Replace an OS X-only temporary file hack. #4606

Replace the temporary file hack currently used to change Bitcoin-Qt's dock icon (OS X) with a buffer-based solution.

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@theuni can you do a test run with this on MacOSX when you have some time?

Actually, looking through the code a bit more, I found the hack in at least one other piece of code. I'm going to fix it later today and will submit a revised pull request at that time. In the meantime, feel free to look at what I've already posted. I have no plans to revise it unless somebody makes a request.

EDIT: After looking at the code more closely, the only other QTemporaryFile instance deals with Growl (an OS X notification system). I don't know enough about Growl to know if the string that mentions the file's location is important. So, for now at least, I'll leave alone my pull request.

will do.

Any reason for not using icon.pixmap().toMacCGImageRef() and cutting out the middle-man ?

Not really. I'm happy to give that a shot and revise the request.

EDIT: Actually, I take that back. Looking at the documentation, it looks like that call was removed from Qt5. As I understand things from pull request #2721, Bitcoin-Qt is supposed to be compatible with Qt4 and Qt5. In fact, that's the pull request where this particular code was committed in the first place. I suppose I could use a Qt4/Qt5 switch and see what happens.

Okay. After doing some more digging, I think the patch should stay as is. The QPixmap::toMacCGImageRef() call was pulled from Qt5 and appears to have been reinstated in Qt5.2 as QtMac::toCGImageRef(). (See http://qt-project.org/doc/qt-5/qtmac.html for more info.) Writing a patch with three paths (Qt4, Qt5.0/5.1, and Qt5.2+) seems a bit silly when we already have a path that should work across Qt4 & Qt5.

@droark Agreed. Instead of three #ifdef paths where this solution is used in a subset of qt versions, it's better to just use it for all so that it gets testing.

ACK. Works fine on 10.9.

We'll likely not be using QT < 5.2 for OSX at any point in the future, but there may be a few devs still building against it. At some point we can remove this and use the platform API if we stumble upon it again.

ACK