自己留着用的 .net 图片水印 方法

using System;
 using System.Drawing;
using System.Drawing.Imaging;
 using System.IO;
 using System.Drawing.Drawing2D;

 namespace JillZhang
 {
  /// <summary>
  /// 给图片添加水印得类得描述
 /// </summary>
  public class WaterMark
 {
   private bool _textMark=false;
   private bool _imgMark=false;
   private string _text="";
  private string _imgPath="";
   private int _markX=0;
  private int _markY=0;
  private float _transparency=1;
  private string _fontFamily="宋体";
  private Color _textColor=Color.Black;
  private bool _textbold=false;
   int[] sizes=new int[]{48,32,16,8,6,4};
  /// <summary>
  /// 实例化一个水印类
   /// </summary>
   public WaterMark()
  {
    
   }
   /// <summary>
   ///　初始化一个只添加文字水印得实例
   /// </summary>
   /// <param name="text">水印文字</param>
   /// <param name="fontFamily">文字字体</param>
   /// <param name="bold">是否粗体</param>
   /// <param name="color">字体颜色</param>
   /// <param name="markX">标记位置横坐标</param>
  /// <param name="markY">标记位置纵坐标</param>
   public WaterMark(string text,string fontFamily,bool bold,Color color,int markX,int markY)
  {
    this._imgMark=false;
    this._textMark=true;
    this._text=text;
    this._fontFamily=fontFamily;
    this._textbold=bold;
   this._textColor=color;
    this._markX=markX;
    this._markY=MarkY;
  }
   /// <summary>
   /// 实例化一个只添加图片水印得实例
  /// </summary>
 /// <param name="imagePath">水印图片路径</param>
 /// <param name="tranparence">透明度</param>
  /// <param name="markX">标记位置横坐标</param>
 /// <param name="markY">标记位置纵坐标</param>
 public WaterMark(string imagePath,float tranparence,int markX,int markY)
 {
  this._textMark=false;
  this._imgMark=true;
  this._imgPath=imagePath;
 this._markX=markX;
  this._markY=MarkY;
   this._transparency=tranparence;
 }
 /// <summary>
 /// 是否添加文字水印
  /// </summary>
 public bool TextMark
 {
   get{return _textMark;}
   set{_textMark=value;}
 }
  /// <summary>
  /// 是否添加图片水印
 /// </summary>
 public bool ImageMark
  {
   get{return _imgMark;}
   set{_imgMark=value;}  
  }
  /// <summary>
  /// 文字水印得内容
   /// </summary>
  public string Text
 {
   get{return _text;}
  set{_text=value;}
 }
 /// <summary>
  /// 图片水印得图片地址
/// </summary>
 public string ImagePath
  {
 get{return _imgPath;}
  set{_imgPath=value;}
 }
 /// <summary>
  /// 添加水印位置得横坐标
 /// </summary>
  public int MarkX
  {
  get{return _markX;}
  set{_markX=value;}
 }
 /// <summary>
 /// 添加水印位置得纵坐标
 /// </summary>
 public int MarkY
  {
  get{return _markY;}
  set{_markY=value;}
 }
 /// <summary>
 /// 水印得透明度
  /// </summary>
 public float Transparency
 {
  get{
  if(_transparency>1.0f)
   {
    _transparency=1.0f;
   }
   return _transparency;}
  set{_transparency=value;}
  }
  /// <summary>
 /// 水印文字得颜色
  /// </summary>
 public Color TextColor
  {
  get{return _textColor;}
   set{_textColor=value;}
}
  /// <summary>
 /// 水印文字得字体
  /// </summary>
  public string TextFontFamily
  {
   get{return _fontFamily;}
   set{_fontFamily=value;}
  }
  /// <summary>
  /// 水印文字是否加粗
  /// </summary>
 public bool Bold
  {
   get{return _textbold;}
   set{_textbold=value;}
  }
 /// <summary>
  /// 添加水印，此方法适用于gif格式得图片
  /// </summary>
  /// <param name="image">需要添加水印得图片</param>
  /// <returns>添加水印之后得图片</returns>
  public Image Mark(Image img)
  {
  try
   {
   //添加文字水印
    if(this.TextMark)
    {
     //根据源图片生成新的Bitmap对象作为作图区，为了给gif图片添加水印，才有此周折
     Bitmap newBitmap=new Bitmap(img.Width,img.Height,PixelFormat.Format24bppRgb); 
     //设置新建位图得分辨率
    newBitmap.SetResolution(img.HorizontalResolution,img.VerticalResolution);
    //创建Graphics对象，以对该位图进行操作
     Graphics g = Graphics.FromImage(newBitmap);
    //消除锯齿
     g.SmoothingMode=SmoothingMode.AntiAlias;
    //将原图拷贝到作图区
    g.DrawImage(img,new Rectangle(0,0,img.Width,img.Height),0,0,img.Width,img.Height,GraphicsUnit.Pixel);
    //声明字体对象
    Font cFont = null;
     //用来测试水印文本长度得尺子
    SizeF size=new SizeF();
    //探测出一个适合图片大小得字体大小，以适应水印文字大小得自适应
    for(int i=0;i<6;i++)
     {
      //创建一个字体对象
      cFont= new Font(this.TextFontFamily,sizes[i]);
      //是否加粗
     if(!this.Bold)
      {
      cFont= new Font(this.TextFontFamily,sizes[i],FontStyle.Regular);
      }
     else
     {
      cFont=new Font(this.TextFontFamily,sizes[i],FontStyle.Bold);
     }
     //测量文本大小
      size=g.MeasureString(this.Text,cFont);
      //匹配第一个符合要求得字体大小
     if((ushort)size.Width<(ushort)img.Width)
     {
     break;
      }
    }
     //创建刷子对象，准备给图片写上文字
    Brush brush= new SolidBrush(this.TextColor);
 //在指定得位置写上文字
    g.DrawString(this.Text,cFont,brush,this.MarkX,this.MarkY);
     //释放Graphics对象
     g.Dispose();   
     //将生成得图片读入MemoryStream
    System.IO.MemoryStream ms = new System.IO.MemoryStream();
     newBitmap.Save(ms,ImageFormat.Jpeg);
    //重新生成Image对象
    img=System.Drawing.Image.FromStream(ms); 
     //返回新的Image对象
    return img;
 
