Review Request: Improve rendering of Plasma Image-Wallpaper list items using QTextDocument to layout the text

[Darío Andrés]

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http://reviewboard.kde.org/r/3417/
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Review request for Plasma.


Summary
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Update BackgroundDelegate to use QTextDocument in order to improve text layouting.
Now, all the text is properly centered and long titles are wordwrapped correctly, maximizing the space usage.

Compare http://bugsfiles.kde.org/attachment.cgi?id=42291 (from the bug report) and the attached screenshot

I also cached some values to avoid a lot of calculations (useless as the ratio is not going to change)
- Should some other values be cached too ? (the smallest font size?)


This addresses bug 232348.
    https://bugs.kde.org/show_bug.cgi?id=232348


Diffs
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  svn://anonsvn.kde.org/home/kde/trunk/KDE/kdebase/workspace/plasma/generic/wallpapers/image/backgrounddelegate.h 1107102 
  svn://anonsvn.kde.org/home/kde/trunk/KDE/kdebase/workspace/plasma/generic/wallpapers/image/backgrounddelegate.cpp 1107102 

Diff: http://reviewboard.kde.org/r/3417/diff


Testing
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I have tested it and it works OK.
There could be a minimal performance drop (as I guess that using QTextDocument takes more time than a few drawText() and QRect constructor calls); however I couldn't really notice it


Screenshots
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Layouting improved
  http://reviewboard.kde.org/r/3417/s/344/


Thanks,

Darío