c#生成自定义图片方法代码实例

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using system.drawing;using system.io;using system.drawing.imaging;using system;namespace treads
{  /// <summary>
  /// 生成略缩图  /// </summary>
  public class class2
  {    private image srcimage;    private string srcfilename= @"x";//获取图片的路径
    private string srcfilename1 = @"x";//要保持图片的新路径
 
    /// <summary>
    /// 回调    /// </summary>
    /// <returns></returns>
    public bool thumbnailcallback()
    {      return false;
    }    /// <summary>
    /// 保存缩略图    /// </summary>
    /// <param name="width"></param>
    /// <param name="height"></param>
    public void savethumbnailimage(int width, int height)
    {      switch (path.getextension(srcfilename).tolower())
      {        case ".png":
          saveimage(width, height, imageformat.png);          break;        case ".gif":
          saveimage(width, height, imageformat.gif);          break;        default:
          saveimage(width, height, imageformat.jpeg);          break;
      }
    }    /// <summary>
    /// 生成缩略图并保存    /// </summary>
    /// <param name="width">缩略图的宽度</param>
    /// <param name="height">缩略图的高度</param>
    /// <param name="imgformat">保存的图像格式</param>
    /// <returns>缩略图的image对象</returns>
    public void saveimage(int width, int height, imageformat imgformat)
    {
      srcimage = image.fromfile(srcfilename);      if (imgformat != imageformat.gif && (srcimage.width > width) || (srcimage.height > height))
      {
        image img;
        image.getthumbnailimageabort callb = new image.getthumbnailimageabort(thumbnailcallback);
        img = srcimage.getthumbnailimage(width, height, callb, intptr.zero);
        srcimage.dispose();
        img.save(srcfilename1, imgformat);
        img.dispose();
      }
    }
 
  }
}

制作网络下载的略缩图

/// <summary>
   /// 制作远程缩略图    /// </summary>
   /// <param name="url">图片url</param>
   /// <param name="newfilename">新图路径</param>
   /// <param name="maxwidth">最大宽度</param>
   /// <param name="maxheight">最大高度</param>
   public static void makeremotethumbnailimage(string url, string newfilename, int maxwidth, int maxheight)
   {
     stream stream = getremoteimage(url);      if (stream == null)        return;
     image original = image.fromstream(stream);
     stream.close();
     makethumbnailimage(original, newfilename, maxwidth, maxheight);
   }  /// <summary>
   /// 获取图片流    /// </summary>
   /// <param name="url">图片url</param>
   /// <returns></returns>
   private static stream getremoteimage(string url)
   {
     httpwebrequest request = (httpwebrequest)httpwebrequest.create(url);
     request.method = "get";
     request.contentlength = 0;
     request.timeout = 20000;
     httpwebresponse response = null;      try
     {
       response = (httpwebresponse)request.getresponse();        return response.getresponsestream();
     }      catch
     {        return null;
     }
   } /// <summary>
   /// 裁剪图片并保存    /// </summary>
   /// <param name="filename">源图路径（绝对路径）</param>
   /// <param name="newfilename">缩略图路径（绝对路径）</param>
   /// <param name="maxwidth">缩略图宽度</param>
   /// <param name="maxheight">缩略图高度</param>
   /// <param name="cropwidth">裁剪宽度</param>
   /// <param name="cropheight">裁剪高度</param>
   /// <param name="x">x轴</param>
   /// <param name="y">y轴</param>
   public static bool makethumbnailimage(string filename, string newfilename, int maxwidth, int maxheight, int cropwidth, int cropheight, int x, int y)
   {      byte[] imagebytes = file.readallbytes(filename);
     image originalimage = image.fromstream(new system.io.memorystream(imagebytes));
     bitmap b = new bitmap(cropwidth, cropheight);      try
     {        using (graphics g = graphics.fromimage(b))
       {          //设置高质量插值法
         g.interpolationmode = interpolationmode.highqualitybicubic;          //设置高质量,低速度呈现平滑程度
         g.smoothingmode = smoothingmode.antialias;
         g.pixeloffsetmode = pixeloffsetmode.highquality;          //清空画布并以透明背景色填充          g.clear(color.transparent);          //在指定位置并且按指定大小绘制原图片的指定部分
         g.drawimage(originalimage, new rectangle(0, 0, cropwidth, cropheight), x, y, cropwidth, cropheight, graphicsunit.pixel);
         image displayimage = new bitmap(b, maxwidth, maxheight);
         saveimage(displayimage, newfilename, getcodecinfo("image/" + getformat(newfilename).tostring().tolower()));          return true;
       }
     }      catch (system.exception e)
     {        throw e;
     }      finally
     {
       originalimage.dispose();
       b.dispose();
     }
   }

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