in my QML file I have the following Repeater. When I emit onDataChanged in my QAbstractListModel the coordinates of the circles are updated and the circles are drawn on the new place. But, I also change the colors of the circles in the model and these colors are not updated (ctx.fillStyle = tcolor). They stay in their initial value:
(there are also other geometric objects, but that is not important for that)

Repeater {
  id: partilcesreapeter
  model: Entrymodel
  delegate: chooser
  DelegateChooser{
    id: chooser
    role: "type"
    DelegateChoice{
      roleValue: "sphere";
      delegate: Item{
         id: sphereimage
         required property string tcolor
         required property int iparticle
         required property int semimajoraxis
         required property int semiminoraxis
         required property int xcoord
         required property int ycoord
         required property int angle
         width: 2.0*Number(semimajoraxis)
         height: 2.0*Number(semiminoraxis)
         x: Number(xcoord - semimajoraxis)
         y: Number(ycoord - semiminoraxis)
         Canvas {
            anchors.fill: parent                        
            onPaint: {
               var ctx = getContext('2d');
               ctx.beginPath();
               ctx.lineWidth = 1
               ctx.strokeStyle = "black"
               ctx.fillStyle = tcolor
               ctx.ellipse(x,y,width,height)
               ctx.stroke();
               ctx.fill();
               }
           }
           rotation: Number(angle)
           DelegateChoice{
              [...]
           }
        }
     }
  }
}

So, what can I do?