macOS: Expand and tighten plumbing of QWindow's requested color space

A QWindow can have a requested target color space via its QSurfaceFormat.
This allows users who know what color space their source material is in,
or who do their own color matching, to ensure a consistent target color
space.

In the past we plumbed this to NSWindow's colorSpace property. This meant
that you could only have one color space per top level, even if child
windows were in play, and we could only set the color space if we were
the ones creating the NSWindow, failing the color space request in cases
where the window was embedded in a non-Qt window hierarchy.

We now store the requested color space in our QNSView, and propagate it
to both the IOSurfaces we use in QCALayerBackingStore, and to the view's
layer, in case it's a CAMetalLayer. We also pick up any changes to the
backing properties of the view, and ensure we update the color space
accordingly.

We still propagate the color space to NSWindow, as for OpenGL we don't
use CAOpenGLLayer (which has a colorSpace property), but instead use
NSOpenGLContext. This is not something we're going to change, so as
a workaround we set the NSWindow color space, which does affect GL
drawing via NSOpenGLContext. The granular color spaces we set on
the IOSurfaces and CAMetalLayer will override the NSWindow state.

Pick-to: 6.7
Change-Id: I5d9765d95140b8523ee09f70ff09a8c9400ffdc7
Reviewed-by: Pavel Dubsky <pavel.dubsky@qt.io>
Reviewed-by: Allan Sandfeld Jensen <allan.jensen@qt.io>
Reviewed-by: Artem Dyomin <artem.dyomin@qt.io>
Reviewed-by: Jøger Hansegård <joger.hansegard@qt.io>

1 files changed, 3 insertions, 0 deletions

diff --git a/src/plugins/platforms/cocoa/qnsview.mm b/src/plugins/platforms/cocoa/qnsview.mm
index 6cb10efa7f..1286e8e382 100644
--- a/src/plugins/platforms/cocoa/qnsview.mm
+++ b/src/plugins/platforms/cocoa/qnsview.mm
@@ -90,6 +90,7 @@ QT_NAMESPACE_ALIAS_OBJC_CLASS(QNSViewMenuHelper);
 @property (assign) NSView* previousSuperview;
 @property (assign) NSWindow* previousWindow;
 @property (retain) QNSViewMenuHelper* menuHelper;
+@property (nonatomic, retain) NSColorSpace *colorSpace;
 @end
 
 @implementation QNSView {
@@ -119,6 +120,8 @@ QT_NAMESPACE_ALIAS_OBJC_CLASS(QNSViewMenuHelper);
     NSDraggingContext m_lastSeenContext;
 }
 
+@synthesize colorSpace = m_colorSpace;
+
 - (instancetype)initWithCocoaWindow:(QCocoaWindow *)platformWindow
 {
     if ((self = [super initWithFrame:NSZeroRect])) {