[Qt-qml] Recommended way to parametrize QML items?

[aaron.kennedy at nokia.com]

Hi,

Another alternative is to use property aliasing:

import QtQuick 1.0

Rectangle {
    property alias bar: content.children
    Row {
        id: content
        anchors.fill: parent
    }
}

Any item assigned to "bar" will be added as a child of (and thus positioned by) the Row.

Cheers,

Aaron

On 18/11/2010, at 2:05 AM, ext Tomas Junnonen wrote:

> On 11/17/2010 04:40 PM, Kellomaki Pertti (Nokia-MS/Tampere) wrote:
>> On 11/17/2010 03:59 PM, Junnonen Tomas (Nokia-MS/Helsinki) wrote:
>>> The parametrized bar item doesn't have to be a direct child of Foo
>>> either. Another way is to use the onBarChanged signal to Do What You
>>> Want(tm), for example if you need to anchor the item.
>>> 
>> Thanks, that clarified things. How do I access bar's anchors within the
>> signal handler though? I tried various permutations but did not quite
>> figure it out yet.
> 
> "bar.anchors.top = top" for instance should just work.
> 
>> Could you modify the example so that Foo has a single Text element
>> saying "This is bar", positioned just below whatever bar happens to be?
> 
> Simple but naive way:
> 
> Foo.qml:
> import QtQuick 1.0
> 
> Rectangle {
>     property Item bar
> 
>     Text {
>         id: label
>         text: "This is bar"
>     }
> 
>     onBarChanged: {
>         children = [bar, label]
>         label.anchors.top = bar.bottom
>     }
> }
> 
> Because QML doesn't support in-place list manipulations, this isn't a 
> very good solution as it restricts you from directly adding items to Foo 
> by essentially hardcoding Foo's children.
> 
> A better way might be to use a placeholder item, a bit like in the 
> original SpinBox implementation you mentioned:
> 
> Foo.qml:
> import QtQuick 1.0
> 
> Rectangle {
>     property Item bar
> 
>     Item {
>         id: barPlaceHolder
>         height: children[0] ? children[0].height : 0
>         width: children[0] ? children[0].width : 0
>     }
> 
>     Text {
>         id: label
>         text: "This is bar"
>         anchors.top: barPlaceHolder.bottom
>     }
> 
>     onBarChanged: {
>         bar.parent = barPlaceHolder
>     }
> }
> 
> Regards,
> Tomas
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