[waffle] [PATCH 11/18] wgl: use wglChoosePixelFormatARB when available

[Emil Velikov]

With this commit we create an assumption that the root window DC
(device context) is compatible with the one for the new window.
Otherwise the pixel format will not be compatible, and we'll fail
at SetPixelFormat().

Signed-off-by: Emil Velikov <emil.l.velikov at gmail.com>
---
 src/waffle/wgl/wgl_config.c | 53 +++++++++++++++++++++++++++++++++++++++++++--
 1 file changed, 51 insertions(+), 2 deletions(-)

diff --git a/src/waffle/wgl/wgl_config.c b/src/waffle/wgl/wgl_config.c
index 5eaf36e..1051153 100644
--- a/src/waffle/wgl/wgl_config.c
+++ b/src/waffle/wgl/wgl_config.c
@@ -27,6 +27,9 @@
 #include <stdlib.h>
 #include <string.h>
 #include <windows.h>
+// XXX: Do we want to include these two, or should we redefine the WGL* consts ?
+#include <GL/gl.h>
+#include <GL/wglext.h>
 
 #include "wcore_config_attrs.h"
 #include "wcore_error.h"
@@ -96,8 +99,54 @@ wgl_config_choose_native(struct wgl_config *config,
                          struct wgl_display *dpy,
                          const struct wcore_config_attrs *attrs)
 {
-    if (0 /* dpy->ARB_pixel_format */) {
-        // XXX: FINISHME
+
+    // Use wglChoosePixelFormatARB if available.
+    if (dpy->ARB_pixel_format) {
+        float fAttribs[1] = { 0 };
+        int iAttribs[] = {
+            WGL_COLOR_BITS_ARB,         attrs->rgba_size,
+            WGL_RED_BITS_ARB,           attrs->red_size,
+            WGL_GREEN_BITS_ARB,         attrs->green_size,
+            WGL_BLUE_BITS_ARB,          attrs->blue_size,
+            WGL_ALPHA_BITS_ARB,         attrs->alpha_size,
+
+            WGL_DEPTH_BITS_ARB,         attrs->depth_size,
+            WGL_STENCIL_BITS_ARB,       attrs->stencil_size,
+
+            WGL_SAMPLE_BUFFERS_ARB,     attrs->sample_buffers,
+            WGL_STEREO_ARB,             attrs->samples,
+
+            WGL_DOUBLE_BUFFER_ARB,      attrs->double_buffered,
+
+            WGL_ACCUM_RED_BITS_ARB,     attrs->accum_buffer,
+            WGL_ACCUM_GREEN_BITS_ARB,   attrs->accum_buffer,
+            WGL_ACCUM_BLUE_BITS_ARB,    attrs->accum_buffer,
+            WGL_ACCUM_ALPHA_BITS_ARB,   attrs->accum_buffer,
+
+            WGL_DRAW_TO_WINDOW_ARB,     GL_TRUE,
+            WGL_ACCELERATION_ARB,       WGL_FULL_ACCELERATION_ARB,
+
+            0,
+        };
+        unsigned int num_formats;
+        bool ok;
+
+        // But first we need a current context to use it...
+        ok = wglMakeCurrent(dpy->hDC, dpy->hglrc);
+        if (!ok)
+            return false;
+
+        ok = dpy->wglChoosePixelFormatARB(dpy->hDC, iAttribs, fAttribs, 1,
+                                          &config->pixel_format, &num_formats);
+
+        wglMakeCurrent(NULL, NULL);
+
+        if (!ok || !num_formats) {
+            wcore_errorf(WAFFLE_ERROR_UNKNOWN,
+                         "wglChoosePixelFormatARB failed");
+            return false;
+        }
+
     }
     else {
         config->pixel_format = ChoosePixelFormat(dpy->hDC, &config->pfd);
-- 
2.0.2