Re: Questions RE: Hit Regions before return to Last Call

Hi Mark,

thanks for sending this out!
However, the issue of event retargeting is still not solved. Since this is
so complex to implement, it is be unlikely that we will have 2 independent
implementations soon and that we won't have to make additional changes to
the spec.


On Tue, Apr 8, 2014 at 2:55 PM, Mark Sadecki <mark@w3.org> wrote:

> As we prepare to move Canvas back to LC (we have committed to get the HTML
> WG
> chairs a stable document *this* week), I reviewed the Hit Regions section
> of
> Canvas L1 ED [1] and had the following questions:
>
> # if control is null
>
> Should we have a step in "The region representing the control" [2]
> processing
> algorithm that matches Step 1 in "The region representing the ID" [3] that
> reads
> something like:
>
> "If control is null, return nothing and abort these steps."
>
> Now that control and ID are both optional, I think we should handle the
> case
> that they are not specified.
>

Yes, we've been going back and forth on that.
Since we now have the 'clearHitRegions' call and it was allowed in the
original proposal, let's allow unbacked regions with no ID.


>
> # clearHitRegions() not defined
>
> While we reference clearHitRegions() in a Note following "The region for a
> pixel" algorithm [4], we don't define a processing algorithm for this
> method.
> Suggest adding one below the removeHitRegion() definition [5].
>
> # Move Note RE: clearRect() and clearHitRegions()
>
> The note referenced above [4] would make more sense following the
> definition of
> removeHitRegion() and clearHitRegions() where we actually discuss methods
> for
> removing and/or clearing Hit Regions.
>
> # Steps 5 & 8 from addHitRegion() [6] are unclear and seem to suggest the
> opposite of their intention.
>
> Steps 5 & 8, as they are worded, seem to suggest to me that if the ID or
> control
> referenced in the arguments object are not null, and they reference the ID
> or
> control of a previous region, then the *previous* region should remain
> associated with this region.  This is in direct conflict with steps 9 & 10
> and
> the behavior we discussed on call, that adding a Hit Region that shares a
> control or ID with a previously referenced region would remove/clear the
> previous region.
>
> I also feel like steps 5 & 8 should both come before or after step 7, not
> before
> and after it.  There may be a reason for this order that I'm not aware of,
> though.
>

It is worded a bit strange but the "previous region for the id/control" is
an object that is used in steps 9 and 10.


>
> I look forward to your feedback,
>
> Mark
>
> [1]
> http://www.w3.org/html/wg/drafts/2dcontext/html5_canvas_CR/#hit-regions
> [2]
>
> http://www.w3.org/html/wg/drafts/2dcontext/html5_canvas_CR/#the-region-representing-the-control
> [3]
>
> http://www.w3.org/html/wg/drafts/2dcontext/html5_canvas_CR/#the-region-identified-by-the-id
> [4]
>
> http://www.w3.org/html/wg/drafts/2dcontext/html5_canvas_CR/#the-region-for-a-pixel
> [5]
>
> http://www.w3.org/html/wg/drafts/2dcontext/html5_canvas_CR/#dom-context-2d-removehitregion
> [6]
>
> http://www.w3.org/html/wg/drafts/2dcontext/html5_canvas_CR/#dom-context-2d-addhitregion
> --
> Mark Sadecki
> Web Accessibility Engineer
> World Wide Web Consortium, Web Accessibility Initiative
> Telephone: +1.617.715.4017
> Email: mark@w3.org
> Web: http://w3.org/People/mark
>
>