Prevent badly formed texture nodes in the scene graph.

A texture based node without a valid texture is not allowed,
as the material and the renderer will only tolerate
well-formed nodes. If a node is missing any part of its material
state it should not be in the scene graph in the first place.

Because of an "optimization" in QSGDefaultImageNode::setTexture
and QSGSimpleTextureNode::setTexture, we must temporarily set
the texture to 0 to ensure that it gets updated properly. This
temporarily puts the node into an invalid state which can lead
to crashes when QSGNode::markDirty() reaches the renderer.

Task-number: QTBUG-34062
Change-Id: Ic1735c9b974b90b3684262de9589133c961bac6e
Reviewed-by: Laszlo Agocs <laszlo.agocs@digia.com>

4 files changed, 10 insertions, 10 deletions

diff --git a/src/quick/items/qquickborderimage.cpp b/src/quick/items/qquickborderimage.cpp
index 3cbcf1937f..9fc9752707 100644
--- a/src/quick/items/qquickborderimage.cpp
+++ b/src/quick/items/qquickborderimage.cpp
@@ -560,10 +560,14 @@ QSGNode *QQuickBorderImage::updatePaintNode(QSGNode *oldNode, UpdatePaintNodeDat
 
     QSGImageNode *node = static_cast<QSGImageNode *>(oldNode);
 
-    if (!node)
+    bool updatePixmap = d->pixmapChanged;
+    if (!node) {
         node = d->sceneGraphContext()->createImageNode();
+        updatePixmap = true;
+    }
 
-    node->setTexture(texture);
+    if (updatePixmap)
+        node->setTexture(texture);
 
     // Don't implicitly create the scalegrid in the rendering thread...
     QRectF innerSourceRect(0, 0, 1, 1);
diff --git a/src/quick/items/qquickimage.cpp b/src/quick/items/qquickimage.cpp
index 3a8fd99a66..d6be13f3c0 100644
--- a/src/quick/items/qquickimage.cpp
+++ b/src/quick/items/qquickimage.cpp
@@ -666,7 +666,6 @@ QSGNode *QQuickImage::updatePaintNode(QSGNode *oldNode, UpdatePaintNodeData *)
     if (d->pixmapChanged) {
         // force update the texture in the node to trigger reconstruction of
         // geometry and the likes when a atlas segment has changed.
-        node->setTexture(0);
         if (texture->isAtlasTexture() && (hWrap == QSGTexture::Repeat || vWrap == QSGTexture::Repeat))
             node->setTexture(texture->removedFromAtlas());
         else
diff --git a/src/quick/scenegraph/qsgdefaultimagenode.cpp b/src/quick/scenegraph/qsgdefaultimagenode.cpp
index 349a92ac7f..11d0e5dbeb 100644
--- a/src/quick/scenegraph/qsgdefaultimagenode.cpp
+++ b/src/quick/scenegraph/qsgdefaultimagenode.cpp
@@ -298,15 +298,13 @@ void QSGDefaultImageNode::setHorizontalWrapMode(QSGTexture::WrapMode wrapMode)
 
 void QSGDefaultImageNode::setTexture(QSGTexture *texture)
 {
-    if (texture == m_material.texture())
-        return;
+    Q_ASSERT(texture);
 
     m_material.setTexture(texture);
     m_materialO.setTexture(texture);
     m_smoothMaterial.setTexture(texture);
-    // Texture cleanup
-    if (texture)
-        m_material.setFlag(QSGMaterial::Blending, texture->hasAlphaChannel());
+    m_material.setFlag(QSGMaterial::Blending, texture->hasAlphaChannel());
+
     markDirty(DirtyMaterial);
 
     // Because the texture can be a different part of the atlas, we need to update it...
diff --git a/src/quick/scenegraph/util/qsgsimpletexturenode.cpp b/src/quick/scenegraph/util/qsgsimpletexturenode.cpp
index 5d9946a37b..fc1d6cecbc 100644
--- a/src/quick/scenegraph/util/qsgsimpletexturenode.cpp
+++ b/src/quick/scenegraph/util/qsgsimpletexturenode.cpp
@@ -173,8 +173,7 @@ QRectF QSGSimpleTextureNode::rect() const
  */
 void QSGSimpleTextureNode::setTexture(QSGTexture *texture)
 {
-    if (m_material.texture() == texture)
-        return;
+    Q_ASSERT(texture);
     m_material.setTexture(texture);
     m_opaque_material.setTexture(texture);
     Q_D(QSGSimpleTextureNode);