Android:如何检测滚动何时结束

Question

我正在使用GestureDetector.SimpleOnGestureListener的onScroll方法在画布上滚动一个大位图.当滚动结束时,我想重绘位图,以防用户想要进一步滚动...离开位图的边缘,但我看不到如何检测滚动何时结束(用户已抬起手指)从屏幕上).

e2.getAction()似乎总是返回值2,所以没有帮助.当压力似乎下降到0.13左右时,e2.getPressure似乎返回相当恒定的值(大约0.25)直到最后的onScroll调用.我想我可以发现这种压力减少,但这远非万无一失.

必须有更好的方法:请有人帮忙吗？

Answer 1

这是我解决问题的方法.希望这可以帮助.

// declare class member variables
private GestureDetector mGestureDetector;
private OnTouchListener mGestureListener;
private boolean mIsScrolling = false;


public void initGestureDetection() {
        // Gesture detection
    mGestureDetector = new GestureDetector(new SimpleOnGestureListener() {
        @Override
        public boolean onDoubleTap(MotionEvent e) {
            handleDoubleTap(e);
            return true;
        }

        @Override
        public boolean onSingleTapConfirmed(MotionEvent e) {
            handleSingleTap(e);
            return true;
        }

        @Override
        public boolean onScroll(MotionEvent e1, MotionEvent e2, float distanceX, float distanceY) {
            // i'm only scrolling along the X axis
            mIsScrolling = true;                
            handleScroll(Math.round((e2.getX() - e1.getX())));
            return true;
        }

        @Override
        /**
         * Don't know why but we need to intercept this guy and return true so that the other gestures are handled.
         * https://code.google.com/p/android/issues/detail?id=8233
         */
        public boolean onDown(MotionEvent e) {
            Log.d("GestureDetector --> onDown");
            return true;
        }
    });

    mGestureListener = new View.OnTouchListener() {
        public boolean onTouch(View v, MotionEvent event) {

            if (mGestureDetector.onTouchEvent(event)) {
                return true;
            }

            if(event.getAction() == MotionEvent.ACTION_UP) {
                if(mIsScrolling ) {
                    Log.d("OnTouchListener --> onTouch ACTION_UP");
                    mIsScrolling  = false;
                    handleScrollFinished();
                };
            }

            return false;
        }
    };

    // attach the OnTouchListener to the image view
    mImageView.setOnTouchListener(mGestureListener);
}