/// <summary>
/// 图像处理类
/// </summary>
public static class ImageHandler
{
/// <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>
private static void MakeThumbnail(Stream PicStream, string thumbnailPath, int width, int height, string mode, string PicExtension)
{
System.Drawing.Image originalImage = System.Drawing.Image.FromStream(PicStream);
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
{
//根据原来的图片格式，保存为原图片格式
switch (PicExtension.ToLower())
{
case "jpg":
//以jpg格式保存缩略图
bitmap.Save(thumbnailPath, System.Drawing.Imaging.ImageFormat.Jpeg);
break;
case "jpeg":
bitmap.Save(thumbnailPath, System.Drawing.Imaging.ImageFormat.Jpeg);
break;
case "pjpeg":
bitmap.Save(thumbnailPath, System.Drawing.Imaging.ImageFormat.Jpeg);
break;
case "gif":
bitmap.Save(thumbnailPath, System.Drawing.Imaging.ImageFormat.Gif);
break;
case "bmp":
bitmap.Save(thumbnailPath, System.Drawing.Imaging.ImageFormat.Bmp);
break;
case "png":
bitmap.Save(thumbnailPath, System.Drawing.Imaging.ImageFormat.Png);
break;
default:
bitmap.Save(thumbnailPath, System.Drawing.Imaging.ImageFormat.Jpeg);
break;
}
}
catch (System.Exception e)
{
throw e;
}
finally
{
originalImage.Dispose();
bitmap.Dispose();
g.Dispose();
}
}
/// <summary>
/// 通过FileUpload上传图片并压缩图片大小
/// 四各形式：1)指定高 按比例缩放; 2)指定宽 按比例缩放; 3)不缩放; 4)指定宽高裁剪(不会变形).
/// </summary>
/// <param name="fu">FileUpload对象</param>
/// <param name="file">文件完整路径Path</param>
/// <param name="width">图片压缩后的宽度</param>
/// <param name="height">图片压缩后的高度</param>
/// <returns>返回文件存储的完整路径</returns>
public static string SavePicture(FileUpload fu, string file, int width, int height)
{
Random myRd = new Random();
string prefix = System.IO.Path.GetExtension(fu.FileName).ToLower();
string fileName = "";
if (prefix.Equals(".jpg") || prefix.Equals(".gif") || prefix.Equals(".jpeg") || prefix.Equals(".pjpeg") || prefix.Equals(".png") || prefix.Equals(".bmp"))
{
string strFileName = DateTime.Now.ToString("yyyyMMddHHmmss") + myRd.Next(1000) + prefix;
string name = System.Web.HttpContext.Current.Server.MapPath(file + strFileName);
fileName = HttpContext.Current.Server.MapPath(file);
string filepath = HttpContext.Current.Server.MapPath("/");
try
{
//获取上传图片的大小
Stream PicStream = fu.PostedFile.InputStream;
MakeThumbnail(PicStream, fileName + strFileName, 500, 375, "HW", prefix);//指定高宽缩放（可能变形）
if (width == 0 && height != 0)//指定高 按比例缩放
{
MakeThumbnail(PicStream, fileName + "small\\" + strFileName, width, height, "H", prefix);
}
else if (width != 0 && height == 0)//指定宽 按比例缩放
{
MakeThumbnail(PicStream, fileName + "small\\" + strFileName, width, height, "W", prefix);
}
else if (width == 0 && height == 0)//不缩放
{
fu.SaveAs(fileName + "small\\" + strFileName);
}
else//指定宽高裁剪(不会变形)
{
MakeThumbnail(PicStream, fileName + "small\\" + strFileName, width, height, "Cut", prefix);
}
//返回图片保存的路径
//fu.SaveAs(fileName + strFileName);//上传原图
return file + strFileName;
}
catch
{
return null;
}
}
else
{
return null;
}
}
/// <summary>
/// 创建文件夹
/// </summary>
/// <param name="directoryPath">文件夹路径</param>
public static void CreatDirectory(string directoryPath)
{
try
{
DirectoryInfo dirInfo;
string new_path = System.Web.HttpContext.Current.Server.MapPath(directoryPath);
dirInfo = new DirectoryInfo(new_path);
if (!dirInfo.Exists)
{
dirInfo.Create();
System.IO.Directory.CreateDirectory(new_path);
}
}
catch (System.Exception E)
{
throw E;
}
}
}