It seem there is a memory leak when using GestureViews.

ViewPositionAnimatorcontains a fromPosHolder and a toPosHolder. But toPosHolder.clear() is never called. As such, view.getViewTreeObserver().removeOnPreDrawListener is never called, and the OnPreDrawListener keep a reference to the GestureView.

Hey alex, thanks for this fastastic library. I noticed that neither GestureImageView/FrameView call requestDisallowInterceptTouchEvent() when they start consuming events. This is bad because they currently don't work well with nested Views that support gestures.

Since I'm using this library in one of my projects, I'd be happy to send a PR if you can guide me :)

how can i make surfaceView have the same function?

     I have write a MapView with surfaceView ,then i wish it can be operated as well as GestureImageView,But it can't work. I hope to get your suggestion ，the following is my code:

package com.jms.cleanse.widget;

import android.annotation.SuppressLint; import android.content.Context; import android.content.res.Resources; import android.graphics.Bitmap; import android.graphics.BitmapFactory; import android.graphics.Canvas; import android.graphics.Color; import android.graphics.Paint; import android.graphics.Path; import android.graphics.PixelFormat; import android.graphics.RectF; import android.support.annotation.NonNull; import android.support.annotation.Nullable; import android.support.v4.content.ContextCompat; import android.util.AttributeSet; import android.util.Log; import android.view.MotionEvent; import android.view.SurfaceHolder; import android.view.SurfaceView;

import com.alexvasilkov.gestures.GestureController; import com.alexvasilkov.gestures.State; import com.alexvasilkov.gestures.views.interfaces.GestureView; import com.jms.cleanse.widget.mapview.POIConfig; import com.jms.cleanse.widget.mapview.ScaleUtils; import com.jms.cleanse.widget.mapview.TestPOI;

import java.util.ArrayList; import java.util.LinkedList; import java.util.List;

/**

• Created by zhoukan on 2018/3/28.
• @desc: 绘制POI / 绘制路径 / */

public class JMMapView extends SurfaceView implements SurfaceHolder.Callback, Runnable,GestureView {

private static final String TAG = "JMMapView";
private final GestureController controller;

private Paint mPaint;
private Canvas canvas;

private SurfaceHolder holder;
private Thread t;
private boolean isDrawing = false;
private List<TestPOI> testPOIS;
private LinkedList<Path> paths;
private LinkedList<RectF> points;

/************ 地图坐标系相关的配置 *************/
private int coodinateX;
private int coodinateY;
private Bitmap cleanseRes;
private Bitmap unCleanseRes;
private Bitmap pathStartRes;
private Bitmap pathEndRes;
private int colorCleanse;
private int colorUnCleanse;
// 地图
private Bitmap map;

private Resources resources;

/* 事件 */
private OnClickListener onClickListener;

@Override
public GestureController getController() {
    return controller;
}

public interface OnClickListener {
    void onPointClick(TestPOI poi, int pos);

    void onPathClick(int pos);
}

public void setOnClickListener(OnClickListener onClickListener) {
    this.onClickListener = onClickListener;
}

public JMMapView(@NonNull Context context) {
    this(context, null);
}

public JMMapView(@NonNull Context context, @Nullable AttributeSet attrs) {
    this(context, attrs, 0);
}

@SuppressLint("ResourceType")
public JMMapView(@NonNull Context context, @Nullable AttributeSet attrs, int defStyleAttr) {
    super(context, attrs, defStyleAttr);

    this.setFocusable(true);
    this.setZOrderOnTop(true);

    holder = getHolder();
    holder.addCallback(this);
    holder.setFormat(PixelFormat.TRANSPARENT);

// this.setSurfaceTextureListener(this);

    mPaint = new Paint(Paint.ANTI_ALIAS_FLAG);
    mPaint.setColor(Color.BLUE);
    mPaint.setStrokeCap(Paint.Cap.ROUND);
    mPaint.setStrokeWidth(5);
    mPaint.setStyle(Paint.Style.STROKE);

    testPOIS = new ArrayList<>();
    paths = new LinkedList<>();
    points = new LinkedList<>();

    resources = getResources();
    cleanseRes = BitmapFactory.decodeStream(resources.openRawResource(POIConfig.cleanseRes));
    unCleanseRes = BitmapFactory.decodeStream(resources.openRawResource(POIConfig.unCleanseRes));
    pathStartRes = BitmapFactory.decodeStream(resources.openRawResource(POIConfig.pathStartRes));
    pathEndRes = BitmapFactory.decodeStream(resources.openRawResource(POIConfig.pathEndRes));

    colorCleanse = ContextCompat.getColor(this.getContext(), POIConfig.pathColorCleanse);
    colorUnCleanse = ContextCompat.getColor(this.getContext(), POIConfig.pathColorUnCleanse);

