[vlc-commits] [Git][videolan/vlc][master] 2 commits: qt: fix undefined behavior when openvg scene graph backend is used

[Steve Lhomme (@robUx4)]

Steve Lhomme pushed to branch master at VideoLAN / VLC


Commits:
a8cd2d21 by Fatih Uzunoglu at 2024-09-02T13:19:54+00:00
qt: fix undefined behavior when openvg scene graph backend is used

When OpenVG is used, the rectangle node provided does not offer
a material. At the same time, it is also not a null pointer but
it explicitly points to memory address "1" as a workaround done
by Qt.

Obviously, that memory address does not contain a real `QSGMaterial`
instance, so dereferencing the material causes segmentation fault.

- - - - -
4447ccb6 by Fatih Uzunoglu at 2024-09-02T13:19:54+00:00
qt: disable pip and backdrop effect when scene graph backend is openvg

- - - - -


2 changed files:

- modules/gui/qt/maininterface/compositor.cpp
- modules/gui/qt/widgets/native/viewblockingrectangle.cpp


Changes:

=====================================
modules/gui/qt/maininterface/compositor.cpp
=====================================
@@ -265,11 +265,12 @@ bool CompositorVideo::commonGUICreateImpl(QWindow* window, CompositorVideo::Flag
 
     m_videoSurfaceProvider = std::make_unique<VideoSurfaceProvider>();
     m_mainCtx->setVideoSurfaceProvider(m_videoSurfaceProvider.get());
-    if (flags & CompositorVideo::CAN_SHOW_PIP)
+    const bool backendIsOpenVg = QQuickWindow::sceneGraphBackend() == QLatin1String("openvg");
+    if (!backendIsOpenVg && (flags & CompositorVideo::CAN_SHOW_PIP))
     {
         m_mainCtx->setCanShowVideoPIP(true);
     }
-    if (flags & CompositorVideo::HAS_ACRYLIC)
+    if (!backendIsOpenVg && (flags & CompositorVideo::HAS_ACRYLIC))
     {
         setBlurBehind(window, true);
     }


=====================================
modules/gui/qt/widgets/native/viewblockingrectangle.cpp
=====================================
@@ -95,7 +95,14 @@ ViewBlockingRectangle::ViewBlockingRectangle(QQuickItem *parent)
 {
     setFlag(QQuickItem::ItemHasContents);
     connect(this, &ViewBlockingRectangle::colorChanged, this, &QQuickItem::update);
-    connect(this, &ViewBlockingRectangle::windowChanged, this, [this] { m_windowChanged = true; });
+    connect(this, &ViewBlockingRectangle::windowChanged, this, [this] {
+        if (window())
+        {
+            // The new window might use an appropriate graphics API:
+            setFlag(QQuickItem::ItemHasContents);
+            m_windowChanged = true;
+        }
+    });
 }
 
 QSGNode *ViewBlockingRectangle::updatePaintNode(QSGNode *oldNode, UpdatePaintNodeData *)
@@ -124,7 +131,18 @@ QSGNode *ViewBlockingRectangle::updatePaintNode(QSGNode *oldNode, UpdatePaintNod
         {
             rectangleNode = window()->createRectangleNode();
             assert(rectangleNode);
-            assert(rectangleNode->material());
+
+            const auto material = rectangleNode->material();
+            if (!material ||
+                material == reinterpret_cast<QSGMaterial*>(1) /* Qt may explicitly set the material pointer to 1 in OpenVG */)
+            {
+                // Scene graph adaptation does not support shading
+                qmlDebug(this) << "ViewBlockingRectangle is being used under an incompatible scene graph adaptation.";
+                delete rectangleNode;
+                setFlag(QQuickItem::ItemHasContents, false);
+                return nullptr;
+            }
+
             rectangleNode->material()->setFlag(QSGMaterial::Blending, false);
         }
     }



View it on GitLab: https://code.videolan.org/videolan/vlc/-/compare/0361de5cbea327c84591dffeae8e597f3f8c98c5...4447ccb63c826a9af5bdcc9f60841c1c881fc02d

-- 
View it on GitLab: https://code.videolan.org/videolan/vlc/-/compare/0361de5cbea327c84591dffeae8e597f3f8c98c5...4447ccb63c826a9af5bdcc9f60841c1c881fc02d
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