QML Behavior on x Producing SegFault

[Tjsail33]

I think the title is pretty self explanatory. I have a block of code that I would like to put the line @Behavior on x { SmoothedAnimation { duration: 1500 } }@ on, but whenever I add that line the program SegFaults whenever the view is loaded. Any thoughts? Below is the relevant section of code.

@
Repeater {
id: nodeRepeater
property int nodeWidth: 385
property int nodeHeight: 300
property int sideMargins: 150
model: ["MainNode.qml","ClusterNode.qml","FanView.qml","DemoNode.qml","StudyAbroadNode.qml"]
Loader {

        id: baseRectangle
        source: modelData

        Behavior on width { SmoothedAnimation { duration: 1500 }}
        Behavior on height { SmoothedAnimation { duration: 1500 }}
        // The following two lines both create SegFaults in the program when uncommented.
        //Behavior on x { SmoothedAnimation { duration: 1500 }}
        //Behavior on y { SmoothedAnimation { duration: 1500 }}

        width: nodeRepeater.nodeWidth
        height: nodeRepeater.nodeHeight

        property bool selected: false

        x: {
            //console.log(index + "  :  " + nodeRepeater.count/2)
            if(index===0) {
                x = appDelegate.getScreenWidth()/2-nodeRepeater.nodeWidth/2
            }
            else {
                x = (index<((nodeRepeater.count)/2) ? nodeRepeater.sideMargins : appDelegate.getScreenWidth()-(nodeRepeater.sideMargins+nodeRepeater.nodeWidth))
            }
        }
        y: {
            if(index===0) {
                y = appDelegate.getScreenHeight()/2-nodeRepeater.nodeHeight/2
            }
            else {
                y = ((index<(nodeRepeater.count/2) ? index : index+0.5-nodeRepeater.count/2)    -((nodeRepeater.count/2)%2))     *((appDelegate.getScreenHeight()-50)/((nodeRepeater.count)/2)) + (((appDelegate.getScreenHeight()-50)/((nodeRepeater.count)/2))-400)/2
            }
        }

        MouseArea {
            id: mainArea
            anchors.fill: parent
            onClicked: baseRectangle.changeFocus()
        }

        function changeFocus() {
            for(var i = 0; i<nodeRepeater.count; i++)
            {
                if(i==index) {
                    if(selected)
                    {
                        if(index===0) {
                            x = appDelegate.getScreenWidth()/2-nodeRepeater.nodeWidth/2
                        }
                        else {
                            x = (index<((nodeRepeater.count)/2) ? nodeRepeater.sideMargins : appDelegate.getScreenWidth()-(nodeRepeater.sideMargins+nodeRepeater.nodeWidth))
                        }
                        if(index===0) {
                            y = appDelegate.getScreenHeight()/2-nodeRepeater.nodeHeight/2
                        }
                        else {
                            y = ((index<(nodeRepeater.count/2) ? index : index+0.5-nodeRepeater.count/2)    -((nodeRepeater.count/2)%2))     *((appDelegate.getScreenHeight()-50)/((nodeRepeater.count)/2)) + (((appDelegate.getScreenHeight()-50)/((nodeRepeater.count)/2))-400)/2
                        }
                        width = nodeRepeater.nodeWidth
                        height = nodeRepeater.nodeHeight
                        selected = false
                        for(var j = 0; j<nodeRepeater.count; j++)nodeRepeater.itemAt(j).visible = true
                    }
                    else
                    {
                        nodeRepeater.itemAt(i).x = 100;
                        nodeRepeater.itemAt(i).y = 100;
                        nodeRepeater.itemAt(i).width = appDelegate.getScreenWidth()-200
                        nodeRepeater.itemAt(i).height = appDelegate.getScreenHeight() -200
                        selected = true
                        for(var j = 0; j<nodeRepeater.count; j++)
                        {
                            if(j==index) continue
                            nodeRepeater.itemAt(j).visible = false
                        }
                    }
                }
            }
        }

@

[chriadam]

Can you provide a more minimal example? Without being able to create the item (due to missing the component qml files) I personally don't know what could be causing the problem.

Also, can you provide a backtrace?

Thanks!

[Tjsail33]

for a more minimal example, you can just change the Loader element to a Rectangle and comment out the Loader's source assignment. This will remove the need for the external QML files, but keep the functionality I need from the program intact. Below is a backtrace from gdb.

