获取ASP.NET VB.NET网站缩略图截图

Question

你好我设法使用ClassWSThumb类（你可以在这里找到它http://www.codeproject.com/KB/aspnet/Website_URL_Screenshot.aspx），以便从网页获取屏幕截图。 下面是类文件：

Imports System.Drawing 
Imports System.Windows.Forms 
Imports System.Threading 
Imports System.IO 

Namespace GetWebSiteThumb 
    Public Class ClassWSThumb 
     Public Shared Function GetWebSiteThumbnail(ByVal Url As String, ByVal BrowserWidth As Integer, ByVal BrowserHeight As Integer, ByVal ThumbnailWidth As Integer, ByVal ThumbnailHeight As Integer) As Bitmap 
      Return New WSThumb(Url, BrowserWidth, BrowserHeight, ThumbnailWidth, ThumbnailHeight).GetWSThumb() 
     End Function 

     Private Class WSThumb 
      Public Sub New(ByVal Url As String, ByVal BW As Integer, ByVal BH As Integer, ByVal TW As Integer, ByVal TH As Integer) 
       __Url = Url 
       __BrowserWidth = BW 
       __BrowserHeight = BH 
       __ThumbnailWidth = TW 
       __ThumbnailHeight = TH 
      End Sub 

      Private __Bitmap As Bitmap = Nothing 
      Private __Url As String = Nothing 
      Private __ThumbnailWidth As Integer 
      Private __ThumbnailHeight As Integer 
      Private __BrowserWidth As Integer 
      Private __BrowserHeight As Integer 

      Public Property Url() As String 
       Get 
        Return __Url 
       End Get 
       Set(ByVal value As String) 
        __Url = value 
       End Set 
      End Property 

      Public ReadOnly Property ThumbnailImage() As Bitmap 
       Get 
        Return __Bitmap 
       End Get 
      End Property 

      Public Property ThumbnailWidth() As Integer 
       Get 
        Return __ThumbnailWidth 
       End Get 
       Set(ByVal value As Integer) 
        __ThumbnailWidth = value 
       End Set 
      End Property 

      Public Property ThumbnailHeight() As Integer 
       Get 
        Return __ThumbnailHeight 
       End Get 
       Set(ByVal value As Integer) 
        __ThumbnailHeight = value 
       End Set 
      End Property 

      Public Property BrowserWidth() As Integer 
       Get 
        Return __BrowserWidth 
       End Get 
       Set(ByVal value As Integer) 
        __BrowserWidth = value 
       End Set 
      End Property 

      Public Property BrowserHeight() As Integer 
       Get 
        Return __BrowserHeight 
       End Get 
       Set(ByVal value As Integer) 
        __BrowserHeight = value 
       End Set 
      End Property 

      Public Function GetWSThumb() As Bitmap 
       Dim __threadStart As New ThreadStart(AddressOf _GenerateWSThumb) 
       Dim __thread As New Thread(__threadStart) 

       __thread.SetApartmentState(ApartmentState.STA) 
       __thread.Start() 
       __thread.Join() 
       Return __Bitmap 
      End Function 

      Private Sub _GenerateWSThumb() 
       Dim __WebBrowser As New WebBrowser() 
       __WebBrowser.ScrollBarsEnabled = False 
       __WebBrowser.Navigate(__Url) 
       AddHandler __WebBrowser.DocumentCompleted, New WebBrowserDocumentCompletedEventHandler(AddressOf WebBrowser_DocumentCompleted) 
       While __WebBrowser.ReadyState <> WebBrowserReadyState.Complete 
        Application.DoEvents() 
       End While 
       __WebBrowser.Dispose() 
      End Sub 

      Private Sub WebBrowser_DocumentCompleted(ByVal sender As Object, ByVal e As WebBrowserDocumentCompletedEventArgs) 
       Dim __WebBrowser As WebBrowser = DirectCast(sender, WebBrowser) 
       __WebBrowser.ClientSize = New Size(Me.__BrowserWidth, Me.__BrowserHeight) 
       __WebBrowser.ScrollBarsEnabled = False 
       __Bitmap = New Bitmap(__WebBrowser.Bounds.Width, __WebBrowser.Bounds.Height) 
       __WebBrowser.BringToFront() 
       __WebBrowser.DrawToBitmap(__Bitmap, __WebBrowser.Bounds) 

       If __ThumbnailHeight <> 0 AndAlso __ThumbnailWidth <> 0 Then 
        __Bitmap = DirectCast(__Bitmap.GetThumbnailImage(__ThumbnailWidth, __ThumbnailHeight, Nothing, IntPtr.Zero), Bitmap) 
       End If 
      End Sub 
     End Class 
    End Class 
End Namespace 

，这里是实施

Protected Sub btnExportToIMG_Click(ByVal sender As Object, ByVal e As System.EventArgs) Handles btnExportToIMG.Click 
     'This Code Exports to Image 
     StartDuration()   
     Dim url As String = "http://somepage" 

     '//example as a Class Method 
     Dim bmp As Bitmap = ClassWSThumb.GetWebSiteThumbnail(url, Int32.Parse(800), Int32.Parse(600), Int32.Parse(800), Int32.Parse(600)) 
     bmp.Save(Server.MapPath("~") + "/exportedpdf/thumbnail.bmp") 
     Image1.ImageUrl = "~/thumbnail.bmp" 
     Image1.Width = 800 
     Image1.Height = 600 
     StopDuration() 


    End Sub 
End Class 

似乎一切都完美的工作，但我碰上的情况是，我不知道如何处理。 如果目标网站有一些需要在就绪状态之后加载的ajax信息，我得到了没有数据的页面的屏幕截图，因为数据尚未加载。

有什么建议吗？

Answer 1

尝试增加在WebBrowser_DocumentCompleted子程序的顶部以下...

'Give the Browser 15 seconds to load Ajax data. 
System.Threading.Thread.Sleep(15000) 

Answer 2

出色的代码。 我在打印页面时遇到问题，页面无法加载所有javascript，我做了一个修改，我在下面展示。它的工作完美，我希望你觉得它有用。

 Private Sub _GenerateWSThumb() 
     Dim __WebBrowser As New WebBrowser() 
     __WebBrowser.ScrollBarsEnabled = False 
     __WebBrowser.ObjectForScripting = True 
     __WebBrowser.Navigate(__Url) 

     While __WebBrowser.ReadyState <> WebBrowserReadyState.Complete 
      Windows.Forms.Application.DoEvents() 
     End While 
     ' start my modification 
     AddHandler __WebBrowser.DocumentCompleted, New WebBrowserDocumentCompletedEventHandler(AddressOf WebBrowser_DocumentCompleted) 

     Dim e As WebBrowserDocumentCompletedEventArgs 
     WebBrowser_DocumentCompleted(__WebBrowser, e) 
     ' end my modification 
     __WebBrowser.Dispose() 
    End Sub 

“Ajax和JavaScript满载