Looks really useful, always been frustrated that getDimensions includes the padding and border sizes (I know that's due to Javascript/ CSS rather that Prototype).
I prefer the 'measure' syntax rather than having to first grab an instance of Element.Layout. However, 'measure' doesn't seem to cache the instances of Element.Layout it uses so looks like it's a costly method at the moment. Perhaps 'measure' could be amended to cache Element.Layout, maybe with a way of grabbing a fresh 'snapshot' when it's needed? Thanks, Mike. On Jan 16, 9:27 am, Andrew Dupont <goo...@andrewdupont.net> wrote: > I've just committed a couple large API additions in a "layout" branch > in our Git repository: > > http://github.com/sstephenson/prototype/tree/layouthttp://github.com/sstephenson/prototype/blob/9d28f04d98307f652a2d85ff... > > It's still very preliminary, but Element.Layout is meant to like a > lazy-loading, memoized subclass of Hash. It gives measurements and > offsets of practically any aspect an element's layout box. It's lazy- > loading because some of these computations are costly and shouldn't be > done unless strictly necessary. > > In other words, I can do something like this... > > var foo = $('foo'); > var layout = foo.getLayout(); > > var width = layout.get('width'); // 144 (or some other number) > var marginBoxWidth = layout.get('margin-box-width'); // 164 (content + > padding + border + margin) > > Behind the scenes, it determined the "width" (i.e., the content box > width) by taking the offsetWidth property from the element (which is > the width of the element's "border box") and subtracting the computed > padding and border widths on both sides. When it did this, it cached > the values for many other measurements, like "border-box-width," > "padding-left," "padding-right," and so on. If any of these values are > requested directly, no further computation is necessary. > > Furthermore, when we ask for the "margin-box-width" (i.e., the space > the element truly commands), it knows it needs to fetch "margin-left" > and "margin-right," but the values of all other properties are already > cached. > > (A caveat: because of the caching, an Element.Layout object should be > treated like a "snapshot" of an element's dimensions. When the > dimensions of an object change, you ought to grab a new instance of > Element.Layout.) > > Take a look at the code and tell me what you think. The API is far > from complete, naturally, but it'd be great to know if people think > this is the right idea. > > Cheers, > Andrew --~--~---------~--~----~------------~-------~--~----~ You received this message because you are subscribed to the Google Groups "Prototype: Core" group. To post to this group, send email to prototype-core@googlegroups.com To unsubscribe from this group, send email to prototype-core-unsubscr...@googlegroups.com For more options, visit this group at http://groups.google.com/group/prototype-core?hl=en -~----------~----~----~----~------~----~------~--~---
