Details
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Bug
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Resolution: Done
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P1: Critical
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5.6.0
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None
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9f4bb9a687277932125a065a53e3f3d8afdebc8b
Description
I found a bug in following QML. The image is not shown.
It works with Qt 5.4. But it's not working with Qt 5.6.
import QtQuick 2.4
import QtQuick.Window 2.2
Window {
width: 1000
height: 900
visible: true
Image {
id: outer
width: 100; height: 100
visible: false
Rectangle {
id: inner
visible: false
z: -1
color: "blue"
x: 50; y: 50; width: 100; height: 100
}
}
MouseArea {
anchors.fill: parent
onClicked: {
outer.source = "Mickey_-_House_of_Mouse.png"
inner.visible = true;
visibleTimer.start();
}
}
Timer {
id : visibleTimer
interval: 200; running: false; repeat:false;
onTriggered: {
outer.visible = true;
}
}
}
As I debugged, a geometry node of Image is not added to scenegraph tree. I think it is caused from following.
static inline QSGNode *qquickitem_before_paintNode(QQuickItemPrivate *d)
{
const QList<QQuickItem *> childItems = d->paintOrderChildItems();
QQuickItem *before = 0;
for (int i=0; i<childItems.size(); ++i) {
QQuickItemPrivate *dd = QQuickItemPrivate::get(childItems.at(i));
// Perform the same check as the in fetchNextNode below.
if (dd->z() < 0 && (dd->explicitVisible || (dd->extra.isAllocated() && dd->extra->effectRefCount)))
before = childItems.at(i);
else
break;
}
return Q_UNLIKELY(before) ? QQuickItemPrivate::get(before)->itemNode() : 0;
}
In short, that returns a transform node which has no parent.
Consequently, it leads to following assertion case .
void QSGNode::insertChildNodeAfter(QSGNode *node, QSGNode *after)
{
//Q_ASSERT_X(!m_children.contains(node), "QSGNode::insertChildNodeAfter", "QSGNode is already a child!");
Q_ASSERT_X(!node->m_parent, "QSGNode::insertChildNodeAfter", "QSGNode already has a parent");
Q_ASSERT_X(after && after->m_parent == this, "QSGNode::insertChildNodeAfter", "The parent of \'after\' is wrong");
Indeed, I tested it in release mode, so no assertion happened.
Just geometry node is skipped because m_firstChild is null.
So the image is just not shown.
In summary,
Conditions for reproduce:
1. Image - rectangle are parent - child relationship.
2. z order of sibling node of image geometry node was negative.
My analysis:
1. qquickitem_before_paintNode returns the transform node for the rectangle as child node. But the node has no parent.
2. In release mode, no assertion happened. it is added without setting m_firstChild.
3. Then, in Renderer::nodeWasAdded, it is skipped to add geometry node of the image into group node, because m_firstChild of childContainerNode is null.
Quick proposal:
Can we check the parent of the child item? Here is some try for that.
static inline QSGNode *qquickitem_before_paintNode(QQuickItemPrivate *d)
{
const QList<QQuickItem *> childItems = d->paintOrderChildItems();
QQuickItem *before = 0;
for (int i=0; i<childItems.size(); ++i) {
QQuickItemPrivate *dd = QQuickItemPrivate::get(childItems.at(i));
// Perform the same check as the in fetchNextNode below.
if (dd->z() < 0 && (dd->explicitVisible || (dd->extra.isAllocated() && dd->extra->effectRefCount)))
before = childItems.at(i);
else
break;
}
if (before) {
QSGNode* beforeNode = QQuickItemPrivate::get(before)->itemNode();
if (beforeNode->parent())
return beforeNode;
}
return 0;
}
Attachments
| For Gerrit Dashboard: QTBUG-56657 | ||||||
|---|---|---|---|---|---|---|
| # | Subject | Branch | Project | Status | CR | V |
| 174566,5 | Add checking "before" as child node | 5.6 | qt/qtdeclarative | Status: MERGED | +2 | 0 |