.net给图片加水印

利用.net中System.Drawing命名空间下的常用类我们就可以轻松的为图片添加文字水印和图片水印，并且可以自定义水印文字和水印图片的大小、位置、颜色、透明度等等！对于jpg 或者png等图片，可以直接通过Graphics g= Graphics.FromImage(image)来获得Graphics对象，但对于gif图片，通过这种方法无法获得Graphics对象，解决这个问题的方法是首先根据.gif 文件的大小生成一个位图作图区，然后将原图复制到作图区，做进行处理，以下是水印添加类的完整代码: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,newRectangle(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MemoryStreamSystem.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GraphicsGraphics g = Graphics.FromImage(newBitmap);//消除锯齿g.SmoothingMode=SmoothingMode.AntiAlias;//拷贝原图到作图区g.DrawImage(img,newRectangle(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1/4System.Drawing.Imagenew_img=markImg.GetThumbnailImage(img.Width/4,markImg.Height*img.Width/markImg.Widt h,callb,new System.IntPtr());//添加水印g.DrawImage(new_img,newRectangle(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Graphicsg.Dispose();//将生成得图片读入MemoryStreamSystem.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,newRectangle(this.MarkX,this.MarkY,markImg.Width,markImg.Height),0,0,markImg.Width,markImg. Height,GraphicsUnit.Pixel,imageAttributes);//释放Graphicsg.Dispose();//将生成得图片读入MemoryStreamSystem.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;}}}}。