Port to Qt5 #1775

This is far away on the horizon, even KDE is not ported yet, and Qt5 is only at beta. But unlike when going from 4.x to 4.x+1 there is some effort in porting:

http://www.kdab.com/porting-from-qt-4-to-qt-5/

However it is possible to make one code base compatible with both versions.

I don't expect it to be a lot of work for bitcoin; we don't use qt3 support, already use #include <QtXX> instead of #include <QtGui/QtXX>, and hardly make use of advanced meta-object features. But there may be some subtle issues.

It's good that you mentioned it and we keep it as remainder :). Did you try to build Qt5 and use it with Bitcoin-Qt yet?

Nope, I haven't ever tried Qt5 yet. Most of the 5.0 changes are concerning QML, Qt Quick and such, which I haven't really used. I guess I prefer the C++ QWidget API to mucking around with JS and XML.

AFAIK Qt 5.0 is now released, but I didn't have time to try Bitcoin-Qt with it. Just wanted to mention :). http://blog.qt.digia.com/blog/2012/12/19/qt-5-0/?utm_source=rss&utm_medium=rss&utm_campaign=qt-5-0

@laanwj I did successfully build Qt5 and a Qt5 based Qt Creator version (2.6.1). I'm now in the process in looking at needed source code changes because of Qt API changes (see https://qt-project.org/doc/qt-5.0/qtdoc/sourcebreaks.html).

So far there were only a few things like changed function names or deprecated things. I'll create a patch, for the changes what are already possible with Qt4, to increase Qt5 compatibility. I was also able to build a static Qt5 version, but I'm not able to build Bitcoin-Qt from it -_-.

Cool! Do you have screenshots? Does it look any different in Qt5?

For example can you try how it looks with the new Fusion style: http://blog.qt.digia.com/blog/2012/10/30/cleaning-up-styles-in-qt5-and-adding-fusion/

I'm in the process of converting removed / deprecated stuff to Qt5 still. I'll report back, when I have done that.

Got it to compile, the changes are really not that invasive. The default Windows theme looks nearly identical. Is there a quick way to switch styles, I can google, but perhaps you have a short and easy answer ^^.

Qt accepts -style <style> on the command line

I didn't know that, so -style fusion should work. I'll try that later, currently my PC is re-building the Qt libs, as I'm missing the default translations and need sqlite for the qrc-editor in Qt Creator.

See #2457

See #2721