[PATCH 2/2] winex11.drv: Make the GL context current even if no drawables were given.

[Ken Thomases]

On Feb 23, 2016, at 3:07 AM, Alexandre Julliard <julliard at winehq.org> wrote:
> 
> Charles Davis <cdavis5x at gmail.com> writes:
> 
>> @@ -1833,26 +1833,29 @@ static BOOL glxdrv_wglMakeCurrent(HDC hdc, struct wgl_context *ctx)
>>         return TRUE;
>>     }
>> 
>> -    if ((gl = get_gl_drawable( WindowFromDC( hdc ), hdc )))
>> +    if (!hdc || (gl = get_gl_drawable( WindowFromDC( hdc ), hdc )))
>>     {
>> -        if (ctx->fmt != gl->format)
>> +        if (gl && ctx->fmt != gl->format)
>>         {
>>             WARN( "mismatched pixel format hdc %p %p ctx %p %p\n", hdc, gl->format, ctx, ctx->fmt );
>>             SetLastError( ERROR_INVALID_PIXEL_FORMAT );
>>             goto done;
>>         }
>> 
>> -        TRACE("hdc %p drawable %lx fmt %p ctx %p %s\n", hdc, gl->drawable, gl->format, ctx->ctx,
>> -              debugstr_fbconfig( gl->format->fbconfig ));
>> +        if (gl)
>> +            TRACE("hdc %p drawable %lx fmt %p ctx %p %s\n", hdc, gl->drawable, gl->format, ctx->ctx,
>> +                  debugstr_fbconfig( gl->format->fbconfig ));
>> +        else
>> +            TRACE("ctx %p (no drawable)\n", ctx->ctx);
>> 
>> -        ret = pglXMakeCurrent(gdi_display, gl->drawable, ctx->ctx);
>> +        ret = pglXMakeCurrent(gdi_display, gl ? gl->drawable : None, ctx->ctx);
>>         if (ret)
>>         {
>>             NtCurrentTeb()->glContext = ctx;
>>             ctx->has_been_current = TRUE;
>>             ctx->hdc = hdc;
>> -            ctx->drawables[0] = gl->drawable;
>> -            ctx->drawables[1] = gl->drawable;
>> +            ctx->drawables[0] = gl ? gl->drawable : 0;
>> +            ctx->drawables[1] = gl ? gl->drawable : 0;
> 
> You really want a separate code path instead of adding pointer checks
> everywhere.

Not to mention that if hdc is NULL, then gl is just uninitialized and all of those checks are invalid, as is the release_gl_drawable() call at the end of the function.

That said, some of the existing code path can be shared by creating a "drawable" variable (of type Drawable).

-Ken