macOS: Experimental Vulkan support via MoltenVK

Add support for QSurface::VulkanSurface and QVulkanWindow.

Usage:
  1) Build MoltenVK according to instructions
  2) Configure Qt: ./configure -I /path/to/MoltenVK/Package/Release/MoltenVK/include
  3) export QT_VULKAN_LIB=/path/to/MoltenVK/Package/Release/MoltenVK/macOS/libMoltenVK.

Implement support for QSurface::VulkanSurface by enabling
layer mode for QNSView and then creating a CAMetalLayer,
which the MoltenVK translation layer can run on.

MoltenVK provides an implementation of the Vulcan API,
which means that the platform integration is similar
to other platforms: implement a QCocoaVulkanInstance
where we pass the QNSView instance to the vkCreateMacOSSurfaceMVK
Vulkan surface constructor function.

Using Vulkan directly without QVulkanWindow is possible, but not
tested.

We currently load libMoltenVK at run-time and use the
existing QT_VULKAN_LIB environment variable to set its
path. For deployment purposes it would be better to
link against MoltenVK.frameworkm, but this

Task-number: QTBUG-66966
Change-Id: I04ec6289c40b199dca9fed32902b5d2ad4e9c030
Reviewed-by: Morten Johan Sørvig <morten.sorvig@qt.io>

1 files changed, 10 insertions, 4 deletions

diff --git a/src/plugins/platforms/cocoa/qcocoawindow.mm b/src/plugins/platforms/cocoa/qcocoawindow.mm
index 7e7740527f..4618db1aa3 100644
--- a/src/plugins/platforms/cocoa/qcocoawindow.mm
+++ b/src/plugins/platforms/cocoa/qcocoawindow.mm
@@ -222,10 +222,16 @@ QCocoaWindow::~QCocoaWindow()
     if (!isForeignWindow())
         [[NSNotificationCenter defaultCenter] removeObserver:m_view];
 
-    // While it is unlikely that this window will be in the popup stack
-    // during deletetion we clear any pointers here to make sure.
-    if (QCocoaIntegration::instance()) {
-        QCocoaIntegration::instance()->popupWindowStack()->removeAll(this);
+    if (QCocoaIntegration *cocoaIntegration = QCocoaIntegration::instance()) {
+        // While it is unlikely that this window will be in the popup stack
+        // during deletetion we clear any pointers here to make sure.
+        cocoaIntegration->popupWindowStack()->removeAll(this);
+
+#if QT_CONFIG(vulkan)
+        auto vulcanInstance = cocoaIntegration->getCocoaVulkanInstance();
+        if (vulcanInstance)
+            vulcanInstance->destroySurface(m_vulkanSurface);
+#endif
     }
 
     [m_view release];