[webkit-qt] QtWebKit 2.3.2 and QtWebKit for Qt 5.1

Allan Sandfeld Jensen kde at carewolf.com
Mon Jul 15 05:12:11 PDT 2013

Hello WebKit-Qt

Thursday I tagged QtWebKit 2.3.2. To avoid confusion I will present both 
QtWebKit for Qt 5.1 and QtWebKit 2.3.2.

The new features in QtWebKit for Qt 5.1 can be seen on http://qt-project.org/wiki/New-Features-in-Qt-5.1 . Let me expand a few interesting ones 

Windows 64bit JIT: In QtWebKit 5.0 and QtWebKit 2.3.1 we only supported 
interpreted JavaScriptCore on 64bit Windows. The issue is that unlike 32bit 
x86, x64 has different calling conversions on Windows and Linux, so the it 
requires different JIT implementations to work on Win64, and on top of that
 Note that x64 is still not as fast as x86 on windows or x64 on linux. Only 
first generation JIT has been implemented, the second generation DFG JIT is 
not available. This work was also cherry-picked forQtWebKit 2.3.2

MIPS JavaScriptCore: MIPS have had second level DFG JIT implemented. This work 
was also cherry-picked for QtWebKit 2.3.2. Note the at WebKit MIPS 
implementation is limited to the O32 binary format and calling convention, and 
requires 64bit floating-point any other MIPS configuration will default to 

Improved garbage collection: Garbage collection have been improved by 
implemented the activity triggered garbage collected and the incremental 
sweeping garbage collector. The first means that garbage collection can now be 
triggered by new allocations. This is more likely to keep the memory usage 
constant, by spending time to find garbage each time more memory are 
allocated. The second means that garbage collection will now run incrementally 
which means JS will now cause shorter CPU stalls when under pressure.

Improved font rendering: In Qt 5.1 QtWebkit now defaults to enabling font 
kerning  Previously kerning could be enabled using '-webkit-font-kerning: 
normal' but  doing so would incur a big performance hit because a complex font 
rendering path would be used (the slowl path used when complex shaping is 
required). In Qt 5.1 we can now renderer kerned text in the fast font 
rendering path, which means we can now enable it when '-webkit-font-kerning' 
is set to 'auto' which is default. This is Qt 5.1 only because it depends on 
new features added there.

Support for WOFF fonts: We have added support for the WOFF web-font format. 
This feature depends on the presence of the zlib library when building WebKit. 
This work was also cherry-picked for QtWebKit 2.3.2.

Qt 5.1 is available at http://qt-project.org/downloads

QtWebKit 2.3 for Qt 4.8 is maintained at https://gitorious.org/+qtwebkit-developers/webkit/qtwebkit-23 and the tarball 2.3.2 is

Best wishes here from Bilbao (Akademy + QtCS)
`Allan Jensen (carewolf)

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