|
dev
newsgroups
|
|||||||||||||||||||||||
|
|||||||||||||||||||||||
Webbrowser UserControlI'm developing a UserControl that essentially a wrapper for Webbrowser.
The caller module will call the Navigate() method for document download. It then call WaitOne() on a ManualResetEvent object. The ManualResetEvent object is supposed to be Set() from WebBrowser's DocumentComplete event handler when download completed. However, when Navigate() is called, it simply stops at the WaitOne() call and never get the Set() from DocumentCompleted event. Can anyone give a hint ? The reason why I try to use WaitOne() is that the Application.Doevents is consuming a lot of CPU resource unnecessarily. Thanks In your case the event handler for DocumentComplete is called on the same
thread as the one calling WaitOne. This means that your call to WaitOne freezes your application and it is unable to respond to the event. HTH, Jakob. Show quote "xela" wrote: > I'm developing a UserControl that essentially a wrapper for Webbrowser. > The caller module will call the Navigate() method for document download. > It then call WaitOne() on a ManualResetEvent object. The ManualResetEvent > object is supposed > to be Set() from WebBrowser's DocumentComplete event handler when download > completed. > > However, when Navigate() is called, it simply stops at the WaitOne() call > and never get the Set() from DocumentCompleted event. > > Can anyone give a hint ? > > The reason why I try to use WaitOne() is that the Application.Doevents is > consuming a lot of CPU resource unnecessarily. > > Thanks > > > Dear Jakob,
I have tried to use a separate thread to navigate. However, it seems the thread has quickly returned, left only the main thread being blocked by WaitOne(). Please find below my coding. I was plagued by this for a long time. Please help. Thanks Public Class CtlBrowser Private mManualEvent1 As ManualResetEvent Private msURL As String Public Sub GoToURL(ByVal sURL As String) Dim t As Thread Dim i As Integer Try mManualEvent1 = New ManualResetEvent(False) msURL = sURL t = New Thread(AddressOf LoadPage) t.Start() mManualEvent1.WaitOne() Catch Console.WriteLine("ERROR: GoToURL()") End Try End Sub Private Sub LoadPage() IE.Navigate(msURL) End Sub Private Sub IE_DocumentComplete(ByVal sender As Object, ByVal e As AxSHDocVw.DWebBrowserEvents2_DocumentCompleteEvent) Handles IE.DocumentComplete Dim sURL As String Try If (msURL).Equals(e.uRL) Then mManualEvent1.Set() End If Catch Console.WriteLine("ERROR") End Try End Sub End Class Show quote "Jakob Christensen" <j**@REMOVEpension.dk> wrote in message news:025DE366-8571-4A2B-A28C-B4AC3ACFA30C@microsoft.com... > In your case the event handler for DocumentComplete is called on the same > thread as the one calling WaitOne. This means that your call to WaitOne > freezes your application and it is unable to respond to the event. > > HTH, Jakob. > -- > http://www.dotninjas.dk > http://www.powerbytes.dk > > > "xela" wrote: > > > I'm developing a UserControl that essentially a wrapper for Webbrowser. > > The caller module will call the Navigate() method for document download. > > It then call WaitOne() on a ManualResetEvent object. The ManualResetEvent > > object is supposed > > to be Set() from WebBrowser's DocumentComplete event handler when download > > completed. > > > > However, when Navigate() is called, it simply stops at the WaitOne() call > > and never get the Set() from DocumentCompleted event. > > > > Can anyone give a hint ? > > > > The reason why I try to use WaitOne() is that the Application.Doevents is > > consuming a lot of CPU resource unnecessarily. > > > > Thanks > > > > > > Accessing controls on a form from another thread is not allowed so spawning
another thread to do the work might get you into trouble. Why is it that you want the main thread to stop and wait while the browser loads the page? You wrote that DoEvents is taking a lot of processing but why do you need to call DoEvents if the alternative is to halt the main thread altogether? Please explain what you are trying to accomplish and I will try to find a solution :-) Regards, Jakob. Show quote "xela" wrote: > Dear Jakob, > > I have tried to use a separate thread to navigate. However, it seems the > thread has quickly returned, left only the main thread being blocked by > WaitOne(). > > Please find below my coding. > I was plagued by this for a long time. Please help. > Thanks > > > Public Class CtlBrowser > Private mManualEvent1 As ManualResetEvent > Private msURL As String > > Public Sub GoToURL(ByVal sURL As String) > Dim t As Thread > Dim i As Integer > > Try > mManualEvent1 = New ManualResetEvent(False) > > msURL = sURL > t = New Thread(AddressOf LoadPage) > t.Start() > > mManualEvent1.WaitOne() > Catch > Console.WriteLine("ERROR: GoToURL()") > End Try > End Sub > > > > Private Sub LoadPage() > IE.Navigate(msURL) > End Sub > > > Private Sub IE_DocumentComplete(ByVal sender As