C#生成高清缩略图

01	/// <summary>

02	/// 为图片生成缩略图

03	/// </summary>

04	/// <param name="phyPath">原图片的路径</param>

05	/// <param name="width">缩略图宽</param>

06	/// <param name="height">缩略图高</param>

07	/// <returns></returns>

08	public System.Drawing.Image GetThumbnail(System.Drawing.Image image, int width, intheight)

09

{

10	Bitmap bmp = newBitmap(width, height);

11	//从Bitmap创建一个System.Drawing.Graphics

12	System.Drawing.Graphics gr = System.Drawing.Graphics.FromImage(bmp);

13

//设置

14	gr.SmoothingMode = System.Drawing.Drawing2D.SmoothingMode.HighQuality;

15	//下面这个也设成高质量

16	gr.CompositingQuality = System.Drawing.Drawing2D.CompositingQuality.HighQuality;

17	//下面这个设成High

18	gr.InterpolationMode = System.Drawing.Drawing2D.InterpolationMode.HighQualityBicubic;

19	//把原始图像绘制成上面所设置宽高的缩小图

20	System.Drawing.Rectangle rectDestination = newSystem.Drawing.Rectangle(0, 0, width, height);

21

22	gr.DrawImage(image, rectDestination, 0, 0, image.Width, image.Height, GraphicsUnit.Pixel);

23	returnbmp;

24

}

调用方法

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01	HttpPostedFile file = photoFile.PostedFile;

02	if(!file.ContentType.Contains("image"))

03

{

04	return"照片格式不合法";

05

}

06	stringext = Path.GetExtension(file.FileName).ToLower();

07	if (ext != ".jpg" && ext != ".gif" && ext != ".png"&& ext != ".jpeg")

08

{

09	return"请您上传jpg、gif、png图片";

10

}

11	if(file.ContentLength > 5 * 1024 * 1024)

12

{

13	return"请您上传512字节内的图片";

14

}

15	stringnewName = Guid.NewGuid().ToString();

16	stringtempPath = "upload/";

17	stringimg = tempPath + newName + ext;

18	stringfilePath = Server.MapPath(img);

19	if(!Directory.Exists(tempPath))

20

{

21	Directory.CreateDirectory(tempPath);

22

}

23	using(System.Drawing.Image originalImage = System.Drawing.Image.FromStream(file.InputStream))

24

{

25	GetThumbnail(originalImage, 504, 374).Save(filePath);

26

}