Acercar y alejar ImageView de Android

Quiero acercar y alejar un ImageView de Android. Probé la mayoría de las muestras, pero en todas ellas la imagen en el ImageView en sí se está acercando y alejando, mientras que quiero acercar y alejar el ImageView. Quiero aumentar el ancho y la altura de ImageView mientras hago zoom y reducir el ancho y alto de ImageView mientras hago zoom. ¿Cómo lo logro?

Hacer dos clases de java

Clase de zoom

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;
    }
}

hacer de segunda clase

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));
   }
}

Siga la clase a continuación, que se utiliza para Acercar y Alejar para 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());
    }
}

Las otras implementaciones aquí tienen algún tipo de defecto. así que básicamente los mezclé y se me ocurrió esto.

Cree una vista personalizada como esta:

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);
    }
}

Luego agrega la imagen como esta:

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

Agregue la vista como esta en XML:

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

Manera simple:

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

Agregue la siguiente línea en build.gradle:

compile 'com.commit451:PhotoView:1.2.4'

solo usa esta clase: TouchImageView

Esta es otra implementación más basada en el código publicado por Nicolas Tyler.

Se corrigieron los siguientes errores:

• Establecer minScaleun número menor que 1 ahora funciona
• No necesita usar setImageBitmap()para configurar la imagen (puede usar, por ejemplosetImageResource()
• Todos los constructores ahora funcionan correctamente

Las siguientes cosas, entre otras, están ordenadas:

• No OnTouchListenerse usa, no es necesario porque la clase solo puede implementar el onTouchEvent()método.

• La asignación right = width * saveScale - width - (2 * redundantXSpace * saveScale);se ha simplificado a lo right = (originalBitmapWidth * saveScale) - widthque, en mi opinión, es mucho menos confuso.

• Se eliminan algunas variables miembro (probablemente se pueden eliminar más estados de esta clase)

No es perfecto, pero aquí tienes:

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:
 * /programming/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;
    }
}

Es viejo, pero esto puede ayudar a alguien más.

A continuación, la clase TouchImageView admite acercar / alejar el zoom al pellizcar o tocar dos veces

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();
    }
}

Uso: puede reemplazar su ImageViewTouchImageView en XML y Java

1. Para 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. Para Java

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

He mejorado la respuesta que obtuve de la pila para ZOOM impecable (dos dedos) / ROTACIÓN (dos dedos) / ARRASTRAR (un dedo) .

// ============================ código XML ==================

<?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>

// ============================ Código 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);
    }

}

// ======================== Simplemente pase cualquier vista que desee hacer zoom / rotar / arrastrar al método viewTransformation (). Muy aplicable para zoom de vista de texto. No pixelará el texto.

Hice mi propia vista de imagen personalizada con pellizcar para hacer zoom. No hay límites / fronteras en Chirag Raval el código de , por lo que el usuario puede arrastrar la imagen fuera de la pantalla.

Aquí está la clase 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);
    }


}