转自:http://www.jb51.net/article/48831.htm
这篇文章主要介绍了c#生成高清缩略图的二个示例,需要的朋友可以参考下

1. 
   
2. /// <summary>
   
3. /// 为图片生成缩略图
   
4. /// </summary>
   
5. /// <param name="phyPath">原图片的路径</param>
   
6. /// <param name="width">缩略图宽</param>
   
7. /// <param name="height">缩略图高</param>
   
8. /// <returns></returns>
   
9. public System.Drawing.Image GetThumbnail(System.Drawing.Image image, int width, intheight)
   
10. {
    
11. Bitmap bmp = newBitmap(width, height);
    
12. //从Bitmap创建一个System.Drawing.Graphics
    
13. System.Drawing.Graphics gr = System.Drawing.Graphics.FromImage(bmp);
    
14. //设置
    
15. gr.SmoothingMode = System.Drawing.Drawing2D.SmoothingMode.HighQuality;
    
16. //下面这个也设成高质量
    
17. gr.CompositingQuality = System.Drawing.Drawing2D.CompositingQuality.HighQuality;
    
18. //下面这个设成High
    
19. gr.InterpolationMode = System.Drawing.Drawing2D.InterpolationMode.HighQualityBicubic;
    
20. //把原始图像绘制成上面所设置宽高的缩小图
    
21. System.Drawing.Rectangle rectDestination = newSystem.Drawing.Rectangle(0, 0, width, height);
    
22. gr.DrawImage(image, rectDestination, 0, 0, image.Width, image.Height, GraphicsUnit.Pixel);
    
23. returnbmp;
    
24. }
    

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调用方法

1. 
   
2. HttpPostedFile file = photoFile.PostedFile;
   
3. if(!file.ContentType.Contains("image"))
   
4. {
   
5. return"照片格式不合法";
   
6. }
   
7. stringext = Path.GetExtension(file.FileName).ToLower();
   
8. if (ext != ".jpg" && ext != ".gif" && ext != ".png"&& ext != ".jpeg")
   
9. {
   
10. return"请您上传jpg、gif、png图片";
    
11. }
    
12. if(file.ContentLength > 5 * 1024 * 1024)
    
13. {
    
14. return"请您上传512字节内的图片";
    
15. }
    
16. stringnewName = Guid.NewGuid().ToString();
    
17. stringtempPath = "upload/";
    
18. stringimg = tempPath + newName + ext;
    
19. stringfilePath = Server.MapPath(img);
    
20. if(!Directory.Exists(tempPath))
    
21. {
    
22. Directory.CreateDirectory(tempPath);
    
23. }
    
24. using(System.Drawing.Image originalImage = System.Drawing.Image.FromStream(file.InputStream))
    
25. {
    
26. GetThumbnail(originalImage, 504, 374).Save(filePath);

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示例2

1. 
   
2. public void MakeThumbnail(string originalImagePath, string thumbnailPath, int width, int height)
   
3. {
   
4. //获取原始图片
   
5. System.Drawing.Image originalImage = System.Drawing.Image.FromFile(originalImagePath);
   
6. //缩略图画布宽高
   
7. int towidth = width;
   
8. int toheight = height;
   
9. //原始图片写入画布坐标和宽高(用来设置裁减溢出部分)
   
10. int x = 0;
    
11. int y = 0;
    
12. int ow = originalImage.Width;
    
13. int oh = originalImage.Height;
    
14. //原始图片画布,设置写入缩略图画布坐标和宽高(用来原始图片整体宽高缩放)
    
15. int bg_x = 0;
    
16. int bg_y = 0;
    
17. int bg_w = towidth;
    
18. int bg_h = toheight;
    
19. //倍数变量
    
20. double multiple = 0;
    
21. //获取宽长的或是高长与缩略图的倍数
    
22. if (originalImage.Width >= originalImage.Height)
    
23. multiple = (double)originalImage.Width / (double)width;
    
24. else
    
25. multiple = (double)originalImage.Height / (double)height;
    
26. //上传的图片的宽和高小等于缩略图
    
27. if (ow <= width && oh <= height)
    
28. {
    
29. //缩略图按原始宽高
    
30. bg_w = originalImage.Width;
    
31. bg_h = originalImage.Height;
    
32. //空白部分用背景色填充
    
33. bg_x = Convert.ToInt32(((double)towidth - (double)ow) / 2);
    
34. bg_y = Convert.ToInt32(((double)toheight - (double)oh) / 2);
    
35. }
    
36. //上传的图片的宽和高大于缩略图
    
37. else
    
38. {
    
39. //宽高按比例缩放
    
40. bg_w = Convert.ToInt32((double)originalImage.Width / multiple);
    
41. bg_h = Convert.ToInt32((double)originalImage.Height / multiple);
    
42. //空白部分用背景色填充
    
43. bg_y = Convert.ToInt32(((double)height - (double)bg_h) / 2);
    
44. bg_x = Convert.ToInt32(((double)width - (double)bg_w) / 2);
    
45. }
    
46. //新建一个bmp图片,并设置缩略图大小.
    
