Handling Touch Events - onInterceptTouchEvent and onTouchEvent

Question

I want to be able to swipe anywhere on the screen to call a certain function. But I also have Buttons in Linear Layouts that I want to be able to click on. If I swipe on a Button I want onInterceptTouchEvent to Intercept the call to the Button's onTouchEvent and perform a swipe action. And if I simply click on a Button I do not want the onInterceptTouchEvent to be called. Rather, I want the Button's onTouchEvent to be called and perform a Button click

But I get errors when I try implementing onInterceptTouchEvent.

Here is my code:

public class Game extends Activity { @Override protected void onCreate(Bundle savedInstanceState) { super.onCreate(savedInstanceState); setContentView(R.layout.game_activity); //other code.... } } @Override public boolean onInterceptTouchEvent(MotionEvent event) { switch (event.getAction()) { case MotionEvent.ACTION_DOWN: break; case MotionEvent.ACTION_CANCEL: case MotionEvent.ACTION_UP: swipeScreen(); //if action recognized as swipe then swipe break; case MotionEvent.ACTION_MOVE: float x = event.getX(); float y = event.getY(); float xDelta = Math.abs(x - mLastX); float yDelta = Math.abs(y - mLastY); if (yDelta > xDelta) { return true; } break; } return false; } @Override public boolean onTouchEvent(MotionEvent event) { ButtonOnClick(); //if not a swipe, then button click return true; }

First the error says: The method onInterceptTouchEvent(MotionEvent) of type Game must override or implement a supertype method

Then instead of return true I change the code to:return super.onInterceptTouchEvent(event) but then I get an error saying: The method onInterceptTouchEvent(MotionEvent) is undefined for the type Activity

Can someone please help?

The onInterceptTouchEvent() method is a member of the ViewGroup class. To implement it, you'll have to subclass a ViewGroup to be used in your layout. — Mike M.
– Mike M., Commented Dec 10, 2014 at 16:37
hm, so how do I subclass my viewgroup? - sorry i'm just new at android — user2456977
– user2456977, Commented Dec 10, 2014 at 16:51

Fier · Accepted Answer · 2015-07-30 01:15:59Z

Note that onInterceptTouchEvent() is a method from the ViewGroup class, and not from Activity.

You can achieve the desired behavior by moving your logic from onInterceptTouchEvent() to dispatchTouchEvent(MotionEvent ev). Remember to call the superclass implementation of dispatchTouchEvent(MotionEvent ev) to handle the events that should be handled normally.

Also note that you should consider a movement to be a swipe only when the delta is bigger than the system constant for touch slop. And I suggest making sure that the user is swiping in the direction you want by testing yDelta / 2 > xDelta instead of yDelta > xDelta.

public class Game extends Activity { private int mSlop; private float mDownX; private float mDownY; private boolean mSwiping; @Override protected void onCreate(Bundle savedInstanceState) { super.onCreate(savedInstanceState); setContentView(R.layout.game_activity); ViewConfiguration vc = ViewConfiguration.get(this) mSlop = vc.getScaledTouchSlop(); //other code.... } @Override public boolean dispatchTouchEvent(MotionEvent ev) { switch (ev.getAction()) { case MotionEvent.ACTION_DOWN: mDownX = ev.getX(); mDownY = ev.getY(); mSwiping = false; break; case MotionEvent.ACTION_CANCEL: case MotionEvent.ACTION_UP: if(mSwiping) { swipeScreen(); //if action recognized as swipe then swipe } break; case MotionEvent.ACTION_MOVE: float x = ev.getX(); float y = ev.getY(); float xDelta = Math.abs(x - mDownX); float yDelta = Math.abs(y - mDownY); if (yDelta > mSlop && yDelta / 2 > xDelta) { mSwiping = true; return true; } break; } return super.dispatchTouchEvent(ev); } }

how to do vice versa? I want only click event and not swipe event

MiguelSlv · Accepted Answer · 2019-07-06 11:18:23Z

I use fernandohur approach (read his post), that is very reusable, self contained and gives everything needed to detect a swipe in any direction.

To use fernandohur onSwipeListener, follow these simple steps. All code is written in Kotlin:

// 1) Add his onSwipeListener to the project. Credits should go to him // 2) Implement an anonymous class for the swipe listener: val onSwipeListener: OnSwipeListener = object : OnSwipeListener() { override fun onSwipe(direction: Direction): Boolean { if (direction == Direction.Up) { //do somethin return true } else if (direction == Direction.Down) { //do something else return true } return super.onSwipe(direction) } } // 3) connect the listener to the view val mDetector = GestureDetectorCompat(this.context, onSwipeListener) // 4) route the touch events to the listener override fun onInterceptTouchEvent(event: MotionEvent?): Boolean { return if (this.mDetector!!.onTouchEvent(event)) { true } else super.onInterceptTouchEvent(event) }

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