Check if Android WebView is consuming touch events

Question

Short version

How can I detect whether Android WebView consumed a touch event? onTouchEvent always returns true and WebViewClient\'s on

Answer 1

This code will handle your scrolling events in a webview. This catch the click down and the click up events, and compares the positions of each one. It never minds that the content within the webview is scrollable, just compare the coordinates in the area of webview.

public class MainActivity extends Activity implements View.OnTouchListener, Handler.Callback {

    private float x1,x2,y1,y2; //x1, y1 is the start of the event, x2, y2 is the end.
    static final int MIN_DISTANCE = 150; //min distance for a scroll event

    private static final int CLICK_ON_WEBVIEW = 1;
    private static final int CLICK_ON_URL = 2;
    private static final int UP_ON_WEBVIEW = 3;


    private final Handler handler = new Handler(this);

    public WebView webView;
    private WebViewClient client;
    private WebAppInterface webAppInt = new WebAppInterface(this);


    @Override
    protected void onCreate(Bundle savedInstanceState) {

        super.onCreate(savedInstanceState);
        setContentView(R.layout.activity_main);
        webView = (WebView)findViewById(R.id.myWebView);
        webView.setOnTouchListener(this);

        client = new WebViewClient();
        webView.setWebViewClient(client);        
        webView.loadDataWithBaseURL("file:///android_asset/", "myweb.html", "text/html", "UTF-8", "");

    }

//HERE START THE IMPORTANT PART
    @Override
    public boolean onTouch(View v, MotionEvent event) {
        if (v.getId() == R.id.myWebView && event.getAction() == MotionEvent.ACTION_DOWN){
            x1 = event.getX();
            y1 = event.getY();
            handler.sendEmptyMessageDelayed(CLICK_ON_WEBVIEW, 200);
        } else if (v.getId() == R.id.myWebView && event.getAction() == MotionEvent.ACTION_UP){
            x2 = event.getX();
            y2 = event.getY();

            handler.sendEmptyMessageDelayed(UP_ON_WEBVIEW, 200);
        }

        return false;
    }

    @Override
    public boolean handleMessage(Message msg) {
        if (msg.what == CLICK_ON_URL){ //if you clic a link in the webview, thats not a scroll
            handler.removeMessages(CLICK_ON_WEBVIEW);
            handler.removeMessages(UP_ON_WEBVIEW);
            return true;
        }
        if (msg.what == CLICK_ON_WEBVIEW){
            //Handle the click in the webview
            Toast.makeText(this, "WebView clicked", Toast.LENGTH_SHORT).show();
            return true;
        }
        if (msg.what == UP_ON_WEBVIEW){
            float deltaX = x2 - x1; //horizontal move distance
            float deltaY = y2 - y1; //vertical move distance
            if ((Math.abs(deltaX) > MIN_DISTANCE) && (Math.abs(deltaX) > Math.abs(deltaY)))
            {
                // Left to Right swipe action
                if (x2 > x1)
                {
                    //Handle the left to right swipe
                    Toast.makeText(this, "Left to Right swipe", Toast.LENGTH_SHORT).show ();
                }

                // Right to left swipe action
                else
                {
                    //Handle the right to left swipe
                    Toast.makeText(this, "Right to Left swipe", Toast.LENGTH_SHORT).show ();
                }

            }
            else if ((Math.abs(deltaY) > MIN_DISTANCE) && (Math.abs(deltaY) > Math.abs(deltaX)))
            {
                // Top to Bottom swipe action
                if (y2 > y1)
                {
                    //Handle the top to bottom swipe
                    Toast.makeText(this, "Top to Bottom swipe", Toast.LENGTH_SHORT).show ();
                }

                // Bottom to top swipe action -- I HIDE MY ACTIONBAR ON SCROLLUP
                else
                {
                    getActionBar().hide();
                    Toast.makeText(this, "Bottom to Top swipe [Hide Bar]", Toast.LENGTH_SHORT).show ();
                }
            }
            return true;
        }
        return false;
    }
}

You can also try to control the speed of the swipe, to detect it as a real swipe or scrolling.

I hope that helps you.