Re: [Mesa3d-users] wglMakeCurrent possible memory leak

[Brian P. <br...@vm...>]

Dimitar Kodjabachev wrote:
> Hello,
> 
> I sent this to mesa3d-dev, which was probably not the right place.

mesa3d-dev is OK since there may be a bug in the Mesa wgl code.  I'm 
cc'ing mesa3d-dev.


> I have the following situation (pseudocode) with Mesa 7.4.4:
> 
> hglrc1 = wglCreateContext(hdc1)
> wglMakeCurrent(hdc1,hglrc1)
> hglrc2 = wglCreateContext(hdc2)
> wglMakeCurrent(hdc2,hglrc2)
> wglMakeCurrent(hdc3,hglrc2)
> wglDeleteContext(hglrc1)
> wglDeleteContext(hglrc2)
> 
> As a result of this sequence of calls, a WMesaFramebuffer structure is leaked.
> The call causing the leak is wglMakeCurrent(hdc3,hglrc2). This is what I know
> so far:
> 
> -> wglMakeCurrent(hdc3,hglrc2) calls
>  -> WMesaMakeCurrent(hglrc2,hdc3) which calls
>  -> wmesa_lookup_framebuffer(hdc3) which returns NULL, as the hdc given to
>      wglMakeCurrent is different from the one given at the time
>      of wglCreateContext
>  -> wmesa_new_framebuffer() is called and a new frame buffer is allocated
> 
> This new frame buffer is not released upon wglDeleteContext(hglrc2).

A rendering context is not the same as a drawing surface.  So deleting 
a rendering context does not imply deleting a surface.


> As far as
> I know, the device context passed to wglMakeCurrent does not have to
> be the same as the one passed to wglCreateContext as long as the the actual
> device and the pixel formats are.  Is this correct or is my usage wrong?

My understanding is that the context passed to wglMakeCurrent() must 
have been created by a call to wglCreateContext().

I don't think I can help with this memory leak.  Maybe someone else 
who works on Windows can help you.

-Brian