Windows QPA: GL: Fix setting the color depths for the GDI fallback

Set the color buffer depths on the PIXELFORMATDESCRIPTOR for
the fallback code path (-platform windows:gl=gdi).

Task-number: QTBUG-66797
Change-Id: Idccd94fdf121803af1c19e34cc86b6f06ca88d90
Reviewed-by: Laszlo Agocs <laszlo.agocs@qt.io>

1 files changed, 9 insertions, 0 deletions

diff --git a/src/plugins/platforms/windows/qwindowsglcontext.cpp b/src/plugins/platforms/windows/qwindowsglcontext.cpp
index 4bdf3167e4..e9c52e2c02 100644
--- a/src/plugins/platforms/windows/qwindowsglcontext.cpp
+++ b/src/plugins/platforms/windows/qwindowsglcontext.cpp
@@ -391,6 +391,15 @@ static PIXELFORMATDESCRIPTOR
         pfd.dwFlags |= PFD_DOUBLEBUFFER;
     pfd.cDepthBits =
         format.depthBufferSize() >= 0 ? format.depthBufferSize() : 32;
+    const int redBufferSize = format.redBufferSize();
+    if (redBufferSize != -1)
+        pfd.cRedBits = BYTE(redBufferSize);
+    const int greenBufferSize = format.greenBufferSize();
+    if (greenBufferSize != -1)
+        pfd.cGreenBits = BYTE(greenBufferSize);
+    const int blueBufferSize = format.blueBufferSize();
+    if (blueBufferSize != -1)
+        pfd.cBlueBits = BYTE(blueBufferSize);
     pfd.cAlphaBits = format.alphaBufferSize() > 0 ? format.alphaBufferSize() : 8;
     pfd.cStencilBits = format.stencilBufferSize() > 0 ? format.stencilBufferSize() : 8;
     if (additional.formatFlags & QWindowsGLAccumBuffer)