Defer setting a QVulkanInstance on the window

...to createRhi(). There is no need for the VkInstance before that
point.

Change-Id: I87f4e8154e96409bccd7844f1bf80b957bb54d69
Reviewed-by: Andy Nichols <andy.nichols@qt.io>

1 files changed, 9 insertions, 0 deletions

diff --git a/src/quick/scenegraph/qsgrhisupport.cpp b/src/quick/scenegraph/qsgrhisupport.cpp
index 5029103cff..e8855ab071 100644
--- a/src/quick/scenegraph/qsgrhisupport.cpp
+++ b/src/quick/scenegraph/qsgrhisupport.cpp
@@ -583,6 +583,15 @@ QRhi *QSGRhiSupport::createRhi(QQuickWindow *window, QOffscreenSurface *offscree
 #if QT_CONFIG(vulkan)
     if (backend == QRhi::Vulkan) {
         QRhiVulkanInitParams rhiParams;
+        // QQuickWindows must get a QVulkanInstance automatically (it is
+        // created when the first window is constructed and is destroyed only
+        // on exit), unless the application decided to set its own. With
+        // QQuickRenderControl, no QVulkanInstance is created, because it must
+        // always be under the application's control then (since the default
+        // instance we could create here would not be configurable by the
+        // application in any way, and that is often not acceptable).
+        if (!window->vulkanInstance() && !wd->renderControl)
+            window->setVulkanInstance(QSGRhiSupport::defaultVulkanInstance());
         rhiParams.inst = window->vulkanInstance();
         if (!rhiParams.inst)
             qWarning("No QVulkanInstance set for QQuickWindow, this is wrong.");