[Interest] QML properties

Jason H jhihn at gmx.com
Tue Apr 12 17:17:19 CEST 2016

> Hi,
> How to correctly name that that when in QML  I write "width: 
> parent.width / 2", for example, then when parent.width changed then 
> changed and width too? I.e. automatic propagation?

Realize that QML properties are Q_PROPERTY, with an onPROPERTYChanged emit event. In this way, when parent.width changes, it fires off the event and any variable connected with a binding (explicitly or implicitly) is recalculated.

Also, realize that you can declare your own properties in QML:

Rectangle {
    property int verticalDivisor: 15

    Rectangle { 
      height: parent.height / verticalDivisor

   onVerticalDivisorChanged: console.log("verticalDivisor:", verticalDivisor)
   Behavior on verticalDivisor { 
      NumberAnimation { ...etc...} 

Now you can animate vertical divisor, as well as provide onVerticalDivisorChanged event handling, as shown above.

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