Object, ByVal e As > AxSHDocVw.DWebBrowserEvents2_DocumentCompleteEvent) Handles > IE.DocumentComplete > Dim sURL As String > > Try > If (msURL).Equals(e.uRL) Then > mManualEvent1.Set() > End If > Catch > Console.WriteLine("ERROR") > End Try > End Sub > > End Class > > > "Jakob Christensen" <j**@REMOVEpension.dk> wrote in message > news:025DE366-8571-4A2B-A28C-B4AC3ACFA30C@microsoft.com... > > In your case the event handler for DocumentComplete is called on the same > > thread as the one calling WaitOne. This means that your call to WaitOne > > freezes your application and it is unable to respond to the event. > > > > HTH, Jakob. > > -- > > http://www.dotninjas.dk > > http://www.powerbytes.dk > > > > > > "xela" wrote: > > > > > I'm developing a UserControl that essentially a wrapper for Webbrowser. > > > The caller module will call the Navigate() method for document download. > > > It then call WaitOne() on a ManualResetEvent object. The > ManualResetEvent > > > object is supposed > > > to be Set() from WebBrowser's DocumentComplete event handler when > download > > > completed. > > > > > > However, when Navigate() is called, it simply stops at the WaitOne() > call > > > and never get the Set() from DocumentCompleted event. > > > > > > Can anyone give a hint ? > > > > > > The reason why I try to use WaitOne() is that the Application.Doevents > is > > > consuming a lot of CPU resource unnecessarily. > > > > > > Thanks > > > > > > > > > > > > Dear Jakob,
I use a Form to hold a UserControl that in turn holds a Webbrowser. The purpose is just to modularize the function so that it can be reused. Below is the caller coding on the Form that holding the UserControl. I use Application.Doevents to wait for the DocumentComplete event to fire and raise another event to the Form that sets mnStatus to 0. Web pages sometimes take half minute or more to load and therefore the Application.Doevents is in a loop and this will consume a lot of CPU resource. If time elapsed is longer than nWait (in seconds), then ShowPage will return false that signals a failure. To improve on the performance, I explore another solution, ie. to use WaitOne(). If it works, then I think Application.Doevents will no longer be needed. Hopefully, you can understand what I mean. Thanks Public Function ShowPage(ByVal sURL As String, ByVal nWait As Integer, ByVal nRetry As Integer) As Boolean Dim i As Integer Dim j As Integer ShowPage = True Try For i = 0 To nRetry Timer1.Enabled = True mnStatus = 1 mnSecond = 0 brw.GoToURL(sURL) Do While (mnStatus = 1) Application.DoEvents() If mnStatus = 0 Then Timer1.Enabled = False Exit Function End If If mnSecond >= nWait Then Exit Do End If Loop Next Timer1.Enabled = False ShowPage = False Catch ex As Exception Timer1.Enabled = False ShowPage = False Console.WriteLine(ex.StackTrace) End Try End Function Show quote "Jakob Christensen" <j**@REMOVEpension.dk> wrote in message news:BC2D4FE4-7875-4FBB-849A-805590D39919@microsoft.com... > Accessing controls on a form from another thread is not allowed so spawning > another thread to do the work might get you into trouble. > > Why is it that you want the main thread to stop and wait while the browser > loads the page? You wrote that DoEvents is taking a lot of processing but > why do you need to call DoEvents if the alternative is to halt the main > thread altogether? > > Please explain what you are trying to accomplish and I will try to find a > solution :-) > > Regards, Jakob. > -- > http://www.dotninjas.dk > http://www.powerbytes.dk > > > "xela" wrote: > > > Dear Jakob, > > > > I have tried to use a separate thread to navigate. However, it seems the > > thread has quickly returned, left only the main thread being blocked by > > WaitOne(). > > > > Please find below my coding. > > I was plagued by this for a long time. Please help. > > Thanks > > > > > > Public Class CtlBrowser > > Private mManualEvent1 As ManualResetEvent > > Private msURL As String > > > > Public Sub GoToURL(ByVal sURL As String) > > Dim t As Thread > > Dim i As Integer > > > > Try > > mManualEvent1 = New ManualResetEvent(False) > > > > msURL = sURL > > t = New Thread(AddressOf LoadPage) > > t.Start() > > > > mManualEvent1.WaitOne() > > Catch > > Console.WriteLine("ERROR: GoToURL()") > > End Try > > End Sub > > > > > > > > Private Sub LoadPage() > > IE.Navigate(msURL) > > End Sub > > > > > > Private Sub IE_DocumentComplete(ByVal sender As Object, ByVal e As > > AxSHDocVw.DWebBrowserEvents2_DocumentCompleteEvent) Handles > > IE.DocumentComplete > > Dim sURL As String > > > > Try > > If (msURL).Equals(e.uRL) Then > > mManualEvent1.Set() > > End If > > Catch > > Console.WriteLine("ERROR") > > End Try > > End Sub > > > > End Class > > > > > > "Jakob Christensen" <j**@REMOVEpension.dk> wrote in message > > news:025DE366-8571-4A2B-A28C-B4AC3ACFA30C@microsoft.com... > > > In your case the event handler for DocumentComplete is called on the same > > > thread as the one