On Thu, 3 Jun 2010, Mattias Gaertner wrote:
On Thu, 3 Jun 2010 20:38:26 +0200 (CEST)
Michael Van Canneyt <mich...@freepascal.org> wrote:
On Thu, 3 Jun 2010, Graeme Geldenhuys wrote:
On 3 June 2010 17:24, Michael Van Canneyt <mich...@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).
I deliberately didn't mention these cases ;)
Michael.
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