    /* make jmmapview support gesture */
    controller = new GestureController(this);
    controller.getSettings().setOverzoomFactor(1f).setPanEnabled(false);
    controller.getSettings().initFromAttributes(context, attrs);
    controller.getSettings().setZoomEnabled(true);
    controller.getSettings().setRotationEnabled(true);
    controller.addOnStateChangeListener(new GestureController.OnStateChangeListener() {
        @Override
        public void onStateChanged(State state) {
            applyState(state);
        }

        @Override
        public void onStateReset(State oldState, State newState) {
            applyState(newState);
        }
    });

}

/**
 *
 * @param state
 */
private void applyState(State state) {

}

@Override
public void surfaceCreated(SurfaceHolder holder) {
    isDrawing = true;
    t = new Thread(this);
    t.start();
}

@Override
public void surfaceChanged(SurfaceHolder holder, int format, int width, int height) {
}

@Override
public void surfaceDestroyed(SurfaceHolder holder) {
    isDrawing = false;
}

@Override
public void run() {
    if (isDrawing) {
        drawMap();
    }
}

/**
 * 绘制地图
 */
private void drawMap() {

    try {
        if (null != holder) {
            canvas = holder.lockCanvas();
            canvas.save();
            if (!canvasChange()) {
                return;
            }
            canvas.drawColor(Color.WHITE);

            drawBitMap();
            drawPath();
            drawPoi();
            canvas.restore();
        }
    } catch (Exception e) {
        e.getStackTrace();
    } finally {

        if (null != canvas) {
            holder.unlockCanvasAndPost(canvas);
        }
    }
}

/**
 * @aim: 进行画布操作，将绘制起点设置为bitmap的左上角，坐标系转换到bitmap的像素坐标系上，方便作图
 */
private boolean canvasChange() {
    if (map != null) {
        // 缩放倍数
        float ratio = ScaleUtils.getScaleRatio(ScaleUtils.ScaleType.CENTER_INSIDE, map, getWidth(), getHeight());
        // 宽的差值
        float dw = getWidth() - map.getWidth() * ratio;
        // 高的差值
        float dh = getHeight() - map.getHeight() * ratio;
        canvas.scale(ratio, ratio);
        // 横屏
        if (getWidth() > getHeight()) {
            canvas.translate(dw / (2 * ratio), 0);
            // 竖屏
        } else {
            canvas.translate(0, dh / (2 * ratio));
        }
        // 计算坐标系的最大值
        coodinateX = map.getWidth();
        coodinateY = map.getHeight();
        Log.d(TAG, "canvasChange: " + coodinateX + ",y" + coodinateY);
    } else {
        return false;
    }
    return true;
}


/**
 * 绘制地图，在绘制之前需要确认bitmap缩放的方式并返回得到的bitmap.
 */
private void drawBitMap() {
    if (map != null) {
        canvas.drawBitmap(map, 0, 0, mPaint);
    }
}

/**
 * 绘制POI点 测试点数据 (-2.5，4.4)
 */
private void drawPoi() {
    TestPOI lastPoi = null;
    for (int i = 0; i < testPOIS.size(); i++) {
        TestPOI poiPoint = testPOIS.get(i);
        if (poiPoint.isCleanse()) {
            canvas.drawBitmap(cleanseRes, null, points.get(i), mPaint);
        } else if (lastPoi != null && lastPoi.isCleanse()) {
            canvas.drawBitmap(cleanseRes, null, points.get(i), mPaint);
        } else {
            canvas.drawBitmap(unCleanseRes, null, points.get(i), mPaint);
        }
        lastPoi = poiPoint;

