+1  This works well for us and I'd love to remove the complexity from  
our build process.  We've dropped the transparency loader for some  
time now and it's solved a lot of our IE6 bugginess (including random  
hard browser lockups!).

On 6-Aug-09, at 11:29 AM, Joel Webber wrote:
>
> If we want to support IE6 fully (which I hate having to do, but it's  
> hard to argue with the fact that it still account for ~20% of the  
> market, depending upon whose stats you use), then I think this is  
> basically the only approach that will work. We all agree that the  
> DirectX filter is far too memory hungry, especially on the old  
> machines that are often still running IE6. Bundling images with  
> disparate palettes into a single 8-bit image is far too  
> unpredictable, which seems pretty unacceptable to me. So I will  
> argue that we should, on IE6:
> - Leave GIFs alone.
> - Turn PNGs with transparency into GIFs.
>   - Open question: How should we clamp the [0, 255] alpha channel to  
> [0, 1]?

In our experience, every transparency clamping preset will result in  
artifacts in IE6 for some subset of images.  To simplify things, I'd  
suggest mapping alpha of 0 to transparent, and alpha of 1-255 ->  
opaque.  If the developer needs more control, they can convert the  
image to a GIF by hand.  Alternatively, it might be useful to allow a  
developer to specify a fallback IE6-only image.

For quantization of partially transparent PNG to GIF, I highly  
recommend the algorithm behind this tool: 
http://members.ozemail.com.au/~dekker/NEUQUANT.HTML 
   There's already a Java version of the code available.

> - Bundle only those images without transparency into PNGs.
> - Stop using the DirectX filter altogether.
>
> Does anyone have any really strong objection to this approach? It  
> will add some extra requests on IE6 under some circumstances, but  
> that's got to be better than either (a) completely mangling bundled  
> images, or (b) blowing massive amounts of memory.



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