// 
  /// 处理图片透明操作  /// 
  /// 原始图片  /// 透明度(0.0---1.0)  /// 
       private Image TransparentImage(Image srcImage, float opacity)  {      float[][] nArray ={ new float[] {1, 0, 0, 0, 0},                          new float[] {0, 1, 0, 0, 0},                          new float[] {0, 0, 1, 0, 0},                          new float[] {0, 0, 0, opacity, 0},                          new float[] {0, 0, 0, 0, 1}};      ColorMatrix matrix = new ColorMatrix(nArray);      ImageAttributes attributes = new ImageAttributes();      attributes.SetColorMatrix(matrix, ColorMatrixFlag.Default, ColorAdjustType.Bitmap);      Bitmap resultImage = new Bitmap(srcImage.Width, srcImage.Height);      Graphics g = Graphics.FromImage(resultImage);      g.DrawImage(srcImage, new Rectangle(0, 0, srcImage.Width, srcImage.Height), 0, 0, srcImage.Width, srcImage.Height, GraphicsUnit.Pixel, attributes);        return resultImage;  }