        /* 绘制起点和终点 */
        if (i == 0) {

// canvas.drawBitmap(pathStartRes,null,getBitmapRectF(poiPoint.getAx(),poiPoint.getAy(),pathStartRes),mPaint); canvas.drawBitmap(pathStartRes, (float) (poiPoint.getAx() - pathStartRes.getWidth() / 2), (float) (poiPoint.getAy() - pathStartRes.getHeight()), mPaint); // canvas.drawRect(getBitmapRectF(poiPoint.getAx(),poiPoint.getAy(),pathEndRes),mPaint); } else if (i > 0 && i == testPOIS.size() - 1) { // canvas.drawBitmap(pathStartRes,null,getBitmapRectF(poiPoint.getAx(),poiPoint.getAy(),pathStartRes),mPaint); // mPaint.setColor(Color.BLUE); // canvas.drawRect(getBitmapRectF(poiPoint.getAx(),poiPoint.getAy(),pathEndRes),mPaint); canvas.drawBitmap(pathEndRes, (float) (poiPoint.getAx() - pathEndRes.getWidth() / 2), (float) (poiPoint.getAy() - pathEndRes.getHeight()), mPaint); } }

}

/**
 * 获取Bitmap矩形区域
 *
 * @param ax
 * @param ay
 * @param bm
 */
private RectF getBitmapRectF(double ax, double ay, Bitmap bm) {

    int w = bm.getWidth();
    int h = bm.getHeight();

    RectF rectF = new RectF();
    rectF.left = (float) (ax - w / 2);
    rectF.top = (float) (ay - h);
    rectF.right = (float) (ay + w / 2);
    rectF.bottom = (float) ay;

    return rectF;
}

@SuppressLint("ResourceType")
private void drawPath() {

    getPathList(this.testPOIS);
    for (int i = 0; i < testPOIS.size(); i++) {
        TestPOI poiPoint = testPOIS.get(i);
        // 最后一个点 直接跳出循环
        if (i == testPOIS.size() - 1) {
            break;
        }
        if (poiPoint.isCleanse()) {
            mPaint.setColor(colorCleanse);
        } else {
            mPaint.setColor(colorUnCleanse);
        }
        canvas.drawPath(paths.get(i), mPaint);
    }

}

@Override
protected void onMeasure(int widthMeasureSpec, int heightMeasureSpec) {
    super.onMeasure(widthMeasureSpec, heightMeasureSpec);
    int w = 0;
    int h = 0;
    if (null != map) {
        w = map.getWidth();
        h = map.getHeight();
    }
    setMeasuredDimension(getDefaultSize(w, widthMeasureSpec), getDefaultSize(h, heightMeasureSpec));
}

/**
 * 设置地图
 */
public void setMap(Bitmap map) {
    this.map = map;
    invalidate();
}

public void setTestPOIS(List<TestPOI> testPOIS) {
    if (testPOIS != null && testPOIS.size() > 0) {
        this.testPOIS.clear();
        this.testPOIS.addAll(testPOIS);
        invalidate();
    }
}

@Override
public boolean onTouchEvent(MotionEvent event) {

    float x = event.getX();
    float y = event.getY();

    switch (event.getAction()) {
        case MotionEvent.ACTION_DOWN:
            // 点被点击
            Log.d(TAG, "onTouchEvent: 我被点了" + x+",y"+y);
            for (int i = 0; i <points.size() ; i++) {
                if (onClickListener!=null){
                    if (points.get(i).contains(x,y)){
                        onClickListener.onPointClick(testPOIS.get(i),i);
                        Log.d(TAG, "onTouchEvent: " + i+"我被点了");
                    }
                }
            }
            break;
        case MotionEvent.ACTION_UP:
            break;
        case MotionEvent.ACTION_CANCEL:
            break;
        case MotionEvent.ACTION_MOVE:
            break;
    }

    return controller.onTouch(this,event);
}

/**
 * 根据poi点得到对应的路径组合
 *
 * @param testPOIS
 */
private void getPathList(List<TestPOI> testPOIS) {

    // 记录上一个点的坐标
    double[] lastPoi = null;
    for (int i = 0; i < testPOIS.size(); i++) {
        TestPOI poiPoint = testPOIS.get(i);
        double[] currentPoi = poiPoint.getAndroidCoordinate(coodinateX, coodinateY);
        Log.d(TAG, "getPathList: x:" + currentPoi[0] + ",y:" + currentPoi[1]);
        if (lastPoi != null) {
            Path p = new Path();
            p.moveTo((float) lastPoi[0], (float) lastPoi[1]);
            p.lineTo((float) currentPoi[0], (float) currentPoi[1]);
            // 添加路径
            paths.add(p);
        }
        lastPoi = currentPoi;
        // 添加矩形区域
        points.add(poiPoint.getRect(currentPoi[0], currentPoi[1], coodinateX, coodinateY, cleanseRes.getWidth() / 2));

    }
}

}

I'm trying to prevent the image from blinking briefly in its final size and position right before the enter a animation runs in the Image Animation (cross-activity) example.

