Android left/right swipe gesture in WebView activity (with clicking on links and vertical scrolling)-ThrowExceptions

Exception or error:

SOLVED, solution is underneath.

I want to replace buttons for navigation in webview to 2 swipe gestures – left and right swipe. This Android: How to handle right to left swipe gestures link really helped me, but I encountered problem – after implementing this code I was unable to click on links/ or scroll through loaded webpage in webview activity(I have used 1st answer from possible answers).

Then I found out that in another answer in this question is something similar – how to scroll in listview – https://stackoverflow.com/a/20005481/3272449, but I wasn’t able to get it running. In logcat i get this debug info:
http://s27.postimg.org/5qfipgi1v/message.png

This is my OnSwipeTouchListener:

import android.view.GestureDetector;
import android.view.GestureDetector.SimpleOnGestureListener;
import android.view.MotionEvent;
import android.view.View;
import android.view.View.OnTouchListener;

public class OnSwipeTouchListener implements OnTouchListener {

private final GestureDetector gestureDetector = new GestureDetector(new GestureListener());

public boolean onTouch(final View view, final MotionEvent motionEvent) {
    return gestureDetector.onTouchEvent(motionEvent);
}

private final class GestureListener extends SimpleOnGestureListener {

    private static final int SWIPE_THRESHOLD = 100;
    private static final int SWIPE_VELOCITY_THRESHOLD = 100;

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

    @Override
    public boolean onFling(MotionEvent e1, MotionEvent e2, float velocityX, float velocityY) {
        boolean result = false;
        try {
            float diffY = e2.getY() - e1.getY();
            float diffX = e2.getX() - e1.getX();
            if (Math.abs(diffX) > Math.abs(diffY)) {
                if (Math.abs(diffX) > SWIPE_THRESHOLD && Math.abs(velocityX) > SWIPE_VELOCITY_THRESHOLD) {
                    if (diffX > 0) {
                        onSwipeRight();
                    } else {
                        onSwipeLeft();
                    }
                }
            }
        } catch (Exception exception) {
            exception.printStackTrace();
        }
        return result;
    }
}

public void onSwipeRight() {
}

public void onSwipeLeft() {
}

public GestureDetector getGestureDetector(){
    return  gestureDetector;
}
}

And my webview activity(stripped):

public class WebViewActivity extends Activity {
private WebView browser;
    private OnSwipeTouchListener onSwipeTouchListener;
@Override
public void onCreate(Bundle savedInstanceState) {
    super.onCreate(savedInstanceState);
    setContentView(R.layout.webview);
            onSwipeTouchListener = new OnSwipeTouchListener() {
public void onSwipeRight() {
    Toast.makeText(WebViewActivity.this, "right", Toast.LENGTH_SHORT).show();
}
public void onSwipeLeft() {
    Toast.makeText(WebViewActivity.this, "left", Toast.LENGTH_SHORT).show();
}
};

browser.setOnTouchListener(onSwipeTouchListener);
} // end of onCreate
@Override
public boolean dispatchTouchEvent(MotionEvent ev){
    onSwipeTouchListener.getGestureDetector().onTouchEvent(ev); 
        return super.dispatchTouchEvent(ev);   
}
} // end of WebViewActivity

How to make left/right swiping, vertical scrolling and clicking on links working at the same time?

SOLUTION: Same solved question:
Fling Gesture and Webview in Android

How to solve:

I’m not familiar enough with the GestureDetector to reliably diagnose your problem. One thing you could try is cloning the event:

@Override
public boolean dispatchTouchEvent(MotionEvent ev){
    onSwipeTouchListener.getGestureDetector().onTouchEvent(MotionEvent.obtain(ev)); 
    return super.dispatchTouchEvent(ev);   
}

Failing that another way to approach this is to use onOverScrolled instead of a GestureDetector:

@Override
protected void onOverScrolled (int scrollX, int scrollY, boolean clampedX, boolean clampedY) {
    if (scrollX > (getWidth() + THRESHOLD) && clampedX) {
        onSwipeLeft();
    }
    if (scrollX < - THRESHOLD && clampedX) {
        onSwipeRight();
    }
    super.onOverScrolled(scrollX, scrollY, clampedX, clampedY);
}

This does assume that your content is not normally scrollable sideways though.

Leave a Reply

Your email address will not be published. Required fields are marked *