c#图片添加水印的实例代码

using System;
using System.Drawing;
using System.Drawing.Drawing2D;
using System.Drawing.Imaging;
using System.IO;
namespace ImageDrawing
{
 /// <summary>
 /// 图片修改类,主要是用来保护图片版权的
 /// </summary>
 public class ImageModification
 {
  #region "member fields"
  private string modifyImagePath=null;
  private string drawedImagePath=null;
  private int rightSpace;
  private int bottoamSpace;
  private int lucencyPercent=70;
  private string outPath=null;
  #endregion
  public ImageModification()
  {
  }
  #region "propertys"
  /// <summary>
  /// 获取或设置要修改的图像路径
  /// </summary>
  public string ModifyImagePath
  {
   get{return this.modifyImagePath;}
   set{this.modifyImagePath=value;}
  }
  /// <summary>
  /// 获取或设置在画的图片路径(水印图片)
  /// </summary>
  public string DrawedImagePath
  {
   get{return this.drawedImagePath;}
   set{this.drawedImagePath=value;}
  }
  /// <summary>
  /// 获取或设置水印在修改图片中的右边距
  /// </summary>
  public int RightSpace
  {
   get{return this.rightSpace;}
   set{this.rightSpace=value;}
  }
  //获取或设置水印在修改图片中距底部的高度
  public int BottoamSpace
  {
   get{return this.bottoamSpace;}
   set{this.bottoamSpace=value;}
  }
  /// <summary>
  /// 获取或设置要绘制水印的透明度,注意是原来图片透明度的百分比
  /// </summary>
  public int LucencyPercent
  {
   get{return this.lucencyPercent;}
   set
   {
    if(value>=0&&value<=100)
     this.lucencyPercent=value;
   }
  }
  /// <summary>
  /// 获取或设置要输出图像的路径
  /// </summary>
  public string OutPath
  {
   get{return this.outPath;}
   set{this.outPath=value;}
  }
  #endregion
  #region "methods"
  /// <summary>
  /// 开始绘制水印
  /// </summary>
  public void DrawImage()
  {
   Image modifyImage=null;
   Image drawedImage=null;
   Graphics g=null;
   try
   {   
    //建立图形对象
    modifyImage=Image.FromFile(this.ModifyImagePath);
    drawedImage=Image.FromFile(this.DrawedImagePath);
    g=Graphics.FromImage(modifyImage);
    //获取要绘制图形坐标
    int x=modifyImage.Width-this.rightSpace;
    int y=modifyImage.Height-this.BottoamSpace;
    //设置颜色矩阵
    float[][] matrixItems ={
             new float[] {1,0},
             new float[] {0,1,(float)this.LucencyPercent/100f,1}};
    ColorMatrix colorMatrix = new ColorMatrix(matrixItems);
    ImageAttributes imgAttr=new ImageAttributes();
    imgAttr.SetColorMatrix(colorMatrix,ColorMatrixFlag.Default,ColorAdjustType.Bitmap);
    //绘制阴影图像
    g.DrawImage(
     drawedImage,
     new Rectangle(x,y,drawedImage.Width,drawedImage.Height),
     0,drawedImage.Height,
     GraphicsUnit.Pixel,imgAttr);
    //保存文件
    string[] allowImageType={".jpg",".gif",".png",".bmp",".tiff",".wmf",".ico"};
    FileInfo file=new FileInfo(this.ModifyImagePath);
    ImageFormat imageType=ImageFormat.Gif;
    switch(file.Extension.ToLower())
    {
     case ".jpg":
      imageType=ImageFormat.Jpeg;
      break;
     case ".gif":
      imageType=ImageFormat.Gif;
      break;
     case ".png":
      imageType=ImageFormat.Png;
      break;
     case ".bmp":
      imageType=ImageFormat.Bmp;
      break;
     case ".tif":
      imageType=ImageFormat.Tiff;
      break;
     case ".wmf":
      imageType=ImageFormat.Wmf;
      break;
     case ".ico":
      imageType=ImageFormat.Icon;
      break;
     default:
      break;
    }
    MemoryStream ms=new MemoryStream();
    modifyImage.Save(ms,imageType);
    byte[] imgData=ms.ToArray();
    modifyImage.Dispose();
    drawedImage.Dispose();
    g.Dispose();
    FileStream fs=null;
    if(this.OutPath==null || this.OutPath=="")
    {
     File.Delete(this.ModifyImagePath);
     fs=new FileStream(this.ModifyImagePath,FileMode.Create,FileAccess.Write);
    }
    else
    {
     fs=new FileStream(this.OutPath,FileAccess.Write);
    }
    if(fs!=null)
    {
     fs.Write(imgData,imgData.Length);
     fs.Close();
    }
   }
   finally
   {
    try
    {
     drawedImage.Dispose();
     modifyImage.Dispose();
     g.Dispose();
    }
    catch{;}
   }
  }
  #endregion
 }
}