Re: [boost] [gui] rectangles and the CSS box model

From: Alan Gutierrez (alan-boost_at_[hidden])
Date: 2004-12-22 05:47:10

* Alan Gutierrez <alan-boost_at_[hidden]> [2004-12-22 05:41]:
> * Reece Dunn <msclrhd_at_[hidden]> [2004-12-22 05:22]:
> > Hi All,
> > 
> > In the "thoughts on a GUI component library" thread there have been 
> > various discussions about the layout of a rectangle and come relating to 
> > CSS. Note that point and size are stable.
> 
> > I personally like the CSS box model (http://www.w3.org/TR/css3-box/) 
> > which can be defined as:
> 
> >    struct css::box_model
> >    {
> >       rect margin;
> >       rect border;
> >       rect padding;
> >       size dimensions; // width and height
> >       // T content;
> >    };
> 
> > The problem with supporting it by default is that we would need:
> 
> > class component: public css::box_model;
> > class graphics::object: public css::box_model;
> 
> > This clearly violates the don't pay for what you don't need rule of C++, 
> > so for a css_block_layout, it needs to contain the box model properties 
> > and a pointer to the component/graphical object. Obviously some level of 
> > support for the CSS box model should be provided, allowing an 
> > implementation of it to be written.
> 
>     I'd imagined a division class that would have the block
>     properties. If you don't want to pay for the borders if they are
>     not needed, and in many cases, they would be the same from
>     division to division, could you use a reference to shared
>     set of demenions?
> 
>     This may aid in the cascading asepct of the stylesheet.
> 
>     struct css::division
>     {
>         box_model   *block;
>         size dimensions;
>     };
> 
>     Each division is going to need it's own size, but the block
>     properties, margin, border, padding, are likely to be common for
>     many divisions.
 
    Actually, now that I think about it, the css box is going to
    cost a lot if it has actual structures. It is going to need a to
    return a margin, say by inspecting the margin it was assigned,
    and if assigned none, return the margin that it inherited. 

    In some cases, a division might have been explicitly assigned a
    border, but in most cases it will choose one based on context.

--
Alan Gutierrez - alan_at_[hidden]