android - 如何确定用户滑动是否从 Android 屏幕的底部边缘开始？

Question

如果用户从屏幕底部边缘向上滑动，我需要显示自定义 View 。我已经实现了 SimpleOnGestureListener 来找出滑动方向，但我不知道如何确定用户是否从底部边缘开始滑动？我的代码是:

public class SimpleGestureFilter extends SimpleOnGestureListener{

    public final static String TAG    = "SimpleOnGestureListener";

    public final static int SWIPE_UP    = 1;
    public final static int SWIPE_DOWN  = 2;
    public final static int SWIPE_LEFT  = 3;
    public final static int SWIPE_RIGHT = 4;

    public final static int MODE_TRANSPARENT = 0;
    public final static int MODE_SOLID       = 1;
    public final static int MODE_DYNAMIC     = 2;

    private final static int ACTION_FAKE = -13; //just an unlikely number
    private int swipe_Min_Distance = 50; //100
    private int swipe_Max_Distance = 1350; //350
    private int swipe_Min_Velocity = 50; //100

    private int mode      = MODE_DYNAMIC;
    private boolean running = true;
    private boolean tapIndicator = false;

    private Activity context;
    private GestureDetector detector;
    private SimpleGestureListener listener;

    public SimpleGestureFilter(Activity context,SimpleGestureListener sgl) {

        this.context = context;
        this.detector = new GestureDetector(context, this);
        this.listener = sgl;
    }

    public void onTouchEvent(MotionEvent event){

        if(!this.running)
            return;  

        boolean result = this.detector.onTouchEvent(event); 

        if(this.mode == MODE_SOLID)
            event.setAction(MotionEvent.ACTION_CANCEL);
        else if (this.mode == MODE_DYNAMIC) {

            if(event.getAction() == ACTION_FAKE)
                event.setAction(MotionEvent.ACTION_UP);
            else if (result)
                event.setAction(MotionEvent.ACTION_CANCEL);
            else if(this.tapIndicator){
                event.setAction(MotionEvent.ACTION_DOWN);
                this.tapIndicator = false;
            }

        }
        //else just do nothing, it's Transparent
    }

    public void setMode(int m){
        this.mode = m;
    }

    public int getMode(){
        return this.mode;
    }

    public void setEnabled(boolean status){
        this.running = status;
    }

    public void setSwipeMaxDistance(int distance){
        this.swipe_Max_Distance = distance;
    }

    public void setSwipeMinDistance(int distance){
        this.swipe_Min_Distance = distance;
    }

    public void setSwipeMinVelocity(int distance){
        this.swipe_Min_Velocity = distance;
    }

    public int getSwipeMaxDistance(){
        return this.swipe_Max_Distance;
    }

    public int getSwipeMinDistance(){
        return this.swipe_Min_Distance;
    }

    public int getSwipeMinVelocity(){
        return this.swipe_Min_Velocity;
    }

    @Override
    public boolean onFling(MotionEvent e1, MotionEvent e2, float velocityX,
            float velocityY) {

        final float xDistance = Math.abs(e1.getX() - e2.getX());
        final float yDistance = Math.abs(e1.getY() - e2.getY());
        //e1.
        Log.i(TAG, "X: "+ Math.abs(e1.getX()));
        Log.i(TAG, "X1: "+ e2.getX());
        Log.i(TAG, "Y: "+ e1.getY());
        Log.i(TAG, "Y1: "+ e1.getY());
        Log.i(TAG, "edge: "+ e1.getEdgeFlags());

        if(xDistance > this.swipe_Max_Distance || yDistance > this.swipe_Max_Distance)
            return false;

        velocityX = Math.abs(velocityX);
        velocityY = Math.abs(velocityY);
        boolean result = false;

        if(velocityX > this.swipe_Min_Velocity && xDistance > this.swipe_Min_Distance){
            if(e1.getX() > e2.getX()) // right to left
            this.listener.onSwipe(SWIPE_LEFT);
            else
                this.listener.onSwipe(SWIPE_RIGHT);

            result = true;
        }
        else if(velocityY > this.swipe_Min_Velocity && yDistance > this.swipe_Min_Distance){
            if(e1.getY() > e2.getY()) // bottom to up
                this.listener.onSwipe(SWIPE_UP);
            else
                this.listener.onSwipe(SWIPE_DOWN);

            result = true;
        }

        return result;
    }

    @Override
    public boolean onSingleTapUp(MotionEvent e) {
        this.tapIndicator = true;
        return false;
    }

    @Override
    public boolean onDoubleTap(MotionEvent arg0) {
        this.listener.onDoubleTap();;
        return true;
    }

    @Override
    public boolean onDoubleTapEvent(MotionEvent arg0) {
        return true;
    }

    @Override
    public boolean onSingleTapConfirmed(MotionEvent arg0) {

        if(this.mode == MODE_DYNAMIC){        // we owe an ACTION_UP, so we fake an
            arg0.setAction(ACTION_FAKE);      //action which will be converted to an ACTION_UP later.
            this.context.dispatchTouchEvent(arg0);
        }   

        return false;
    }

    public static interface SimpleGestureListener{
        void onSwipe(int direction);
        void onDoubleTap();
    }

}

Answer 1

您可以使用MotionEvent.getEdgeFlags()确定用户是否从边缘滑动。

public void onTouchEvent(MotionEvent event){

    if (ev.getAction() == MotionEvent.ACTION_DOWN
            && ev.getEdgeFlags() == MotionEvent.EDGE_BOTTOM) {
        // do something
    }

}