Rework pixel format selection on Windows

Author: lb90

test/wgl_common.c

@@ -27,41 +27,79 @@
 
 static int (*test_callback)(HDC hdc);
 
+static int
+find_pixel_format(HDC hdc)
+{
+    DWORD required_flags = PFD_DRAW_TO_WINDOW |
+                           PFD_SUPPORT_OPENGL;
+    DWORD unwanted_flags = PFD_NEED_PALETTE |
+                           PFD_NEED_SYSTEM_PALETTE;
+    PIXELFORMATDESCRIPTOR pfd;
+    int best_index = 0;
+    int best_distance = 1;
+
+    for (int index = 1;
+         DescribePixelFormat(hdc, index, sizeof (pfd), &pfd) && best_distance != 0;
+         index++)
+    {
+        int distance;
+
+        if (pfd.nSize < sizeof (pfd) || pfd.nVersion != 1)
+            continue;
+
+        if (pfd.iPixelType != PFD_TYPE_RGBA)
+            continue;
+
+        if (pfd.iLayerType != PFD_MAIN_PLANE)
+            continue;
+
+        if ((pfd.dwFlags & required_flags) != required_flags)
+            continue;
+
+        if ((pfd.dwFlags & unwanted_flags) != 0)
+            continue;
+
+        distance = 1000 * !!(pfd.dwFlags & PFD_GENERIC_FORMAT) +
+                   100 * !!(pfd.dwFlags & PFD_GENERIC_ACCELERATED) +
+                   10 * !!(pfd.cColorBits != 24 && pfd.cColorBits != 32) +
+                   10 * !!(pfd.cRedBits != 8 || pfd.cGreenBits != 8 || pfd.cBlueBits != 8) +
+                   !(pfd.dwFlags & PFD_DOUBLEBUFFER);
+        if (best_index == 0 || distance < best_distance) {
+            best_index = index;
+            best_distance = distance;
+        }
+    }
+
+    return best_index;
+}
+
 static void
 setup_pixel_format(HDC hdc)
 {
-    PIXELFORMATDESCRIPTOR pfd = {
-        sizeof(PIXELFORMATDESCRIPTOR),
-        1,
-        PFD_SUPPORT_OPENGL |
-        PFD_DRAW_TO_WINDOW |
-        PFD_DOUBLEBUFFER,
-        PFD_TYPE_RGBA,
-        32,
-        0, 0, 0, 0, 0, 0,
-        0,
-        0,
-        0,
-        0, 0, 0, 0,
-        16,
-        0,
-        0,
-        PFD_MAIN_PLANE,
-        0,
-        0, 0, 0,
-    };
+    PIXELFORMATDESCRIPTOR pfd;
     int pixel_format;
+    int ret;
 
-    pixel_format = ChoosePixelFormat(hdc, &pfd);
+    pixel_format = find_pixel_format(hdc);
     if (!pixel_format) {
-        fputs("ChoosePixelFormat failed.\n", stderr);
-        exit(1);
+        fputs("Could not find suitable pixel format.\n", stderr);
+        exit(77); /* skip */
     }
 
+    DescribePixelFormat(hdc, pixel_format, sizeof (pfd), &pfd);
+
     if (SetPixelFormat(hdc, pixel_format, &pfd) != TRUE) {
         fputs("SetPixelFormat() failed.\n", stderr);
         exit(1);
     }
+
+    SetLastError(0);
+    ret = GetPixelFormat(hdc);
+    if (ret == 0) {
+        unsigned int code = GetLastError();
+        fprintf(stderr, "GetPixelFormat failed with error code %u\n", code);
+        exit(1);
+    }
 }
 
 static LRESULT CALLBACK