One option of the addHitregion method is a Path2D path: partial dictionary HitRegionOptions { Path2D? path = null; } which is specified as "A Path2D object that describes the pixels that form part of the region. If this member is not provided or is set to null, the current default path is used instead." See also https://developer.mozilla.org/en-US/docs/Web/API/CanvasRenderingContext2D.addHitRegion#Options So, code like this would create a hit region for the given path p: ctx = c.getContext('2d'), p = new Path2D(); p.arc(75, 75, 50, 0, 2 * Math.PI); ctx.fill(p); ctx.addHitRegion({id: 'p', path: p}); This is already in blink: https://chromium.googlesource.com/chromium/blink/+/master/Source/core/html/canvas/HitRegionOptions.idl

AFAIK :roc is the most involved around canvas standardization. I assume it's something we want, if so bounce it to Milan who might be able to schedule someone to implement this.

Should be trivial to implement, and sounds reasonable, though it's not all that important either.

I wont have time. Looks like we don't really have a canvas 2D owner. To :milan for scheduling.

Florian, do you have a pointer to the standard for this? In particular, I'm not clear what happens to the current path in this scenario.

Never mind, I see the link to the standard, but it's the same I found - I guess I'm assuming that if there is a current path, it would just be discarded at this point and replaced with the one in addHitRegion...

This is just a prep, but was the most work for this issue - without CanvasPath in a separate file, we get a circular dependency between CanvasRenderingContext2D.h and (generated) CanvasRenderingContext2DBinding.h that I couldn't get rid of any other way.

Comment on attachment 8571535 [details] [diff] [review] Part 1. CanvasPath into a separate file, to avoid circular dependency. r=roc Review of attachment 8571535 [details] [diff] [review]: ----------------------------------------------------------------- It would be slightly better to make dom/canvas/CanvasPath.h an "hg copy" of CanvasRenderingContext2D.h.

Same file, but CanvasPath.h is now an hg copy of CanvasRenderingContext2D.h

needs dom peer review for the changes in dom/webidl/CanvasRenderingContext2D.webidl

Comment on attachment 8571998 [details] [diff] [review] Part 1. Take CanvasPath into a separate file, to avoid circular dependency. Carry r=roc webidl file modified, need dom peer review.

Comment on attachment 8571536 [details] [diff] [review] Part 2. Add path option to addHitRegion. r=gw280 Review of attachment 8571536 [details] [diff] [review]: ----------------------------------------------------------------- Please send an intent to implement/ship email to dev-platform. Thanks!

(In reply to :Ehsan Akhgari (not reading bugmail, needinfo? me!) from comment #13) > Comment on attachment 8571536 [details] [diff] [review] > Part 2. Add path option to addHitRegion. r=gw280 > > Review of attachment 8571536 [details] [diff] [review]: > ----------------------------------------------------------------- > > Please send an intent to implement/ship email to dev-platform. Thanks! It's been about a week on dev-platform, no comments so far.

(In reply to Milan Sreckovic [:milan] from comment #14) > (In reply to :Ehsan Akhgari (not reading bugmail, needinfo? me!) from > comment #13) > > Comment on attachment 8571536 [details] [diff] [review] > > Part 2. Add path option to addHitRegion. r=gw280 > > > > Review of attachment 8571536 [details] [diff] [review]: > > ----------------------------------------------------------------- > > > > Please send an intent to implement/ship email to dev-platform. Thanks! > > It's been about a week on dev-platform, no comments so far. That means you're good to go! :-)

Indeed!

https://hg.mozilla.org/integration/mozilla-inbound/rev/e27def3ae3a3 https://hg.mozilla.org/integration/mozilla-inbound/rev/6f2b97191ec1

https://hg.mozilla.org/mozilla-central/rev/e27def3ae3a3 https://hg.mozilla.org/mozilla-central/rev/6f2b97191ec1

https://developer.mozilla.org/en-US/Firefox/Releases/39#Interfaces.2FAPIs.2FDOM https://developer.mozilla.org/en-US/docs/Web/API/CanvasRenderingContext2D/addHitRegion