- From: David Woolley <david@djwhome.demon.co.uk>
- Date: Mon, 2 Jul 2001 23:33:11 +0100 (BST)
- To: w3c-wai-ig@w3.org
> The screen buffer would tell one the current colour, and this can be > compared with the 'transparent colour' for a given object. The screen buffer colour would be the background colour (including any content underlying the image). The fact that there is a colour associated with transparency in GIF is an implementation artefact; that colour can actually be the same as a non-transparent colour, as it isn't the colour that matters but the entry number in the colour table. Any use of the GIF transparent colour is far too implementation dependent for a graphic formats independent standard. PNG doesn't have this artefact, as it has a proper alpha (transparency) channel. PNG can actually do intermediate levels of transparency, which is where things get really ambigous if you associate links and transparent material. The feeling when this was discussed on the SVG (www-svg) and/or styles (www-style) list was that PNG with a zero alpha channel was an extreme case of partial transparency, and therefore ought to still hide material below it. On the other hand, the view was that areas set transparent with style="color: transparent" ought to ignore mouse clicks and let them through to the underlying layer. I'd suggest you have a look at the discussions in the archives of those lists.
Received on Monday, 2 July 2001 19:12:23 UTC