Intent to implement: Hit regions (canvas)

139 views

Skip to first unread message

unread,

May 23, 2014, 8:42:38 AM5/23/14

to blin...@chromium.org

Contact emails

Spec

Summary

Allows the author to establish regions on a canvas 2D context. These regions can be associated with HTML elements

and they will inherit their ARIA properties. In addition, mouse events will be updated so events that fire on a canvas and

that hit a region, the id of that region is a member of the event.

We should provide following things at least:

- CRC2D.addHitRegion(HitRegionOptions); method

- CRC2D.removeHitRegion(); method

- HitRegionOptions (id, control and so on)

Motivation

Canvas authors are starting to create more complex user interface in canvas that can only could only [sic] map

to several underlying elements ([a] spline editor, for example, would map to several range controls). To enable

a better canvas+fallback DOM coding pattern, it seems prudent to enable easier canvas hit testing and event handling.

In the current HTML5 specification, authors are advised to create a fallback DOM under the canvas element to enable

screen readers and screen magnifiers to interact with canvas user interfaces. The size and position of those elements

are not defined, which causes problems for accessibility tools - what size/position should they report for these elements?

Because canvas elements usually respond to user input, it seems prudent to solve the hit testing and accessibility

Compatibility Risk

Low; It seems that some parts of the features has already been implemented in Firefox. (by Rik)

Ongoing technical constraints

None

Will this feature be supported on all five Blink platforms (Windows, Mac, Linux, Chrome OS and Android)?

Yes

OWP launch tracking bug?

Link to entry on the feature dashboard

Requesting approval to ship?

Reply all

Reply to author

Forward

0 new messages