Asp.net Method for adding a translucent image or text watermark to an image (2)

In the previous article, I talked about how to add text watermarks to images Uploaded By C #. This section describes how to add translucent image watermarks. Parameter: http://hi.baidu.com/1987raymond/blog/item/017a6a4ee9a8ca01b2de0543 . Html

The following is the implementation of the ImageWatermarkPainter class:

 

Using System;
Using System. Text;
Using System. IO;
Using System. Drawing;
Using System. Drawing. Imaging;

Namespace Juice. Common. Drawing
{
   /// <Summary>
   /// Image watermark painter
   /// </Summary>
   Public sealed class ImageWatermarkPainter: WatermarkPainter
   {
       /// <Summary>
       /// Constructor
       /// </Summary>
       /// <Param name = "rawImagePath"> </param>
       /// <Param name = "alpha"> </param>
       /// <Param name = "watermarkImage"> </param>
       Public ImageWatermarkPainter (string rawImagePath, int alpha, string watermarkImage)
           : Base (rawImagePath, alpha)
       {
           WatermarkImagePath = watermarkImage;
       }

       Private string m_WatermarkImagePath;

       /// <Summary>
       /// Watermark image path
       /// </Summary>
       Public string WatermarkImagePath
       {
           Get {return m_WatermarkImagePath ;}
           Set {m_WatermarkImagePath = value ;}
       }

       Private Image m_WatermarkImage;
       /// <Summary>
       /// Watermark image object
       /// </Summary>
       Public Image WatermarkImage
       {
           Get
           {
               If (null = m_WatermarkImage)
                   M_WatermarkImage = Image. FromFile (WatermarkImagePath );
               Return m_WatermarkImage;
           }
       }

       /// <Summary>
       /// Add a watermark
       /// </Summary>
       /// <Param name = "graphics"> </param>
       /// <Param name = "newImage"> </param>
       /// <Returns> </returns>
       Protected override bool AddWatermark (Graphics graphics, Bitmap newImage)
       {
           If (string. IsNullOrEmpty (WatermarkImagePath ))
               Return false;
           If (! System. IO. File. Exists (WatermarkImagePath ))
               Throw new FileNotFoundException (string. Format ("file {0} not found.", WatermarkImagePath ));
           If (WatermarkImage. Width + 10)> newImage. Width | (WatermarkImage. Height + 10)> newImage. Height)
               Return false;
           Using (ImageAttributes attributes = new ImageAttributes ())
           {
               Float alpha = WatermarkAlpha/255.0f;
               Float [] [] colorMatrixElements = {
  New float [] {1.0f, 0.0f, 0.0f, 0.0f, 0.0f },
  New float [] {0.0f, 1.0f, 0.0f, 0.0f, 0.0f },
  New float [] {0.0f, 0.0f, 1.0f, 0.0f, 0.0f },
  New float [] {0.0f, 0.0f, 0.0f, alpha, 0.0f },
  New float [] {0.0f, 0.0f, 0.0f, 0.0f, 1.0f}
};
               ColorMatrix colorMatrix = new ColorMatrix (colorMatrixElements );
               /// Set the color adjustment Matrix
               Attributes. SetColorMatrix (colorMatrix, ColorMatrixFlag. Default, ColorAdjustType. Bitmap );