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02 July 2008

PNG, Transparency, IE6, AlphaImageLoader, and SSL

Well, you did not expect to get away without problems here, did you?

In case you try to run one of the AlphaImageLoader fixes out there in order to teach Internet Explorer 6 to handle PNG images with transparent alpha channel information somehow gracefully... and in case you try to run this over SSL (https), you might or might not have run into problems where your images all disappeared. One moment, while you where still testing over unencrypted http, everything was there, then you go the the HTTPS site and all you see is your images blinking up before disappearing.

Been there, done that. It's the same problem with IE6 and SSL over and over. What you have to do is give those images a header that allows them to be cached. In Zope it will be enough to associate them with an "Accelerated HTTP Cache Manager". It's still not very nice and there are lots of caveats. We didn't expect better from IE though, did we?

Forgot to mention what got me to the solution:

This problem is happening because Internet Explorer requires that any content retrieved by the browser that is to be opened by a plugin must be cached. In this case, the ImageBundle .png file is opened by AlphaImageLoader, which qualifies as a plugin.

(From this google-web-toolkit issue page.)


Posted by betabug at 16:19 | Comments (1) | Trackbacks (0)
ch athens
Life in Athens (Greece) for a foreigner from the other side of the mountains. And with an interest in digital life and the feeling of change in a big city. Multilingual English - German - Greek.
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Comments
Re: PNG, Transparency, IE6, AlphaImageLoader, and SSL

What I don't know is what are you doing supporting IE6 :?

So Microsoft abandoned these users. And now, because Microsoft did such a great job, we continue supporting them.

2001 was a great year, but that was 7 years ago.

Posted by: graffic at July 05,2008 13:22
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