On Mon, 5 Apr 2010, Hans-Peter Diettrich wrote:
Michael Van Canneyt schrieb:
I have been thinking about layout managers. I think that this should be an
add-on
to the currently existing layouting (to preserve delphi compatibility): I
imagine a component that one drops on a form. One sets the 'target' control
(control whose children should be managed) and some properties.
I imagine a Layout property for TWinControls, or an intermediate layer, that
is initialized to the Delphi compatible manager. That property then can be
assigned any other layout manager.
That is the same as what I am saying, only the arrow points in the opposite
direction. I want to avoid this extra TWinControl property.
The only thing I am unsure about is whether TControl should be made
TLayout-aware.
As far as I understand, a layouter only needs to be able to handle
rectangles,
within some restrictions (some callbacks to get min/max rectangles). It
need not know anything about TControl or it's properties, and as such could
be implemented totally independent of the LCL.
The layout should take into account the standard TControl properties,
including alignment, constraints and anchors. It also should use the layout
managers of child controls, for forward/backward transfer of autosize
information.
This is *exactly* what I want to avoid.
- Either one uses the 'ordinary' delphi properties, and only those.
- Or one uses layouters.
But not a mixture of both, which will be a source of implementation/usage
problems and confusion. Keep it simple.
Once this split works correctly, you can always later try to create a
TLayout descendent which tries to mimic Delphi behaviour, taking into
account all TControl/TWincontrol properties; Then remove all old code
and insert the new layouter.
In my opinion, this approach guarantees has a bigger chance of success
than immediatly trying to do everything at once...
Michael.
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