On Mon, Aug 16, 2010 at 3:07 PM, Clemens Zeidler <
clemens.zeidler@xxxxxxxxxxxxxx> wrote:
Am 16.08.2010, 21:40 Uhr, schrieb Stephan Assmus <superstippi@xxxxxx>:
Am 16.08.2010 00:46, schrieb Clemens:
Hi,
after a long time I wrote a gui app again and I was amazed how easy
it is
to setup a basic view layout with the layout engine and the layout
friendly
constructors :-).
But when I run my program nothing showed up! The problem was that I
haven't call the SetLayout method. I remember I did this mistake
earlier so
maybe also other people will run into it. Why I have to set the layout
manually? Because the window does not know which kind of BLayout is
needed?
Can we provide a default BWindow layout to omit the SetLayout call or
set
one in AddChild if needed? I feel the SetLayout call is not very
intuitive.
At first I always found this step unintuitive as well, but once you
know
the system better, it becomes clear why it's needed/useful: You can for
example directly attach children to the otherwise inaccessible
top-level
BView. A regular layout with a BMenuBar and another view below it does
not
require another view above, but only a vertical BGroupLayout attached
"directly" to the window. In any case, there are forms of using the
BLayoutBuilder that does not require adding an extra layout, like
passing
the window pointer to the builder, I believe. We should advertise those
forms in the examples. Of course adding a default vertical
BGroupLayout to
the window, if there is none otherwise, would remove this pitfall.
Maybe ask in AddChild if the new view has a Layout and in this case add
a
default BGroupLayout to the (layout less) window? So you can still use
it in
the way you described it above.
One of the main problems with this is compatibility, for example, if
non-layouted window had a view added that was from an external source
(eg. a
translator's config view) that had a layout, the window would then have a
layout set and all the views would be re-added to the layout, so they
would
all end up in a vertical arrangement. This could cause some very
confusing
bugs. After R1, it would probably be good to have a default layout, but
until then, I don't think it is feasible.
Plus, the layout builders Stippi mentioned are really handy!
--Alex
