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Latests build cannot print PDF Options
serializer
Posted: Friday, April 5, 2019 8:33:35 AM
Rank: Advanced Member
Groups: Member

Joined: 5/9/2016
Posts: 61
There is a big problem with printing PDF in the newer builds. I have tested the two latest builds and they have the same problem. I know a build that works and that is: 18.3.46.0

What is happening is that I start a process which calls the print commands. I am able to print 1 document. Next time it hangs - and it hangs at:

Quote:
mt.WaitOne()


Again, this is not happening on 18.3.46.0. I am able to call this method as many times as I want. Here is the full code:

Quote:
Private Sub StartPDFPrintProcessEO(ByVal psc As PrinterSettingsClass)
If TaskProcess.Task.TaskDebugging Then
LogAPI.Log(False, LogClass.EventT.Debug, "StartPDFPrintProcessEO->Start", TaskProcess)
End If
'Create objects for printer and page settings and PrintDocument
AddHandler EO.Base.Runtime.Exception, AddressOf EOException

Dim ps As New System.Drawing.Printing.PrinterSettings()

Dim pgs As New System.Drawing.Printing.PageSettings()

pgs.Margins = New System.Drawing.Printing.Margins(psc.MarginLeft, psc.MarginRight, psc.MarginTop, psc.MarginBottom)

' print range
Select Case psc.PrintRange
Case EnmPrintRange.AllPages
' do nothing
Case EnmPrintRange.CurrentPage
pgs.PrinterSettings.PrintRange = System.Drawing.Printing.PrintRange.CurrentPage
Case EnmPrintRange.Selection
pgs.PrinterSettings.PrintRange = System.Drawing.Printing.PrintRange.Selection
Case EnmPrintRange.SomePages
pgs.PrinterSettings.PrintRange = System.Drawing.Printing.PrintRange.Selection
End Select


If TaskProcess.Task.TaskDebugging Then
LogAPI.Log(False, LogClass.EventT.Debug, "StartPDFPrintProcessEO->Setting printer: " & psc.SelectedPrinter, TaskProcess)
End If
'Set printer name
ps.PrinterName = psc.SelectedPrinter

'Set PageMargins (if required)
ps.DefaultPageSettings.Margins.Left = psc.MarginLeft
ps.DefaultPageSettings.Margins.Right = psc.MarginRight
ps.DefaultPageSettings.Margins.Top = psc.MarginTop
ps.DefaultPageSettings.Margins.Bottom = psc.MarginBottom

' copies
ps.Copies = psc.NoOfCopies
If TaskProcess.Task.TaskDebugging Then
LogAPI.Log(False, LogClass.EventT.Debug, "StartPDFPrintProcessEO->Adding printer settings", TaskProcess)
End If
pgs.PrinterSettings = ps

Dim pdfdoc As New PdfDocument(psc.File, psc.Password)

' add support for printing specific pages
If psc.SelectedPages IsNot Nothing Then
Dim selectedPages As String = GetSelectedPages(psc.SelectedPages)
Dim pages() As String = selectedPages.Split(",".ToCharArray)

' create integer list of pages to print
Dim intPagesToPrint As New List(Of Integer)
For Each strPage As String In pages
intPagesToPrint.Add(CInt(strPage))
Next

' create list of pdf pages to remove
Dim lstRemovePages As New List(Of PdfPage)
Dim i As Integer = 1
For Each pdfPage As PdfPage In pdfdoc.Pages
If Not intPagesToPrint.Contains(i) Then
lstRemovePages.Add(pdfPage)
End If
i += 1
Next

' remove pages from document
For Each pdfPage As PdfPage In lstRemovePages
pdfdoc.Pages.Remove(pdfPage)
Next
End If

Dim IsLandscape As Boolean = False
If pdfdoc.Pages.Count > 0 Then
IsLandscape = pdfdoc.Pages(0).Size.Width > pdfdoc.Pages(0).Size.Height
End If

Select Case psc.PageSettings.PaperOrientation
Case EnmOrientation.Landscape
pgs.PrinterSettings.DefaultPageSettings.Landscape = True
Case EnmOrientation.Portrait
pgs.PrinterSettings.DefaultPageSettings.Landscape = False
Case EnmOrientation.Auto
pgs.PrinterSettings.DefaultPageSettings.Landscape = IsLandscape
End Select

If TaskProcess.Task.TaskDebugging Then
LogAPI.Log(False, LogClass.EventT.Debug, "StartPDFPrintProcessEO->Before sending print", TaskProcess)
End If
mt = pdfdoc.Print(ps, pgs)
If TaskProcess.Task.TaskDebugging Then
LogAPI.Log(False, LogClass.EventT.Debug, "StartPDFPrintProcessEO->After sending print", TaskProcess)
End If
mt.WaitOne()

If TaskProcess.Task.TaskDebugging Then
LogAPI.Log(False, LogClass.EventT.Debug, "StartPDFPrintProcessEO->After mt.WaitOne", TaskProcess)
End If
RemoveHandler EO.Base.Runtime.Exception, AddressOf EOException
If TaskProcess.Task.TaskDebugging Then
LogAPI.Log(False, LogClass.EventT.Debug, "StartPDFPrintProcessEO->Removing exception", TaskProcess)
End If
End Sub
eo_support
Posted: Friday, April 12, 2019 9:54:00 AM
Rank: Administration
Groups: Administration

Joined: 5/27/2007
Posts: 21,360
Hi,

This is just let you know that we have posted a new build (build 19.1.11) that MAY have resolved this issue for you. While trying to reproduce your issue, we have discovered another issue related to loading a second PDF file into the same PdfViewer. The new build have fixed that issue. So please try to download it from our download page and see if it resolves your issue and we can then go from there.

