector(context, new ScaleListener());
    mCriticPoints = new float[9];
    setImageMatrix(mMatrix);
    setScaleType(ScaleType.MATRIX);
}

private int getBmWidth() {
    Drawable drawable = getDrawable();
    if (drawable != null) {
        return drawable.getIntrinsicWidth();
    }
    return 0;
}

private int getBmHeight() {
    Drawable drawable = getDrawable();
    if (drawable != null) {
        return drawable.getIntrinsicHeight();
    }
    return 0;
}

//endregion . Privates .

// region . Internal classes .

private class ScaleListener extends ScaleGestureDetector.SimpleOnScaleGestureListener {

    @Override
    public boolean onScaleBegin(ScaleGestureDetector detector) {
        mode = ZOOM;
        return true;
    }

    @Override
    public boolean onScale(ScaleGestureDetector detector) {
        float scaleFactor = detector.getScaleFactor();
        float newScale = mScale * scaleFactor;
        if (newScale < maxScale && newScale > minScale) {
            mScale = newScale;
            float width = getWidth();
            float height = getHeight();
            mRight = (mOriginalBitmapWidth * mScale) - width;
            mBottom = (mOriginalBitmapHeight * mScale) - height;

            float scaledBitmapWidth = mOriginalBitmapWidth * mScale;
            float scaledBitmapHeight = mOriginalBitmapHeight * mScale;

            if (scaledBitmapWidth <= width || scaledBitmapHeight <= height) {
                mMatrix.postScale(scaleFactor, scaleFactor, width / 2, height / 2);
            } else {
                mMatrix.postScale(scaleFactor, scaleFactor, detector.getFocusX(), detector.getFocusY());
            }
        }
        return true;
    }
}

// endregion . Internal classes .
}

Способ вызова диалогового окна "О программе и поддержке"

 public void setupAboutSupport() {

    try {

        // The About&Support AlertDialog is active
        activeAboutSupport=true;

        View messageView;
        int orientation=this.getResources().getConfiguration().orientation;

        // Inflate the about message contents
        messageView = getLayoutInflater().inflate(R.layout.about_support, null, false);

        ContextThemeWrapper ctw = new ContextThemeWrapper(this, R.style.MyCustomTheme_AlertDialog1);
        AlertDialog.Builder builder = new AlertDialog.Builder(ctw);
        builder.setIcon(R.mipmap.ic_launcher);
        builder.setTitle(R.string.action_aboutSupport);
        builder.setView(messageView);

        TouchImageView imgDisplay = (TouchImageView) messageView.findViewById(R.id.action_infolinks_about_support);
        imgDisplay.setMaxZoom(3f);

        Bitmap bitmap = BitmapFactory.decodeResource(getResources(), R.mipmap.myinfolinks_about_support);

        int imageWidth = bitmap.getWidth();
        int imageHeight = bitmap.getHeight();
        int newWidth;

        // Calculate the new About_Support image width
        if(orientation==Configuration.ORIENTATION_PORTRAIT ) {
            // For 7" up to 10" tablets
            //if ((getResources().getConfiguration().screenLayout & Configuration.SCREENLAYOUT_SIZE_MASK) == Configuration.SCREENLAYOUT_SIZE_XLARGE) {
            if (SingletonMyInfoLinks.isTablet) {
                    // newWidth = widthScreen - (two borders of about_support layout and 20% of width Screen)
                newWidth = widthScreen - ((2 * toPixels(8)) + (int)(widthScreen*0.2));
            } else newWidth = widthScreen - ((2 * toPixels(8)) + (int)(widthScreen*0.1));

        } else {
            // For 7" up to 10" tablets
            //if ((getResources().getConfiguration().screenLayout & Configuration.SCREENLAYOUT_SIZE_MASK) == Configuration.SCREENLAYOUT_SIZE_XLARGE) {
            if (SingletonMyInfoLinks.isTablet) {
                newWidth = widthScreen - ((2 * toPixels(8)) + (int)(widthScreen*0.5));

            } else newWidth = widthScreen - ((2 * toPixels(8)) + (int)(widthScreen*0.3));
        }

