Asp.net中图片生成缩略图

 

      网上找了串代码，个人 觉得写得很详细，考虑也很周全 地址:

http://www.cnblogs.com/ghd258/archive/2006/02/26/337957.html  稍加修改。

 

      贴出代码，备用：

      /// <summary> /// 上传文件 /// </summary> /// <param name="sender"></param> /// <param name="e"></param> protected void btnUpLoadFile_Click(object sender, EventArgs e) { if (fileUpload1.HasFile) { string savePath = Server.MapPath("~/images/maxPic"); if (!System.IO.Directory.Exists(savePath)) { System.IO.Directory.CreateDirectory(savePath); } savePath = savePath + "//" + fileUpload1.FileName; fileUpload1.SaveAs(savePath); MakeThumbnail(Server.MapPath("~/images/maxPic/ll.jpg"), Server.MapPath("~/images/minPic/ll_1.jpg"), 100,80, "Cut"); } }

 

其中 fileUpload1 是FileUpload空控件名。

 

下面是生成缩略图的代码，可以按高、宽、等比例缩放：

 

  /// <summary> /// 生成缩略图 /// </summary> /// <param name="originalImagePath">源图路径（相对路径）</param> /// <param name="thumbnailPath">缩略图路径（相对路径）</param> /// <param name="width">缩略图宽度</param> /// <param name="height">缩略图高度</param> /// <param name="mode">生成缩略图的方式</param> public static void MakeThumbnail(string originalImagePath, string thumbnailPath, int width, int height, string mode) { System.Drawing.Image originalImage =System.Drawing.Image.FromFile(originalImagePath); int towidth = width; int toheight = height; int x = 0; int y = 0; int ow = originalImage.Width; int oh = originalImage.Height; switch (mode) { case "HW"://指定高宽缩放（可能变形) break; case "W"://指定宽，高按比例 toheight = originalImage.Height * width / originalImage.Width; break; case "H"://指定高，宽按比例 towidth = originalImage.Width * height / originalImage.Height; break; case "Cut"://指定高宽裁减（不变形） if ((double)originalImage.Width / (double)originalImage.Height > (double)towidth / (double)toheight) { oh = originalImage.Height; ow = originalImage.Height * towidth / toheight; y = 0; x = (originalImage.Width - ow) / 2; } else { ow = originalImage.Width; oh = originalImage.Width * height / towidth; x = 0; y = (originalImage.Height - oh) / 2; } break; default: break; } //新建一个bmp图片 System.Drawing.Image bitmap = new System.Drawing.Bitmap(towidth, toheight); //新建一个画板 Graphics g = System.Drawing.Graphics.FromImage(bitmap); //设置高质量插值法 g.InterpolationMode = System.Drawing.Drawing2D.InterpolationMode.High; //设置高质量,低速度呈现平滑程度 g.SmoothingMode = System.Drawing.Drawing2D.SmoothingMode.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, towidth, toheight), new Rectangle(x, y, ow, oh), GraphicsUnit.Pixel); try { //以jpg格式保存缩略图 bitmap.Save(thumbnailPath, System.Drawing.Imaging.ImageFormat.Jpeg); } catch (System.Exception e) { throw e; } finally { originalImage.Dispose(); bitmap.Dispose(); g.Dispose(); } }

 

       注意添加命名空间：

 

            using System.Drawing;
            using System.Drawing.Imaging;