calling WaitOne. This means that your call to WaitOne > > > freezes your application and it is unable to respond to the event. > > > > > > HTH, Jakob. > > > -- > > > http://www.dotninjas.dk > > > http://www.powerbytes.dk > > > > > > > > > "xela" wrote: > > > > > > > I'm developing a UserControl that essentially a wrapper for Webbrowser. > > > > The caller module will call the Navigate() method for document download. > > > > It then call WaitOne() on a ManualResetEvent object. The > > ManualResetEvent > > > > object is supposed > > > > to be Set() from WebBrowser's DocumentComplete event handler when > > download > > > > completed. > > > > > > > > However, when Navigate() is called, it simply stops at the WaitOne() > > call > > > > and never get the Set() from DocumentCompleted event. > > > > > > > > Can anyone give a hint ? > > > > > > > > The reason why I try to use WaitOne() is that the Application.Doevents > > is > > > > consuming a lot of CPU resource unnecessarily. > > > > > > > > Thanks > > > > > > > > > > > > > > > > > > xela
Why not retain the loop with DoEvents, but each time around the loop go to sleep for, say, 100 ms? This way your cpu percentage will drop to almost nothing and the application will still be responsive. HTH Charles Show quote "xela" <xelavb***@yahoo.com.hk> wrote in message news:OFxhkF8yFHA.3312@TK2MSFTNGP09.phx.gbl... > Dear Jakob, > > I use a Form to hold a UserControl that in turn holds a Webbrowser. The > purpose is just to modularize the function so that it can be reused. > > Below is the caller coding on the Form that holding the UserControl. I use > Application.Doevents to wait for the DocumentComplete event to fire and > raise another event to the Form that sets mnStatus to 0. Web pages > sometimes > take half minute or more to load and therefore the Application.Doevents is > in a loop and this will consume a lot of CPU resource. If time elapsed is > longer than nWait (in seconds), then ShowPage will return false that > signals > a failure. > > To improve on the performance, I explore another solution, ie. to use > WaitOne(). If it works, then I think Application.Doevents will no longer > be > needed. > > Hopefully, you can understand what I mean. > > Thanks > > > Public Function ShowPage(ByVal sURL As String, ByVal nWait As Integer, > ByVal nRetry As Integer) As Boolean > Dim i As Integer > Dim j As Integer > > ShowPage = True > > Try > For i = 0 To nRetry > Timer1.Enabled = True > mnStatus = 1 > mnSecond = 0 > > brw.GoToURL(sURL) > Do While (mnStatus = 1) > Application.DoEvents() > > If mnStatus = 0 Then > Timer1.Enabled = False > Exit Function > End If > If mnSecond >= nWait Then > Exit Do > End If > Loop > Next > > Timer1.Enabled = False > ShowPage = False > Catch ex As Exception > Timer1.Enabled = False > ShowPage = False > Console.WriteLine(ex.StackTrace) > End Try > End Function > > > "Jakob Christensen" <j**@REMOVEpension.dk> wrote in message > news:BC2D4FE4-7875-4FBB-849A-805590D39919@microsoft.com... >> Accessing controls on a form from another thread is not allowed so > spawning >> another thread to do the work might get you into trouble. >> >> Why is it that you want the main thread to stop and wait while the >> browser >> loads the page? You wrote that DoEvents is taking a lot of processing >> but >> why do you need to call DoEvents if the alternative is to halt the main >> thread altogether? >> >> Please explain what you are trying to accomplish and I will try to find a >> solution :-) >> >> Regards, Jakob. >> -- >> http://www.dotninjas.dk >> http://www.powerbytes.dk >> >> >> "xela" wrote: >> >> > Dear Jakob, >> > >> > I have tried to use a separate thread to navigate. However, it seems > the >> > thread has quickly returned, left only the main thread being blocked by >> > WaitOne(). >> > >> > Please find below my coding. >> > I was plagued by this for a long time. Please help. >> > Thanks >> > >> > >> > Public Class CtlBrowser >> > Private mManualEvent1 As ManualResetEvent >> > Private msURL As String >> > >> > Public Sub GoToURL(ByVal sURL As String) >> > Dim t As Thread >> > Dim i As Integer >> > >> > Try >> > mManualEvent1 = New ManualResetEvent(False) >> > >> > msURL = sURL >> > t = New Thread(AddressOf LoadPage) >> > t.Start() >> > >> > mManualEvent1.WaitOne() >> > Catch >> > Console.WriteLine("ERROR: GoToURL()") >> > End Try >> > End Sub >> > >> > >> > >> > Private Sub LoadPage() >> > IE.Navigate(msURL) >> > End Sub >> > >> > >> > Private Sub IE_DocumentComplete(ByVal sender As Object, ByVal e As >> > AxSHDocVw.DWebBrowserEvents2_DocumentCompleteEvent) Handles >> > IE.DocumentComplete >> > Dim sURL As String >> > >> > Try >> > If (msURL).Equals(e.uRL) Then >> > mManualEvent1.Set() >> > End If >> > Catch >> > Console.WriteLine("ERROR") >> > End Try >> > End Sub >> > >> > End Class >> > >> > >> > "Jakob Christensen" <j**@REMOVEpension.dk> wrote in message >> > news:025DE366-8571-4A2B-A28C-B4AC3ACFA30C@microsoft.com... >> > > In