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  1. Qt
  2. QTBUG-56038

Create contentItem lazily where possible

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Details

    • Suggestion
    • Resolution: Done
    • P3: Somewhat important
    • 5.8.0 Beta
    • 5.7.0
    • Quick: Controls 2
    • None
    • 0e3636a4692c9cf89d994f3fe5c1c110b4c6ee61

    Description

      Container controls such as Pane and its subclasses should create the default content item lazily, instantiating it only if needed. Now they all have declared an empty item in QML:

      contentItem: Item { }

      just to ensure that the default property contentData has always an item to forward the data to. However, the default content item is unnecessarily created when someone writes:

      Pane {
    contentItem: ColumnLayout {
        ...
    }
}

      Affected controls:

      $ git grep "contentItem: Item { }" 
src/imports/controls/Drawer.qml:    contentItem: Item { }
src/imports/controls/Frame.qml:    contentItem: Item { }
src/imports/controls/GroupBox.qml:    contentItem: Item { }
src/imports/controls/Page.qml:    contentItem: Item { }
src/imports/controls/Pane.qml:    contentItem: Item { }
src/imports/controls/Popup.qml:    contentItem: Item { }
src/imports/controls/ToolBar.qml:    contentItem: Item { }
src/imports/controls/material/Drawer.qml:    contentItem: Item { }
src/imports/controls/material/Frame.qml:    contentItem: Item { }
src/imports/controls/material/Page.qml:    contentItem: Item { }
src/imports/controls/material/Pane.qml:    contentItem: Item { }
src/imports/controls/material/Popup.qml:    contentItem: Item { }
src/imports/controls/material/ToolBar.qml:    contentItem: Item { }
src/imports/controls/universal/Drawer.qml:    contentItem: Item { }
src/imports/controls/universal/Frame.qml:    contentItem: Item { }
src/imports/controls/universal/GroupBox.qml:    contentItem: Item { }
src/imports/controls/universal/Page.qml:    contentItem: Item { }
src/imports/controls/universal/Pane.qml:    contentItem: Item { }
src/imports/controls/universal/Popup.qml:    contentItem: Item { }
src/imports/controls/universal/ToolBar.qml:    contentItem: Item { }

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        Issue Links

          relates to

          Bug - A problem which impairs or prevents the functions of the product. QTBUG-54347 Runtime error when used custom popup based on QQuickPopup from Quick Controls 2

          • P2: Important - Urgent, should be fixed, but will not stop the release.
          • Closed
          For Gerrit Dashboard: QTBUG-56038
          # Subject Branch Project Status CR V
          172019,3 Create contentItem lazily where possible 5.8 qt/qtquickcontrols2 Status: MERGED +2 0

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              Unassigned Unassigned
              jpnurmi J-P Nurmi
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              Dates

                Created:
                Updated:
                Resolved:

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