        // Get the scale factor
        float scaleFactor = (float)newWidth/(float)imageWidth;
        // Calculate the new About_Support image height
        int newHeight = (int)(imageHeight * scaleFactor);
        // Set the new bitmap corresponding the adjusted About_Support image
        bitmap = Bitmap.createScaledBitmap(bitmap, newWidth, newHeight, true);

        // Rescale the image
        imgDisplay.setImageBitmap(bitmap);

        dialogAboutSupport = builder.show();

        TextView textViewVersion = (TextView) dialogAboutSupport.findViewById(R.id.action_strVersion);
        textViewVersion.setText(Html.fromHtml(getString(R.string.aboutSupport_text1)+" <b>"+versionName+"</b>"));

        TextView textViewDeveloperName = (TextView) dialogAboutSupport.findViewById(R.id.action_strDeveloperName);
        textViewDeveloperName.setText(Html.fromHtml(getString(R.string.aboutSupport_text2)+" <b>"+SingletonMyInfoLinks.developerName+"</b>"));

        TextView textViewSupportEmail = (TextView) dialogAboutSupport.findViewById(R.id.action_strSupportEmail);
        textViewSupportEmail.setText(Html.fromHtml(getString(R.string.aboutSupport_text3)+" "+SingletonMyInfoLinks.developerEmail));

        TextView textViewCompanyName = (TextView) dialogAboutSupport.findViewById(R.id.action_strCompanyName);
        textViewCompanyName.setText(Html.fromHtml(getString(R.string.aboutSupport_text4)+" "+SingletonMyInfoLinks.companyName));

        Button btnOk = (Button) dialogAboutSupport.findViewById(R.id.btnOK);

        btnOk.setOnClickListener(new View.OnClickListener() {
            @Override
            public void onClick(View v) {
                dialogAboutSupport.dismiss();
            }
        });

        dialogAboutSupport.setOnDismissListener(new DialogInterface.OnDismissListener() {
            @Override
            public void onDismiss(final DialogInterface dialog) {
                // the About & Support AlertDialog is closed
                activeAboutSupport=false;
            }
        });

        dialogAboutSupport.getWindow().setBackgroundDrawable(new ColorDrawable(SingletonMyInfoLinks.atualBackgroundColor));

        /* Effect that image appear slower */
        // Only the fade_in matters
        AlphaAnimation fade_out = new AlphaAnimation(1.0f, 0.0f);
        AlphaAnimation fade_in = new AlphaAnimation(0.0f, 1.0f);
        AlphaAnimation a = false ? fade_out : fade_in;

        a.setDuration(2000); // 2 sec
        a.setFillAfter(true); // Maintain the visibility at the end of animation
        // Animation start
        ImageView img = (ImageView) messageView.findViewById(R.id.action_infolinks_about_support);
        img.startAnimation(a);

    } catch (Exception e) {
        //Log.e(SingletonMyInfoLinks.appNameText +"-" +  getLocalClassName() + ": ", e.getMessage());
    }
}

Просто измените ACTION_MOVE_EVENT в ответе Чирага Равала , чтобы установить ZOOM_IN LIMIT

float[] values = new float[9]; matrix.getValues(values);
                //0.37047964 is limit for zoom in
                if(values[Matrix.MSCALE_X]>0.37047964) {
                    matrix.set(savedMatrix);
                    matrix.postScale(scale, scale, mid.x, mid.y);
                    view.setImageMatrix(matrix);
                }else if (scale>1){
                    matrix.set(savedMatrix);
                    matrix.postScale(scale, scale, mid.x, mid.y);
                    view.setImageMatrix(matrix);
                }

Я знаю, что это немного поздно для этого ответа, но я надеюсь, что это кому-то поможет.

Я искал то же самое (масштабирование с помощью щипка и перетаскивание изображения) и нашел ссылка на блог разработчиков Android.

Прекрасно работает. Никаких артефактов или чего-то подобного. Он использует ScaleGestureDetector.