your case the event handler for DocumentComplete is called on the > same >> > > thread as the one calling WaitOne. This means that your call to > WaitOne >> > > freezes your application and it is unable to respond to the event. >> > > >> > > HTH, Jakob. >> > > -- >> > > http://www.dotninjas.dk >> > > http://www.powerbytes.dk >> > > >> > > >> > > "xela" wrote: >> > > >> > > > I'm developing a UserControl that essentially a wrapper for > Webbrowser. >> > > > The caller module will call the Navigate() method for document > download. >> > > > It then call WaitOne() on a ManualResetEvent object. The >> > ManualResetEvent >> > > > object is supposed >> > > > to be Set() from WebBrowser's DocumentComplete event handler when >> > download >> > > > completed. >> > > > >> > > > However, when Navigate() is called, it simply stops at the >> > > > WaitOne() >> > call >> > > > and never get the Set() from DocumentCompleted event. >> > > > >> > > > Can anyone give a hint ? >> > > > >> > > > The reason why I try to use WaitOne() is that the > Application.Doevents >> > is >> > > > consuming a lot of CPU resource unnecessarily. >> > > > >> > > > Thanks >> > > > >> > > > >> > > > >> > >> > >> > > > Dear Charles,
Since the download thread actually is the main thread, unless you can separate the threads, if you issue sleep command, the downloading action will also be stopped. Regards Show quote "Charles Law" <bl***@nowhere.com> wrote in message news:uM1hXFAzFHA.1256@TK2MSFTNGP09.phx.gbl... > xela > > Why not retain the loop with DoEvents, but each time around the loop go to > sleep for, say, 100 ms? This way your cpu percentage will drop to almost > nothing and the application will still be responsive. > > HTH > > Charles > > > "xela" <xelavb***@yahoo.com.hk> wrote in message > news:OFxhkF8yFHA.3312@TK2MSFTNGP09.phx.gbl... > > Dear Jakob, > > > > I use a Form to hold a UserControl that in turn holds a Webbrowser. The > > purpose is just to modularize the function so that it can be reused. > > > > Below is the caller coding on the Form that holding the UserControl. I use > > Application.Doevents to wait for the DocumentComplete event to fire and > > raise another event to the Form that sets mnStatus to 0. Web pages > > sometimes > > take half minute or more to load and therefore the Application.Doevents is > > in a loop and this will consume a lot of CPU resource. If time elapsed is > > longer than nWait (in seconds), then ShowPage will return false that > > signals > > a failure. > > > > To improve on the performance, I explore another solution, ie. to use > > WaitOne(). If it works, then I think Application.Doevents will no longer > > be > > needed. > > > > Hopefully, you can understand what I mean. > > > > Thanks > > > > > > Public Function ShowPage(ByVal sURL As String, ByVal nWait As Integer, > > ByVal nRetry As Integer) As Boolean > > Dim i As Integer > > Dim j As Integer > > > > ShowPage = True > > > > Try > > For i = 0 To nRetry > > Timer1.Enabled = True > > mnStatus = 1 > > mnSecond = 0 > > > > brw.GoToURL(sURL) > > Do While (mnStatus = 1) > > Application.DoEvents() > > > > If mnStatus = 0 Then > > Timer1.Enabled = False > > Exit Function > > End If > > If mnSecond >= nWait Then > > Exit Do > > End If > > Loop > > Next > > > > Timer1.Enabled = False > > ShowPage = False > > Catch ex As Exception > > Timer1.Enabled = False > > ShowPage = False > > Console.WriteLine(ex.StackTrace) > > End Try > > End Function > > > > > > "Jakob Christensen" <j**@REMOVEpension.dk> wrote in message > > news:BC2D4FE4-7875-4FBB-849A-805590D39919@microsoft.com... > >> Accessing controls on a form from another thread is not allowed so > > spawning > >> another thread to do the work might get you into trouble. > >> > >> Why is it that you want the main thread to stop and wait while the > >> browser > >> loads the page? You wrote that DoEvents is taking a lot of processing > >> but > >> why do you need to call DoEvents if the alternative is to halt the main > >> thread altogether? > >> > >> Please explain what you are trying to accomplish and I will try to find a > >> solution :-) > >> > >> Regards, Jakob. > >> -- > >> http://www.dotninjas.dk > >> http://www.powerbytes.dk > >> > >> > >> "xela" wrote: > >> > >> > Dear Jakob, > >> > > >> > I have tried to use a separate thread to navigate. However, it seems > > the > >> > thread has quickly returned, left only the main thread being blocked by > >> > WaitOne(). > >> > > >> > Please find below my coding. > >> > I was plagued by this for a long time. Please help. > >> > Thanks > >> > > >> > > >> > Public Class CtlBrowser > >> > Private mManualEvent1 As ManualResetEvent > >> > Private msURL As String > >> > > >> > Public Sub GoToURL(ByVal sURL As String) > >> > Dim t As Thread > >> > Dim i As Integer > >> > > >> > Try > >> > mManualEvent1 = New ManualResetEvent(False) > >> > > >> > msURL = sURL > >> > t = New Thread(AddressOf