Re: [OpenLayers-Users] OpenLayers accessibility

[christopher.schmidt]

On Aug 20, 2010, at 4:40 PM, ext William Martin wrote:

> All,
> 
> Is there any way, short of rolling a custom variant, to make OpenLayers add 
> ALT text to its images?

There's nothing like this currently. However, you could probably achieve this
by modifying OpenLayers.Util.createImage and 
OpenLayers.Util.createAlphaImageDiv,
modifying them to set the alt attribute; this code is used for almost all
image creation in the library, so I expect this would resolve most of the
cases.

-- Chris

> Currently the tile images I'm getting are added something like this:
> 
> <img 
>   style="width: 256px; height: 256px; position: relative;" 
>   src="{URL snipped}" 
>   class="olTileImage" 
>   id="OpenLayersDiv2089">
> 
> When my screen reader encounters that, it reads the URL for the image, which 
> is:
> 
> http://opencache.statkart.no/gatekeeper/gk/gk.open?LAYERS=topo2&amp;FORMAT=image%2Fjpeg&amp;SERVICE=WMS&amp;VERSION=1.1.1&amp;REQUEST=GetMap&amp;STYLES=&amp;EXCEPTIONS=application%2Fvnd.ogc.se_inimage&amp;SRS=EPSG%3A4326&amp;BBOX=0,56.25,11.25,67.5&amp;WIDTH=256&amp;HEIGHT=256
> 
> Keep in mind that it's reading this aloud, so somethin like "1.25" comes out 
> as "one point two five".  Multiply that pain by 34 for the initially loaded 
> tiles.
> 
> Then the map controls have HTML like this:
> 
> <img 
>   id="OpenLayers.Control.PanZoomBar_2159_panup_innerImage" 
>   style="position: relative; width: 18px; height: 18px;"
>   src="http://openlayers.org/api/img/north-mini.png";>
> 
> Again, a screen reader reads the contents of the SRC attribute because 
> there's no ALT text.
> 
> Maps are inherently visual/spatial, and therefore of little use to a blind 
> visitor.  I'd like to set blank ALT text on all the images, thus:
> 
> <img 
>   style="width: 256px; height: 256px; position: relative;" 
>   src="{URL snipped}" 
>   class="olTileImage" 
>   id="OpenLayersDiv2089"
>   alt="">
> 
> ... which will cause screen readers to silently skip over the image.  Then 
> I'd add ALT text for the entire map:
> 
> <div id="access-note">Image: Map of Norway.</div>
> <div id="map">{OpenLayers would fill in the map here}</div>
> 
> That way, any blind visitors would be told that there's a map of Norway 
> there, but not troubled with endless, mindless recitations of image SRC 
> attributes for a map they can't use.  All of my site's content is actually 
> available without the maps -- the maps are a useful navigational interface, 
> but all the actual site content can be read without them.
> 
> So, can I make it add blank ALT text to the tile and control images?
> 
> Will Martin
> 
> _______________________________________________
> Users mailing list
> Users@openlayers.org
> http://openlayers.org/mailman/listinfo/users

_______________________________________________
Users mailing list
Users@openlayers.org
http://openlayers.org/mailman/listinfo/users