[haiku-development] Re: Automatically set window / view Layout

  • From: Alex Wilson <yourpalal2@xxxxxxxxx>
  • To: haiku-development@xxxxxxxxxxxxx
  • Date: Mon, 16 Aug 2010 17:24:03 -0600

On Mon, Aug 16, 2010 at 4:54 PM, Clemens Zeidler <
clemens.zeidler@xxxxxxxxxxxxxx> wrote:

> Am 17.08.2010, 10:46 Uhr, schrieb Alex Wilson <yourpalal2@xxxxxxxxx>:
>  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
> Ok understand, and if we only add a layout if there are no other layout
> less views attached to a window? (just guessing)

Closer, but no good, BButtons, for example don't have layouts, so in that
case it would not have a layout, even if you perhaps wanted one, so the
behaviour would become somewhat unpredictable. Also, this still doesn't
alleviate the problem that theoretically, one might have a
non-layout-supporting window that ends up with a layout.


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