How are implicit dimensions of QtQuick items propagated?

Question

I am trying to implement a component which should by default (if no width was explicitly set) take up as much space as it needs (i.e. depending on its implicitWidth). And if width was set at definition it should shrink its contents to fit in the provided area.

Here's an example:

import QtQuick 2.2
import QtQuick.Window 2.0

Window {
    width: 200
    height: 100
    visible: true

    property bool restricted: false

    Component {
        id: external

        FocusScope {
            implicitWidth: column.implicitWidth
            implicitHeight: column.implicitHeight
            focus: true

            Column {
                id: column
                width: parent.width > 0 ? parent.width : undefined
                Text {
                    id: label
                    width: parent.width > 0 ? parent.width : undefined
                    elide: Text.ElideRight
                    font.pixelSize: 24
                    text: "1234567890"
                }
            }

            Keys.onRightPressed: label.text += label.text
        }
    }

    Loader {
        width: restricted ? 100 : undefined
        sourceComponent: external
        focus: true
        Keys.onReturnPressed: restricted = !restricted
    }
}

In this sample two modes are controlled by auxiliary bool property, and I want it to support two forms of declaration:

Explicit width. Text should elide.

Loader {
    width: 100
    sourceComponent: external
    focus: true
}

Loader width should be enough to fit the whole text without eliding.
```
Loader {
    sourceComponent: external
    focus: true
}
```

Motivation is that such a component will be defined in a separate file and is being designed to be placed in different parts of UI with both behaviors desired depending on current needs. This sample with inline component declaration is only for demonstration purpose.

UPDATE:

The following trick parent.width > 0 ? parent.width : undefined works, but only for initial setup. If component contents change and implicitWidth is updated (in an unrestricted mode) the width of the component does not change (i.e. Text remains elided).

For example, press right key just right after launching example. You should see that Text has become elided, but its width did not increased twice regardless the fact that string was duplicated.

How are implicit dimensions of QtQuick items propagated?

0 Answers0