47. System.Drawing.Image bitmap = new System.Drawing.Bitmap(towidth, toheight);
    
48. //新建一个画板
    
49. System.Drawing.Graphics g = System.Drawing.Graphics.FromImage(bitmap);
    
50. //设置高质量插值法
    
51. g.InterpolationMode = System.Drawing.Drawing2D.InterpolationMode.HighQualityBilinear;
    
52. //设置高质量,低速度呈现平滑程度
    
53. g.SmoothingMode = System.Drawing.Drawing2D.SmoothingMode.HighQuality;
    
54. //清空画布并设置背景色
    
55. g.Clear(System.Drawing.ColorTranslator.FromHtml("#F2F2F2"));
    
56. //在指定位置并且按指定大小绘制原图片的指定部分
    
57. //第一个System.Drawing.Rectangle是原图片的画布坐标和宽高,第二个是原图片写在画布上的坐标和宽高,最后一个参数是指定数值单位为像素
    
58. g.DrawImage(originalImage, new System.Drawing.Rectangle(bg_x, bg_y, bg_w, bg_h), new System.Drawing.Rectangle(x, y, ow, oh), System.Drawing.GraphicsUnit.Pixel);
    
59. try
    
60. {
    
61. //获取图片类型
    
62. string fileExtension = System.IO.Path.GetExtension(originalImagePath).ToLower();
    
63. //按原图片类型保存缩略图片,不按原格式图片会出现模糊,锯齿等问题.
    
64. switch (fileExtension)
    
65. {
    
66. case ".gif": bitmap.Save(thumbnailPath, System.Drawing.Imaging.ImageFormat.Gif); break;
    
67. case ".jpg": bitmap.Save(thumbnailPath, System.Drawing.Imaging.ImageFormat.Jpeg); break;
    
68. case ".bmp": bitmap.Save(thumbnailPath, System.Drawing.Imaging.ImageFormat.Bmp); break;
    
69. case ".png": bitmap.Save(thumbnailPath, System.Drawing.Imaging.ImageFormat.Png); break;
    
70. }
    
71. }
    
72. catch (System.Exception e)
    
73. {
    
74. throw e;
    
75. }
    
76. finally
    
77. {
    
78. originalImage.Dispose();
    
79. bitmap.Dispose();
    
80. g.Dispose();
    
81. }
    
82. }

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转自:http://www.jb51.net/article/48831.htm
这篇文章主要介绍了c#生成高清缩略图的二个示例,需要的朋友可以参考下

1. 
   
2. /// <summary>
   
3. /// 为图片生成缩略图
   
4. /// </summary>
   
5. /// <param name="phyPath">原图片的路径</param>
   
6. /// <param name="width">缩略图宽</param>
   
7. /// <param name="height">缩略图高</param>
   
8. /// <returns></returns>
   
9. public System.Drawing.Image GetThumbnail(System.Drawing.Image image, int width, intheight)
   
10. {
    
11. Bitmap bmp = newBitmap(width, height);
    
12. //从Bitmap创建一个System.Drawing.Graphics
    
13. System.Drawing.Graphics gr = System.Drawing.Graphics.FromImage(bmp);
    
14. //设置
    
15. gr.SmoothingMode = System.Drawing.Drawing2D.SmoothingMode.HighQuality;
    
16. //下面这个也设成高质量
    
17. gr.CompositingQuality = System.Drawing.Drawing2D.CompositingQuality.HighQuality;
    
18. //下面这个设成High
    
19. gr.InterpolationMode = System.Drawing.Drawing2D.InterpolationMode.HighQualityBicubic;
    
20. //把原始图像绘制成上面所设置宽高的缩小图
    
21. System.Drawing.Rectangle rectDestination = newSystem.Drawing.Rectangle(0, 0, width, height);
    
22. gr.DrawImage(image, rectDestination, 0, 0, image.Width, image.Height, GraphicsUnit.Pixel);
    
23. returnbmp;
    
24. }
    

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调用方法

1. 
   
2. HttpPostedFile file = photoFile.PostedFile;
   
3. if(!file.ContentType.Contains("image"))
   
4. {
   
5. return"照片格式不合法";
   
6. }
   
7. stringext = Path.GetExtension(file.FileName).ToLower();
   
8. if (ext != ".jpg" && ext != ".gif" && ext != ".png"&& ext != ".jpeg")
   
9. {
   
10. return"请您上传jpg、gif、png图片";
    
11. }
    
12. if(file.ContentLength > 5 * 1024 * 1024)
    
13. {
    
14. return"请您上传512字节内的图片";
    
15. }
    
16. stringnewName = Guid.NewGuid().ToString();
    
17. stringtempPath = "upload/";
    
18. stringimg = tempPath + newName + ext;
    
19. stringfilePath = Server.MapPath(img);
    
20. if(!Directory.Exists(tempPath))
    
21. {
    
22. Directory.CreateDirectory(tempPath);
    
23. }
    
24. using(System.Drawing.Image originalImage = System.Drawing.Image.FromStream(file.InputStream))
    
25. {
    
26. GetThumbnail(originalImage, 504, 374).Save(filePath);

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示例2

1. 
   
