- From: Alan Chuter <achuter@technosite.es>
- Date: Tue, 03 Nov 2009 17:17:41 +0100
- To: Public BPWG <public-bpwg@w3.org>
- CC: Henny Swan <hennys@opera.com>, Yeliz Yesilada <yesilady@cs.man.ac.uk>
The document says "Canvas ... is not inherently accessible and so should not be used as the sole means of conveying information." [1] Perhaps the word "alternative" is needed here, "If you need to use canvas, then provide an alternative." I think that as this is about dynamic graphics the document should also add the proviso that the alternative should be updated as the image is redrawn, if that changes its meaning. How this is done in canvas I don't know, probably by the same script that updates the image. Updates to the DOM (which would be used for the alternative) are detected by some current mobile screen readers. This also applies to SVG. SVG supports accessibility but in practice it requires a text alternative for the whole image. Another solution might be to require that it be used in an accessibility-supported way, as defined by WCAG [2]. [1] http://www.w3.org/TR/mwabp/#bp-canvas [2] http://www.w3.org/TR/WCAG20/#accessibility-supporteddef -- Alan Chuter Departamento de Usabilidad y Accesibilidad Consultor Technosite - Grupo Fundosa Fundación ONCE Tfno.: 91 121 03 30 Fax: 91 375 70 51 achuter@technosite.es http://www.technosite.es
Received on Tuesday, 3 November 2009 16:21:28 UTC