For this scenario I need the image to not be invisible, so it starts visible, but when I do that this happens every single time:

I click on the image

It shows like this instantly for what feels like 1 animation frame

And quickly switches to the actual animation/transition (imagine this growing from the original image to the final size in the new activity)

So for a very fast 1 frame kinda moment the image is shown in its final size and position right before it starts animating from the clicked area.

I tried setting the setState manually into the gesture view even before the image is set in it, also after. I also tried to set the enter with the initial x, y and zoom and false for animation, just to make sure the image is starting from the expected position and size. I even confirmed the states and fromPos were being stored correctly in the getPositionAnimator(), but no difference.

Isn't there any way to ensure that the very first time the GestureView display the image is at the specified position + zoom we expect or define?

Dear Alex, rotating the device will not re-adjust a photo to fit the screen. Instead you have to zoom out to make it fit.

image.getController().getSettings().setFillViewport(true); image.getController().getSettings().setOverzoomFactor(10f); image.getController().getSettings().setDoubleTapZoom(2f); image.getController().getSettings().setMaxZoom(20f); image.getController().getSettings().setFitMethod(Fit.INSIDE);

Manifest android:configChanges="orientation|keyboardHidden|screenSize|locale"

I was trying to come up with a way to vertically offset the image inside a GestureImageView when I noticed an erratic pattern that is not consistent.

Initially I tried to play with .setViewPort(), but that only controls the size of the image, not the position. Then I checked padding and it works, to a certain degree.

If I set the padding manually in the xml layout file the image is exactly positioned as I expect it to be, but because there is UI that overlaps the view and that UI can be toggled with sliding animation I tried to animate the padding as well.

The top and left padding animations work perfectly, but for some reason the bottom and right do not work the same way, it feels like they are being completely ignored.

This video shows a basic example of what I am describing, please ignore the jerkiness/jumps because those are due to the fullscreen entering/exiting and are irrelevant to this example.

The top and left padding animation are working as expected, however the right and bottom padding values are not. Worse, they seem to be "taken into account" when the values are set back to normal.

This feels like the viewport position is being correctly updated, but the resizing/scale of it is not.

To replicate this problem replace the following code in this location: https://github.com/alexvasilkov/GestureViews/blob/master/sample/src/main/java/com/alexvasilkov/gestures/sample/demo/adapter/PhotoPagerAdapter.java#L66-L78

With this

    @Override
    public ViewHolder onCreateViewHolder(@NonNull ViewGroup container) {
        final ViewHolder holder = new ViewHolder(container);

        holder.image.setOnClickListener(view -> {
            onImageClick();

            // here we are simply animating all paddings of the view at the same
            // time to 200px or 0px depending on if there is a padding already set
            boolean show = holder.image.getPaddingTop() == 0;
            ValueAnimator.AnimatorUpdateListener updateListener2 = animation -> {
                holder.image.setPadding(
                    (int) animation.getAnimatedValue(),
                    (int) animation.getAnimatedValue(),
                    (int) animation.getAnimatedValue(),
                    (int) animation.getAnimatedValue()
                );
            };
            ValueAnimator valueAnimator = ObjectAnimator.ofInt(show ? 0 : 200, show ? 200 : 0);
            valueAnimator.setDuration(1000);
            valueAnimator.addUpdateListener(updateListener2);
            valueAnimator.start();
            // end of code modification, everything else is the original untouched code

        });

        settingsController.apply(holder.image);

        holder.image.getController().enableScrollInViewPager(viewPager);
        holder.image.getPositionAnimator().addPositionUpdateListener((position, isLeaving) ->
                holder.progress.setVisibility(position == 1f ? View.VISIBLE : View.INVISIBLE));
        return holder;
    }

Can we get this fixed somehow?

Note: I tried to play with changing the UI heights/real positions (not translations, but actual view repositioning) with the GestureView constrained between them, but this interferes with the gesture behavior since the height adjustments are interpreted as gestures as well if the user is touching the view during the UI transitions. I also tried to just leave the view constrained with no views changing dimensions, but when the enter/leave animation is automatically clipped at the edges of the view (as if the view limits were the device screen limits).

The only working solution that has almost worked is to play with the padding and I cannot think of anything else to try.

is there any simple tutorial to show how to use animations? i have used GestureViews to create a comic book and want to zoom to different parts of the page. any help will be regarded.

How can i return view to default rotation state with animation, after rotating with fingers? Now when i rotate view with fingers it stays in rotated state.

