Android点击屏幕出现水波纹效果

参照：http://blog.csdn.net/Poison_H/article/details/43735445。点击手机屏幕实现水波效果，如下图：

【核心代码】

public class WaterWaveView extends SurfaceView implements SurfaceHolder.Callback { // 背景图的宽度和高度   private int backWidth;   private int backHeight;   /**  * buf1 和 buf2是波能缓冲区，分别代表了每个点的前一时刻和后一时刻的波幅数据  */  private short[] buf1;  private short[] buf2;   private int[] bitmap1;  private int[] bitmap2;  private Bitmap bgImage = null;  // 是否第一次加载  private boolean firstLoad = false;   WavingThread wavingThread = new WavingThread();  // 显示一个surface的抽象接口，使你可以控制surface的大小和格式， 以及在surface上编辑像素，和监视surace的改变  SurfaceHolder mSurfaceHolder = null;   private int doubleWidth;   private int fiveWidth;  // 持续时间  private int loopTime;   private int bitmapLen;    public WaterWaveView(Context context)
    { super(context);  mSurfaceHolder = getHolder();  mSurfaceHolder.addCallback(this);  } @Override  protected void onSizeChanged(int w, int h, int oldw, int oldh)
    { if (!firstLoad)
        { // 背景图  bgImage = BitmapFactory.decodeResource(this.getResources(), R.drawable.bg);  bgImage = Bitmap.createScaledBitmap(bgImage, w, h, false);// 缩放而已  backWidth = bgImage.getWidth();  backHeight = bgImage.getHeight();   buf2 = new short[backWidth * backHeight];  buf1 = new short[backWidth * backHeight];   bitmap2 = new int[backWidth * backHeight];  bitmap1 = new int[backWidth * backHeight];   // 将bgImage的像素拷贝到bitmap1数组中，用于渲染。。。  bgImage.getPixels(bitmap1, 0, backWidth, 0, 0, backWidth, backHeight);  bgImage.getPixels(bitmap2, 0, backWidth, 0, 0, backWidth, backHeight);   for (int i = 0; i < backWidth * backHeight;   i)
            { buf2[i] = 0;  buf1[i] = 0;  } doubleWidth = backWidth << 1;   fiveWidth = 5 * backWidth;   loopTime = ((backHeight - 4) * backWidth) >> 1;   bitmapLen = backWidth * backHeight - 1;   firstLoad = true;  }
    } class WavingThread extends Thread
    { boolean running = true;   public void setRunning(boolean running)
        { this.running = running;  } @Override  public void run()
        {
            Canvas c = null;  while (running)
            {
                c = mSurfaceHolder.lockCanvas();  makeRipple();  doDraw(c);  mSurfaceHolder.unlockCanvasAndPost(c);  }
        }
    } /*******************************************************  * 计算波能数据缓冲区  *******************************************************/  private void makeRipple()
    { int k = fiveWidth;  int xoff = 0, yoff = 0;  int cp = 0;   int tarClr = 0;  int i = fiveWidth;  while (i < loopTime)
        { // 波能扩散  buf2[k] = (short) (((buf1[k - 2]   buf1[k   2]   buf1[k - doubleWidth]   buf1[k   doubleWidth]) >> 1) - buf2[k]);   // 波能衰减  buf2[k] = (short) (buf2[k] - (buf2[k] >> 5));   // 求出该点的左上的那个点xoff,yoff  cp = k - doubleWidth - 2;   xoff = buf2[cp - 2] - buf2[cp   2];  yoff = buf2[cp - doubleWidth] - buf2[k - 2];   tarClr = k   yoff * doubleWidth   xoff;  if (tarClr > bitmapLen || tarClr < 0)
            {
                k  = 2;  continue;  } // 复制象素  bitmap2[k] = bitmap1[tarClr];  k  = 2;    i;  } short[] tmpBuf = buf2;  buf2 = buf1;  buf1 = tmpBuf;   } /*****************************************************  * 增加波源 x坐标 y坐标 波源半径 波源能量  *****************************************************/  private void touchWater(int x, int y, int stonesize, int stoneweight)
    { // 判断坐标是否在屏幕范围内  if (x   stonesize > backWidth)
        { return;  } if (y   stonesize > backHeight)
        { return;  } if (x - stonesize < 0)
        { return;  } if (y - stonesize < 0)
        { return;  } // 产生波源，填充前导波能缓冲池  int endStoneX = x   stonesize;  int endStoneY = y   stonesize;  int squaSize = stonesize * stonesize;  int posy = y - stonesize;  int posx = x - stonesize;  for (posy = y - stonesize; posy < endStoneY;   posy)
        { for (posx = x - stonesize; posx < endStoneX;   posx)
            { if ((posx - x) * (posx - x)   (posy - y) * (posy - y) < squaSize)
                { buf1[backWidth * posy   posx] = (short) -stoneweight;  }
            }
        }
    } /*****************************************************  * 增加波源 x坐标 y坐标 波源半径 波源能量  *****************************************************/  private void trickWater(int x, int y, int stonesize, int stoneweight)
    { // 判断坐标是否在屏幕范围内  if (x   stonesize > backWidth)
        { return;  } if (y   stonesize > backHeight)
        { return;  } if (x - stonesize < 0)
        { return;  } if (y - stonesize < 0)
        { return;  } // 产生波源，填充波能缓冲池  int endStoneX = x   stonesize;  int endStoneY = y   stonesize;  int posy = y - stonesize;  int posx = x - stonesize;  for (posy = y - stonesize; posy < endStoneY;   posy)
        { for (posx = x - stonesize; posx < endStoneX;   posx)
            { if (posy >= 0 && posy < backHeight && posx >= 0 && posx < backWidth)
                { buf1[backWidth * posy   posx] = (short) -stoneweight;  }
            }
        }
    } @Override  public boolean onTouchEvent(MotionEvent event)
    { if (event.getAction() == MotionEvent.ACTION_DOWN)
        { // 设置波源半径和波源能量  touchWater((int) event.getX(), (int) event.getY(), 200, 300);  } else if (event.getAction() == MotionEvent.ACTION_MOVE)
        {
            trickWater((int) event.getX(), (int) event.getY(), 200, 300);  } return true;  } protected void doDraw(Canvas canvas)
    { /**  * Parameters: 1.colors 2.offset 3.stride 4.x 5. y 6.width 7.height  * 8.hasAlpha 9. paint  */  //绘制  canvas.drawBitmap(bitmap2, 0, backWidth, 0, 0, backWidth, backHeight, false, null);   } @Override  public void surfaceCreated(SurfaceHolder holder)
    { wavingThread.setRunning(true);  wavingThread.start();   } @Override  public void surfaceDestroyed(SurfaceHolder holder)
    { boolean retry = true;  wavingThread.setRunning(false);  // 非暴力关闭线程，直到此次该线程运行结束之前，主线程停止运行，以防止Surface被重新激活  while (retry)
        { try  { wavingThread.join(); // 阻塞current  // Thread(当前执行线程)直到被调用线程(thread)完成。  retry = false;  } catch (InterruptedException e)
            {
            }
        }
    } @Override  public void surfaceChanged(SurfaceHolder holder, int format, int width, int height)
    { // TODO Auto-generated method stub   }
}

waterWaveView = new WaterWaveView(this); setContentView(waterWaveView);