Cocoa: Option handling.

Add qt_mac_resolveOption().

Support setting options using either an environment
variable or a QWindow property, with a default fallback
value. The options are resolved with precedence in
the mentioned order.

Adds options for the following:
NSView setWantsBestResolutionOPenGLSurface
NSVIew setWantsLayer
NSOpenGLContext NSOpenGLCPSurfaceOrder

The window properties use the _q_mac_camelCase format.
The environment variables use the QT_MAC_ALL_CAPS format.

Change-Id: I1978a02d62e107a2120d81ffdd0f7b32f7731644
Reviewed-by: Gabriel de Dietrich <gabriel.dedietrich@digia.com>

src/plugins/platforms/cocoa/qcocoaglcontext.mm

@@ -42,6 +42,7 @@
 #include "qcocoaglcontext.h"
 #include "qcocoawindow.h"
 #include "qcocoaautoreleasepool.h"
+#include "qcocoahelpers.h"
 #include <qdebug.h>
 #include <QtCore/private/qcore_mac_p.h>
 #include <QtPlatformSupport/private/cglconvenience_p.h>
@@ -151,6 +152,11 @@ QCocoaGLContext::QCocoaGLContext(const QSurfaceFormat &format, QPlatformOpenGLCo
         [m_context setValues:&zeroOpacity forParameter:NSOpenGLCPSurfaceOpacity];
     }
 
+
+    // OpenGL surfaces can be ordered either above(default) or below the NSWindow.
+    const GLint order = qt_mac_resolveOption(1, "QT_MAC_OPENGL_SURFACE_ORDER");
+    [m_context setValues:&order forParameter:NSOpenGLCPSurfaceOrder];
+
     updateSurfaceFormat();
 }
 

src/plugins/platforms/cocoa/qcocoahelpers.h

@@ -162,6 +162,39 @@ CGContextRef qt_mac_cg_context(QPaintDevice *pdev);
 CGImageRef qt_mac_toCGImage(const QImage &qImage, bool isMask, uchar **dataCopy);
 QImage qt_mac_toQImage(CGImageRef image);
 
+template<typename T>
+T qt_mac_resolveOption(const T &fallback, const QByteArray &environment)
+{
+    // check for environment variable
+    if (!environment.isEmpty()) {
+        QByteArray env = qgetenv(environment);
+        if (!env.isEmpty())
+            return T(env.toInt()); // works when T is bool, int.
+    }
+
+    return fallback;
+}
+
+template<typename T>
+T qt_mac_resolveOption(const T &fallback, QWindow *window, const QByteArray &property, const QByteArray &environment)
+{
+    // check for environment variable
+    if (!environment.isEmpty()) {
+        QByteArray env = qgetenv(environment);
+        if (!env.isEmpty())
+            return T(env.toInt()); // works when T is bool, int.
+    }
+
+    // check for window property
+    if (window && !property.isNull()) {
+        QVariant windowProperty = window->property(property);
+        if (windowProperty.isValid())
+            return windowProperty.value<T>();
+    }
+
+    // return default value.
+    return fallback;
+}
 QT_END_NAMESPACE
 
 #endif //QCOCOAHELPERS_H

src/plugins/platforms/cocoa/qcocoawindow.mm

@@ -252,9 +252,15 @@ QCocoaWindow::QCocoaWindow(QWindow *tlw)
         // problem, except if the appilcation wants to have a "custom" viewport.
         // (like the hellogl example)
         if (QSysInfo::MacintoshVersion >= QSysInfo::MV_10_7
-            && tlw->surfaceType() == QSurface::OpenGLSurface)
-            [m_contentView setWantsBestResolutionOpenGLSurface:YES];
+            && tlw->surfaceType() == QSurface::OpenGLSurface) {
+            BOOL enable = qt_mac_resolveOption(YES, tlw, "_q_mac_wantsBestResolutionOpenGLSurface",
+                                                          "QT_MAC_WANTS_BEST_RESOLUTION_OPENGL_SURFACE");
+            [m_contentView setWantsBestResolutionOpenGLSurface:enable];
+        }
 #endif
+        BOOL enable = qt_mac_resolveOption(NO, tlw, "_q_mac_wantsLayer",
+                                                     "QT_MAC_WANTS_LAYER");
+        [m_contentView setWantsLayer:enable];
     }
     setGeometry(tlw->geometry());
     recreateWindow(parent());