跨越屏幕的可绘制形状

Question

我目前正在处理我的第一个Android应用程序，并且想知道如何实现onFling方法，使位于屏幕底部的Drawable Shape被抛到屏幕顶部。首先是用于实现游戏屏幕的.java文件。

Game1.java

package com.example.mdm71.flyingbird;


import android.app.Activity;
import android.os.Bundle;
import android.support.v4.view.GestureDetectorCompat;
import android.view.GestureDetector;
import android.view.MotionEvent;
import android.widget.ImageView;
import android.widget.Toast;


public class Game1 extends Activity implements GestureDetector.OnGestureListener, GestureDetector.OnDoubleTapListener {

    private ImageView gestureImage;
    private GestureDetectorCompat gDetector;

    @Override
    protected void onCreate(Bundle savedInstanceState) {
        super.onCreate(savedInstanceState);
        setContentView(R.layout.gamescreen);
        gestureImage = (ImageView)findViewById(R.id.thrown_ball);
        this.gDetector = new GestureDetectorCompat(this, this);
        gDetector.setOnDoubleTapListener(this);
    }

    @Override
    public boolean onTouchEvent(MotionEvent event){
        this.gDetector.onTouchEvent(event);
        return super.onTouchEvent(event);
    }

    @Override
    public boolean onDown(MotionEvent event){
        return false;
    }

    @Override
    public void onShowPress(MotionEvent motionEvent) {
        return;
    }

    @Override
    public boolean onSingleTapUp(MotionEvent motionEvent) {
        return false;
    }

    @Override
    public boolean onScroll(MotionEvent motionEvent, MotionEvent motionEvent1, float v, float v1) {
        return false;
    }

    @Override
    public boolean onFling(MotionEvent event1, MotionEvent event2, float velocityX, float velocityY){
        Toast.makeText(this, "Fling Event performed", Toast.LENGTH_LONG).show();

        return true;
    }

    @Override
    public void onLongPress(MotionEvent event){
        return;
    }


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

    @Override
    public boolean onDoubleTap(MotionEvent motionEvent) {
        return false;
    }

    @Override
    public boolean onDoubleTapEvent(MotionEvent motionEvent) {
        return false;
    }
}

这是定义形状的文件：

Shapes.xml

<?xml version="1.0" encoding="utf-8"?>
<shape
    xmlns:android="http://schemas.android.com/apk/res/android"
    xmlns:tools="http://schemas.android.com/tools"
    android:id="@+id/thrown_ball"
    android:shape="oval">

    <corners
        android:radius="20px"
        android:topLeftRadius="20px"
        android:topRightRadius="20px"
        android:bottomLeftRadius="20px"
        android:bottomRightRadius="20px" />

    <size
    android:width="100px"
    android:height="100px" />

    <solid
        android:color="#000000" />
</shape>