Error In Implementing Android Double Tap

I implemented OnDoubleTapListener in my Activity class and override three methods as follow. @Override public boolean onDoubleTap(MotionEvent e) { // TODO Auto-generat

Solution 1:

Try out this:

publicclassMyViewextendsView {

    GestureDetector gestureDetector;

    publicMyView(Context context, AttributeSet attrs) {
        super(context, attrs);

        // creating new gesture detector
        gestureDetector = newGestureDetector(context, newGestureListener());
    }

    // skipping measure calculation and drawing// delegate the event to the gesture detector@OverridepublicbooleanonTouchEvent(MotionEvent e) {
        return gestureDetector.onTouchEvent(e);
    }


    privateclassGestureListenerextendsGestureDetector.SimpleOnGestureListener {

        @OverridepublicbooleanonDown(MotionEvent e) {
            returntrue;
        }
        // event when double tap occurs@OverridepublicbooleanonDoubleTap(MotionEvent e) {
            floatx= e.getX();
            floaty= e.getY();

            Log.d("Double Tap", "Tapped at: (" + x + "," + y + ")");

            returntrue;
        }
    }
}

Solution 2:

GestureDetector will consume the touch events you already have on children for example, if you do not want that you can use the following code instead, I do not use ACTION_UP so I do not need to consume the event (only the second tap will be consumed)

publicclassDoubleTapDetector {

    publicinterfaceOnDoubleTapListener {
        booleanonDoubleTap(MotionEvent e);

        booleanonDoubleTapEvent(MotionEvent e);
    }

    privateint mDoubleTapSlopSquare;

    privatestaticfinalintDOUBLE_TAP_TIMEOUT= ViewConfiguration.getDoubleTapTimeout();
    privatestaticfinalintDOUBLE_TAP_MIN_TIME=40;

    privatestaticfinalintDOUBLE_TAP_SLOP=100;

    private OnDoubleTapListener mDoubleTapListener;

    private MotionEvent mCurrentDownEvent;

    publicDoubleTapDetector(Context context, OnDoubleTapListener listener) {
        mDoubleTapListener = listener;
        init(context);
    }

    privatevoidinit(Context context) {
        if (mDoubleTapListener == null) {
            thrownewNullPointerException("OnDoubleTapListener must not be null");
        }

        int doubleTapSlop;
        if (context == null) {
            doubleTapSlop = DOUBLE_TAP_SLOP;
        } else {
            finalViewConfigurationconfiguration= ViewConfiguration.get(context);
            doubleTapSlop = configuration.getScaledDoubleTapSlop();
        }
        mDoubleTapSlopSquare = doubleTapSlop * doubleTapSlop;
    }

    publicbooleanonTouchEvent(MotionEvent ev) {
        finalintaction= ev.getAction();

        booleanhandled=false;

        switch (action) {
        case MotionEvent.ACTION_DOWN:
            if ((mCurrentDownEvent != null) &&
                isConsideredDoubleTap(mCurrentDownEvent, ev)) {
                // This is a second tap// Give a callback with the first tap of the double-tap
                handled |= mDoubleTapListener.onDoubleTap(mCurrentDownEvent);
                // Give a callback with down event of the double-tap
                handled |= mDoubleTapListener.onDoubleTapEvent(ev);
            } else {
                // This is a first tap
            }

            if (mCurrentDownEvent != null) {
                mCurrentDownEvent.recycle();
            }
            mCurrentDownEvent = MotionEvent.obtain(ev);
            break;
        }

        return handled;
    }

    privatebooleanisConsideredDoubleTap(MotionEvent firstDown, MotionEvent secondDown) {
        finallongdeltaTime= secondDown.getEventTime() - firstDown.getEventTime();
        if (deltaTime > DOUBLE_TAP_TIMEOUT || deltaTime < DOUBLE_TAP_MIN_TIME) {
            returnfalse;
        }

        intdeltaX= (int) firstDown.getX() - (int) secondDown.getX();
        intdeltaY= (int) firstDown.getY() - (int) secondDown.getY();
        return (deltaX * deltaX + deltaY * deltaY < mDoubleTapSlopSquare);
    }

}

Usage:

DoubleTapDetector doubleTapDetector = newDoubleTapDetector(conversationWindow, newDoubleTapDetector.OnDoubleTapListener() {
        @OverridepublicbooleanonDoubleTap(MotionEvent e) {
            // Double tap detected.returnfalse;
        }

        @OverridepublicbooleanonDoubleTapEvent(MotionEvent e) {
            returnfalse;
        }
    });

someView.setOnTouchListener(newView.OnTouchListener() {
        @OverridepublicbooleanonTouch(View view, MotionEvent e) {
            return doubleTapDetector.onTouchEvent(e);
        }
    });