[haiku-development] Re: BBox and layout

On Thu, 10 May 2012 13:02:47 +1200, Ingo Weinhold <ingo_weinhold@xxxxxx> wrote: 


How would you solve that BBox problem?

I think it's mainly a question of how you want to see BBox:
1. As a labeled frame for some container. It would have two child layout items: the frame label and the content. The API would provide setters for both (there's already SetLabel(), SetContent() would need to be added) and BBox would lay them out. The content item would be laid out to either fit the frame tightly -- the creator of the item would have to make sure that it has pleasant insets itself -- or already with additional default insets -- the creator of the item would (usually) give it zero insets. In the latter case BBox should have a setter to override the default insets. 2. As a container with a frame. It would have a regular layout which manages children as usual plus a separate frame label item which doesn't belong to the layout and is laid out by BBox directly. Furthermore BBox sets the insets on the layout to fit the frame -- as in option 1 either tightly or with
ok that are basically the ideas Alex and I came up with as well. Point 2. is a bit tricky because you could easily overwrite the automatically set inset: 

BLayout* layout = new BGroupLayout();
box->SetLayout(layout);
        // sets the content area offset
layout->SetInset(..);
        // overwrites the offset again
So this would goes wrong quite often because you can't expect developers keeping the order when to call SetLayout. However, BBox setter and getter for a default inset are a solution but IMHO not very intuitive...
Point 1. should work fine but from my own experience I would just try to call SetLayout on the BBox to set the layout in the content area. That would result in a messed up BBox. Another problem occurs if you want, for whatever reasons, a content layout that is bigger than the content area. You can't do that in this solution.
I don't think BView::SetInset is duplicated functionality. One can see BView as a kind of a special "super layout" that holds only one child layout. From this point of view it also deserves a SetInset method like a real BLayout.
I can also imagine some other use-cases for BView::SetInset but back to BBox: It would solves the problem I pointed out for solution 2. the BView inset would place the layout tightly in the content area. The layout inset can be used to further positioning the layout in the content area. Following the principle "make common tasks easy but rare tasks possible" it also solves the problem from 1. where a content layout bigger than the content area is not possible. Here one could mess with BBox::SetInset to resize the content layout. 

To sum up I think BView::SetInset is not a too bad idea :-)

Cheers,
        Clemens

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