上传缩略图，等比例压缩
前些日子一位同学问我怎么上传缩略图，并可以指定图片的尺度而且进行等比压缩。晚上，自己没事在网上看到一些网友发的帖子，都是挺好，最后我也写了一个上传的方法。供大家参考：
代码
1
public
byte
[] UploadFile(FileUpload f_Ifile,
int
ThumbnailWidth,
int
ThumbnailHeight,
string
resPathId,
string
otherPath)
2
{
3
try
4
{
5
//
获取客户端指定上传文件的访问
6
HttpPostedFile upfile
=
f_Ifile.PostedFile;
7
//
得到上传文件的长度
8
int
UpfileLength
=
upfile.ContentLength;
9
//
没有选择上传的文件
10
if
(UpfileLength
==
0
)
11
{
12
return
null
;
13
}
14
//
得到上传文件的客户端MIME类型
15
string
contentType
=
upfile.ContentType;
16
byte
[] fileArray
=
new
Byte[UpfileLength];
17
Stream fileStream
=
upfile.InputStream;
18
fileStream.Read(fileArray,
0
, UpfileLength);
19
string
filename
=
Path.GetFileName(upfile.FileName);
20
string
sExt
=
upfile.FileName.Substring(upfile.FileName.LastIndexOf(
"
.
"
)).ToLower();
21
//
读取xml判断上传的文件格式及大小
22
string
xmlPath
=
System.Web.HttpContext.Current.Server.MapPath(
"
~/File.xml
"
);
23
bool
postfix
=
Tools.UpDownFile.VerdictPostfixByFile(filename, xmlPath,
"
FileManager
"
,
"
id
"
,
"
UpImgFile
"
,
"
format
"
);
24
bool
size
=
Tools.UpDownFile.VerdictSizeByFile(f_Ifile, xmlPath,
"
FileManager
"
,
"
id
"
,
"
ImageSize
"
,
"
size
"
);
25
System.Drawing.Image xImage;
26
//
缩略图的高，宽
27
int
PhotoHeight, PhotoWidth;
28
//
创建新的图形
29
Rectangle NewPhoto;
30
//
位图图像
31
System.Drawing.Bitmap xBitmap;
32
//
路径
33
//
string filePath = "";
34
if
(postfix
==
true
&&
size
==
true
)
35
{
36
xImage
=
System.Drawing.Bitmap.FromStream(upfile.InputStream);
37
//
赋值，高和宽
38
//
this.ThumbnailHeight = xImage.Height.ToString();
39
//
this.ThumbnailWidth = xImage.Width.ToString();
40
if
(
this
.txtwidth.Text
==
""
)
41
{
42
ThumbnailWidth
=
Convert.ToInt32(xImage.Width.ToString());
43
}
44
else
45
{
46
ThumbnailWidth
=
Convert.ToInt32(
this
.txtwidth.Text);
47
}
48
if
(
this
.txtheight.Text
==
""
)
49
{
50
ThumbnailHeight
=
Convert.ToInt32(xImage.Height.ToString());
51
}
52
else
53
{
54
ThumbnailHeight
=
Convert.ToInt32(
this
.txtheight.Text);
55
}
56
//
上传资源模块的缩略图
57
if
(resPathId
!=
""
&&
otherPath
==
""
)
58
{
59
ResPath rp
=
BLL.ResPathManager.GetResPathByResModelId(Convert.ToInt32(resPathId));
60
if
(rp.ResPaths
!=
""
)
61
{
62
filepath
=
rp.ResPaths
+
@"
\Pic
"
;
63
}
64
else
65
{
66
return
null
;
67
}
68
}
69
//
上传的不是资源文件的缩略图
70
else
if
(resPathId
==
""
&&
otherPath
!=
""
)
71
{
72
filepath
=
otherPath;
73
if
(
!
Tools.IOHelp.CreateDirectory(filepath))
74
{
75
return
null
;
76
}
77
}
78
else
79
{
80
return
null
;
81
}
82
string
ranNum
=
Tools.FormatStr.GetUpFileName()
+
sExt;
83
filepath
=
filepath
+
@"
\
"
+
ranNum;
84
xBitmap
=
new
System.Drawing.Bitmap(fileStream);
85
86
PhotoHeight
=
xBitmap.Height;
87
PhotoWidth
=
xBitmap.Width;
88
if
(Convert.ToDecimal(PhotoHeight)
/
Convert.ToDecimal(PhotoWidth)
>
Convert.ToDecimal(PhotoHeight)
/
Convert.ToDecimal(PhotoWidth))
89
{
90
PhotoHeight
=
Convert.ToInt16((Convert.ToDecimal(ThumbnailHeight)
/
Convert.ToDecimal(ThumbnailWidth))
*
Convert.ToDecimal(PhotoWidth));
91
NewPhoto
=
new
Rectangle(Convert.ToInt16((Convert.ToDecimal(xBitmap.Width)
-
Convert.ToDecimal(PhotoWidth))
/
2
),
0
, PhotoWidth, PhotoHeight);
92
}
93
else
if
(Convert.ToDecimal(PhotoHeight)
/
Convert.ToDecimal(PhotoWidth)
<
Convert.ToDecimal(ThumbnailHeight)
/
Convert.ToDecimal(ThumbnailWidth))
94
{
95
PhotoWidth
=
Convert.ToInt16((Convert.ToDecimal(ThumbnailWidth)
/
Convert.ToDecimal(ThumbnailHeight))
*
Convert.ToDecimal(PhotoHeight));
96
97
NewPhoto
=
new
98
Rectangle(Convert.ToInt16((Convert.ToDecimal(xBitmap.Width)
-
Convert.ToDecimal(PhotoWidth))
/
2
),
0
, PhotoWidth, PhotoHeight);
99
}
100
else
101
{
102
NewPhoto
=
new
Rectangle(
0
,
0
, PhotoWidth, PhotoHeight);
103
}
104
105
System.Drawing.Image myBitmap;
106
myBitmap
=
xBitmap.Clone(NewPhoto, System.Drawing.Imaging.PixelFormat.DontCare);
107
System.Drawing.Image.GetThumbnailImageAbort myCallback
=
new
System.Drawing.Image.GetThumbnailImageAbort(ThumbnailCallback);
108
System.Drawing.Image myThumbnail
=
xImage.GetThumbnailImage(ThumbnailWidth, ThumbnailHeight, myCallback, IntPtr.Zero);
109
110
myThumbnail.Save(filepath);
111
this
.Label1.Text
=
ranNum;
112
113
myThumbnail.Dispose();
114
myBitmap.Dispose();
115
xBitmap.Dispose();
116
return
fileArray;
117
}
118
}
119
catch
(Exception ex)
120
{
121
122
return
null
;
123
}
124
return
null
;
125
}
上述为上传缩略图的方法，涉及到读取xml文件和存储地址，不是很完整，掉了个方法，补上：
private
static
bool
ThumbnailCallback() {
return
false
; }