Why parent.height doesn't work

[VincentLiu]

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

[z3dd]

Try this:

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

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

[GrecKo]

@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.

[z3dd]

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

[stcorp]

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