我想知道是否有人知道一个简单的方法让.pdf文件在加载时触发readystate。我正在构建一个程序来打开url并截取屏幕截图，然后将它们放入excel中。
Web浏览器将正确加载html文档，但在加载While Not pageready文件时卡在.pdf中。浏览器控件正确呈现.pdf。
Private Sub btngo_Click(ByVal sender As System.Object, ByVal e As System.EventArgs) Handles btngo.Click
Dim file As String
Dim Obj As New Object
Dim result As String
Dim sheet As String = "sheet1"
Dim xlApp As New Excel.Application
If lblpath.Text <> "" Then
file = lblpath.Text
Dim xlWorkBook = xlApp.Workbooks.Open(file)
Dim xlWorkSheet = xlWorkBook.Worksheets(sheet)
Dim range = xlWorkSheet.UsedRange
ProgressBar1.Value = 0
For rCnt = 4 To range.Rows.Count
'url cell
Obj = CType(range.Cells(rCnt, 2), Excel.Range)
' Obj.value now contains the value in the cell..
Try
' Creates an HttpWebRequest with the specified URL.
Dim myHttpWebRequest As HttpWebRequest = CType(WebRequest.Create(Obj.value), HttpWebRequest)
' Sends the request and waits for a response.
Dim myHttpWebResponse As HttpWebResponse = CType(myHttpWebRequest.GetResponse(), HttpWebResponse)
If myHttpWebResponse.StatusCode = HttpStatusCode.OK Then
result = myHttpWebResponse.StatusCode
WebBrowser1.ScrollBarsEnabled = False
WebBrowser1.Navigate(myHttpWebRequest.RequestUri)
WaitForPageLoad()
CaptureWebBrowser(WebBrowser1)
End If
' Release the resources of the response.
myHttpWebResponse.Close()
Catch ex As WebException
result = (ex.Message)
Catch ex As Exception
result = (ex.Message)
End Try
RichTextBox1.AppendText(result & " " & Obj.value & vbNewLine)
If radpre.Checked = True Then
range.Cells(rCnt, 3).value = result
ElseIf radcob.Checked = True Then
range.Cells(rCnt, 4).value = result
ElseIf radpost.Checked = True Then
range.Cells(rCnt, 5).value = result
End If
ProgressBar1.Value = rCnt / range.Rows.Count * 100
Next
With xlApp
.DisplayAlerts = False
xlWorkBook.SaveAs(lblpath.Text.ToString)
.DisplayAlerts = True
End With
xlWorkBook.Close()
xlApp.Quit()
'reclaim memory
Marshal.ReleaseComObject(xlApp)
xlApp = Nothing
End If
End Sub
Private Function CaptureWebBrowser(ByVal wb As WebBrowser) As Image
Try
Dim hBitmap As Bitmap = New Bitmap(wb.Width, wb.Height)
wb.DrawToBitmap(hBitmap, wb.Bounds)
Dim img As Image = hBitmap
Return img
Catch ex As Exception
MessageBox.Show(ex.Message)
End Try
Return Nothing
End Function
Private Sub WaitForPageLoad()
AddHandler WebBrowser1.DocumentCompleted, New WebBrowserDocumentCompletedEventHandler(AddressOf PageWaiter)
While Not pageready
Application.DoEvents()
End While
pageready = False
End Sub
Private Sub PageWaiter(ByVal sender As Object, ByVal e As WebBrowserDocumentCompletedEventArgs)
If WebBrowser1.ReadyState = WebBrowserReadyState.Complete Then
pageready = True
RemoveHandler WebBrowser1.DocumentCompleted, New WebBrowserDocumentCompletedEventHandler(AddressOf PageWaiter)
End If
End Sub
我对反馈非常满意。我非常喜欢提供的答案Noseratio。我不知道使用代码模式不是最佳实践。打开.pdf或任何其他文档时，基于网络的readyState永远不会从0更改。看到这个程序对我来说只是一种不工作的方式，我只对捕获.html和.htm感到满意。
我的要求是
程序解析和检索反馈的速度远远快于我能够手动执行的速度。 .html和.htm的屏幕截图为excel文件的非技术查看者提供了从生产到COB以及返回生产环境的成功迁移的证据。
Noseratio所述的此代码不遵循最佳做法，也不符合高质量要求。这是一个快速而肮脏的实现。
Option Infer On
Imports Microsoft.Office.Interop
Imports System.Net
Imports System.Runtime.InteropServices
Public Class Form1
Public Property pageready As Boolean
Private Sub OpenToolStripMenuItem_Click(ByVal sender As System.Object, ByVal e As System.EventArgs) Handles OpenToolStripMenuItem.Click
OpenFileDialog1.ShowDialog()
End Sub
Private Sub OpenFileDialog1_FileOk(ByVal sender As System.Object, ByVal e As System.ComponentModel.CancelEventArgs) Handles OpenFileDialog1.FileOk
lblpath.Text = OpenFileDialog1.FileName.ToString
End Sub
Private Sub btngo_Click(ByVal sender As System.Object, ByVal e As System.EventArgs) Handles btngo.Click
Dim file As String
Dim Obj As New Object
Dim result As String
Dim sheet As String = "sheet1"
Dim xlApp As New Excel.Application
Dim img As Bitmap
Dim path As String = "C:\Documents and Settings\user\My Documents\Visual Studio 2010\Projects\COB-HTML-Tool\COB-HTML-Tool\bin\Debug\tmp.bmp"
If lblpath.Text <> "" Then
file = lblpath.Text
Dim xlWorkBook = xlApp.Workbooks.Open(file)
Dim xlWorkSheet = xlWorkBook.Worksheets(sheet)
Dim range = xlWorkSheet.UsedRange
ProgressBar1.Value = 0
For rCnt = 4 To range.Rows.Count
'url cell
Obj = CType(range.Cells(rCnt, 2), Excel.Range)
' Obj.value now contains the value in the cell..
