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Re: How do I create a loop for a window to react to volatile changes to a global variable? [message #51335 is a reply to message #51334]

Mon, 11 March 2019 12:44

Oblivion
Messages: 1094
Registered: August 2007

Senior Contributor

Hello slashupp,

If you are calling a method of the main window (main thread), then add a GuiLock "in" that method, it is better that way.

E.g.:

#include <CtrlLib/CtrlLib.h>

using namespace Upp;

class ThreadTest : public TopWindow {
	Button    start;
	ArrayCtrl array;
public:
	ThreadTest() 
	{
		SetRect(0, 0, 800, 600);
		CenterScreen();
		array.AddColumn("Number");
		Add(array.HSizePos().VSizePos(0, 30));
		Add(start.SetLabel("Start Thread").RightPos(2, 120).BottomPos(2, 26));
		
		start << [=] {  RunThread(); };
	}
	void RunThread()
	{
		Thread t;
		t.Run([=]{
			for(int i = 1; i < 30000; i++) {
                                // GuiLock __;
 				SetArray(i);
                         }
		});
		t.Detach();
	}
	void SetArray(int n)
	{
		GuiLock __;
		array.Add(n);
		if(n == 10) { // Resize window from within thread...
			SetRect(0, 0, 640, 480);
		}
	}
	
};

GUI_APP_MAIN
{
	ThreadTest().Run();
}

Also,
Quote:

I added "GuiLock __;" in the methods but then get:
"Assertion failed in ..../CtrlCore/GtkCapture.cpp, line 41 IsMainThread()"

AFAIK, this means that, that specific method -or other methods called within it- can only be called from the main thread.

In some cases you may want to create a customized event loop in the main thread.

E.g:

	void Run()
	{
		OpenMain();
		while(IsOpen()) {
			ProcessEvents();
                        GuiSleep(10);
			ProcessMyThreadsEvents(); // It's up to you how to precess your threads' events.
		}
	}

Best regards,
Oblivion

Github page: https://github.com/ismail-yilmaz
upp-components: https://github.com/ismail-yilmaz/upp-components
Bobcat the terminal emulator: https://github.com/ismail-yilmaz/Bobcat

[Updated on: Mon, 11 March 2019 13:06]

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