Ссылка на ZoomLib: https://drive.google.com/uc?export=download&id=0B34PUThnUsjVaHpkaGk0Z1hSRU0

@Override
protected void onCreate(Bundle savedInstanceState) {
super.onCreate(savedInstanceState);
setContentView(R.layout.dummy_layout_for_zooming);// Activity layout 
mZoomLinearLayout = (LinearLayout) findViewById(R.id.mZoomLinearLayout);// LinearLayout inside Activity layout
View v = ((LayoutInflater) getSystemService(Context.LAYOUT_INFLATER_SERVICE)).inflate(R.layout.layout_for_zoom, null, false);// View wants to zoom
v.setLayoutParams(new LinearLayout.LayoutParams(LinearLayout.LayoutParams.FILL_PARENT, LinearLayout.LayoutParams.FILL_PARENT));
ZoomView zoomView = new ZoomView(this);// intialize lib
zoomView.addView(v);
mZoomLinearLayout.addView(zoomView);
}

Я думаю, что вы хотите увеличивать и уменьшать масштаб изображения view, потому что ваше изображение маленькое, и увеличение изображения там не позволит изображению выйти из просмотра изображения. Вместо этого изображение начинает исчезать из границ при увеличении масштаба. Я думаю, вы хотите, чтобы изображение выходило за пределы изображения, пока мы увеличиваем масштаб.

Итак, есть два приема (по моему мнению), чтобы добиться этого -

1. Измените параметры макета представления изображения, чтобы охватить весь внешний вид или группу представлений во время выполнения, пока мы собираемся увеличить изображение.
2. Сделайте развернутое изображение или полноэкранное изображение (высота и ширина = внешний вид или группа представлений) в XML-файле и отключите его видимость. Когда мы собираемся увеличить изображение, загрузите изображение из small Image View в полное Img View, сопоставьте изображение в fullImgView с изображением в smallImgView и сделайте его видимым.

Уловка № 1 не работает, когда представление изображения очень сильно вложено в другие представления (например, в представлении вложенного ресайклера).

Уловка № 2 работает всегда :-)

Вот реализация трюка №2 -

public class ZoomOnTouchListener extends AppCompatActivity implements View.OnTouchListener {

    private Matrix matrix = new Matrix();

    private boolean isfullImgViewActive = false;
    // above boolean gets true when when we firstly move 2 fingers on the smallImgView and in this case smallImgView gets invisible and fullImgView gets visible
    // and false if smallImgView is visible and fullImgView is gone

    private float[] matrixArray = new float[9];
    private float orgScale;

    private PointF start = new PointF();
    private PointF prevP1 = new PointF();
    private PointF prevP2 = new PointF();
    private PointF mid = new PointF();
    private float oldDist = 1f;

    private ImageView mfullImgView;
    private ImageView smallImgView;

    @Override
    protected void onCreate(@Nullable Bundle savedInstanceState) {
        super.onCreate(savedInstanceState);
        setContentView(R.layout.activity_main);

        mfullImgView = (ImageView)findViewById(R.id.imgView2);
        mfullImgView.setVisibility(View.GONE);
        smallImgView = (ImageView)findViewById(R.id.imgView);
        smallImgView.setOnTouchListener(this);    

    }

    @Override
    public boolean onTouch(View v, MotionEvent event) {
        //Log.i("0", "OnTouch()");
        if(v instanceof ImageView) {
            ImageView imgView = (ImageView) v;

            boolean isImgViewSmall = (imgView == smallImgView);

            switch (event.getAction() & MotionEvent.ACTION_MASK) {

                case MotionEvent.ACTION_DOWN:   // first finger down only

                    //Log.i("T", "Motion Event: ACTION_DOWN");

                    if(isImgViewSmall)
                        start.set(event.getX(), event.getY());

                    prevP1.set(event.getX(), event.getY());

                    return true;

                case MotionEvent.ACTION_POINTER_DOWN: //second finger and other fingers down

                    prevP1.set(event.getX(0), event.getY(0));
                    prevP2.set(event.getX(1), event.getY(1));

                    oldDist = spacing(event);

                    midPoint(mid, event);

                    break;

                case MotionEvent.ACTION_MOVE:   //it doesn't mean fingers are moved. In this case, all pointers which are active are batched together
                                                // this case occurs after action_down or action_pointer_down

