Qt5 -> KDE5?

John Layt johnlayt at googlemail.com
Mon May 9 18:53:02 BST 2011

On Monday 09 May 2011 17:03:18 Olivier Goffart wrote:
> With Qt5 around the corner[1], I think it is time to start thinking about
> KDE5

TBH, we'd be fools to release a KDE 5.0 based on Qt 5.0 shortly after it's 
release.  The sensible approach is to wait for Qt 5.1 and release KDE 5.0 
after that.  This realistically gives us at least 18 months before a KDE 5.0 
release.  Our primary focus should first be getting what we want into Qt 5.  
Once we see what actually makes it into Qt 5 then we can make plans on what 
KDE 5 will look like.

Between Platform 11 and the QCS and a beta release in 6 months there's a lot 
of decisions and a lot of code in a fairly short time. If there are topics 
anyone wants discussed at Platform 11 please add them to 
http://community.kde.org/KDE_Core/Platform_11#Topics and if needed do a 
detailed write-up on a linked wiki page.

One thing to consider is how long the Qt5 code migration will take.  The Qt4  
-> Qt5 code might be fairly simple, but we still have a lot of Qt3Support code 
left in KDE4 that will have to be gone before KDE5, and if anything happens 
around QLocale/QDateTime/QSettings then thats some core code to adapt 
everything to.  I suspect we will have to skip a release cycle and take 9-12 
months to do it properly, probably starting around teh Qt 5.0 release.

Personally here's my Qt5/KDE5 wish/todo list:
* QDateTime to gain proper timezone and calendar system support so we can drop 
ours, otherwise fix my mistakes in KCalendarSystem
* KLocale and QLocale to merge as much as possible, otherwise split KLocale 
into a settings container and formatting functions to get rid of circular 
* Geolocation api
* Printing nirvana

I'll leave the graphics stack to those who know better, but I suspect the leap 
to QML will be too disruptive and dely things too much.  Perhaps continue 
calling the QWidget KDE v4 and save the v5 for QML after another 6-12 months?

With regards to printing, the CPD, and the Qt patch-set I'm sitting on waiting 
for OpenGov, if it is now going to take 18-24 months to get those features 
into our coders and users hands then that's too long.  I'm seriously 
considering a short-term fork of QPrinter with a cleaned up api and new 
features we can ship with KDE 4.8.  What I learn from that can then go into 
Qt5, or give us a fallback if Qt5 doesn't deliver.



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