Thanks!
serializer
Posted: Friday, April 12, 2019 9:55:28 AM
Rank: Advanced Member
Groups: Member

Joined: 5/9/2016
Posts: 61
Was just going to email/post back. This build indeed solves my problem too. Thanks
eo_support
Posted: Friday, April 12, 2019 10:58:38 AM
Rank: Administration
Groups: Administration

Joined: 5/27/2007
Posts: 21,360
serializer wrote:
Was just going to email/post back. This build indeed solves my problem too. Thanks


Great. Thanks for confirming the fix!
serializer
Posted: Thursday, May 2, 2019 4:55:20 PM
Rank: Advanced Member
Groups: Member

Joined: 5/9/2016
Posts: 61
It seems it is not fixed anyway. Many prints later it hangs again and application needs to be restarted.
serializer
Posted: Friday, May 3, 2019 8:17:39 AM
Rank: Advanced Member
Groups: Member

Joined: 5/9/2016
Posts: 61
Customer who is receiving the problem is printing 14 pages x 14 copies. He does this operation 2-3 times before it starts hanging again.
eo_support
Posted: Saturday, May 4, 2019 1:32:15 PM
Rank: Administration
Groups: Administration

Joined: 5/27/2007
Posts: 21,360
Hi,

We do not know what caused this problem. Is it possible for you to leave debug monitor running when this happens again? See here for more details:

https://www.essentialobjects.com/doc/common/remote_debug.aspx

Thanks!
serializer
Posted: Sunday, May 5, 2019 3:42:56 AM
Rank: Advanced Member
Groups: Member

Joined: 5/9/2016
Posts: 61
It is not possible to install this on end user customer computer. But I am sure you can reproduce this if you print out the same amout as described.
serializer
Posted: Tuesday, May 7, 2019 11:11:05 AM
Rank: Advanced Member
Groups: Member

Joined: 5/9/2016
Posts: 61
I have found one way to reproduce this. Try launching Print of a file in 3 threads at the same time. Some will get timeout and some will hang. Nothing will print. But if I print one at a time this works.
eo_support
Posted: Wednesday, May 8, 2019 3:26:26 PM
Rank: Administration
Groups: Administration

Joined: 5/27/2007
Posts: 21,360
Hi,

This does not prove much ---- the WebView class is NOT thread safe by design, thus other classes that are based on this class is not thread safe either (except for classes that explicitly stated are multi-thread safe). So you simply can not drive it in multiple threads. Member variables will get corrupted this way and all kind of strange things will happen.

Thanks!
serializer
Posted: Thursday, May 9, 2019 10:59:03 AM
Rank: Advanced Member
Groups: Member

Joined: 5/9/2016
Posts: 61
eo_support wrote:
Hi,

This does not prove much ---- the WebView class is NOT thread safe by design, thus other classes that are based on this class is not thread safe either (except for classes that explicitly stated are multi-thread safe). So you simply can not drive it in multiple threads. Member variables will get corrupted this way and all kind of strange things will happen.

Thanks!


I assumed it was thread safe. I added lock on thread and now concurrent threads work - but still, after some hours of printing a lot it fails by hanging. I think you can can easily reproduce this by printing from the same process, many pages and many times. This behaviour is new since a couple of versions. When this support case was opened you had a fix you said and it made things better = it took longer before it was reproduced.

While you test this on a larger scale can you point me to an older version where this worked as usual as I am getting more and more customers that cannot print anymore with my program and this component.
eo_support
Posted: Thursday, May 9, 2019 3:07:44 PM
Rank: Administration
Groups: Administration

Joined: 5/27/2007
Posts: 21,360
Hi,

Since we do not know the exact cause for this issue, we can not tell you for certain what is the last version that does not have this problem. However the best bet would be the last 2018 build. 2019 build uses a newer version of Chromium browser engine that brought in millions line of new code. As such we would recommend you to use the latest 2018 build (18.3.46) while we investigate this issue.

As to threading, just adding lock is not enough. You must reroute all the calls to the same thread that creates the WebView. In another word, each WebView is associated to the thread in which it is created, and all methods (except for a few) of the WebView object can only be safely called in that thread. They are not designed to be called in other threads.

Beside the thread issue, you may also want to check re-entering issue. Some of the WebView methods runs a local message pump. This message pump can allow additional user input such as clicking a button which triggers another call. This can cause problems as well.

Thanks!


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