LoadPage) > >> > t.Start() > >> > > >> > mManualEvent1.WaitOne() > >> > Catch > >> > Console.WriteLine("ERROR: GoToURL()") > >> > End Try > >> > End Sub > >> > > >> > > >> > > >> > Private Sub LoadPage() > >> > IE.Navigate(msURL) > >> > End Sub > >> > > >> > > >> > Private Sub IE_DocumentComplete(ByVal sender As Object, ByVal e As > >> > AxSHDocVw.DWebBrowserEvents2_DocumentCompleteEvent) Handles > >> > IE.DocumentComplete > >> > Dim sURL As String > >> > > >> > Try > >> > If (msURL).Equals(e.uRL) Then > >> > mManualEvent1.Set() > >> > End If > >> > Catch > >> > Console.WriteLine("ERROR") > >> > End Try > >> > End Sub > >> > > >> > End Class > >> > > >> > > >> > "Jakob Christensen" <j**@REMOVEpension.dk> wrote in message > >> > news:025DE366-8571-4A2B-A28C-B4AC3ACFA30C@microsoft.com... > >> > > In your case the event handler for DocumentComplete is called on the > > same > >> > > thread as the one calling WaitOne. This means that your call to > > WaitOne > >> > > freezes your application and it is unable to respond to the event. > >> > > > >> > > HTH, Jakob. > >> > > -- > >> > > http://www.dotninjas.dk > >> > > http://www.powerbytes.dk > >> > > > >> > > > >> > > "xela" wrote: > >> > > > >> > > > I'm developing a UserControl that essentially a wrapper for > > Webbrowser. > >> > > > The caller module will call the Navigate() method for document > > download. > >> > > > It then call WaitOne() on a ManualResetEvent object. The > >> > ManualResetEvent > >> > > > object is supposed > >> > > > to be Set() from WebBrowser's DocumentComplete event handler when > >> > download > >> > > > completed. > >> > > > > >> > > > However, when Navigate() is called, it simply stops at the > >> > > > WaitOne() > >> > call > >> > > > and never get the Set() from DocumentCompleted event. > >> > > > > >> > > > Can anyone give a hint ? > >> > > > > >> > > > The reason why I try to use WaitOne() is that the > > Application.Doevents > >> > is > >> > > > consuming a lot of CPU resource unnecessarily. > >> > > > > >> > > > Thanks > >> > > > > >> > > > > >> > > > > >> > > >> > > >> > > > > > > > xela
> Since the download thread actually is the main thread, unless you can That's the reason for keeping the period short. Using 100 ms will still > separate the threads, if you issue sleep command, the downloading action > will also be stopped. allow your page to download and will keep the cpu percentage low as well. Have you tried it? Charles Show quote "xela" <xelavb***@yahoo.com.hk> wrote in message news:eHtgqKizFHA.3812@TK2MSFTNGP09.phx.gbl... > Dear Charles, > > Since the download thread actually is the main thread, unless you can > separate the threads, if you issue sleep command, the downloading action > will also be stopped. > > Regards > > "Charles Law" <bl***@nowhere.com> wrote in message > news:uM1hXFAzFHA.1256@TK2MSFTNGP09.phx.gbl... >> xela >> >> Why not retain the loop with DoEvents, but each time around the loop go >> to >> sleep for, say, 100 ms? This way your cpu percentage will drop to almost >> nothing and the application will still be responsive. >> >> HTH >> >> Charles >> >> >> "xela" <xelavb***@yahoo.com.hk> wrote in message >> news:OFxhkF8yFHA.3312@TK2MSFTNGP09.phx.gbl... >> > Dear Jakob, >> > >> > I use a Form to hold a UserControl that in turn holds a Webbrowser. The >> > purpose is just to modularize the function so that it can be reused. >> > >> > Below is the caller coding on the Form that holding the UserControl. I > use >> > Application.Doevents to wait for the DocumentComplete event to fire and >> > raise another event to the Form that sets mnStatus to 0. Web pages >> > sometimes >> > take half minute or more to load and therefore the Application.Doevents > is >> > in a loop and this will consume a lot of CPU resource. If time elapsed > is >> > longer than nWait (in seconds), then ShowPage will return false that >> > signals >> > a failure. >> > >> > To improve on the performance, I explore another solution, ie. to use >> > WaitOne(). If it works, then I think Application.Doevents will no >> > longer >> > be >> > needed. >> > >> > Hopefully, you can understand what I mean. >> > >> > Thanks >> > >> > >> > Public Function ShowPage(ByVal sURL As String, ByVal nWait As > Integer, >> > ByVal nRetry As Integer) As Boolean >> > Dim i As Integer >> > Dim j As Integer >> > >> > ShowPage = True >> > >> > Try >> > For i = 0 To nRetry >> > Timer1.Enabled = True >> > mnStatus = 1 >> > mnSecond = 0 >> > >> > brw.GoToURL(sURL) >> > Do While (mnStatus = 1) >> > Application.DoEvents() >> > >> > If mnStatus = 0 Then >> > Timer1.Enabled = False >> > Exit Function >> > End If >> > If mnSecond >= nWait Then >> > Exit Do >> > End If >> > Loop >> > Next >> > >> > Timer1.Enabled = False >> > ShowPage = False >> > Catch ex As Exception >> > Timer1.Enabled = False >> > ShowPage = False >> > Console.WriteLine(ex.StackTrace) >> > End Try >> > End Function >> > >> > >> > "Jakob Christensen" <j**@REMOVEpension.dk> wrote