SurfaceView实现红包雨平移动画

public class TranslateSurfaceView extends SurfaceView implements DrawInterface {
  private DrawHandler drawHandler;
  private int width;
  private int height;
  private Bitmap bitmap;
  private int bitmapWidth;
  private int bitmapHeight;
  private Toast toast;
  private int count = 0;
 
  private ArrayList moveList = new ArrayList();
 
  public TranslateSurfaceView(Context context) {
    this(context, null);
  }
 
  public TranslateSurfaceView(Context context, AttributeSet attrs) {
    this(context, attrs, -1);
  }
 
  public TranslateSurfaceView(Context context, AttributeSet attrs, int defStyleAttr) {
    super(context, attrs, defStyleAttr);
    init();
  }
 
  private void init() {
    SurfaceHolder holder = getHolder();
    setZOrderOnTop(true);
    holder.setFormat(PixelFormat.TRANSLUCENT);
  }
 
  @Override
  protected void onMeasure(int widthMeasureSpec, int heightMeasureSpec) {
    super.onMeasure(widthMeasureSpec, heightMeasureSpec);
    width = getMeasuredWidth();
    height = getMeasuredHeight();
  }
 
  public void prepare() {
    DrawThread drawThread = new DrawThread();
    drawThread.start();
    drawHandler = new DrawHandler(drawThread.getLooper(), this);
    bitmap = BitmapFactory.decodeResource(getResources(), R.drawable.icon_redenvelope2);
    bitmapWidth = bitmap.getWidth();
    bitmapHeight = bitmap.getHeight();
 
  }
 
  public void addMoveModel(MoveModel moveModel) {
    moveList.add(moveModel);
  }
 
  public void start() {
    count = 0;
    moveList.clear();
    for (int i = 0; i  width || moveModel.y > height) {
        resetMoveModel(moveModel);
      } else {
        moveModel.y += moveModel.randomY;
      }
    }
    holder.unlockCanvasAndPost(canvas);
    drawHandler.sendEmptyMessage(DrawHandler.START_DRAW_KEY);
  }
 
  @Override
  public void stopDraw() {
    drawHandler.removeMessages(DrawHandler.START_DRAW_KEY);
  }
 
  @Override
  public boolean onTouchEvent(MotionEvent event) {
    int action = event.getActionMasked();
    switch (action) {
      case MotionEvent.ACTION_DOWN:
        checkInRect((int) event.getX(), (int) event.getY());
        break;
    }
    return true;
  }
 
  /**
   * 是否点击在红包区域
   * @param x
   * @param y
   */
  private void checkInRect(int x, int y) {
    int length = moveList.size();
    for (int i = 0; i