    }
    //添加图像水印
    if(this.ImageMark)
    {
     //获得水印图像
    Image markImg = Image.FromFile(this.ImagePath);
     //创建颜色矩阵
     float[][] ptsArray ={ 
          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, this.Transparency, 0}, //注意：此处为0.0f为完全透明，1.0f为完全不透明
          new float[] {0, 0, 0, 0, 1}}; 
     ColorMatrix colorMatrix= new ColorMatrix(ptsArray);
     //新建一个Image属性
     ImageAttributes imageAttributes= new ImageAttributes();
     //将颜色矩阵添加到属性
     imageAttributes.SetColorMatrix(colorMatrix,ColorMatrixFlag.Default,
      ColorAdjustType.Default);
    //生成位图作图区
     Bitmap newBitmap=new Bitmap(img.Width,img.Height,PixelFormat.Format24bppRgb);
     //设置分辨率
     newBitmap.SetResolution(img.HorizontalResolution,img.VerticalResolution);
     //创建Graphics
     Graphics g = Graphics.FromImage(newBitmap);
     //消除锯齿
     g.SmoothingMode=SmoothingMode.AntiAlias;
    //拷贝原图到作图区
     g.DrawImage(img,new Rectangle(0,0,img.Width,img.Height),0,0,img.Width,img.Height,GraphicsUnit.Pixel);
     //如果原图过小
     if(markImg.Width>img.Width||markImg.Height>img.Height)
     {
      System.Drawing.Image.GetThumbnailImageAbort callb=null;
      //对水印图片生成缩略图,缩小到原图得1/4
      System.Drawing.Image new_img=markImg.GetThumbnailImage(img.Width/4,markImg.Height*img.Width/markImg.Width,callb,new System.IntPtr());
      //添加水印
      g.DrawImage(new_img,new Rectangle(this.MarkX,this.MarkY,new_img.Width,new_img.Height),0,0,new_img.Width,new_img.Height,GraphicsUnit.Pixel,imageAttributes);
     //释放缩略图
      new_img.Dispose();
      //释放Graphics
     g.Dispose();
      //将生成得图片读入MemoryStream
     System.IO.MemoryStream ms = new System.IO.MemoryStream();
     newBitmap.Save(ms,ImageFormat.Jpeg);
　　　　　　　　　　//返回新的Image对象
      img=Image.FromStream(ms);
      return img;
     }
      //原图足够大
     else
     {
      //添加水印
      g.DrawImage(markImg,new Rectangle(this.MarkX,this.MarkY,markImg.Width,markImg.Height),0,0,markImg.Width,markImg.Height,GraphicsUnit.Pixel,imageAttributes);
      //释放Graphics
     g.Dispose();
      //将生成得图片读入MemoryStream
     System.IO.MemoryStream ms = new System.IO.MemoryStream();
      newBitmap.Save(ms,ImageFormat.Jpeg);
      //返回新的Image对象
      img=Image.FromStream(ms);
      return img;
     }     
    }
    return img;
   }
   catch
   {
               return img;   
   }   
 }
  
 }
}