以前在页面上实现缩略图必须借助第三方组件现在有了NET就可以很轻松地实现缩略图下面就是实现缩略图的例子
查看例子
代码如下
Thumbnailaspx
＜%@ Page Language=vb AutoEventWireup=false Codebehind=Thumbnailaspxvb
Inherits=aspxWebThumbnail %＞
＜!DOCTYPE HTML PUBLIC //WC//DTD HTML Transitional//EN＞
＜HTML＞
＜HEAD＞
＜title＞在ASPNET里轻松实现缩略图＜/title＞
＜meta content=Microsoft Visual StudioNET name=GENERATOR＞
＜meta content=Visual Basic name=CODE_LANGUAGE＞
＜meta content=JavaScript name=vs_defaultClientScript＞
＜meta content=http://schemasmicrosoftcom/intellisense/ie name=vs_targetSchema＞
＜/HEAD＞
＜body MS_POSITIONING=GridLayout＞
＜asp:Label id=Label runat=server＞＜/asp:Label＞
＜form id=Form method=post runat=server enctype=multipart/formdata＞
＜INPUT type=file name=file width=＞＜br＞＜br＞
＜asp:Button id=Button runat=server＞＜/asp:Button＞
＜/form＞
＜/body＞
＜/HTML＞
后代码Thumbnailaspxvb
Imports System
Imports SystemWeb
Imports SystemDrawing
Imports SystemIO
Imports SystemDrawingImaging
Public Class Thumbnail
Inherits SystemWebUIPage
Protected WithEvents Label As SystemWebUIWebControlsLabel
Protected WithEvents Button As SystemWebUIWebControlsButton
#Region Web Form Designer Generated Code
This call is required by the Web Form Designer
＜SystemDiagnosticsDebuggerStepThrough()＞ Private Sub InitializeComponent()
End Sub
Private Sub Page_Init(ByVal sender As SystemObject ByVal e As SystemEventArgs) Handles MyBaseInit
CODEGEN: This method call is required by the Web Form Designer
Do not modify it using the code editor
InitializeComponent()
End Sub
#End Region
Private Sub Page_Load(ByVal sender As SystemObject ByVal e As SystemEventArgs) Handles MyBaseLoad
LabelText = ＜h＞在ASPNET里轻松实现缩略图＜/h＞
ButtonText = 上载并显示缩略图
End Sub
Private Sub Button_Click(ByVal sender As Object ByVal e As SystemEventArgs) Handles ButtonClick
Dim MyFileColl As HttpFileCollection = HttpContextCurrentRequestFiles
Dim MyPostedFile As HttpPostedFile = MyFileCollItem()
If LCase(MyPostedFileContentTypeToString())IndexOf(image) ＜ Then
ResponseWrite(无效的图形格式)
Exit Sub
End If
GetThumbNail(MyPostedFileFileName MyPostedFileContentTypeToString()_
False MyPostedFileInputStream)
End Sub
Private Function GetImageType(ByVal strContentType) As SystemDrawingImagingImageFormat
Select Case (strContentTypeToString()ToLower())
Case image/pjpeg
GetImageType = SystemDrawingImagingImageFormatJpeg
Case image/gif
GetImageType = SystemDrawingImagingImageFormatGif
Case image/bmp
GetImageType = SystemDrawingImagingImageFormatBmp
Case image/tiff
GetImageType = SystemDrawingImagingImageFormatTiff
Case image/xicon
GetImageType = SystemDrawingImagingImageFormatIcon
Case image/xpng
GetImageType = SystemDrawingImagingImageFormatPng
Case image/xemf
GetImageType = SystemDrawingImagingImageFormatEmf
Case image/xexif
GetImageType = SystemDrawingImagingImageFormatExif
Case image/xwmf
GetImageType = SystemDrawingImagingImageFormatWmf
Case Else
GetImageType = SystemDrawingImagingImageFormatMemoryBmp
End Select
End Function
Private Sub GetThumbNail(ByVal strFileName ByVal iWidth ByVal iheight ByVal strContentType _
ByVal blnGetFromFile ByVal ImgStream)
Dim oImg As Image
If blnGetFromFile Then
oImg = oImgFromFile(strFileName)
Else
oImg = oImgFromStream(ImgStream)
End If
oImg = oImgGetThumbnailImage(iWidth iheight Nothing (New IntPtr())Zero)
Dim strGuid As String = (New Guid())NewGuid()ToString()ToUpper()
Dim strFileExt As String = strFileNameSubstring(strFileNameLastIndexOf())
保存到本地
oImgSave(ServerMapPath(images) + \ + strGuid + strFileExt GetImageType(strContentType))
直接输出url文件
ResponseRedirect(images/ + strGuid + strFileExt)
以下显示在屏幕上
ResponseContentType = strContentType
Dim MemStream As New MemoryStream()
注意这里如果直接用 oImgSave(ResponseOutputStream GetImageType(strContentType))
对不同的格式可能会出错比如Png格式
oImgSave(MemStream GetImageType(strContentType))
MemStreamWriteTo(ResponseOutputStream)
End Sub
End Class