Like in the video: https://youtu.be/Jh-OJjtHJmQ

how implement it? i dont get it.

i use:

            mImageView.getPositionAnimator().enter(viewAnim, true);

and i get:

java.lang.NullPointerException: Attempt to invoke virtual method 'void com.alexvasilkov.gestures.GestureController.resetState()' on a null object reference

the Api does the zoom function amazingly.

Is it possible to go the opposite direction and have a function to shrink the images (make the image smaller than the image view)?

Currently, the image snaps back to the size of the image view when trying to shrink the image.

I have a layout structure as such:

<ConstraintLayout/>
    <ScrollView/>
        <GestureFrameLayout/>
            <ConstraintLayout/>   <-- has an image as background around 2500px

When I try to zoom in after moving down the scrollview (let's say to the bottom of the child element of scrollview), then when I try to pan upwards to the top of the image that is the background of my ConstraintLayout (whilst still zoomed in), I am restricted to only going upwards to a fraction of the height.

Here is an image trying to explain the issue:

exm: GestureTransitions.from(mViewBinding.rvRelation, listTracker).into(mViewBinding.vpRelation, pagerTracker);

Hello, may I ask how to keep the entered list rvRelation not hidden or in the state of display? Now I have a requirement that the list rvRelation remains displayed, how should I set it? thank you

Hello, i have complex view. its like a book with images and text. build with GestureFrameLayout and ViewPager in it. I am using GestureFrameLayout to have posibility zoom in/out to/from elements. With images it works ok. but when zooming to EditText keyboard not showing and EditText not changing its value when typing. if i remove zooming keyboard shows and EditText works like expected. Can you help me please ? Thanks!

