Skip animation if its target is null

[Mark81]

Qt 6.2.0, I have this animation:

SequentialAnimation {
    id: selectedContent
    running: false

    ParallelAnimation {
        PropertyAnimation { target: view; properties: "opacity"; duration: 500; to: 0.0}
        PropertyAnimation { target: view.currentItem; properties: "y"; duration: 500; to: view.height * 2}
    }

    ScriptAction { script: flow.selectedContent(view.currentIndex) }

    ParallelAnimation {
        PropertyAnimation { target: view; properties: "opacity"; duration: 500; to: 1.0}
        PropertyAnimation { target: view.currentItem; properties: "y"; duration: 500; to: view.height / 2}
    }
}

It may happen that view.currentItem is null. When it happens the application crashes.
How can I skip a ParallelAnimation animation its target is null?
I tried to put an if clause inside but it's not a valid syntax.

I cannot just skip the whole SequentialAnimation because the execution of the script can change the view.currentItem. That means it should, say, skip the first ParallelAnimation (due to view.currentItem === null) but not the second one (as the script has changed it and now it's not null anymore).

[GrecKo]

Could you share a bit more about what you want to do to give more context? We might find another solution to your problem.
Also what is view? a StackView, a ListView, a Container?

[Mark81]

view is a PathView:

PathView {
    id: view
    property int item_gap: 60
    property bool isSEM

    anchors.fill: parent
    pathItemCount: 3
    preferredHighlightBegin: 0.5
    preferredHighlightEnd: 0.5
    highlightRangeMode: PathView.StrictlyEnforceRange
    highlightMoveDuration: 1000
    snapMode: PathView.SnapToItem
    rotation: -90

    model: modelContent
    delegate: DelegateContent { }

    path: Path {
        startX: view.width + item_gap; startY: view.height / 2
        PathAttribute { name: "iconScale"; value: 0.7 }
        PathAttribute { name: "iconOpacity"; value: 0.1 }
        PathAttribute { name: "iconOrder"; value: 0 }
        PathLine {x: view.width / 2; y: view.height / 2; }
        PathAttribute { name: "iconScale"; value: 1 }
        PathAttribute { name: "iconOpacity"; value: 1 }
        PathAttribute { name: "iconOrder"; value: 9 }
        PathLine {x: -item_gap; y: view.height / 2; }
    }
    ...

It may happen that the model has zero elements, so there is no currentItem (null). The script will populate the model so the second part of the animation should run anyway. For this reason I asked how to skip (or just avoid a crash!) if the target of an animation is null.

[KH-219Design]

Does 'crash' in your case refer to a segfault? A total abrupt abnormal termination, such as the kind resulting in a dump?

If so, can you capture and post the backtrace/callstack of the crash?

Can you share a minimum reproducible sample project? (Maybe even a pure QML mini-app that could be launched with qmlscene and bypass the need to compile anything?)

[Mark81]

@KH-219Design yes, it's a segmentation fault.
Would you please tell me how to capture the backtrace/callstack? When debugging I can see only a lot of disassembled code, but no one function (in any thread) is my code.

I can prepare a sample project for you. In the meanwhile, can we generalize a bit the question?

How to skip a step in a SequentialAnimation if some conditions are met?