On Thu, Aug 6, 2009 at 11:20 AM, Sven Brunken <s...@extjs.com> wrote:
> Dropping transparency support in IE6 is a bad idea. Too many business > people just still use IE6. Also saying that developers that need > transparent images in IE6 should not use ImageBundle is that good. > When writing my app I don’t want to care where it is running after I > finished it. It should just run and fit well in that browser. > Would converting transparency to single-bit alpha for IE6 work for you? Ie, a pixel is either transparent or not, no gradation (and therefore no anti-aliasing). > Adding good support for transparency in IE6 is not that big and should > really be considered. > When you say "good support", what exactly do you mean? I think it is not practical to support image bundles with transparency in the same manner as all the other browsers on IE6. Various approaches that I know of: 1. *bundling everything into one PNG keeping alpha* doesn't work in the general case due to memory requirements of the alpha filter, runtime cost of not using filter on IE7 2. *bundling everything into one GIF* doesn't work in the general case because you only have an 8-bit palette to share between all the images 3. *detect images with transparency and "bundle" them separately* works, but defeats the point of image bundles (though the user code is unchanged and works properly on other platforms), runtime cost for IE6/7 permutation 4. *encode all transparency as single-bit alpha on IE6 *lose antialiasing, keep extra image bundles just for IE, runtime cost for IE6/IE7 permutation We are currently at #1, without runtime detection of IE7. Fixing that is relatively easy. #2 seems a non-starter, though it could be useful for specific cases where palettes are small -- still since it isn't a general solution it doesn't seem worthwhile. #3 seems straightforward and will continue to work but loses the benefit of image bundles on IE6. #4, assuming I am remembering correctly that IE6 does support single-bit alpha in PNGs, seems the best compromise but the most work. -- John A. Tamplin Software Engineer (GWT), Google --~--~---------~--~----~------------~-------~--~----~ http://groups.google.com/group/Google-Web-Toolkit-Contributors -~----------~----~----~----~------~----~------~--~---
