[webkit-qt] Proposal for switching image decoders from Qt to WebCore

[Simon Hausmann]

Hi,

I'd like to propose that we switch over to using the WebCore image decoders.

Zoltan has spent some time comparing performance and memory usage between the 
ImageDecoderQt (and the qt plugins for image decoding) and the WebCore image 
decoders, in https://bugs.webkit.org/show_bug.cgi?id=71555

My interpretation of the result is that performance and memory usage wise 
there's not much of a difference. However the WebCore image decoders have some 
advantages that are of a different nature:

    1) They are an actively maintained piece of code. Unfortunately the Qt 
image decoder plugins are subject to less tender loving care. The WebCore 
decoders are used by pretty much all other ports, and from my totally biased 
point of view we have also found them working great for the N9 with the Qt 
based browser/webkit.

    2) They support image downsampling, which is particularly nice for mobile 
devices with less memory than our gigabyte filled workstations.

    3) The jpeg decoder supports progressive/interlaced jpegs, which is again 
an nice thing for image loading over slow connections.


Therefore I'd like to re-open https://bugs.webkit.org/show_bug.cgi?id=32410 .

Any opinions / objections / thoughts?


Simon