[fpc-pascal] WriteComponent not outputting a hierarchy of components?

[Mattias Gaertner]

On Thu, 3 Jun 2010 20:38:26 +0200 (CEST)
Michael Van Canneyt <michael at freepascal.org> wrote:

> 
> 
> On Thu, 3 Jun 2010, Graeme Geldenhuys wrote:
> 
> > On 3 June 2010 17:24, Michael Van Canneyt <michael at freepascal.org> wrote:
> >>
> >> You must override GetChildren.
> >>
> >> In the LCL, TWinControl overrides GetChildren to write child controls.
> >>
> >> It is documented.
> >
> > But why is GetChildren needed? Why can't TWriter use ComponentCount
> > and Components[] like I have done in the TraverseComponents()
> > recursive procedure?
> 
> Because Borland decided otherwise.
> 
> Actually, there is a good reason: some components create internal 
> components they own, and which they don't want to have streamed.
> The 'GetChildren' allows you to control what gets streamed and 
> what not.

For example a TOpenDialog is not in Controls, so it must be put into
GetChildren.

 
> > "  Adds component to children list which have no parent.
> >    (TWinControl only lists components with parents) "
> 
> 
> >
> > Is that still true?  In fpGUI I set Owner and Parent. What is
> > different in fpGUI (compared to LCL or VCL) is that Owner = Parent,
> > always. I don't see a need for them to be different - one widget can
> > just as easily manage the lifespan of another widget. Re-parenting a
> > widgets also works in fpGUI, by simply transferring the ownership to
> > the new parent widget (inserting into Components[] array).
> 
> In LCL the owner is always the form. Otherwise the form variables
> would not work.

Yes, and no.
Think about Frames, Ancestors and special created components (e.g.
TSynEdit creates some components owned by itself).

Graeme,
you might want to take a look at
lazarus/designnonlcl/mywidgetset.pas


Mattias