in message >> > news:BC2D4FE4-7875-4FBB-849A-805590D39919@microsoft.com... >> >> Accessing controls on a form from another thread is not allowed so >> > spawning >> >> another thread to do the work might get you into trouble. >> >> >> >> Why is it that you want the main thread to stop and wait while the >> >> browser >> >> loads the page? You wrote that DoEvents is taking a lot of processing >> >> but >> >> why do you need to call DoEvents if the alternative is to halt the >> >> main >> >> thread altogether? >> >> >> >> Please explain what you are trying to accomplish and I will try to >> >> find > a >> >> solution :-) >> >> >> >> Regards, Jakob. >> >> -- >> >> http://www.dotninjas.dk >> >> http://www.powerbytes.dk >> >> >> >> >> >> "xela" wrote: >> >> >> >> > Dear Jakob, >> >> > >> >> > I have tried to use a separate thread to navigate. However, it >> >> > seems >> > the >> >> > thread has quickly returned, left only the main thread being blocked > by >> >> > WaitOne(). >> >> > >> >> > Please find below my coding. >> >> > I was plagued by this for a long time. Please help. >> >> > Thanks >> >> > >> >> > >> >> > Public Class CtlBrowser >> >> > Private mManualEvent1 As ManualResetEvent >> >> > Private msURL As String >> >> > >> >> > Public Sub GoToURL(ByVal sURL As String) >> >> > Dim t As Thread >> >> > Dim i As Integer >> >> > >> >> > Try >> >> > mManualEvent1 = New ManualResetEvent(False) >> >> > >> >> > msURL = sURL >> >> > t = New Thread(AddressOf LoadPage) >> >> > t.Start() >> >> > >> >> > mManualEvent1.WaitOne() >> >> > Catch >> >> > Console.WriteLine("ERROR: GoToURL()") >> >> > End Try >> >> > End Sub >> >> > >> >> > >> >> > >> >> > Private Sub LoadPage() >> >> > IE.Navigate(msURL) >> >> > End Sub >> >> > >> >> > >> >> > Private Sub IE_DocumentComplete(ByVal sender As Object, ByVal e > As >> >> > AxSHDocVw.DWebBrowserEvents2_DocumentCompleteEvent) Handles >> >> > IE.DocumentComplete >> >> > Dim sURL As String >> >> > >> >> > Try >> >> > If (msURL).Equals(e.uRL) Then >> >> > mManualEvent1.Set() >> >> > End If >> >> > Catch >> >> > Console.WriteLine("ERROR") >> >> > End Try >> >> > End Sub >> >> > >> >> > End Class >> >> > >> >> > >> >> > "Jakob Christensen" <j**@REMOVEpension.dk> wrote in message >> >> > news:025DE366-8571-4A2B-A28C-B4AC3ACFA30C@microsoft.com... >> >> > > In your case the event handler for DocumentComplete is called on > the >> > same >> >> > > thread as the one calling WaitOne. This means that your call to >> > WaitOne >> >> > > freezes your application and it is unable to respond to the event. >> >> > > >> >> > > HTH, Jakob. >> >> > > -- >> >> > > http://www.dotninjas.dk >> >> > > http://www.powerbytes.dk >> >> > > >> >> > > >> >> > > "xela" wrote: >> >> > > >> >> > > > I'm developing a UserControl that essentially a wrapper for >> > Webbrowser. >> >> > > > The caller module will call the Navigate() method for document >> > download. >> >> > > > It then call WaitOne() on a ManualResetEvent object. The >> >> > ManualResetEvent >> >> > > > object is supposed >> >> > > > to be Set() from WebBrowser's DocumentComplete event handler >> >> > > > when >> >> > download >> >> > > > completed. >> >> > > > >> >> > > > However, when Navigate() is called, it simply stops at the >> >> > > > WaitOne() >> >> > call >> >> > > > and never get the Set() from DocumentCompleted event. >> >> > > > >> >> > > > Can anyone give a hint ? >> >> > > > >> >> > > > The reason why I try to use WaitOne() is that the >> > Application.Doevents >> >> > is >> >> > > > consuming a lot of CPU resource unnecessarily. >> >> > > > >> >> > > > Thanks >> >> > > > >> >> > > > >> >> > > > >> >> > >> >> > >> >> > >> > >> > >> >> > > You write that you want ShowPage to return false, if the web page takes
longer than a given number of seconds to complete. Do you want ShowPage to cancel the page request if it takes to long and then return false or what is the idea? Regards, Jakob. Show quote "xela" wrote: > Dear Jakob, > > I use a Form to hold a UserControl that in turn holds a Webbrowser. The > purpose is just to modularize the function so that it can be reused. > > Below is the caller coding on the Form that holding the UserControl. I use > Application.Doevents to wait for the DocumentComplete event to fire and > raise another event to the Form that sets mnStatus to 0. Web pages sometimes > take half minute or more to load and therefore the Application.Doevents is > in a loop and this will consume a lot of CPU resource. If time elapsed is > longer than nWait (in seconds), then ShowPage will return false that signals > a failure. > > To improve on the performance, I explore another solution, ie. to use > WaitOne(). If it works, then I think Application.Doevents will no longer be > needed. > > Hopefully, you can understand what I mean. > > Thanks > > > Public Function ShowPage(ByVal sURL As String, ByVal nWait As Integer, > ByVal nRetry As Integer) As Boolean > Dim i As Integer > Dim j As