2. public void MakeThumbnail(string originalImagePath, string thumbnailPath, int width, int height)
   
3. {
   
4. //获取原始图片
   
5. System.Drawing.Image originalImage = System.Drawing.Image.FromFile(originalImagePath);
   
6. //缩略图画布宽高
   
7. int towidth = width;
   
8. int toheight = height;
   
9. //原始图片写入画布坐标和宽高(用来设置裁减溢出部分)
   
10. int x = 0;
    
11. int y = 0;
    
12. int ow = originalImage.Width;
    
13. int oh = originalImage.Height;
    
14. //原始图片画布,设置写入缩略图画布坐标和宽高(用来原始图片整体宽高缩放)
    
15. int bg_x = 0;
    
16. int bg_y = 0;
    
17. int bg_w = towidth;
    
18. int bg_h = toheight;
    
19. //倍数变量
    
20. double multiple = 0;
    
21. //获取宽长的或是高长与缩略图的倍数
    
22. if (originalImage.Width >= originalImage.Height)
    
23. multiple = (double)originalImage.Width / (double)width;
    
24. else
    
25. multiple = (double)originalImage.Height / (double)height;
    
26. //上传的图片的宽和高小等于缩略图
    
27. if (ow <= width && oh <= height)
    
28. {
    
29. //缩略图按原始宽高
    
30. bg_w = originalImage.Width;
    
31. bg_h = originalImage.Height;
    
32. //空白部分用背景色填充
    
33. bg_x = Convert.ToInt32(((double)towidth - (double)ow) / 2);
    
34. bg_y = Convert.ToInt32(((double)toheight - (double)oh) / 2);
    
35. }
    
36. //上传的图片的宽和高大于缩略图
    
37. else
    
38. {
    
39. //宽高按比例缩放
    
40. bg_w = Convert.ToInt32((double)originalImage.Width / multiple);
    
41. bg_h = Convert.ToInt32((double)originalImage.Height / multiple);
    
42. //空白部分用背景色填充
    
43. bg_y = Convert.ToInt32(((double)height - (double)bg_h) / 2);
    
44. bg_x = Convert.ToInt32(((double)width - (double)bg_w) / 2);
    
45. }
    
46. //新建一个bmp图片,并设置缩略图大小.
    
47. System.Drawing.Image bitmap = new System.Drawing.Bitmap(towidth, toheight);
    
48. //新建一个画板
    
49. System.Drawing.Graphics g = System.Drawing.Graphics.FromImage(bitmap);
    
50. //设置高质量插值法
    
51. g.InterpolationMode = System.Drawing.Drawing2D.InterpolationMode.HighQualityBilinear;
    
52. //设置高质量,低速度呈现平滑程度
    
53. g.SmoothingMode = System.Drawing.Drawing2D.SmoothingMode.HighQuality;
    
54. //清空画布并设置背景色
    
55. g.Clear(System.Drawing.ColorTranslator.FromHtml("#F2F2F2"));
    
56. //在指定位置并且按指定大小绘制原图片的指定部分
    
57. //第一个System.Drawing.Rectangle是原图片的画布坐标和宽高,第二个是原图片写在画布上的坐标和宽高,最后一个参数是指定数值单位为像素
    
58. g.DrawImage(originalImage, new System.Drawing.Rectangle(bg_x, bg_y, bg_w, bg_h), new System.Drawing.Rectangle(x, y, ow, oh), System.Drawing.GraphicsUnit.Pixel);
    
59. try
    
60. {
    
61. //获取图片类型
    
62. string fileExtension = System.IO.Path.GetExtension(originalImagePath).ToLower();
    
63. //按原图片类型保存缩略图片,不按原格式图片会出现模糊,锯齿等问题.
    
64. switch (fileExtension)
    
65. {
    
66. case ".gif": bitmap.Save(thumbnailPath, System.Drawing.Imaging.ImageFormat.Gif); break;
    
67. case ".jpg": bitmap.Save(thumbnailPath, System.Drawing.Imaging.ImageFormat.Jpeg); break;
    
68. case ".bmp": bitmap.Save(thumbnailPath, System.Drawing.Imaging.ImageFormat.Bmp); break;
    
69. case ".png": bitmap.Save(thumbnailPath, System.Drawing.Imaging.ImageFormat.Png); break;
    
70. }
    
71. }
    
72. catch (System.Exception e)
    
73. {
    
74. throw e;
    
75. }
    
76. finally
    
77. {
    
78. originalImage.Dispose();
    
79. bitmap.Dispose();
    
80. g.Dispose();
    
81. }
    
82. }

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