Opt-In Class - Is it possible to get the (Parent) Window?

PaulS

I have placed the Opt-In class in a window.
Now I want the loop through all the controls in that window and therefore I need to known what the (Parent) Window is in which the Opt-In Class is placed.
I've tried ParentWindow but the result is Nothing.
Is it possible to get this information?

Garry

Hi Paul,

At the moment, no. An opt-in class placed on a window is not a visual child of that window, so it does not get a parent window reference. That’s why ParentWindow is returning Nothing.

For now, the intended pattern is to pass the window to the class explicitly from the window, for example from the window’s Opening event:

OptIn1.Initialise(Me)

and then store that window reference inside your opt-in class if it needs to inspect the window’s controls.

I’ll make a note that this behaviour should be documented more clearly, because I can see why placing the class on a window makes it feel like it should know which window it belongs to.

PaulS

Hi Garry,
Unf

Garry

What does “Unf” mean?

PaulS

Hi Garry,

Unfortunately this isn't working.
The control events are fired before the Opening event of the Window/Container Control.
This prevents me from doing things like adding a label in front of the control(s)
This is a major setback for me. My framework relies heavily on knowing the parent Window/ContainerControl.

Garry

Paul, this should be much easier in the next release: https://feedback.objo.dev/feature/657

I’ve added a new base class called DesignerComponent for exactly this kind of opt-in designer class. The idea is that a plain opt-in class remains just a plain object, but if your class needs to know which window or container owns it, you make it inherit from DesignerComponent.

How to use it

Create your class as normal.
Make it inherit from DesignerComponent.
Tick Available in Visual Designer for the class.
In the Control Library, enable Include Opt-In Classes.
Drag the class onto the window/container shelf.
Use the Attached(owner As Object) event, Me.Owner, or Me.OwnerWindow.

The key difference from passing the window in Window.Opening is timing. Attached fires during designer-generated construction, after Studio has created/added the controls and wired generated event handlers, but before child control Opening events fire.

Example:

Class ControlLabeller Inherits DesignerComponent

  Event Attached(owner As Object)
    If owner IsA Window Then
      AddLabelsToWindow(Window(owner))
    ElseIf owner IsA ContainerControl Then
      AddLabelsToContainer(ContainerControl(owner))
    End If
  End Event

  Private Sub AddLabelsToWindow(w As Window)
    For Each c As Control In w.Controls()
      Var label As New Label
      label.Text = c.Name
      label.Left = c.Left
      label.Top = c.Top - 18
      label.Width = c.Width
      label.Height = 16

      w.Add(label)
    Next c
  End Sub

  Private Sub AddLabelsToContainer(container As ContainerControl)
    For Each c As Control In container.Controls()
      Var label As New Label
      label.Text = c.Name
      label.Left = c.Left
      label.Top = c.Top - 18
      label.Width = c.Width
      label.Height = 16

      container.Add(label)
    Next c
  End Sub

End Class

For a component placed directly on a window shelf:

Me.Owner       # the Window
Me.OwnerWindow # the same Window

For a component placed on a reusable container shelf:

Me.Owner       # the ContainerControl
Me.OwnerWindow # may be Nothing during Attached if the container is not in a window yet

So for your case, if the component is intended to inspect or alter controls on the same designer surface, use the owner parameter from Attached. If it is on a window, cast it to Window; if it is on a container, cast it to ContainerControl.

This means you no longer need the Window.Opening workaround just to pass Me into the component.

PaulS

This is looking great! Thank you.