Tuesday, August 15th, 2006
IE 7: Are transparent PNGs using Native support?
There was a big hubbub when we found out that IE 7’s XHR support isn’t really native.
Jose Jeria did some poking around to see if transparent PNG support is native or not:
While developing an intranet for IE 6 only (yes, trust me, it sucks) I noticed that it was not possible to combine certain filters. Transparent PNG:s were used for buttons that needed to look disabled. A combination of the AlphaImageLoader with the Alpha filter should have done the trick, but it didn’t seem to like this combination. It should have looked like this:
But IE failed rendering the PNG with opacity applied to it, and instead it rendered it like this:
This must be a bug in IE’s filter implementation. So what I did next was to test the same image with opacity applied to it in IE 7, since they now claim they have native transparent PNG support. But… the results were exactly the same. Which makes you wonder if it’s not just the same filter as in IE 6 being applied under the hood
Oh, freaking awesome. Just as I was getting excited about being able to use PNG’s in IE without being subjected to AlphaImageLoader’s numerous bugs…
On the upside, you can use lower security settings to use XHR and PNG. That means paranoid intranets get a better user experience. Not much of a gain but better than nothing.
The following limitation in IE7 is known:
Regarding Tevo’s comment about IE7 “limitation”…
This is not a limitation; the huge majority of browsers do not have any problem with it so it’s rather a misconception in IE7. How easy to throw the stone to filters… But hey, as usual, as soon as IE is mentionned what would you expect?
@nat: That is why I wrote “limitation IN IE7”. Oh dear.
@Tevo: ^^. Now that we talk about it, wouldn’t it be more accurate to talk about IE as a limitation in itself?… [sarcastic mode OFF]
looked like what? where is the picture?
Man, snook.ca’s design makes me want to die. Besides, it’s not arguing we’re tired of, it’s pointing out IE’s numerous and horrible flaws.
Is that die in a good way or a bad way? I can’t tell. If it’s good, thanks. If it’s bad… well, I’m changing the design. :)
IE7 PNG transparency, and Flash
Alpha support for PNG images is one of many fixes and features we can get excited about in IE7. Well… sort of. Following news that the new PNG transparency support might not be as native as previously supposed, I ran…
See http://blogs.msdn.com/ie/archive/2005/04/26/412263.aspx for a post about how alpha channel support was achieved for IE7.
Thanks
-Dave
For ie7:
If you give the image style an AlphaImageLoader and then wrap it with a container to set the Alpha filter it seems to work – See the example here: http://miedlar.com/dev/pngtest/
bmiedlar, not that the png’s quality is ruined by doing this. Also, it doesn’t even show up in IE 6, adding more headaches.
Agreed – its not the ideal solution – but usable for ie7 if you need it to work – as it still has png advantages over gifs for overlays when the background is not consistently known. http://miedlar.com/dev/pngtest/color.htm