Integer > > ShowPage = True > > Try > For i = 0 To nRetry > Timer1.Enabled = True > mnStatus = 1 > mnSecond = 0 > > brw.GoToURL(sURL) > Do While (mnStatus = 1) > Application.DoEvents() > > If mnStatus = 0 Then > Timer1.Enabled = False > Exit Function > End If > If mnSecond >= nWait Then > Exit Do > End If > Loop > Next > > Timer1.Enabled = False > ShowPage = False > Catch ex As Exception > Timer1.Enabled = False > ShowPage = False > Console.WriteLine(ex.StackTrace) > End Try > End Function > > > "Jakob Christensen" <j**@REMOVEpension.dk> wrote in message > news:BC2D4FE4-7875-4FBB-849A-805590D39919@microsoft.com... > > Accessing controls on a form from another thread is not allowed so > spawning > > another thread to do the work might get you into trouble. > > > > Why is it that you want the main thread to stop and wait while the browser > > loads the page? You wrote that DoEvents is taking a lot of processing but > > why do you need to call DoEvents if the alternative is to halt the main > > thread altogether? > > > > Please explain what you are trying to accomplish and I will try to find a > > solution :-) > > > > Regards, Jakob. > > -- > > http://www.dotninjas.dk > > http://www.powerbytes.dk > > > > > > "xela" wrote: > > > > > Dear Jakob, > > > > > > I have tried to use a separate thread to navigate. However, it seems > the > > > thread has quickly returned, left only the main thread being blocked by > > > WaitOne(). > > > > > > Please find below my coding. > > > I was plagued by this for a long time. Please help. > > > Thanks > > > > > > > > > Public Class CtlBrowser > > > Private mManualEvent1 As ManualResetEvent > > > Private msURL As String > > > > > > Public Sub GoToURL(ByVal sURL As String) > > > Dim t As Thread > > > Dim i As Integer > > > > > > Try > > > mManualEvent1 = New ManualResetEvent(False) > > > > > > msURL = sURL > > > t = New Thread(AddressOf LoadPage) > > > t.Start() > > > > > > mManualEvent1.WaitOne() > > > Catch > > > Console.WriteLine("ERROR: GoToURL()") > > > End Try > > > End Sub > > > > > > > > > > > > Private Sub LoadPage() > > > IE.Navigate(msURL) > > > End Sub > > > > > > > > > Private Sub IE_DocumentComplete(ByVal sender As Object, ByVal e As > > > AxSHDocVw.DWebBrowserEvents2_DocumentCompleteEvent) Handles > > > IE.DocumentComplete > > > Dim sURL As String > > > > > > Try > > > If (msURL).Equals(e.uRL) Then > > > mManualEvent1.Set() > > > End If > > > Catch > > > Console.WriteLine("ERROR") > > > End Try > > > End Sub > > > > > > End Class > > > > > > > > > "Jakob Christensen" <j**@REMOVEpension.dk> wrote in message > > > news:025DE366-8571-4A2B-A28C-B4AC3ACFA30C@microsoft.com... > > > > In your case the event handler for DocumentComplete is called on the > same > > > > thread as the one calling WaitOne. This means that your call to > WaitOne > > > > freezes your application and it is unable to respond to the event. > > > > > > > > HTH, Jakob. > > > > -- > > > > http://www.dotninjas.dk > > > > http://www.powerbytes.dk > > > > > > > > > > > > "xela" wrote: > > > > > > > > > I'm developing a UserControl that essentially a wrapper for > Webbrowser. > > > > > The caller module will call the Navigate() method for document > download. > > > > > It then call WaitOne() on a ManualResetEvent object. The > > > ManualResetEvent > > > > > object is supposed > > > > > to be Set() from WebBrowser's DocumentComplete event handler when > > > download > > > > > completed. > > > > > > > > > > However, when Navigate() is called, it simply stops at the WaitOne() > > > call > > > > > and never get the Set() from DocumentCompleted event. > > > > > > > > > > Can anyone give a hint ? > > > > > > > > > > The reason why I try to use WaitOne() is that the > Application.Doevents > > > is > > > > > consuming a lot of CPU resource unnecessarily. > > > > > > > > > > Thanks > > > > > > > > > > > > > > > > > > > > > > > > > > > Dear Jakob,
If the web page just takes too long to download (longer than the given no. of seconds), the ShowPage function just return false to the calling routine to indicate the failure; otherwise return true. Regards Show quote "Jakob Christensen" <j**@REMOVEpension.dk> wrote in message news:1EB95CE9-9B0E-4A37-BA59-BA5B96325B68@microsoft.com... > You write that you want ShowPage to return false, if the web page takes > longer than a given number of seconds to complete. Do you want ShowPage to > cancel the page request if it takes to long and then return false or what is > the idea? > > Regards, Jakob. > > -- > http://www.dotninjas.dk > http://www.powerbytes.dk > > > "xela" wrote: > > > Dear Jakob, > > > > I use a Form to hold a UserControl that in turn holds a Webbrowser. The > > purpose is just to modularize the function so that it can be reused. > > > > Below is the caller coding on the Form that holding the UserControl. I use > > Application.Doevents to wait for the DocumentComplete event to fire and > > raise another event to the Form