Using QuickPDF in Multi-Thread app

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   Platform: Windows 2016 Server  Lazarus 2.0.10, FreePascal 3.2.0
Web App:  Brook 5 Framework  QuickPDF Library 10.13Uses clause contains:  ComObj, ActiveX,  DebenuPDFLibrary64AX1013_10_13_TLB;                           
I need use the QuickPDF library in a non-main thread of my web app.  However, when I run the code to create a library object:

...
var
   qpdfDCL: TAxcPDFLibrary;
begin
    qpdfDCL := TAxcPDFLibrary.Create(frmMain);
...

I always get this error message:
  CheckSynchronize called from non-main thread

What is the correct, thread-safe way, to .Create, use and .Free, the QuickPDFLibrary in a non-main thread?

Thanks in advance.

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RedOctober2018 Members Profile Find Members Posts Team Player Joined: 22 Jun 18 Location: West Status: Offline Points: 25	Post Options Post Reply Quote RedOctober2018 Report Post Thanks(0) Quote Reply Topic: Using QuickPDF in Multi-Thread app Posted: 04 Jul 21 at 10:45PM
	Platform: Windows 2016 Server Lazarus 2.0.10, FreePascal 3.2.0 Web App: Brook 5 Framework QuickPDF Library 10.13 Uses clause contains: ComObj, ActiveX, DebenuPDFLibrary64AX1013_10_13_TLB; I need use the QuickPDF library in a non-main thread of my web app. However, when I run the code to create a library object: ... var qpdfDCL: TAxcPDFLibrary; begin qpdfDCL := TAxcPDFLibrary.Create(frmMain); ... I always get this error message: CheckSynchronize called from non-main thread What is the correct, thread-safe way, to .Create, use and .Free, the QuickPDFLibrary in a non-main thread? Thanks in advance.

Ingo Members Profile Find Members Posts Moderator Group Joined: 29 Oct 05 Status: Offline Points: 3529	Post Options Post Reply Quote Ingo Report Post Thanks(0) Quote Reply Posted: 04 Jul 21 at 10:50PM
	Hi, think this haven't to do with QuickPDF itself. Try Google with CheckSynchronize... Think you'll get the solution of your issue in the www ;-) Edited by Ingo - 04 Jul 21 at 10:51PM
	Cheers, Ingo

RedOctober2018 Members Profile Find Members Posts Team Player Joined: 22 Jun 18 Location: West Status: Offline Points: 25	Post Options Post Reply Quote RedOctober2018 Report Post Thanks(0) Quote Reply Posted: 04 Jul 21 at 11:22PM
	Hi Ingo, Yes, I researched this problem and found CoInitialize and CoUnitialize, but no matter where I call these in relation to the call to create a QuickPDFLibrary object, I get an error message. I suspect there is a call to CheckSynchronize inside the QuickPDFLibrary which means it always needs to be in the main thread. But it can't be, because I'm using QPDF Lib in the non-main thread. CoInitialize must be called within the non-main thread. UnCoInitialize must not be called in the non-main thread, it must be called in the main thread. That's why I just asked the open ended question "what is the correct way to do this" which usually elicits a broader and more complete answer than asking a more narrowly focused question.

Ingo Members Profile Find Members Posts Moderator Group Joined: 29 Oct 05 Status: Offline Points: 3529	Post Options Post Reply Quote Ingo Report Post Thanks(0) Quote Reply Posted: 05 Jul 21 at 10:51PM
	Hi, i've made a complete scan through all source elements of version 18.11 ... There isn't a single Synchronize... Nothing. CoInitialize i've found - but i didn't found UnCoInitialize. Edited by Ingo - 05 Jul 21 at 10:54PM
	Cheers, Ingo