@

Program received signal SIGSEGV, Segmentation fault.
0x002d93c8 in ?? () from /usr/lib/i386-linux-gnu/libQtDeclarative.so.4
(gdb) bt
#0 0x002d93c8 in ?? () from /usr/lib/i386-linux-gnu/libQtDeclarative.so.4
#1 0x002d93b8 in ?? () from /usr/lib/i386-linux-gnu/libQtDeclarative.so.4
#2 0x002d93b8 in ?? () from /usr/lib/i386-linux-gnu/libQtDeclarative.so.4
#3 0x002d93b8 in ?? () from /usr/lib/i386-linux-gnu/libQtDeclarative.so.4
#4 0x002daa2e in QDeclarativeContext::setContextProperty(QString const&, QObject*) ()
from /usr/lib/i386-linux-gnu/libQtDeclarative.so.4
#5 0x0804e09f in MainWindow::swapView (this=0xbffff2c8, view=1) at ../Axiom/AppDelegate.cpp:89
#6 0x0804ecfa in Slideshow::changeToMainView (this=0x8326228) at ../Axiom/SlideshowViewController.cpp:52
#7 0x080cb414 in Slideshow::qt_metacall (this=0x8326228, _c=QMetaObject::InvokeMetaMethod, _id=2,
_a=0x81c72f0) at moc_SlideshowViewController.cpp:80
#8 0x010dab7d in QMetaObject::metacall(QObject*, QMetaObject::Call, int, void**) ()
from /usr/lib/i386-linux-gnu/libQtCore.so.4
#9 0x010e5685 in QMetaCallEvent::placeMetaCall(QObject*) () from /usr/lib/i386-linux-gnu/libQtCore.so.4
#10 0x010ecb52 in QObject::event(QEvent*) () from /usr/lib/i386-linux-gnu/libQtCore.so.4
#11 0x005ffd84 in QApplicationPrivate::notify_helper(QObject*, QEvent*) ()
from /usr/lib/i386-linux-gnu/libQtGui.so.4
#12 0x00605133 in QApplication::notify(QObject*, QEvent*) () from /usr/lib/i386-linux-gnu/libQtGui.so.4
#13 0x010d419e in QCoreApplication::notifyInternal(QObject*, QEvent*) ()
from /usr/lib/i386-linux-gnu/libQtCore.so.4
#14 0x010d7f93 in QCoreApplicationPrivate::sendPostedEvents(QObject*, int, QThreadData*) ()
from /usr/lib/i386-linux-gnu/libQtCore.so.4
#15 0x010d80ec in QCoreApplication::sendPostedEvents(QObject*, int) ()
from /usr/lib/i386-linux-gnu/libQtCore.so.4
---Type <return> to continue, or q <return> to quit---
#16 0x011026a4 in ?? () from /usr/lib/i386-linux-gnu/libQtCore.so.4
#17 0x01d7425f in g_main_context_dispatch () from /lib/i386-linux-gnu/libglib-2.0.so.0
#18 0x01d74990 in ?? () from /lib/i386-linux-gnu/libglib-2.0.so.0
#19 0x01d74c2a in g_main_context_iteration () from /lib/i386-linux-gnu/libglib-2.0.so.0
#20 0x01102ada in QEventDispatcherGlib::processEvents(QFlagsQEventLoop::ProcessEventsFlag) ()
from /usr/lib/i386-linux-gnu/libQtCore.so.4
#21 0x006b7e7a in ?? () from /usr/lib/i386-linux-gnu/libQtGui.so.4
#22 0x010d31dd in QEventLoop::processEvents(QFlagsQEventLoop::ProcessEventsFlag) ()
from /usr/lib/i386-linux-gnu/libQtCore.so.4
#23 0x010d3421 in QEventLoop::exec(QFlagsQEventLoop::ProcessEventsFlag) ()
from /usr/lib/i386-linux-gnu/libQtCore.so.4
#24 0x010d819d in QCoreApplication::exec() () from /usr/lib/i386-linux-gnu/libQtCore.so.4
#25 0x005fd924 in QApplication::exec() () from /usr/lib/i386-linux-gnu/libQtGui.so.4
#26 0x080ca586 in main (argc=1, argv=0xbffff3a4) at ../Axiom/main.cpp:20
@

[chriadam]

Are you able to use a debug version of QtDeclarative? From that backtrace it's difficult to see what's going on. I tried to reproduce given your instructions (with Qt4.8 built from git), but while I get various warnings:

file:///home/chriadam/depot/testdpl/segfaultonbehaviour/test.qml:14: ReferenceError: Can't find variable: nodeRepeater
file:///home/chriadam/depot/testdpl/segfaultonbehaviour/test.qml:28: ReferenceError: Can't find variable: index
file:///home/chriadam/depot/testdpl/segfaultonbehaviour/test.qml:20: ReferenceError: Can't find variable: index
file:///home/chriadam/depot/testdpl/segfaultonbehaviour/test.qml:13: ReferenceError: Can't find variable: nodeRepeater

I then tried with QtQuick 2.0 (latest QtDeclarative from git) and got similar warnings but again no crash:

file:///home/chriadam/depot/testdpl/segfaultonbehaviour/test.qml:28: ReferenceError: index is not defined
file:///home/chriadam/depot/testdpl/segfaultonbehaviour/test.qml:20: ReferenceError: index is not defined
file:///home/chriadam/depot/testdpl/segfaultonbehaviour/test.qml:14: ReferenceError: nodeRepeater is not defined
file:///home/chriadam/depot/testdpl/segfaultonbehaviour/test.qml:13: ReferenceError: nodeRepeater is not defined

I don't get any segmentation fault.

Cheers,
Chris