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Hi Christian,

as this is only MHO about KJanusWidget and friends I'm CCing core-devel.

On Monday 03 April 2006 12:42, Christian Ehrlicher wrote:
> Since I'm relativly new to kde my only work on kdelibs is to make them
> compile on win32 and wipe out all qt3-stuff (and do some courois checkins
> from time to time ;) ).
> If you want, I can take a look at KJanusWidget... if you tell me what I
> have to do.

Well, I can't exactly tell you what to do, only where to start.

my motivation for the changes
=3D=3D=3D=3D=3D=3D=3D=3D=3D=3D=3D=3D=3D=3D=3D=3D=3D=3D=3D=3D=3D=3D=3D=3D=3D=
=3D=3D=3D=3D
When writing kdelibs/kutils/ksettings, especially the Dialog class, I had t=
o=20
circumvent the limitations of KJanusWidget and add new methods to it in ord=
er=20
to achieve what I wanted. The task could be described with the following=20
(abstract) use case:
=2D collect dialog pages that come with some kind of hierarchy information
=2D if there's only one dialog page
  -> create a simple dialog showing only that page
=2D if there's a flat hierarchy of pages
  -> create a dialog with an iconview on the left to select the pages
=2D if there's a tree hierarchy of pages
  -> create a dialog with a treeview on the left to select the pages

=2D some time later new pages need to be added (because the user activated =
a new=20
component); too avoid confusion the pages should appear always at the same=
=20
position in the treeview (or iconview)

the problems with KJanusWidget
=3D=3D=3D=3D=3D=3D=3D=3D=3D=3D=3D=3D=3D=3D=3D=3D=3D=3D=3D=3D=3D=3D=3D=3D=3D=
=3D=3D=3D=3D=3D
in short: the class does too much while providing too little flexibility
1. You cannot add pages and then later decide what presentation you want, t=
he=20
"Face" has to be decided on on construction. (Feels like the Face enum=20
selects a different class with the same methods, and those methods don't ev=
en=20
make sense for all Face settings. I think it'd be more logical if there wer=
e=20
a common base class and subclasses to implement those Faces - but see below=
=20
for another idea.)
2. The creation of tree hierarchies has a cumbersome API. One has to identi=
fy=20
pages using names and stringlists of those names.
3. Because of (2.) there's no way to insert pages at a predefined position.=
=20
You can only append pages to the end of a level. Example:
A
|-x
|-z
C
|-x
There's no way to create
A
|-x
|-z
B
|-x
C
|-x
without creating a whole new dialog. (which is what KSettings::Dialog does)

Idea for a new KJanusWidget
=3D=3D=3D=3D=3D=3D=3D=3D=3D=3D=3D=3D=3D=3D=3D=3D=3D=3D=3D=3D=3D=3D=3D=3D=3D=
=3D=3D
short version: use Qt4's Interview
=2D> KJanusView and KJanusWidget split
Tasks:
1. identify needed roles to extend Qt::ItemDataRole
1.a) The model returns all data to let KJanusView see whether a navigation =
is=20
needed and whether that needs to be a TreeView. (It should always be possib=
le=20
to override no nav. with IconView and TreeView representation and IconView=
=20
with TreeView.)
1.b) The model returns data to fill the navigation. Most of the predefined=
=20
roles can be used for that, simply by setting the model on the navigation=20
view.
I think especially the possibility to use the Qt::CheckStateRole is=20
interesting to make KSettings::Dialog more usable.
1.c) Additional roles could be:
PageWidgetRole  The widget to be shown in the dialog
PageHeaderRole  The header above the page widget

2. Write an (abstract?) base class to ease development of dialog models and=
 to=20
be used internally in KJanusWidget.

3. Write KJanusView that can use either an IconView or a TreeView to displa=
y=20
the navigation and that shows the according widget using the PageWidgetRole=
=20
on selection of a page in the view.

4. Write KJanusWidget that has an interface like the current KJanusWidget b=
ut=20
uses KJanusView internally and that doesn't necessarily decide on the Face =
on=20
construction.

=2D-=20
C'ya
        Matthias
________________________________________________________
Matthias Kretz (Germany)                            <><
http://Vir.homelinux.org/
MatthiasKretz@gmx.net, kretz@kde.org,
Matthias.Kretz@urz.uni-heidelberg.de

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