[Lazarus] Autosize behaviour

[Mattias Gaertner]

On Mon, 5 Apr 2010 10:48:00 +0200 (CEST)
Michael Van Canneyt <michael at freepascal.org> wrote:

> 
> 
> On Mon, 5 Apr 2010, Mattias Gaertner wrote:
> 
> > On Sun, 4 Apr 2010 19:21:00 +0200 (CEST)
> > Michael Van Canneyt <michael at freepascal.org> wrote:
> >
> >> Hi,
> >>
> >> In delphi, setting a panel's AutoSize property to 'true' and aligning it to a
> >> form edge, makes the panel disappear when the project is run.
> >> This is logical, because, if there are no controls on the panel,
> >> the needed size is zero.
> >
> > Yes, and this is the problem. A visible control must not have the size
> > 0,0. It makes no sense. This is bad in the designer. The gtk does not
> > like it.
> > Therefore the LCL ignores the child bounds if no childs are there.
> >
> >
> >> In Lazarus, the panel is still shown.
> >>
> >> Is this a known bug ?
> >
> > A feature. You are the first asking. Do you need it?
> 
> What is "need"... The current behaviour is definitely not compatible to delphi.
> 
> In Delphi, you can make dock zones along the edges of your
> form by dropping 4 panels and aligning them along the edges of the form. 
> If autosize=true, then they have size 0 when the app is run (not when designed), 
> but you can dock controls on them, since there is a "fuzzy" zone of 10 pixels.
> No code is needed, and you can then dock toolbars etc. along the edges of the form.

I see. 

I changed a few things:

TPanel paints its borders itself and sets AdjustClientRect. This was
ignored when no childs were there. I fixed that bug. Now empty panels
are autosized to 2,2 (the 1 pixel border).
Panels without borders will autosize to 0,0, unless the interface
limits this to 1,1 - like the gtk.

 
> If lazarus is not compatible:
> It means that I must put width/height=0 manually in the IDE (or do this when 
> the form is created), and enable autosizing as soon as the first control is 
> docked on the panel, and when a docked control is removed from the panel, I must
> put width/height again to zero, manually.
> 
> IMHO Autosize should do what it says at runtime, not with exceptions: fit the
> children. If there are none: size=0. For aligned, this means just the 
> dimension which is orthogonal to the aligned dimension: alRight -> width=0.

AutoSize means: use a nice size - the preferred size. 
For example a TLabel has no childs. 

 
> I agree it is all rather sloppy, but then I think Layouting as a whole is sloppy :-)
> 
> Unless someone has a better idea for dock zones around the edge of a form
> without having to write code...


Mattias