Android ImageView Zoom-in and Zoom-Out

Question

I want to Zoom-in and Zoom-out an Android ImageView. I tried most of the samples but in all of them the image in the ImageView itself is getting Zoomed-in and Zoomed-out, wh

Answer 1

Here is my solution, it is based on @alexbirkett's solution.

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 .
}

Answer 2

just use this class : TouchImageView

Answer 3

Step 1: First you add dependencies in build.gradle(Module:app) file.

dependencies {

     implementation 'com.jsibbold:zoomage:1.2.0'

    }

Step 2: Next create a class

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;

}

Step 3 : Next create a layout xml file

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:-

Answer 4

Please follow the below class, that is used for Zoom in and Zoom Out for 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());
    }
}

Answer 5

I know it is a bit late for this answer, but I hope it helps someone.

I was looking for the same thing (Zoom using pinch, and dragging image) and I found this Android Developers Blog link.

Works perfect. No artifacts or what so ever. It uses ScaleGestureDetector.

Answer 6

I am Using this one it is working perfectly.

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

My a MyZoomableImageViewTouch class is below:

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;
        }
    }
}