ANDROID - BASIC GESTURE DETECTION

Chintoo Semi

Total Post:79

Points:395
Posted by  Chintoo Semi
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  1. Chintoo Semi

    Post:79

    Points:395
    Android - basic gesture detection

    I've been battling to get fling gesture detection working on my Android application today.Nothing has worked for me please help

  1. Mayank Tripathi

    Post:807

    Points:4035
    Android - basic gesture detection

    Let your activity implement OnClickListener as usual:

    public class SelectFilterActivity extends Activity implements OnClickListener
    {
        private static final int SWIPE_MIN_DISTANCE = 120;
        private static final int SWIPE_MAX_OFF_PATH = 250;
        private static final int SWIPE_THRESHOLD_VELOCITY = 200;
        private GestureDetector gestureDetector;
        View.OnTouchListener gestureListener;
        @Override
        protected void onCreate(Bundle savedInstanceState) {
            super.onCreate(savedInstanceState);
            /* ... */
            // Gesture detection
            gestureDetector = new GestureDetector(this, new MyGestureDetector());
            gestureListener = new View.OnTouchListener() {
                public boolean onTouch(View v, MotionEvent event) {
                    return gestureDetector.onTouchEvent(event);
                }
            };
        }
        class MyGestureDetector extends SimpleOnGestureListener {
            @Override
            public boolean onFling(MotionEvent e1, MotionEvent e2, float velocityX, float velocityY) {
                try {
                    if (Math.abs(e1.getY() - e2.getY()) > SWIPE_MAX_OFF_PATH)
                        return false;
                    // right to left swipe
                    if(e1.getX() - e2.getX() > SWIPE_MIN_DISTANCE && Math.abs(velocityX) > SWIPE_THRESHOLD_VELOCITY) {
                        Toast.makeText(SelectFilterActivity.this, "Left Swipe", Toast.LENGTH_SHORT).show();
                    }  else if (e2.getX() - e1.getX() > SWIPE_MIN_DISTANCE && Math.abs(velocityX) > SWIPE_THRESHOLD_VELOCITY) {
                        Toast.makeText(SelectFilterActivity.this, "Right Swipe", Toast.LENGTH_SHORT).show();
                    }
                } catch (Exception e) {
                    // nothing
                }
                return false;
            }
                @Override
            public boolean onDown(MotionEvent e) {
                  return true;
            }
        }
    }

    Attach your gesture listener to all the views you add to the main layout;

    // Do this for each view added to the grid
    imageView.setOnClickListener(SelectFilterActivity.this); 
    imageView.setOnTouchListener(gestureListener);
    Watch in awe as your overridden methods are hit, both the onClick(View v) of the activity and the onFling of the gesture listener.

    public void onClick(View v) {
            Filter f = (Filter) v.getTag();
            FilterFullscreenActivity.show(this, input, f);
    }
    The post 'fling' dance is optional but encouraged.

    Hope this helps someone else!

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