[haiku-development] Re: Automatically set window / view Layout
- From: "Clemens Zeidler" <clemens.zeidler@xxxxxxxxxxxxxx>
- To: haiku-development@xxxxxxxxxxxxx
- Date: Tue, 17 Aug 2010 09:07:35 +1200
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.
Cheers
Clemens
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