Expose the list of preferred instance extensions to rendercontrol users

As all QRhi stuff is private, it needs to have a public counterpart in
Qt Quick in order to fully support the case of Vulkan-based
QQuickRenderControl usage.

Change-Id: Iaf9a7aa56022acd31af6ebf16de6b83a04966ff4
Reviewed-by: Andy Nichols <andy.nichols@qt.io>

1 files changed, 28 insertions, 0 deletions

diff --git a/src/quick/items/qquickgraphicsconfiguration.cpp b/src/quick/items/qquickgraphicsconfiguration.cpp
index dcdd069d03..4d64cf0827 100644
--- a/src/quick/items/qquickgraphicsconfiguration.cpp
+++ b/src/quick/items/qquickgraphicsconfiguration.cpp
@@ -39,6 +39,10 @@
 
 #include "qquickgraphicsconfiguration_p.h"
 
+#if QT_CONFIG(vulkan)
+#include <QtGui/private/qrhivulkan_p.h>
+#endif
+
 QT_BEGIN_NAMESPACE
 
 /*!
@@ -139,6 +143,30 @@ QQuickGraphicsConfiguration::~QQuickGraphicsConfiguration()
 }
 
 /*!
+    \return the list of Vulkan instance extensions Qt Quick prefers to
+    have enabled on the VkInstance.
+
+    In most cases Qt Quick is responsible for creating a QVulkanInstance. This
+    function is not relevant then. On the other hand, when using
+    QQuickRenderControl in combination with Vulkan-based rendering, it is the
+    application's responsibility to create a QVulkanInstance and associate it
+    with the (offscreen) QQuickWindow. In this case, it is expected that the
+    application queries the list of instance extensions to enable, and passes
+    them to QVulkanInstance::setExtensions() before calling
+    QVulkanInstance::create().
+
+    \since 6.1
+ */
+QByteArrayList QQuickGraphicsConfiguration::preferredInstanceExtensions()
+{
+#if QT_CONFIG(vulkan)
+    return QRhiVulkanInitParams::preferredInstanceExtensions();
+#else
+    return {};
+#endif
+}
+
+/*!
     Sets the list of additional \a extensions to enable on the graphics device
     (such as, the \c VkDevice).