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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]

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