C#裁剪照片并保存

/// <summary>
///
/// </summary>
/// <summary>
/// 生成缩略图
/// </summary>
/// <param name="sSavePath">源图路径（物理路径）</param>
/// <param name="sThumbExtension">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 string UpLoadImage(HtmlInputFile upImage, string sSavePath, string sThumbExtension, int intThumbWidth, int intThumbHeight)
{
string sThumbFile = "";
string sFilename = "";

if (upImage.PostedFile != null)
{
HttpPostedFile myFile = upImage.PostedFile;
int nFileLen = myFile.ContentLength;
if (nFileLen == 0)
return "没有选择上传图片";

//获取upImage选择文件的扩展名
string extendName = System.IO.Path.GetExtension(myFile.FileName).ToLower();
//判断是否为图片格式
if (extendName != ".jpg" && extendName != ".jpge" && extendName != ".gif" && extendName != ".bmp" && extendName != ".png")
return "图片格式不正确";

byte[] myData = new Byte[nFileLen];
myFile.InputStream.Read(myData, 0, nFileLen);

sFilename = System.IO.Path.GetFileName(myFile.FileName);
int file_append = 0;
//检查当前文件夹下是否有同名图片,有则在文件名+1
while (System.IO.File.Exists(System.Web.HttpContext.Current.Server.MapPath(sSavePath + sFilename)))
{
file_append++;
sFilename = System.IO.Path.GetFileNameWithoutExtension(myFile.FileName)
+ file_append.ToString() + extendName;
}
System.IO.FileStream newFile
= new System.IO.FileStream(System.Web.HttpContext.Current.Server.MapPath(sSavePath + sFilename),
System.IO.FileMode.Create, System.IO.FileAccess.Write);
newFile.Write(myData, 0, myData.Length);
newFile.Close();

//以上为上传原图

try
{
//原图加载
using (System.Drawing.Image sourceImage = System.Drawing.Image.FromFile(System.Web.HttpContext.Current.Server.MapPath(sSavePath + sFilename)))
{
//原图宽度和高度
int width = sourceImage.Width;
int height = sourceImage.Height;
int smallWidth;
int smallHeight;

//获取第一张绘制图的大小,(比较 原图的宽/缩略图的宽 和 原图的高/缩略图的高)
if (((decimal)width) / height <= ((decimal)intThumbWidth) / intThumbHeight)
{
smallWidth = intThumbWidth;
smallHeight = intThumbWidth * height / width;
}
else
{
smallWidth = intThumbHeight * width / height;
smallHeight = intThumbHeight;
}
//判断缩略图在当前文件夹下是否同名称文件存在
file_append = 0;
sThumbFile = sThumbExtension + System.IO.Path.GetFileNameWithoutExtension(myFile.FileName) + extendName;

while (System.IO.File.Exists(System.Web.HttpContext.Current.Server.MapPath(sSavePath + sThumbFile)))
{
file_append++;
sThumbFile = sThumbExtension + System.IO.Path.GetFileNameWithoutExtension(myFile.FileName) +
file_append.ToString() + extendName;
}
//缩略图保存的绝对路径
string smallImagePath = System.Web.HttpContext.Current.Server.MapPath(sSavePath) + sThumbFile;

//新建一个图板,以最小等比例压缩大小绘制原图
using (System.Drawing.Image bitmap = new System.Drawing.Bitmap(smallWidth, smallHeight))
{
//绘制中间图
using (System.Drawing.Graphics g = System.Drawing.Graphics.FromImage(bitmap))
{
//高清,平滑
g.InterpolationMode = System.Drawing.Drawing2D.InterpolationMode.High;
g.SmoothingMode = System.Drawing.Drawing2D.SmoothingMode.HighQuality;
g.Clear(Color.Black);
g.DrawImage( sourceImage,
new System.Drawing.Rectangle(0, 0, smallWidth, smallHeight),
new System.Drawing.Rectangle(0, 0, width, height),
System.Drawing.GraphicsUnit.Pixel
);
}
//新建一个图板,以缩略图大小绘制中间图
using (System.Drawing.Image bitmap1 = new System.Drawing.Bitmap(intThumbWidth, intThumbHeight))
{
//绘制缩略图
using (System.Drawing.Graphics g = System.Drawing.Graphics.FromImage(bitmap1))
{
//高清,平滑
g.InterpolationMode = System.Drawing.Drawing2D.InterpolationMode.High;
g.SmoothingMode = System.Drawing.Drawing2D.SmoothingMode.HighQuality;
g.Clear(Color.Black);
int lwidth = (smallWidth - intThumbWidth) / 2;
int bheight = (smallHeight - intThumbHeight) / 2;
g.DrawImage(bitmap, new Rectangle(0, 0, intThumbWidth, intThumbHeight), lwidth, bheight, intThumbWidth, intThumbHeight, GraphicsUnit.Pixel);
g.Dispose();
bitmap1.Save(smallImagePath, System.Drawing.Imaging.ImageFormat.Jpeg);
}
}
}
}
}
catch
{
//出错则删除
System.IO.File.Delete(System.Web.HttpContext.Current.Server.MapPath(sSavePath + sFilename)); return "图片格式不正确";
}
//返回缩略图名称
return sThumbFile;
}
return "没有选择图片";
}