Try
' Creates an HttpWebRequest with the specified URL.
Dim myHttpWebRequest As HttpWebRequest = CType(WebRequest.Create(Obj.value), HttpWebRequest)
' Sends the request and waits for a response.
Dim myHttpWebResponse As HttpWebResponse = CType(myHttpWebRequest.GetResponse(), HttpWebResponse)
If myHttpWebResponse.StatusCode = HttpStatusCode.OK Then
result = myHttpWebResponse.StatusCode
Dim len As Integer = myHttpWebRequest.RequestUri.ToString.Length - 4
If myHttpWebRequest.RequestUri.ToString.Substring(len) = ".htm" Or
myHttpWebRequest.RequestUri.ToString.Substring(len - 1) = ".html" Or
myHttpWebRequest.RequestUri.ToString.Substring(len) = ".asp" Then
WebBrowser1.Navigate(myHttpWebRequest.RequestUri)
WaitForPageLoad()
img = CaptureWebBrowser(WebBrowser1)
img.Save(path)
End If
End If
' Release the resources of the response.
myHttpWebResponse.Close()
Catch ex As WebException
result = (ex.Message)
Catch ex As Exception
result = (ex.Message)
End Try
RichTextBox1.AppendText(result & " " & Obj.value & vbNewLine)
If radpre.Checked = True Then
range.Cells(rCnt, 3).value = result
If img Is Nothing Then
Else
If Dir(path) <> "" Then
range.Cells(rCnt, 4).Select()
Dim opicture As Object
opicture = xlApp.ActiveSheet.Pictures.Insert(path)
opicture.ShapeRange.LockAspectRatio = True
opicture.ShapeRange.width = 170
opicture.ShapeRange.height = 170
My.Computer.FileSystem.DeleteFile(path)
End If
End If
ElseIf radcob.Checked = True Then
range.Cells(rCnt, 5).value = result
If img Is Nothing Then
Else
If Dir(path) <> "" Then
range.Cells(rCnt, 6).Select()
Dim opicture As Object
opicture = xlApp.ActiveSheet.Pictures.Insert(path)
opicture.ShapeRange.LockAspectRatio = True
opicture.ShapeRange.width = 170
opicture.ShapeRange.height = 170
My.Computer.FileSystem.DeleteFile(path)
End If
End If
ElseIf radpost.Checked = True Then
range.Cells(rCnt, 7).value = result
If img Is Nothing Then
Else
If Dir(path) <> "" Then
range.Cells(rCnt, 8).Select()
Dim opicture As Object
opicture = xlApp.ActiveSheet.Pictures.Insert(path)
opicture.ShapeRange.LockAspectRatio = True
opicture.ShapeRange.width = 170
opicture.ShapeRange.height = 170
My.Computer.FileSystem.DeleteFile(path)
End If
End If
End If
ProgressBar1.Value = rCnt / range.Rows.Count * 100
Next
With xlApp
.DisplayAlerts = False
xlWorkBook.SaveAs(lblpath.Text.ToString)
.DisplayAlerts = True
End With
xlWorkBook.Close()
xlApp.Quit()
'reclaim memory
Marshal.ReleaseComObject(xlApp)
xlApp = Nothing
End If
End Sub
Private Function CaptureWebBrowser(ByVal wb As WebBrowser) As Image
Try
wb.ScrollBarsEnabled = False
Dim hBitmap As Bitmap = New Bitmap(wb.Width, wb.Height)
wb.DrawToBitmap(hBitmap, wb.Bounds)
Dim img As Image = hBitmap
Return img
Catch ex As Exception
MessageBox.Show(ex.Message)
End Try
Return Nothing
End Function
Private Sub WaitForPageLoad()
AddHandler WebBrowser1.DocumentCompleted, New WebBrowserDocumentCompletedEventHandler(AddressOf PageWaiter)
While Not pageready
Application.DoEvents()
System.Threading.Thread.Sleep(200)
End While
pageready = False
End Sub
Private Sub PageWaiter(ByVal sender As Object, ByVal e As WebBrowserDocumentCompletedEventArgs)
If WebBrowser1.ReadyState = WebBrowserReadyState.Complete Then
pageready = True
RemoveHandler WebBrowser1.DocumentCompleted, New WebBrowserDocumentCompletedEventHandler(AddressOf PageWaiter)
End If
End Sub
End Class
答案 0 :(得分：0)
不幸的是，您将无法使用webBrowser.DrawToBitmap来获取PDF视图的快照。在撰写本文时， Adobe Acrobat Reader ActiveX控件不支持在自定义设备上下文中呈现，因此此方法不起作用，以及发送WM_PRINT或调用{ {1}}，直接在通过WebBrowser上的Reader ActiveX对象上（我试过了，I'm not alone）。正确的解决方案是使用第三方PDF呈现组件。
在旁注中，您应该避免使用这样的代码模式：
IViewObject::Draw这是一个busy waiting紧密的循环，徒劳地消耗CPU周期。至少，在循环中添加一些While Not pageready
Application.DoEvents()
End While
，但总体上你应该避免使用using Application.DoEvents。