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  1. Qt
  2. QTBUG-89568

Binding delegate height to ListView height causes delegates to be created unnecessarily

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    Description

      If Listview has a delegate with height binding to ListView, it creates all the delegate instances in the start and then delete them to keep only required ones.
      Please refer to the attached sample. 

          ListView {
        id: listView
        anchors.fill: parent
        onHeightChanged: console.log("ListView height changed to:", height)
        model: listModel
        delegate: Rectangle {
            width: listView.width / 2
            height: listView.height
            border.width: 1
            radius: 10
            Text {
                anchors.centerIn: parent
                text: name
            }
            Component.onCompleted: console.log("onCompleted:", ListView.view, index)
            Component.onDestruction: console.log("onDestruction:", ListView.view, index)
        }
    }

      If Model has 7 items, the output is 

      qml: onCompleted: QQuickListView(0x27e9478f000) 0
qml: onCompleted: QQuickListView(0x27e9478f000) 1
qml: onCompleted: QQuickListView(0x27e9478f000) 2
qml: onCompleted: QQuickListView(0x27e9478f000) 3
qml: onCompleted: QQuickListView(0x27e9478f000) 4
qml: onCompleted: QQuickListView(0x27e9478f000) 5
qml: onCompleted: QQuickListView(0x27e9478f000) 6
qml: ListView height changed to: 480
qml: onDestruction: QQuickListView(0x27e9478f000) 6
qml: onDestruction: QQuickListView(0x27e9478f000) 5
qml: onDestruction: QQuickListView(0x27e9478f000) 4
qml: onDestruction: QQuickListView(0x27e9478f000) 3
qml: onDestruction: QQuickListView(0x27e9478f000) 2

      Attachments

        1. qtbug89568.zip
          2 kB
          Shveta Mittal

        Issue Links

          depends on

          Bug - A problem which impairs or prevents the functions of the product. QTBUG-75109 tst_QQuickListView::currentIndex() is failing

          • P1: Critical - Urgent and Important, will STOP the release if matched with set FixVersion field. This includes regressions from the last version that are not edge cases; Data loss; Build issues; All but the most unlikely crashes/lockups/hanging; Serious usability issues and embarrassing bugs & Bugs critical to a deliverable. This is the highest possible priority for requirements.
          • Closed
          relates to

          Task - A task that needs to be done. QTBUG-104204 Meta-task for issues related to ListView filling a window

          • P3: Somewhat important - Should be fixed, but doesn't affect the release in any way.
          • Reported

          Activity

            People

              mitch_curtis Mitch Curtis
              shmittal Shveta Mittal (Inactive)
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              Dates

                Created:
                Updated: