ListView delegate height animation

Question

I have a ListView with a SwipeDelegate as delegate. It's contentItem consists of a ColumnLayout with two RowLayouts inside. Now I want the second RowLayout to unfold, if I click the delegate. This works like it should, but I want the "expand" to be animated, so that it smoothly unfolds. I tired it with Behaviour on height { NumberAnimation {} } but it did not work. How can I achive this?

ListView {
    id: myView
    visible: count > 0

    clip: true
    boundsBehavior: Flickable.StopAtBounds
    model: mymodel

    Component.onCompleted: {
        Layout.preferredHeight = Qt.binding(function() {
            return myView.contentHeight
        })
    }

    spacing: 3

    delegate: SwipeDelegate {
        id: delegate
        width: myView.width
        hoverEnabled: false

        property bool expanded: false

        onClicked: {
            expanded = !expanded
        }


        contentItem: ColumnLayout {

            Behavior on height { NumberAnimation {} }

            RowLayout {
                Layout.fillWidth: true

                CheckBox {
                    id: chkSel
                    Layout.fillHeight: true
                    checked: model.sel
                    padding: 0
                    rightPadding: 5
                    spacing: 0
                }

                Label {
                    Layout.fillWidth: true
                    font.pointSize: 14
                    font.bold: true
                    text: model.nr
                }

                Image {
                    id: swipeTipArrow
                    sourceSize.height: parent.height * 0.9
                    fillMode: Image.PreserveAspectFit
                    opacity: 0
                    source: "left.svg"
                }
            }

            RowLayout {
                Layout.fillWidth: true
                visible: delegate.expanded

                Label {
                    Layout.fillWidth: true
                    font.pointSize: 12
                    text: model.nr2
                }
            }
        }
}

Jürgen Lutz · Accepted Answer · 2025-07-24 07:43:35Z

0

Move the animation to the SwipeDelegate and change the size of the delegate according the expanded state:

...

delegate: SwipeDelegate {
            id: delegate
            width: myView.width
            hoverEnabled: false

            property bool expanded: false
            onClicked: {
                expanded = !expanded
            }
            height: expanded ? 100 : 40 // TODO change to correct sizes
            Behavior on height { NumberAnimation {}}

            ...
            
        }

...

answered Jul 24 at 7:43

Jürgen Lutz

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6 Comments

Me3nTaL Jul 24 at 8:01

I cannot set the height directly, because it is calculated dynamically by the ColumnLayout of the contentItem.

Jürgen Lutz Jul 24 at 13:31

Then relate to the implicitHeight of the ColumnLayout: height: layout1.implicitHeight

Me3nTaL Jul 24 at 13:55

Now the animation works, but the height is not high enough and text is cut off

Jürgen Lutz Jul 24 at 14:08

Hm, tested it and works for me. Both texts are displayed correctly.

Jürgen Lutz Jul 24 at 14:22

Can you try it without the Image?

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