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[APPROVED] GLCtrl flickering on Win32 [message #42441]

Fri, 14 March 2014 18:44

Klugier
Messages: 1085
Registered: September 2012
Location: Poland, Kraków

Senior Contributor

Hello,

It seems that GLCtrl flickers when window is resized on M$ Windows. The main problem with current implementation is that "WindowProc" method does not support resizing events like "WM_SIZE" and "WM_ERASEBKGND". The other thing that was wrong is calling glFinish() (We should only use "glFlush" in case when doubleBuffering is off).

So, below is the corrected implementation "WindowProc" method(GLCtrl/Win32GLCtrl.cpp - line 87):

LRESULT GLCtrl::GLPane::WindowProc(UINT message, WPARAM wParam, LPARAM lParam)
{
	if((message == WM_PAINT || message == WM_SIZE || message == WM_ERASEBKGND) && hDC && hRC) 
	{
		PAINTSTRUCT ps;
		BeginPaint(GetHWND(), &ps);
		ActivateContext();
		ctrl->GLPaint();
		ctrl->doubleBuffering ? SwapBuffers(hDC) : glFlush();
		EndPaint(GetHWND(), &ps);
		return 0;
	}
	
	return DHCtrl::WindowProc(message, wParam, lParam);
}

// **********

The second less important thing is that GLDraw dosen't support resizing by default. The first solution is improve virtual method GLResize(int w, int h) part of GLCtrl class. Implementation: (GLCtrl.h - several header changes, GLCtrl.cpp - GLResize implementation)

void GLCtrl::GLResize(int w, int h)
{
	glViewport(0, 0, (GLsizei)w, (GLsizei)h);
}

The second option is writting documentation for GLDraw for instance: "If you want to have GLDraw resizing you should override GLResize method with following code: glViewport(0, 0, (GLsizei)w, (GLsizei)h);.".

// **********

At the end I have one question: can we move "GLEW" from GLDraw to separate module or plugin. It would help a lot...

P.S.
Tested on NVIDIA & Intel GPU.

Sincerely,
Klugier

Attachment: GLCtrl.cpp
(Size: 1.03KB, Downloaded 260 times)
Attachment: GLCtrl.h
(Size: 3.33KB, Downloaded 258 times)
Attachment: Win32GLCtrl.cpp
(Size: 2.27KB, Downloaded 507 times)