android – View Pager + ImageView +Pinch Zoom + Rotation-ThrowExceptions

Exception or error:

I want to implement Pinch Zoom on Imageview, with in View Pager similar to Default Android Gallery. I have found multiple source over GitHub, But the zoom and sliding just work for only first image.

What I have tried:

1.) TouchImageView

2.) PhotoView

3.) Android Touch Gallery

All the above links works fine for single image view. But when it comes to Images in View pager, They have some glitches and only works fine for first image in the View Pager. When we scroll over to 3rd 4th image in view pager, Dragging functionality not working as expected if the image is zoomed.

Please if any one knows any good library for doing this, then provide me the link for them.

How to solve:

EDIT 2: Example code has been pushed to the master branch of TouchImageView. Here is a link to the example activity and a link to the ExtendedViewPager.


EDIT: added code adapting the example link to TouchImageView. Note: you will need the latest code, which is currently in the dev branch. In the future, this will be included in v1.2.0. You know you have the latest code if TouchImageView overrides canScrollHorizontally.

Step 1: Extend ViewPager and override canScroll to call canScrollHorizontallyFroyo.

public class ExtendedViewPager extends ViewPager {

public ExtendedViewPager(Context context) {
    super(context);
}

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

@Override
protected boolean canScroll(View v, boolean checkV, int dx, int x, int y) {
    if (v instanceof TouchImageView) {
        return ((TouchImageView) v).canScrollHorizontallyFroyo(-dx);
    } else {
        return super.canScroll(v, checkV, dx, x, y);
    }
}

}

Step 2: Modify TouchImageView by adding canScrollHorizontallyFroyo:

public boolean canScrollHorizontallyFroyo(int direction) {
    return canScrollHorizontally(direction);
}

Step 3: Your activity

public class TouchImageViewActivity extends Activity {

@Override
    public void onCreate(Bundle savedInstanceState) {
        super.onCreate(savedInstanceState);
        setContentView(R.layout.main);
        ExtendedViewPager mViewPager = (ExtendedViewPager) findViewById(R.id.view_pager);
        setContentView(mViewPager);
        mViewPager.setAdapter(new TouchImageAdapter());
    }

    static class TouchImageAdapter extends PagerAdapter {

            private static int[] images = { R.drawable.img1, R.drawable.img2, R.drawable.img3 };

            @Override
            public int getCount() {
                    return images.length;
            }

            @Override
            public View instantiateItem(ViewGroup container, int position) {
                    TouchImageView img = new TouchImageView(container.getContext());
                    img.setImageResource(images[position]);
                    container.addView(img, LayoutParams.MATCH_PARENT, LayoutParams.MATCH_PARENT);
                    return img;
            }

            @Override
            public void destroyItem(ViewGroup container, int position, Object object) {
                    container.removeView((View) object);
            }

            @Override
            public boolean isViewFromObject(View view, Object object) {
                    return view == object;
            }

    }
}

Step 4: main.xml

<com.example.touch.ExtendedViewPager 
    xmlns:android="http://schemas.android.com/apk/res/android"
    android:id="@+id/view_pager"
    android:layout_width="match_parent"
    android:layout_height="match_parent" />

TouchImageView is actually my project. I currently have a fix in the dev branch for integration with ViewPagers, which will be pushed to master in an upcoming release. Unfortunately, this fix is only applicable for API 14 and greater since honeycomb and earlier do not call canScrollHorizontally. If you need to support older APIs, then you will need to implement a workaround in your ViewPager. Here is an example.

###

I found pretty solution with ImageViewZoom library.
In order to scroll zoomed image in ViewPager I created own ViewPager:

public class ExtendedViewPager extends ViewPager {

    public ExtendedViewPager(Context context) {
        super(context);
    }

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

    @Override
    protected boolean canScroll(View v, boolean checkV, int dx, int x, int y) {
        if (v instanceof ImageViewTouch) {
            return ((ImageViewTouch) v).canScroll(dx);
        } else {
            return super.canScroll(v, checkV, dx, x, y);
        }
    }
}

See more https://gist.github.com/atermenji/3781644

###

After several hours of testing the solutions above I have finally found the awesome Subsampling Scale Image View library, which works even with standard ViewPager from Android Support Package.

