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Re: Canui Canvas User interface

From: Charles Pritchard <chuck@jumis.com>
Date: Mon, 03 Oct 2011 09:21:22 -0700
Message-ID: <4E89E102.3080701@jumis.com>
To: public-canvas-api@w3.org
On 10/1/11 6:35 AM, paniz alipour wrote:
> Hello All,
>
> Some days ago I was looking for some points in the area of Canvas ,I 
> found this web site:http://canui.sourceforge.net/examples/index.html
>
> A web site for designing user interface via Canvas.I view the source 
> of this page I didn't find Canvas tag,but when I used Developert Tools 
> of google
>
> Chrome I saw Canvas Tag! what was the reason and what's your opinion 
> about it?
>

It's great to see another public domain (no attribution required) Canvas 
UI library.

The author was very careful to use one Canvas layer per complex component.


This project represents a second public domain, open source, 
implementation of common UI widgets such as combobox and checkbox.

The option to "show the structure of the controls" is quite similar to 
the rendertree dumps that are used by WebKit developers when debugging 
and/or verifying rendered output.

Note that the render tree does have bounding box information, and that 
information could easily be passed to the accessibility APIs of the user 
agent, if a method were available to do so.

....

Once again, I urge vendors to consider supporting the Canvas sub-tree. 
With vendor support, I could easily contribute to projects such as canui 
with patches that enable an accessible DOM.

For WebKit, this would mean allowing focus to pass to elements in the 
Canvas sub-tree, which is the correct behavior per the HTML5 specification.

A patch was started in February, and has since been abandoned.
https://bugs.webkit.org/show_bug.cgi?id=50126

Following a patch, to allow focus, authors require means to share 
sufficient information for the Accessibility methods of WebKit to return 
bounding box information:

See:
LayoutRect AccessibilityRenderObject::boundingBoxRect
http://trac.webkit.org/browser/trunk/Source/WebCore/accessibility/AccessibilityRenderObject.cpp


I urge WebKit vendors to consider the consequences of their continued 
inaction. Projects such as canui and w3canvas could easily support an 
accessible sub-tree: browser vendors take note.

-Charles
Received on Monday, 3 October 2011 16:22:05 GMT

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