[PATCH 0/1] MR1828: winex11: Check pixel format flags in X11DRV_wglChoosePixelFormatARB.

[Rémi Bernon (＠rbernon)]

The check was dropped in e392e0ac2846edc25610723c19d6a796372017e1, leaving the dwFlags variable unused.

I have no idea if it was indeed unnecessary or if it was dropped by mistake but either we need to keep the check, or we should remove the variable.

[PATCH 1/1] winex11: Check pixel format flags in X11DRV_wglChoosePixelFormatARB.

[Rémi Bernon]

From: Rémi Bernon

The check was dropped in e392e0ac2846edc25610723c19d6a796372017e1,
leaving the dwFlags variable unused.
---
 dlls/winex11.drv/opengl.c | 2 +-
 1 file changed, 1 insertion(+), 1 deletion(-)

diff --git a/dlls/winex11.drv/opengl.c b/dlls/winex11.drv/opengl.c
index 52f363461e4..5179c4e6405 100644
--- a/dlls/winex11.drv/opengl.c
+++ b/dlls/winex11.drv/opengl.c
@@ -2633,7 +2633,7 @@ static BOOL X11DRV_wglChoosePixelFormatARB( HDC hdc, const int *piAttribIList, c
         }

for (i = 0; i < nb_pixel_formats; ++i)
-            if (pixel_formats[i].fmt_id == fmt_id)
+            if (pixel_formats[i].fmt_id == fmt_id && (pixel_formats[i].dwFlags & dwFlags) == dwFlags)
                 break;

if (i == nb_pixel_formats)

[Paul Gofman (＠gofman)]

This ultimately deserves a test, even if out of tree one. I made some ad-hoc one [1] and in confirms (tested on Windows / AMD) that the formats with missing flags do not appear in the list (i. e., the change is correct). It also conforms to spec [2] where flags are listed as exact match criteria.

The only thing here
```
         for (i = 0; i < nb_pixel_formats; ++i)
-            if (pixel_formats[i].fmt_id == fmt_id)
+            if (pixel_formats[i].fmt_id == fmt_id && (pixel_formats[i].dwFlags & dwFlags) == dwFlags)
                 break;
```
The loop just searches for fmt_id in our format list, it makes no sense to continue searching once format is found, the flag check should probably go after the loop. I don't recall the details now (my patch is from almost 2 years ago) but that's probably how I lost that flags check back then.

1. [test.patch](/uploads/b3ae677c8a7072b069d8dfc779cd8002/test.patch)
2. https://registry.khronos.org/OpenGL/extensions/ARB/WGL_ARB_pixel_format.txt

[Paul Gofman (＠gofman)]

PS the test can probably be included as well? With ```+        WGL_SUPPORT_GDI_ARB, 1,``` part dropped, as limiting the list of formats further will void the testing for depth bits currently performed in the test. It is just that WGL_DRAW_TO_WINDOW_ARB, WGL_SUPPORT_OPENGL_ARB don't limit format list in Wine here so I added it as a sanity check for patch testing.