[whatwg] remove resetClip from the Canvas 2D spec

Ian Hickson ian at hixie.ch
Fri Aug 9 13:20:03 PDT 2013

On Fri, 9 Aug 2013, Stephen White wrote:
> Although Skia could support resetClip() via SkRegion::kReplace_Op, it's 
> problematic for the API in general, and I think we should avoid it.
> In particular, it makes it impossible to place a display list (SkPicture 
> in Skia parlance) inside a parent display list containing a clip and be 
> assured that the child will not draw outside the given region, since the 
> child display list can always resetClip() its way out of the parent's 
> clip. It probably also prevents culling optimizations for the same 
> reason.
> For example, if one used Skia to draw the entirety of a browser UI 
> including chrome and content, the resetClip() inside the web page 
> contents would overwrite the browser UI. Obviously we don't do that in 
> Chrome, but it goes some idea of the problem at the API level.

This is a quite widely requested feature. What should we do to address 
this request instead?

Ian Hickson               U+1047E                )\._.,--....,'``.    fL
http://ln.hixie.ch/       U+263A                /,   _.. \   _\  ;`._ ,.
Things that are impossible just take longer.   `._.-(,_..'--(,_..'`-.;.'

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