###

My solution using ImageViewZoom Library is based on this custom ViewPager:

public class ImageViewTouchViewPager extends ViewPager {

    public ImageViewTouchViewPager(Context context) {
        super(context);
    }

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

    @Override
    protected boolean canScroll(View v, boolean checkV, int dx, int x, int y) {
        if (v instanceof ImageViewTouch) {
            ImageViewTouch imageViewTouch = (ImageViewTouch)v;
            if (imageViewTouch.getScale() == imageViewTouch.getMinScale()) {
                return super.canScroll(v, checkV, dx, x, y);
            }
            return imageViewTouchCanScroll(imageViewTouch, dx);
        } else {
            return super.canScroll(v, checkV, dx, x, y);
        }
    }


    /**
     * Determines whether the ImageViewTouch can be scrolled.
     *
     * @param direction - positive direction value means scroll from right to left,
     *                  negative value means scroll from left to right
     * @return true if there is some more place to scroll, false - otherwise.
     */
    private boolean imageViewTouchCanScroll(ImageViewTouch v, int direction){
        RectF bitmapRect = v.getBitmapRect();
        Rect imageViewRect = new Rect();
        getGlobalVisibleRect(imageViewRect);

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

        if (direction < 0) {
            return Math.abs(bitmapRect.right - imageViewRect.right) > 1.0f;
        }else {
            return Math.abs(bitmapRect.left - imageViewRect.left) > 1.0f;
        }

    }
}

###

I corrected the previous solution . You can scroll page , when ImageViewTouch is mode zoom.

public class ImageViewTouchViewPager extends ViewPager {

public ImageViewTouchViewPager(Context context) {
    super(context);
}

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

@Override
protected boolean canScroll(View v, boolean checkV, int dx, int x, int y) {
    if (v instanceof ImageViewTouch) {
        ImageViewTouch imageViewTouch = (ImageViewTouch)v;
        return imageViewTouchCanScroll(imageViewTouch, dx);
    } else {
        return super.canScroll(v, checkV, dx, x, y);
    }
}


/**
 * Determines whether the ImageViewTouch can be scrolled.
 *
 * @param direction - positive direction value means scroll from right to left,
 *                  negative value means scroll from left to right
 * @return true if there is some more place to scroll, false - otherwise.
 */
private boolean imageViewTouchCanScroll(ImageViewTouch imageViewTouch, int direction){
    int widthScreen = getWidthScreen();

    RectF bitmapRect = imageViewTouch.getBitmapRect();
    Rect imageViewRect = new Rect();
    getGlobalVisibleRect(imageViewRect);

    int widthBitmapViewTouch = (int)bitmapRect.width();

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

    if(widthBitmapViewTouch < widthScreen){
        return false;
    }

    if (direction < 0) {
        return Math.abs(bitmapRect.right - imageViewRect.right) > 1.0f;
    }else {
        return Math.abs(bitmapRect.left - imageViewRect.left) > 1.0f;
    }

}

private int getWidthScreen(){
    WindowManager wm = (WindowManager) getContext().getSystemService(Context.WINDOW_SERVICE);
    Display display = wm.getDefaultDisplay();

    Point size = new Point();
    display.getSize(size);
    return size.x;
}

}

###

For Those who are struggling to disable viewpager when the image is in pinched to zoom state & enable when the image is in original state. I just made some changes as answered by Mike.

import android.content.Context
import android.util.AttributeSet
import android.util.Log
import android.view.MotionEvent
import android.view.View
import android.view.ViewGroup
import androidx.viewpager.widget.ViewPager


class DCExtendedViewPager : ViewPager {


    private val TAG = DCExtendedViewPager::class.java.simpleName

    private var onImageState: OnImageState? = null

    private var touchImageViewCustom: DCTouchImageViewLatest? = null


    var isScroll: Boolean = true

    interface OnImageState {
        fun checkImageState(isImageInOriginalState: Boolean)
    }


    constructor(context: Context) : super(context)

    constructor(context: Context, attrs: AttributeSet) : super(context, attrs)


    override fun canScroll(view: View, checkV: Boolean, dx: Int, x: Int, y: Int): Boolean {
        return if (view is DCTouchImageViewLatest) {
            //   touchImageView=view
            // canScrollHorizontally is not supported for Api < 14. To get around this issue,
            // ViewPager is extended and canScrollHorizontallyFroyo, a wrapper around
            // canScrollHorizontally supporting Api >= 8, is called.
            Log.e("ExtendedViewPager", "canScroll zoomedRect" + view.zoomedRect)

            view.canScrollHorizontallyFroyo(-dx)

        } else {
            super.canScroll(view, checkV, dx, x, y)
        }
    }

    override fun onTouchEvent(event: MotionEvent): Boolean {
        Log.e(TAG, "onTouchEventenable" + isScroll)
        return if (isScroll) {
            super.onTouchEvent(event)
        } else false

    }

    override fun onInterceptTouchEvent(event: MotionEvent): Boolean {

        Log.e(TAG, "onInterceptTouchEvent")

        Log.e(TAG, "currenrLayoutView called")
        val currenrLayoutView = getCurrentParentView()
        getTouchImageViewInstance(currenrLayoutView!!)

        return if (isScroll) {
            super.onInterceptTouchEvent(event)
        } else false

