Rework how we search for winsys configs

When creating new onscreen framebuffers we need to take the
configuration in cogl terms and translate that into a configuration
applicable to any given winsys, e.g. an EGLConfig or a GLXFBConfig
or a PIXELFORMATDESCRIPTOR.

Also when we first create a context we typically have to do a very
similar thing because most OpenGL winsys APIs also associate a
framebuffer config with the context and all future configs need to be
compatible with that.

This patch introduces an internal CoglFramebufferConfig to wrap up some
of the configuration parameters that are common to CoglOnscreenTemplate
and to CoglFramebuffer so we aim to re-use code when dealing with the
above two problems.

This patch also aims to rework the winsys code so it can be more
naturally extended as we start adding more configureability to how
onscreen framebuffers are created.

Reviewed-by: Neil Roberts <neil@linux.intel.com>

1 files changed, 13 insertions, 5 deletions

diff --git a/cogl/winsys/cogl-winsys-wgl.c b/cogl/winsys/cogl-winsys-wgl.c
index f3bc8ba6..8306f278 100644
--- a/cogl/winsys/cogl-winsys-wgl.c
+++ b/cogl/winsys/cogl-winsys-wgl.c
@@ -316,7 +316,8 @@ pixel_format_is_better (const PIXELFORMATDESCRIPTOR *pfa,
 }
 
 static int
-choose_pixel_format (HDC dc, PIXELFORMATDESCRIPTOR *pfd)
+choose_pixel_format (CoglFramebufferConfig *config,
+                     HDC dc, PIXELFORMATDESCRIPTOR *pfd)
 {
   int i, num_formats, best_pf = 0;
   PIXELFORMATDESCRIPTOR best_pfd;
@@ -341,6 +342,11 @@ choose_pixel_format (HDC dc, PIXELFORMATDESCRIPTOR *pfd)
              already found */
           (best_pf == 0 || pixel_format_is_better (&best_pfd, pfd)))
         {
+          if (config->swap_chain->has_alpha && pfd->cAlphaBits == 0)
+            continue;
+          if (config->need_stencil && pfd->cStencilBits == 0)
+            continue;
+
           best_pf = i;
           best_pfd = *pfd;
         }
@@ -445,7 +451,8 @@ create_context (CoglDisplay *display, GError **error)
 
       wgl_display->dummy_dc = GetDC (wgl_display->dummy_hwnd);
 
-      pf = choose_pixel_format (wgl_display->dummy_dc, &pfd);
+      pf = choose_pixel_format (&display->onscreen_template->config,
+                                wgl_display->dummy_dc, &pfd);
 
       if (pf == 0 || !SetPixelFormat (wgl_display->dummy_dc, pf, &pfd))
         {
@@ -784,9 +791,10 @@ _cogl_winsys_onscreen_init (CoglOnscreen *onscreen,
   wgl_onscreen->client_dc = GetDC (hwnd);
 
   /* Use the same pixel format as the dummy DC from the renderer */
-  pf = GetPixelFormat (wgl_display->dummy_dc);
-  DescribePixelFormat (wgl_display->dummy_dc, pf, sizeof (pfd), &pfd);
-  if (!SetPixelFormat (wgl_onscreen->client_dc, pf, &pfd))
+  pf = choose_pixel_format (&framebuffer->config,
+                            wgl_onscreen->client_dc, &pfd);
+
+  if (pf == 0 || !SetPixelFormat (wgl_onscreen->client_dc, pf, &pfd))
     {
       g_set_error (error, COGL_WINSYS_ERROR,
                    COGL_WINSYS_ERROR_CREATE_ONSCREEN,