Open Bug 935992 Opened 9 years ago Updated 4 years ago

Firefox does not support accessibility hit testing of canvas fallback content


(Core :: Canvas: 2D, defect, P2)

28 Branch




(Reporter: richschwer, Unassigned)




(Keywords: access, html5, parity-chrome)

User Agent: Mozilla/5.0 (Macintosh; Intel Mac OS X 10.9; rv:28.0) Gecko/20100101 Firefox/28.0 (Beta/Release)
Build ID: 20131105214748

Steps to reproduce:

I used the Firefox 28.0a nigthly. Then enable the new canvas 2D API for drawing focus rings:

Turned on canvas.focusring.enabled in about:config

Load this file in the browser. Tab to the first checkbox and then the second checkbox. If you use Inspect32 and run the mouse pointer over the first checkbox it only says canvas. 

There is a bug with the location on the second checkbox.

In this example there are two fallback content sliders representing the hour and minute hand. These also cannot be found using the pointer and inspect32.

Actual results:

If you use Inspect32 and run the mouse pointer over the first checkbox it only reports canvas as the accessible object.

Expected results:

It should have reported the accessible for the first checkbox, including its location information in inspect32. 

It appears that the hit test is stopping at canvas and not proceeding to the fallback content.
Depends on: 935383
Keywords: access, html5
OS: Mac OS X → Windows XP
Priority: -- → P2
Whiteboard: parity-chrome-canary
Ever confirmed: true
It seems nsLayoutUtils::GetFrameForPoint we rely on doesn't see a shadow content of the canvas. Robert, do you have ideas how to workaround it?
Call nsLayoutUtils::GetFramesForArea and walk through the resulting list, ignoring canvas frames?
The spec needs to be updated for this to work. Only keyboard navigation is specced today, not mouse.
Assignee: nobody → cabanier
Depends on: 958232
Depends on: 958241
Depends on: 959820
Depends on: 960195
Depends on: 1004579
Depends on: 1004499
As Rik was not active on Bugzilla since last year, I remove him as assignee.

Assignee: cabanier → nobody
OS: Windows XP → Unspecified
Hardware: x86 → Unspecified
Mass bug change to replace various 'parity' whiteboard flags with the new canonical keywords. (See bug 1443764 comment 13.)
Keywords: parity-chrome
Whiteboard: parity-chrome-canary → -canary
Whiteboard: -canary
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