                    //Log.i("Tag", event.getX()+","+event.getY());
                    if(event.getPointerCount() == 2) {

                        PointF newMid = new PointF();
                        midPoint(newMid,event);

                        float newDist = spacing(event);

                        float scale = newDist/oldDist;

                        if( !isfullImgViewActive){   // is smallImgView is visible and mfullImgView is gone
                            Log.i("tag", "true");

                            isfullImgViewActive = true;

                            matrix.set(imgView.getImageMatrix());   //note:- do not write matrix = imgView.getImageMatrix() because it gives the smallImgView's matrix reference to the matrix variable and changes on matrix will reflect on smallImgView
                            matrix.getValues(matrixArray);

                            orgScale = matrixArray[0];

                            smallImgView.setVisibility(View.INVISIBLE);

                            mfullImgView.setImageDrawable(smallImgView.getDrawable());
                            mfullImgView.setScaleType(ImageView.ScaleType.MATRIX);

                            mfullImgView.setVisibility(View.VISIBLE);

                            //To map the image of mFullImgView to that of smallImgView we have to 
                            // translate the mFullImgView's image
                            matrix.postTranslate(tx, ty);
                            /////////////NOTE///////////////
                            //here (tx,ty) are coordinates of top-left corner of smallimgView and 
                            // they MUST be relative to the origin of Outermost view or view group 
                            // where fullImgView is placed. So find tx,ty in your case by yourself

                            mfullImgView.setImageMatrix(matrix);      
                        }

                        if(isImgViewSmall) {
                            matrix.postScale(scale, scale, mid.x + tx, mid.y + ty);
                        }
                        else{
                            matrix.postScale(scale, scale, mid.x, mid.y);
                        }
                        oldDist = newDist;

                        matrix.postTranslate(newMid.x - mid.x, newMid.y - mid.y);

                        matrix.getValues(matrixArray);

                        mid.set(newMid);


                        prevP1.set(event.getX(0), event.getY(0));
                        prevP2.set(event.getX(1), event.getY(1));

                    }

                    else if(event.getPointerCount() == 1 ){

                        if(isfullImgViewActive) {

                            matrix.postTranslate(event.getX() - prevP1.x, event.getY() - prevP1.y);
                            matrix.getValues(matrixArray);
                        }

                        prevP1.set(event.getX(0), event.getY(0));

                    }

                    break;

                case MotionEvent.ACTION_POINTER_UP: // second finger lifted

                    //Now if pointer of index 0 is lifted then pointer of index 1 will get index 0;
                    if(event.getActionIndex() == 0 && isfullImgViewActive){
                        Log.i("TAg", event.getActionIndex()+"");
                        prevP1.set(prevP2);
                    }

                    break;

                case MotionEvent.ACTION_UP: // first finger lifted or all fingers are lifted

                    if(isImgViewSmall && !isfullImgViewActive) {

                        imgView.setScaleType(ImageView.ScaleType.FIT_CENTER);

                        int xDiff = (int) Math.abs(event.getX() - start.x);
                        int yDiff = (int) Math.abs(event.getY() - start.y);
                        if (xDiff == 0 && yDiff == 0) {
                            imgView.performClick();
                            return true;
                        }
                    }

                    if(isfullImgViewActive){
                        if(matrixArray[0] <= orgScale){  //matrixArray[0] is Scale.X value

                            mfullImgView.setOnTouchListener(null);
                            mfullImgView.setImageDrawable(null);
                            mfullImgView.setVisibility(View.GONE);

                            smallImgView.setOnTouchListener(this);
                            smallImgView.setScaleType(ImageView.ScaleType.FIT_CENTER);
                            smallImgView.setVisibility(View.VISIBLE);

                            isfullImgViewActive = false;

                        }
                        else if(matrixArray[0] > orgScale && isImgViewSmall){  //if the imgView was smallImgView

                            smallImgView.setOnTouchListener(null);
                            smallImgView.setScaleType(ImageView.ScaleType.FIT_CENTER);
                            smallImgView.setVisibility(View.GONE);  // or View.INVISIBLE