java.lang.IllegalStateException: You should call enter(...) before calling update(...)
    at com.alexvasilkov.gestures.animation.ViewPositionAnimator.cleanBeforeUpdateInternal(ViewPositionAnimator.java:4)
    at com.alexvasilkov.gestures.transition.ViewsTransitionAnimator.onFromViewChanged(ViewsTransitionAnimator.java:4)
    at com.alexvasilkov.gestures.transition.ViewsCoordinator.setFromInternal(ViewsCoordinator.java:3)
    at com.alexvasilkov.gestures.transition.internal.FromRecyclerViewListener$1.onChildViewAttachedToWindow(FromRecyclerViewListener.java:9)
    at androidx.recyclerview.widget.RecyclerView.dispatchChildAttached(RecyclerView.java:7)
    at androidx.recyclerview.widget.ChildHelper.addView(ChildHelper.java:7)
    at androidx.recyclerview.widget.RecyclerView$LayoutManager.addViewInt(RecyclerView.java:13)
    at androidx.recyclerview.widget.RecyclerView$LayoutManager.addView(RecyclerView.java:2)
    at androidx.recyclerview.widget.RecyclerView$LayoutManager.addView(RecyclerView.java:1)
    at androidx.recyclerview.widget.GridLayoutManager.layoutChunk(GridLayoutManager.java:19)
    at androidx.recyclerview.widget.LinearLayoutManager.fill(LinearLayoutManager.java:12)
    at androidx.recyclerview.widget.LinearLayoutManager.onLayoutChildren(LinearLayoutManager.java:67)
    at androidx.recyclerview.widget.GridLayoutManager.onLayoutChildren(GridLayoutManager.java:3)
    at androidx.recyclerview.widget.RecyclerView.dispatchLayoutStep2(RecyclerView.java:8)
    at androidx.recyclerview.widget.RecyclerView.onMeasure(RecyclerView.java:12)
    at android.view.View.measure(View.java:23466)
    at android.view.ViewGroup.measureChildWithMargins(ViewGroup.java:6834)
    at android.widget.FrameLayout.onMeasure(FrameLayout.java:185)
    at android.view.View.measure(View.java:23466)
    at android.widget.RelativeLayout.measureChildHorizontal(RelativeLayout.java:715)
    at android.widget.RelativeLayout.onMeasure(RelativeLayout.java:461)
    at android.view.View.measure(View.java:23466)
    at android.widget.RelativeLayout.measureChildHorizontal(RelativeLayout.java:715)
    at android.widget.RelativeLayout.onMeasure(RelativeLayout.java:461)
    at android.view.View.measure(View.java:23466)
    at android.view.ViewGroup.measureChildWithMargins(ViewGroup.java:6834)
    at android.widget.FrameLayout.onMeasure(FrameLayout.java:185)
    at android.view.View.measure(View.java:23466)
    at android.view.ViewGroup.measureChildWithMargins(ViewGroup.java:6834)
    at android.widget.FrameLayout.onMeasure(FrameLayout.java:185)
    at android.view.View.measure(View.java:23466)
    at android.view.ViewGroup.measureChildWithMargins(ViewGroup.java:6834)
    at androidx.coordinatorlayout.widget.CoordinatorLayout.onMeasureChild(CoordinatorLayout.java:1)
    at androidx.coordinatorlayout.widget.CoordinatorLayout.onMeasure(CoordinatorLayout.java:53)
    at android.view.View.measure(View.java:23466)
    at android.widget.RelativeLayout.measureChildHorizontal(RelativeLayout.java:715)
    at android.widget.RelativeLayout.onMeasure(RelativeLayout.java:461)
    at android.view.View.measure(View.java:23466)
    at android.view.ViewGroup.measureChildWithMargins(ViewGroup.java:6834)
    at android.widget.FrameLayout.onMeasure(FrameLayout.java:185)
    at androidx.appcompat.widget.ContentFrameLayout.onMeasure(ContentFrameLayout.java:21)
    at android.view.View.measure(View.java:23466)
    at android.view.ViewGroup.measureChildWithMargins(ViewGroup.java:6834)
    at android.widget.LinearLayout.measureChildBeforeLayout(LinearLayout.java:1565)
    at android.widget.LinearLayout.measureVertical(LinearLayout.java:847)
    at android.widget.LinearLayout.onMeasure(LinearLayout.java:726)
    at android.view.View.measure(View.java:23466)
    at android.view.ViewGroup.measureChildWithMargins(ViewGroup.java:6834)
    at android.widget.FrameLayout.onMeasure(FrameLayout.java:185)
    at android.view.View.measure(View.java:23466)
    at android.view.ViewGroup.measureChildWithMargins(ViewGroup.java:6834)
    at android.widget.LinearLayout.measureChildBeforeLayout(LinearLayout.java:1565)
    at android.widget.LinearLayout.measureVertical(LinearLayout.java:847)
    at android.widget.LinearLayout.onMeasure(LinearLayout.java:726)
    at android.view.View.measure(View.java:23466)
    at android.view.ViewGroup.measureChildWithMargins(ViewGroup.java:6834)
    at android.widget.FrameLayout.onMeasure(FrameLayout.java:185)
    at com.android.internal.policy.DecorView.onMeasure(DecorView.java:847)
    at android.view.View.measure(View.java:23466)
    at android.view.ViewRootImpl.performMeasure(ViewRootImpl.java:2954)
    at android.view.ViewRootImpl.measureHierarchy(ViewRootImpl.java:1753)
    at android.view.ViewRootImpl.performTraversals(ViewRootImpl.java:2041)
    at android.view.ViewRootImpl.doTraversal(ViewRootImpl.java:1636)
    at android.view.ViewRootImpl$TraversalRunnable.run(ViewRootImpl.java:7946)
    at android.view.Choreographer$CallbackRecord.run(Choreographer.java:1092)
    at android.view.Choreographer.doCallbacks(Choreographer.java:893)
    at android.view.Choreographer.doFrame(Choreographer.java:812)
    at android.view.Choreographer$FrameDisplayEventReceiver.run(Choreographer.java:1078)
    at android.os.Handler.handleCallback(Handler.java:907)
    at android.os.Handler.dispatchMessage(Handler.java:105)
    at android.os.Looper.loop(Looper.java:216)
    at android.app.ActivityThread.main(ActivityThread.java:7625)
    at java.lang.reflect.Method.invoke(Method.java)
    at com.android.internal.os.RuntimeInit$MethodAndArgsCaller.run(RuntimeInit.java:524)

Recently I try to implement a cross activities demo. But I found that the ToActivity will flash at the moment it finished(). I use a SimpleTracker to generate ViewTransitionAnimator like:

GestureTransitions.from(fromRecyclerView, fromTracker).into(viewPager, pagerTracker)

only different is that fromRecyclerView is in FromActivity and viewPager in ToActivity.

I try to hide/show origin ImageView like your sample code but pageAdapter.getViewHolder always return null. I don't know how to do it.

I want create a class like this

class ReaderCellView extends DraweeView implements GestureView{
//...
}

but both DraweeView and GestureView has function getController() and the return type is different.

And I think it is better to make the function of a Interface as special as we can.