that sets mnStatus to 0. Web pages sometimes > > take half minute or more to load and therefore the Application.Doevents is > > in a loop and this will consume a lot of CPU resource. If time elapsed is > > longer than nWait (in seconds), then ShowPage will return false that signals > > a failure. > > > > To improve on the performance, I explore another solution, ie. to use > > WaitOne(). If it works, then I think Application.Doevents will no longer be > > needed. > > > > Hopefully, you can understand what I mean. > > > > Thanks > > > > > > Public Function ShowPage(ByVal sURL As String, ByVal nWait As Integer, > > ByVal nRetry As Integer) As Boolean > > Dim i As Integer > > Dim j As Integer > > > > ShowPage = True > > > > Try > > For i = 0 To nRetry > > Timer1.Enabled = True > > mnStatus = 1 > > mnSecond = 0 > > > > brw.GoToURL(sURL) > > Do While (mnStatus = 1) > > Application.DoEvents() > > > > If mnStatus = 0 Then > > Timer1.Enabled = False > > Exit Function > > End If > > If mnSecond >= nWait Then > > Exit Do > > End If > > Loop > > Next > > > > Timer1.Enabled = False > > ShowPage = False > > Catch ex As Exception > > Timer1.Enabled = False > > ShowPage = False > > Console.WriteLine(ex.StackTrace) > > End Try > > End Function > > > > > > "Jakob Christensen" <j**@REMOVEpension.dk> wrote in message > > news:BC2D4FE4-7875-4FBB-849A-805590D39919@microsoft.com... > > > Accessing controls on a form from another thread is not allowed so > > spawning > > > another thread to do the work might get you into trouble. > > > > > > Why is it that you want the main thread to stop and wait while the browser > > > loads the page? You wrote that DoEvents is taking a lot of processing but > > > why do you need to call DoEvents if the alternative is to halt the main > > > thread altogether? > > > > > > Please explain what you are trying to accomplish and I will try to find a > > > solution :-) > > > > > > Regards, Jakob. > > > -- > > > http://www.dotninjas.dk > > > http://www.powerbytes.dk > > > > > > > > > "xela" wrote: > > > > > > > Dear Jakob, > > > > > > > > I have tried to use a separate thread to navigate. However, it seems > > the > > > > thread has quickly returned, left only the main thread being blocked by > > > > WaitOne(). > > > > > > > > Please find below my coding. > > > > I was plagued by this for a long time. Please help. > > > > Thanks > > > > > > > > > > > > Public Class CtlBrowser > > > > Private mManualEvent1 As ManualResetEvent > > > > Private msURL As String > > > > > > > > Public Sub GoToURL(ByVal sURL As String) > > > > Dim t As Thread > > > > Dim i As Integer > > > > > > > > Try > > > > mManualEvent1 = New ManualResetEvent(False) > > > > > > > > msURL = sURL > > > > t = New Thread(AddressOf LoadPage) > > > > t.Start() > > > > > > > > mManualEvent1.WaitOne() > > > > Catch > > > > Console.WriteLine("ERROR: GoToURL()") > > > > End Try > > > > End Sub > > > > > > > > > > > > > > > > Private Sub LoadPage() > > > > IE.Navigate(msURL) > > > > End Sub > > > > > > > > > > > > Private Sub IE_DocumentComplete(ByVal sender As Object, ByVal e As > > > > AxSHDocVw.DWebBrowserEvents2_DocumentCompleteEvent) Handles > > > > IE.DocumentComplete > > > > Dim sURL As String > > > > > > > > Try > > > > If (msURL).Equals(e.uRL) Then > > > > mManualEvent1.Set() > > > > End If > > > > Catch > > > > Console.WriteLine("ERROR") > > > > End Try > > > > End Sub > > > > > > > > End Class > > > > > > > > > > > > "Jakob Christensen" <j**@REMOVEpension.dk> wrote in message > > > > news:025DE366-8571-4A2B-A28C-B4AC3ACFA30C@microsoft.com... > > > > > In your case the event handler for DocumentComplete is called on the > > same > > > > > thread as the one calling WaitOne. This means that your call to > > WaitOne > > > > > freezes your application and it is unable to respond to the event. > > > > > > > > > > HTH, Jakob. > > > > > -- > > > > > http://www.dotninjas.dk > > > > > http://www.powerbytes.dk > > > > > > > > > > > > > > > "xela" wrote: > > > > > > > > > > > I'm developing a UserControl that essentially a wrapper for > > Webbrowser. > > > > > > The caller module will call the Navigate() method for document > > download. > > > > > > It then call WaitOne() on a ManualResetEvent object. The > > > > ManualResetEvent > > > > > > object is supposed > > > > > > to be Set() from WebBrowser's DocumentComplete event handler when > > > > download > > > > > > completed. > > > > > > > > > > > > However, when Navigate() is called, it simply stops at the WaitOne() > > > > call > > > > > > and never get the Set() from DocumentCompleted event. > > > > > > > > > > > > Can anyone give a hint ? > > > > > > > > > > > > The reason why I try to use WaitOne() is that the > > Application.Doevents > > > > is > > > > > > consuming a lot of CPU resource unnecessarily. > > > > > > > > > > > > Thanks > > > > > > > > > > > > > > > > > > > > > > > > > > > > > > > > > > > >  |
|||||||||||||||||||||||
Other interesting topics