                            mfullImgView.setOnTouchListener(this);
                        }
                    }

                    return true;


            }
            //end of Switch statement


            if(isfullImgViewActive) {   //active means visible
                mfullImgView.setImageMatrix(matrix); // display the transformation on screen
            }

            return true; // indicate event was handled
        }
        else
            return false;
    }


    private float spacing(MotionEvent event)
    {
        float x = event.getX(0) - event.getX(1);
        float y = event.getY(0) - event.getY(1);
        return (float) Math.sqrt(x * x + y * y);
    }


    private void midPoint(PointF point, MotionEvent event)
    {
        float x = event.getX(0) + event.getX(1);
        float y = event.getY(0) + event.getY(1);
        point.set(x / 2, y / 2);
    }

}

ПРИМЕЧАНИЕ. - Не устанавливайте OnClickListener на mfullImgView перед установкой для него onTouchListener. Настройка, которая позволит fullImageView (если он виден) украсть событие касания опускания второго пальца вниз после его первого подъема, потому что мы хотим, чтобы smallImgView принимал все события касания, пока все пальцы не будут подняты для первого время.

Я использую этот, он отлично работает.

<your.packagename.MyZoomableImageViewTouch
        android:id="@+id/mediaImage"
        android:layout_width="fill_parent"
        android:layout_height="fill_parent"
        android:scaleType="matrix"/>

Мой класс MyZoomableImageViewTouch находится ниже:

public class MyZoomableImageViewTouch extends ImageViewTouch
{

    static final float SCROLL_DELTA_THRESHOLD = 1.0f;

    public MyZoomableImageViewTouch(Context context, AttributeSet attrs, int defStyle)
    {
        super(context, attrs, defStyle);
        init();
    }

    public MyZoomableImageViewTouch(Context context, AttributeSet attrs) {
        super(context, attrs);
        init();
    }

    public MyZoomableImageViewTouch(Context context)
    {
        super(context);
        init();
    }

    private void init() {
        View.OnTouchListener listener = new View.OnTouchListener() {
            @Override
            public boolean onTouch(View v, MotionEvent event) {
                if (getScale() > 1f) {
                    getParent().requestDisallowInterceptTouchEvent(true);
                } else {
                    getParent().requestDisallowInterceptTouchEvent(false);
                }
                return false;
            }
        };
        setOnTouchListener(listener);
        setDisplayType(DisplayType.FIT_TO_SCREEN);
    }

    @Override
    protected float onDoubleTapPost(float scale, float maxZoom) {
        if (scale != 1f) {
            mDoubleTapDirection = 1;
            return 1f;
        }
        if (mDoubleTapDirection == 1) {
            mDoubleTapDirection = -1;
            if ((scale + (mScaleFactor * 2)) <= maxZoom) {
                return scale + mScaleFactor;
            } else {
                mDoubleTapDirection = -1;
                return maxZoom;
            }
        } else {
            mDoubleTapDirection = 1;
            return 1f;
        }
    }

    @Override
    public boolean canScroll(int direction) {
        RectF bitmapRect = getBitmapRect();
        updateRect(bitmapRect, mScrollRect);
        Rect imageViewRect = new Rect();
        getGlobalVisibleRect(imageViewRect);

        if (null == bitmapRect) {
            return false;
        }

        if (Math.abs(bitmapRect.right - imageViewRect.right) < SCROLL_DELTA_THRESHOLD) {
            if (direction < 0) {
                return false;
            }
        }

        if (Math.abs(bitmapRect.left - mScrollRect.left) < SCROLL_DELTA_THRESHOLD) {
            if (direction > 0) {
                return false;
            }
        }
        return true;
    }

    @Override
    public boolean onScroll(MotionEvent e1, MotionEvent e2, float distanceX, float distanceY)
    {
        if (getScale() == 1f) return false;
        if (distanceX != 0 && !canScroll((int) -distanceX)) {
            getParent().requestDisallowInterceptTouchEvent(false);
            return false;
        } else {
            getParent().requestDisallowInterceptTouchEvent(true);
            mUserScaled = true;
            scrollBy(-distanceX, -distanceY);
            invalidate();
            return true;
        }
    }
}