Example usage for android.view ViewGroup onInterceptTouchEvent

Introduction

In this page you can find the example usage for android.view ViewGroup onInterceptTouchEvent.

Prototype

public boolean onInterceptTouchEvent(MotionEvent ev) 

Source Link

Document

Implement this method to intercept all touch screen motion events.

Usage

From source file:com.marshalchen.ultimaterecyclerview.UltimateRecyclerView.java

@Override
public boolean onTouchEvent(MotionEvent ev) {
    URLogs.d("ev---" + ev);
    if (mCallbacks != null) {

        switch (ev.getActionMasked()) {
        case MotionEvent.ACTION_UP:
        case MotionEvent.ACTION_CANCEL:
            mIntercepted = false;//from w  w w . j av a  2 s. c  o m
            mDragging = false;
            mCallbacks.onUpOrCancelMotionEvent(mObservableScrollState);
            break;
        case MotionEvent.ACTION_MOVE:
            if (mPrevMoveEvent == null) {
                mPrevMoveEvent = ev;
            }
            float diffY = ev.getY() - mPrevMoveEvent.getY();
            mPrevMoveEvent = MotionEvent.obtainNoHistory(ev);
            if (getCurrentScrollY() - diffY <= 0) {
                // Can't scroll anymore.

                if (mIntercepted) {
                    // Already dispatched ACTION_DOWN event to parents, so stop here.
                    return false;
                }

                // Apps can set the interception target other than the direct parent.
                final ViewGroup parent;
                if (mTouchInterceptionViewGroup == null) {
                    parent = (ViewGroup) getParent();
                } else {
                    parent = mTouchInterceptionViewGroup;
                }

                // Get offset to parents. If the parent is not the direct parent,
                // we should aggregate offsets from all of the parents.
                float offsetX = 0;
                float offsetY = 0;
                for (View v = this; v != null && v != parent; v = (View) v.getParent()) {
                    offsetX += v.getLeft() - v.getScrollX();
                    offsetY += v.getTop() - v.getScrollY();
                }
                final MotionEvent event = MotionEvent.obtainNoHistory(ev);
                event.offsetLocation(offsetX, offsetY);

                if (parent.onInterceptTouchEvent(event)) {
                    mIntercepted = true;

                    // If the parent wants to intercept ACTION_MOVE events,
                    // we pass ACTION_DOWN event to the parent
                    // as if these touch events just have began now.
                    event.setAction(MotionEvent.ACTION_DOWN);

                    // Return this onTouchEvent() first and set ACTION_DOWN event for parent
                    // to the queue, to keep events sequence.
                    post(new Runnable() {
                        @Override
                        public void run() {
                            parent.dispatchTouchEvent(event);
                        }
                    });
                    return false;
                }
                // Even when this can't be scrolled anymore,
                // simply returning false here may cause subView's click,
                // so delegate it to super.
                return super.onTouchEvent(ev);
            }
            break;
        }
    }
    return super.onTouchEvent(ev);
}

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