    }


    fun isViewPagerScrollValid(): Boolean {

        Log.e(TAG, "getFocusedChild()" + focusedChild)


        val currenrLayoutView = getCurrentParentView()


        var zoomRect = getTouchImageViewInstance(currenrLayoutView!!)?.zoomedRect
        var orgzoomRect = getTouchImageViewInstance(currenrLayoutView)?.originalRectF


        Log.e(TAG, "onInterceptTouchEvent zoomRect" + zoomRect)
        Log.e(TAG, "onInterceptTouchEvent orgzoomRect" + orgzoomRect)
        Log.e(TAG, "onInterceptTouchEvent onImageState" + onImageState)
        var scrollEnable = (zoomRect == orgzoomRect)


        // postLater(getTouchImageViewInstance(currenrLayoutView!!)!!)

        onImageState?.checkImageState(scrollEnable)
        Log.e(TAG, "onInterceptTouchEvent" + scrollEnable)


        return scrollEnable

    }


    fun setImageStateListner(onImageState: OnImageState) {
        this.onImageState = onImageState
    }


    fun getTouchImageViewInstance(accessingView: View): DCTouchImageViewLatest? {


        if (touchImageViewCustom == null) {

            try {
                for (index in 0 until (accessingView as ViewGroup).childCount) {

                    var nextChild = accessingView.getChildAt(index)

                    Log.e(TAG, "nextChild" + nextChild)

                    if (nextChild is ViewGroup) {
                        getTouchImageViewInstance(nextChild)
                    } else if (nextChild is View) {
                        if (nextChild is DCTouchImageViewLatest) {
                            touchImageViewCustom = nextChild
                            setListner()
                            break
                        }
                    }
                }

            } catch (ex: Exception) {
                ex.printStackTrace()
            }


        }


        Log.e(TAG, "getTouchImageViewInstance" + touchImageViewCustom)

        return touchImageViewCustom
    }

    private fun setListner() {

        touchImageViewCustom?.setOnDCTouchImageViewLatestListener(object : DCTouchImageViewLatest.OnDCTouchImageViewLatestListener {
            override fun onMove() {
                Log.e(TAG, "onMove Called")
                isScroll = isViewPagerScrollValid()
            }

        })

    }


    //Call this method from onPageSelected of viewpager
    fun viewPageChanged() {
        Log.e(TAG, "viewPageChanged called")
        touchImageViewCustom = null
    }


    fun getCurrentParentView(): View? {
        try {
            Log.e(TAG, "getCurrentView called")
            val currentItem = currentItem
            for (i in 0 until childCount) {
                val child = getChildAt(i)
                val layoutParams = child.layoutParams as ViewPager.LayoutParams

                val f = layoutParams.javaClass.getDeclaredField("position") //NoSuchFieldException
                f.isAccessible = true
                val position = f.get(layoutParams) as Int //IllegalAccessException

                Log.e(TAG, "currentItem" + currentItem)

                if (!layoutParams.isDecor && currentItem == position) {
                    Log.e(TAG, "getCurrentView" + child)
                    return child
                }
            }
        } catch (e: NoSuchFieldException) {
            Log.e(TAG, e.toString())
        } catch (e: IllegalArgumentException) {
            Log.e(TAG, e.toString())
        } catch (e: IllegalAccessException) {
            Log.e(TAG, e.toString())
        }

        return null
    }


}

In TouchImageView class, call getOriginalRectF() from setImageBitmap, setImageDrawable & setImageURI.

 public RectF getOriginalRectF(){

        Log.e(TAG,"getOriginalRectF called viewWidth"+viewWidth);
        Log.e(TAG,"getOriginalRectF called viewHeight"+viewHeight);

        if(originalRectF==null && viewHeight>0 && viewWidth>0){
            if (mScaleType == ScaleType.FIT_XY) {
                throw new UnsupportedOperationException("getZoomedRect() not supported with FIT_XY");
            }
            PointF topLeft = transformCoordTouchToBitmap(0, 0, true);
            PointF bottomRight = transformCoordTouchToBitmap(viewWidth, viewHeight, true);

            float w = getDrawableWidth(getDrawable());
            float h = getDrawableHeight(getDrawable());


            Log.e(TAG,"getOriginalRectF height"+h);
            Log.e(TAG,"getOriginalRectF width"+w);

            Log.e("getOriginalRectF","getZoomedRect topLeft"+topLeft.x +"-"+topLeft.y);
            Log.e("getOriginalRectF","getZoomedRect bottomRight"+bottomRight.x +"-"+bottomRight.y);


            originalRectF=new  RectF(topLeft.x / w, topLeft.y / h, bottomRight.x / w, bottomRight.y / h);


        }


        return originalRectF;

    }

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