Android 通过onTouchEvent判断是否为双击事件

通过onTouchEvent判断是否为双击事件，通过前面一次up 跟本次down之间的时间差，并且点击的点的坐标偏移来确定是否为双击事件DOUBLE_TAP_TIMEOUT。

        boolean isMove = false;
        private final int DOUBLE_TAP_TIMEOUT = 200;
        private MotionEvent mCurrentDownEvent;
        private boolean mDoubleTapEnabled = false;
        private MotionEvent mPreviousUpEvent;
        @Override
        public void onTouchEvent(MotionEvent event) {
            Log.e(LOG_TAG, "MotionEvent="+ event.getAction()+",isMove="+isMove);
            Log.e(LOG_TAG, "mPreviousUpEvent="+ mPreviousUpEvent+",mCurrentDownEvent="+mCurrentDownEvent);
            if (event.getAction() == MotionEvent.ACTION_MOVE) {                
                isMove = true;
            }
            else if (event.getAction() == MotionEvent.ACTION_DOWN) {
                if (mPreviousUpEvent != null && mCurrentDownEvent != null 
                        && isConsideredDoubleTap(mCurrentDownEvent, mPreviousUpEvent, event)
                        ) {
                    if (mDoubleTapEnabled && Environment.getExternalStorageState().equals("mounted")) {                        
                        Toast.makeText(getApplicationContext(), getResources().getString(R.string.double_click), Toast.LENGTH_LONG).show();
                        
                    }
                }
                mCurrentDownEvent = MotionEvent.obtain(event);
            }else if (event.getAction() == MotionEvent.ACTION_UP){
                mPreviousUpEvent = MotionEvent.obtain(event);
                isMove = false;
            }
        }
        private boolean isConsideredDoubleTap(MotionEvent firstDown, MotionEvent firstUp, MotionEvent secondDown){
            if (secondDown.getEventTime() - firstUp.getEventTime() > DOUBLE_TAP_TIMEOUT) {
                return false;
            }        
            int deltaX =(int) firstUp.getX() - (int)secondDown.getX();
            int deltaY =(int) firstUp.getY()- (int)secondDown.getY();             
            return deltaX * deltaX + deltaY * deltaY < 10000;
        }