Wednesday, September 23, 2015

PyQt5 on WinPython with mingw

Getting PyQt5 running on WinPython required a lot of tweaking. WinPython (32 bit) comes with mingw. This is installed in E:\WinPython-32bit-\python-2.7.10\share\mingwpy. Following the instructions on the PyQt5 download page I first downloaded SIP from this page. I downloaded the zip file for windows. Following these instructions I configured sip for mingw by running

python --platform win32-g++

The next step then is to run make. However if you start a WinPython Command Prompt you do not have make. I fixed this by copying an old msys installation, from an older (not connected to WinPython) mingw installation, to the mingw folder in the WinPython folder (as noted above). Then by changing the fstab file in msys/1.0/etc to this e:/WinPython-32bit- /mingw I have a msys system setup for working with the mingw from the WinPython distribution. From a msys shell I can then run make and make install for sip.

Next step is to do the same for PyQt5 download. However, there the script does not recognize the --platform switch. Use the --spec=win32-g++ switch is also not good enough. The problem is that it somehow still puts "windows" commands in the Makefiles it generates for rename, deleting files folders etc. I could only fix this by changing some code in the script. In the function run_qmake I added the lines


(do this before the "if recursive:" statement). While you are busy editing the file you can also follow the advice in this forum post to handle any issues with mismatching licenses. Somehow was detecting a different Qt version. This version was actually located in the site-packages/PyQt4 folder (in WinPython-32bit- By temporarily renaming this PyQt4 folder you can fix this issue.

After this. If you run

python --spec=win32-g++

from a msys shell should create the right Makefile (note that this means you have to put WinPython in your system path (environment variables in control panel from advanced system settings in the control panel of windows) because otherwise you have no python in your msys shell. Then you can run make and make install from the msys shell.

Then you are almost done. If at this stage you run a PyQt5 python script it will probably complain that it 'Failed to load platform plugin "windows"'. This was a tricky one to solve. For c++ qt applications it is usually enough to copy the plugins folder to the location of your executable (+ any other needed qt dll's), but what is the location of your executable in this case? I only managed to get it running by adding a new environment variable: