CODEWITHSUNDEEP
androidtouchmulti-touch
dzep
dzep

Reputation: 695

Android : How to Allow Only One Touch?

How to allow only one touch on Android? I don't want to support multi-touch and I want my app to discard other touches if my one of my fingers is already touching the screen. It's like using exclusive touch on iOS.

Also, is there a way to set the number of touches allowed?

Thanks!

EDIT: Minimum target API = 8.

Upvotes: 3

Views: 5582

Answers (2)

Abhijit Chakra
Abhijit Chakra

Reputation: 3236

yes you can disable the multi-touch by using this android:splitMotionEvents="false" or android:windowEnableSplitTouch="false"

Upvotes: 3

asloob
asloob

Reputation: 1326

You will have to keep track of the pointer id of the first touch and use only the touch events corressponding to that touch. Here is good example from The official Android blog "Making Sense of Multitouch "

private static final int INVALID_POINTER_ID = -1;

// The ‘active pointer’ is the one currently moving our object.
private int mActivePointerId = INVALID_POINTER_ID;

// Existing code ...

@Override
public boolean onTouchEvent(MotionEvent ev) {
    final int action = ev.getAction();
    switch (action & MotionEvent.ACTION_MASK) {
    case MotionEvent.ACTION_DOWN: {
        final float x = ev.getX();
        final float y = ev.getY();

        mLastTouchX = x;
        mLastTouchY = y;

        // Save the ID of this pointer
        mActivePointerId = ev.getPointerId(0);
        break;
    }

    case MotionEvent.ACTION_MOVE: {
        // Find the index of the active pointer and fetch its position
        final int pointerIndex = ev.findPointerIndex(mActivePointerId);
        final float x = ev.getX(pointerIndex);
        final float y = ev.getY(pointerIndex);

        final float dx = x - mLastTouchX;
        final float dy = y - mLastTouchY;

        mPosX += dx;
        mPosY += dy;

        mLastTouchX = x;
        mLastTouchY = y;

        invalidate();
        break;
    }

    case MotionEvent.ACTION_UP: {
        mActivePointerId = INVALID_POINTER_ID;
        break;
    }

    case MotionEvent.ACTION_CANCEL: {
        mActivePointerId = INVALID_POINTER_ID;
        break;
    }

    case MotionEvent.ACTION_POINTER_UP: {
        // Extract the index of the pointer that left the touch sensor
        final int pointerIndex = (action & MotionEvent.ACTION_POINTER_INDEX_MASK) 
                >> MotionEvent.ACTION_POINTER_INDEX_SHIFT;
        final int pointerId = ev.getPointerId(pointerIndex);
        if (pointerId == mActivePointerId) {
            // This was our active pointer going up. Choose a new
            // active pointer and adjust accordingly.
            final int newPointerIndex = pointerIndex == 0 ? 1 : 0;
            mLastTouchX = ev.getX(newPointerIndex);
            mLastTouchY = ev.getY(newPointerIndex);
            mActivePointerId = ev.getPointerId(newPointerIndex);
        }
        break;
    }
    }

    return true;
}

Upvotes: 2

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