[whatwg] remove resetClip from the Canvas 2D spec

Rik Cabanier cabanier at gmail.com
Tue Jan 29 18:10:20 PST 2013

On Tue, Jan 29, 2013 at 5:27 PM, Tab Atkins Jr. <jackalmage at gmail.com>wrote:

> On Tue, Jan 29, 2013 at 5:00 PM, Rik Cabanier <cabanier at gmail.com> wrote:
> > All,
> >
> > we were looking at how resetClip [1] could be implemented in WebKit.
> > Looking over the Core Graphics implementation, this feature can't be
> > implemented without significant overhead. I also found an email from 2007
> > where Maciej states the same concern. [2]
> >
> > Since no browser has implemented it, can it be removed from the spec?
> >
> > Rik
> >
> > 1:
> >
> http://www.whatwg.org/specs/web-apps/current-work/multipage/the-canvas-element.html#dom-context-2d-resetclip
> > 2: http://permalink.gmane.org/gmane.org.w3c.whatwg.discuss/10582
> It seems kinda bizarre that it's hard to reset, given that you can
> remove it by saving and restoring context.
> It seems bizarre that it would *ever* be hard to reset, to be honest.
> That's just plain weird.  I mean, just what *does* CoreGraphics do
> with restore()?

It restores the graphics state back to the state at 'save' time and this
includes the clip area.
'Clip' is a nested operation so every clip will be the intersection of the
existing clip area and the new one.

PDF also has no initclip/resetClip and since CG is based on that model,
maybe they didn't bother to add it.
I can certainly see its use though (it's used quite often in PostScript)

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