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Why parent.height doesn't work



  • Hi, I have a simple trouble about using parent information. I wonder under what scenarios does it works. Below is my code snippet:

    Page {
    
        id: mainPage
    
        height: Screen.desktopAvailableHeight - 55 - 30
        width: Screen.desktopAvailableHeight * 1.1
    
        ColumnLayout {
    
            anchors.fill: parent
            spacing: parent.height * 0.1    // DOESN'T WORK
    
            Text {
    
                text: qsTr("请选择下列一项功能:")
    
                font.pointSize: 16
    
                Layout.leftMargin: mainPage.width * 0.05     // DOESN'T WORK
            }
    
            ........
    }
    

    Both the "spacing: parent.height * 0.1" and "Layout.leftMargin: mainPage.width * 0.05" are 0 !! However, in the Qt Creator Design mode, both of them are correct.
    Can anyone give me some suggestions? Or actually I didn't use a recommended form to refer to parent information? Thanks



  • Try this:

    spacing: Math.floor(parent.height * 0.1)
    

    Edit: Also, you probably should not specify anchor points for ColumnLayout.


  • Qt Champions 2018

    @z3dd said in Why parent.height doesn't work:

    Edit: Also, you probably should not specify anchor points for ColumnLayout.

    Why not ? That's the point of layouts, you specify a size and it will spread its children to fill it. If you don't want that, use a Column.



  • @GrecKo Oh yes, you right! I must have mixed up Column and ColumnLayout.



  • Try using parent.implicitHeight. I've found that this sometimes works when height doesn't work as expected


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