[函数名称]

  哈哈镜效果函数  WriteableBitmap DistortingMirrorProcess(WriteableBitmap src, int x, int y)

[算法说明]

  哈哈镜效果图像实际上是一种图像形变特效而已，对于这个特效，我们可以通过三角变换来实现。

  1，对于哈哈镜效果变换，首先它有两个参数，原点坐标和特效影响因子。

  对于图像中的像素点P(x,y)，假设原点坐标为X，Y，那么，根据三角函数变换可以得到：

  当前像素P的相对坐标cX,cY:

        /// <summary>
        /// Distorting mirror process.
        /// </summary>
        /// <param name="src">The source image.</param>
        /// <param name="x">Origin of coordinates in x direction.</param>
        /// <param name="y">Origin of coordinates in y direction.</param>
        /// <returns></returns>
         public static WriteableBitmap DistortingMirrorProcess(WriteableBitmap src, int x, int y)////哈哈镜特效
         {
             if (src != null)
             {
                 int w = src.PixelWidth;
                 int h = src.PixelHeight;
                 WriteableBitmap srcImage = new WriteableBitmap(w, h);
                 byte[] temp = src.PixelBuffer.ToArray();
                 byte[] tempMask = (byte[])temp.Clone();
                 int radius = 0;
                 double theta = 0;
                 int tX = 0;
                 int tY = 0;
                 int mapX = 0;
                 int mapY = 0;
                 int mapR=0;
                 for (int j = 0; j < h; j++)
                 {
                     for (int i = 0; i < w; i++)
                     {
                         tX = i - x;
                         tY = j - y;
                         theta = Math.Atan2((double)tY, (double)tX);
                         radius = (int)Math.Sqrt((double)(tX * tX + tY * tY));
                         mapR = (int)(Math.Sqrt((double)radius * 100));
                         mapX = x + (int)(mapR * Math.Cos(theta));
                         mapY = y + (int)(mapR * Math.Sin(theta));
                         temp[i * 4 + j * w * 4] = tempMask[mapX * 4 + mapY * w * 4];
                         temp[i * 4 + 1 + j * w * 4] = tempMask[mapX * 4 + 1 + mapY * w * 4];
                         temp[i * 4 + 2 + j * w * 4] = tempMask[mapX * 4 + 2 + mapY * w * 4];
                     }
                 }
                 Stream sTemp = srcImage.PixelBuffer.AsStream();
                 sTemp.Seek(0, SeekOrigin.Begin);
                 sTemp.Write(temp, 0, w * 4 * h);
                 return srcImage;
             }
             else
             {
                 return null;
             }
         }

[图像效果]