Array as Observable

[Josef Heinen]

How would I use an array as Observable (within a Repeater)? I both tried using it as a model parameter or as a value parameter in the delegate. In the first case the window is empty, in the second case an error occurs ("Unable to assign qmlwrap::qvariant_any_t to double").

ENV["QT_QUICK_CONTROLS_STYLE"] = "Fusion"

using QML
using Observables

mktempdir() do folder
  path = joinpath(folder, "test.qml")
  write(path, """
import QtQuick 2.12
import QtQuick.Controls 2.4
import org.julialang 1.1

ApplicationWindow {
  title: "Test"
  visible: true
  Grid {
    rows: 5
    columns: 1
    Repeater {
      model: 5
      delegate: Row {
        Slider {
          value: slider
        }
      }
    }
  }
}
  """)

  slider = Observable(zeros(5))

  loadqml(path; slider=slider)
  exec_async()

  while true
    sleep(1)
    slider[][5] = rand()
  end

end

[Bart Janssens]

Hi Josef,

This probably isn't exactly what you are looking for, but with a Repeater you need to use a ListModel:

ENV["QT_QUICK_CONTROLS_STYLE"] = "Fusion"

using QML
using Qt5QuickControls2_jll

mktempdir() do folder
  path = joinpath(folder, "test.qml")
  write(path, """
import QtQuick 2.12
import QtQuick.Controls 2.4
import org.julialang 1.1

ApplicationWindow {
  title: "Test"
  visible: true
  Grid {
    rows: 5
    columns: 1
    Repeater {
      model: slider
      delegate: Row {
        Slider {
          onValueChanged: {
            sliderval = value;
          }

          Component.onCompleted: {
            value = sliderval;
          }
        }
      }
    }
  }
}
  """)

  slidervalues = (collect(0.2:0.2:1.0))
  slider = ListModel(slidervalues)
  addrole(slider, "sliderval", identity, setindex!)

  loadqml(path; slider=slider)
  exec()

  println("slider values: $slidervalues")
end

At this time, Observables doesn't really fit into that, I'm assuming you want to update the ListModel from Julia here?

[Josef Heinen]

Hi Bart, thanks for you help. This works fine, but how would I now inform the Qt5 run-time to update the slider widget(s) (from an asynchronously triggered function)?

[Bart Janssens]

OK, this appears to do the trick:

ENV["QT_QUICK_CONTROLS_STYLE"] = "Fusion"

using QML
using Qt5QuickControls2_jll

qml_data = QByteArray("""
import QtQuick 2.12
import QtQuick.Controls 2.4
import org.julialang 1.1

ApplicationWindow {
  title: "Test"
  visible: true
  Grid {
    rows: 5
    columns: 1
    Repeater {
      model: slider
      delegate: Row {
        Slider {
          id: sliderControl
          onValueChanged: {
            sliderval = value;
          }

          Component.onCompleted: {
            value = sliderval;
          }
          Connections {
            target: slider
            function onDataChanged() { sliderControl.value = sliderval; }
          }
        }
      }
    }
  }
}
  """)

slidervalues = (collect(0.2:0.2:1.0))
slider = ListModel(slidervalues)
addrole(slider, "sliderval", identity, setindex!)

qengine = init_qmlengine()
ctx = root_context(qengine)
set_context_property(ctx, "slider", slider)

qcomp = QQmlComponent(qengine)
set_data(qcomp, qml_data, QML.QUrl())
create(qcomp, qmlcontext());

exec_async()

After the exec_async, you can use the REPL to modify the sliders like this:

slider[1] = 1

[Josef Heinen]

Thanks a lot. That works fine ...