asp缩略图生成方法

/// <summary>
/// 上传本地图片，同时生成缩略图（可选）
/// </summary>
/// <param name="fudImage">FileUpload控件</param>
/// <param name="strSelfPath">本模块的保存路径</param>
/// <param name="width">缩略图宽度</param>
/// <param name="height">缩略图高度</param>
/// <param name="intFlag">标识是否要生成缩略图（0--是，1--否）</param>
/// <returns>上传原图的路径</returns>
public static string ImageSave(FileUpload fudImage, int width, int height)
{
string strResult = string.Empty;
try
{
//当前日时
string strAllTime = System.DateTime.Now.ToString("yyyyMMddhhmmss");
//取得文件的扩展名,并转换成小写
string fileExtension = System.IO.Path.GetExtension(fudImage.FileName).ToLower();
//取得实际保存地址
string normalPath = System.Web.HttpContext.Current.Server.MapPath(ConfigurationManager.AppSettings["NormalPa th"]);
//缩略图保存路径
string thumbnailPath = System.Web.HttpContext.Current.Server.MapPath(ConfigurationManager.AppSettings["Thumbnai lPath"]);
if (!File.Exists(normalPath)) //如果/up_flie/Album/不存在，则创建/up_flie/Album/，用于存放缩略图
{
System.IO.Directory.CreateDirectory(normalPath);
}
FileInfo file = new FileInfo(strAllTime + fileExtension); //FileInfo对象表示磁盘或网络位置上的文件。

提供文件的路径，就可以创建一个FileInfo对象
string webFilePathNor = normalPath + "/" + ; //源图上传路径
string webFilePathThumb = thumbnailPath + "/" + ; //缩略图的保存路径
fudImage.SaveAs(webFilePathNor); //保存源图
if (!File.Exists(thumbnailPath))
{
System.IO.Directory.CreateDirectory(thumbnailPath);
}
MakeThumbnail(webFilePathNor, webFilePathThumb, width, height, "Cut"); //生成保存缩略图
strResult = ConfigurationManager.AppSettings["ThumbnailPath"] + "/" + ;
}
catch (Exception ex)
{
strResult = "LoadingError";
throw new Exception(ex.Message.ToString());
}
return strResult;
}
/// <summary>
/// 生成缩略图
/// </summary>
/// <param name="originalImagePath">源图路径（物理路径）</param>
/// <param name="thumbnailPath">缩略图路径（物理路径）</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
System.Drawing.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(System.Drawing.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 System.Drawing.Rectangle(0, 0, towidth, toheight),
new System.Drawing.Rectangle(x, y, ow, oh),
System.Drawing.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();
}
}。