macOS: Don't require setting all three color buffer sizes in QSurfaceFormat

Change-Id: Iaa6eb4d64f549a31aa5c53145e8b37facec4ea78
Reviewed-by: Andy Nichols <andy.nichols@qt.io>
Reviewed-by: Tor Arne Vestbø <tor.arne.vestbo@qt.io>

2 files changed, 9 insertions, 14 deletions

diff --git a/src/gui/kernel/qsurfaceformat.cpp b/src/gui/kernel/qsurfaceformat.cpp
index 1a814ec21f..4e2bcad50f 100644
--- a/src/gui/kernel/qsurfaceformat.cpp
+++ b/src/gui/kernel/qsurfaceformat.cpp
@@ -554,10 +554,6 @@ int QSurfaceFormat::alphaBufferSize() const
 
 /*!
     Set the desired \a size in bits of the red channel of the color buffer.
-
-    \note On Mac OSX, be sure to set the buffer size of all color channels,
-    otherwise this setting will have no effect. If one of the buffer sizes is not set,
-    the current bit-depth of the screen is used.
 */
 void QSurfaceFormat::setRedBufferSize(int size)
 {
@@ -569,10 +565,6 @@ void QSurfaceFormat::setRedBufferSize(int size)
 
 /*!
     Set the desired \a size in bits of the green channel of the color buffer.
-
-    \note On Mac OSX, be sure to set the buffer size of all color channels,
-    otherwise this setting will have no effect. If one of the buffer sizes is not set,
-    the current bit-depth of the screen is used.
 */
 void QSurfaceFormat::setGreenBufferSize(int size)
 {
@@ -584,10 +576,6 @@ void QSurfaceFormat::setGreenBufferSize(int size)
 
 /*!
     Set the desired \a size in bits of the blue channel of the color buffer.
-
-    \note On Mac OSX, be sure to set the buffer size of all color channels,
-    otherwise this setting will have no effect. If one of the buffer sizes is not set,
-    the current bit-depth of the screen is used.
 */
 void QSurfaceFormat::setBlueBufferSize(int size)
 {
diff --git a/src/plugins/platforms/cocoa/qcocoaglcontext.mm b/src/plugins/platforms/cocoa/qcocoaglcontext.mm
index e45ea7efd3..d91b2cabaf 100644
--- a/src/plugins/platforms/cocoa/qcocoaglcontext.mm
+++ b/src/plugins/platforms/cocoa/qcocoaglcontext.mm
@@ -197,8 +197,15 @@ NSOpenGLPixelFormat *QCocoaGLContext::pixelFormatForSurfaceFormat(const QSurface
         attrs << NSOpenGLPFAStencilSize << format.stencilBufferSize();
     if (format.alphaBufferSize() > 0)
         attrs << NSOpenGLPFAAlphaSize << format.alphaBufferSize();
-    if (format.redBufferSize() > 0 && format.greenBufferSize() > 0 && format.blueBufferSize() > 0) {
-        const int colorSize = format.redBufferSize() + format.greenBufferSize() + format.blueBufferSize();
+
+    auto rbz = format.redBufferSize();
+    auto gbz = format.greenBufferSize();
+    auto bbz = format.blueBufferSize();
+    if (rbz > 0 || gbz > 0 || bbz > 0) {
+        auto fallbackSize = qMax(rbz, qMax(gbz, bbz));
+        auto colorSize = (rbz > 0 ? rbz : fallbackSize)
+                       + (gbz > 0 ? gbz : fallbackSize)
+                       + (bbz > 0 ? bbz : fallbackSize);
         attrs << NSOpenGLPFAColorSize << colorSize << NSOpenGLPFAMinimumPolicy;
     }