[BlackBerry-Python] PySide for BB10

[Martin Kolman]

16.1.2013 03:06, Peter Hansen:
> On 2013-01-15 20:12, Martin Kolman wrote:
>> relevant part of the debug log for "from PySide.QtGui import 
>> QApplication":
>>
>> dlopen("PySide/QtGui.so", 2);
>> ldd:FATAL: Unresolved symbol "_Z17init_QPrinterInfoP7_object" called
>> from QtGui.so
>
> This reminds me a lot of when Ritesh and I were trying to get the 
> basic PySide build working for the PlayBook, and had to strip out 
> certain things that didn't look likely to be compatible.  I don't 
> recall the specifics but you'd see signs of them in our patch files at 
> http://hg.microcode.ca/blackberry-py/src/500d90ca1dbee18fbc58ed1921d464c39377892b/patches/02-pyside-qnx.patch?at=pyside
>
> I just peeked there, and QSound was one of them.  I wouldn't think 
> QPrinterInfo would have the pieces needed to support it, so stripping 
> it out in similar fashion seems like a reasonable step.
>
> -Peter
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As you might have already noticed, I got PySide working and already 
submitted a working application (Mieru) for review to (App)World. So, 
how did I do that ? :)

First, I would like to thank to Peter, Micke & all others who helped me 
here & on #bbx-python. Without you I would not have succeeded! :)



Barebones PySide at BB10 howto

When adapting the work PySide port for Playbook I have encountered two 
main issues - weird segfaults in QtGui & missing symbols.

I've solved the first issue thanks to Micke by manually loading the Qt 
Libraries before the corressponding PySide module is loaded, like this:

from ctypes import *
qtcore = CDLL('libQtCore.so.4')
qtdecl = CDLL('libQtDeclarative.so.4')
qtgui = CDLL('libQtGui.so.4')

Just run this before importing modules from PySide & you are safe.

After solving this issue, importing the PySide modules still resulted in 
segfault due to missing symbols, such as QPrinterInfo, QDeviceInfo and 
others. Those Classes indeed are not available in the BB10 Qt libraries.
After Peters suggestion, I've solved it by progressively removing all 
the offending classes. The resulting modified PySide source code is here:
https://github.com/M4rtinK/pyside-bb10/tree/bb10
I've also pushed Shiboken source just with the Playbook patches (any new 
ones were not necessary) here:
https://github.com/M4rtinK/shiboken-bb10/tree/bb10

Just grab the sources & follow the PySide for Playbook guide[1] and you 
should get a working PySide build for BB10. :)



Using on device Qt Libraries

BB10 contains a fully usable Qt 4.8.4 build, you you can skip the custom 
Qt build and just compile against the Qt libraries in the NDK. The 
resulting base package size is about 3.7 MB as only the PySide libraries 
need to be bundled in.



Qt Components

If your application requires Qt Components, you can use the Qt 
Components I've modified to work on the high-DPI BB10 device screen. My 
work is based on the Ineans Qt components clone and is available here:
https://qt.gitorious.org/~martink/qt-components/martinks-ineans-qt-components/commits/bb10
See the README for information how to build & use them. :)
The components should be compatible with the usual com.nokia.meego 1.0 
namespace and the application indeed looks basically the same as on 
Harmattan at Nokia N9. :)
Screenshots:
http://t.co/JTj6KWvj
or
http://modrana.org/images/bb10/mieru/release_screenshots/



Slow QtQuick

By default, QtQuick application don't use the OpenGL viewport, which 
results in bad performance (only the software viewport/rasterizer is 
used). To enabled OpenGL, add this to you bar-descriptor.xml:

<env var="QBB_USE_OPENGL" value="1"/>

Note that QtQuick with OpenGL is reportedly still a bit experimental and 
weird issues might show up. But by enabling it, you get at least the 
same performance as on Harmattan at N9 (which is nice, considering the much 
larger resolution).



Mieru - a case study

I managed to cram the final signed Mieru bar package to 6.9 MB
The package includes:
*  stripped PySide libraries
*  Mieru Python (including byte-compiled files) & QML source
*  stripped unrar binary
*  stripped libmagic.so & 2MB (when uncompressed) magic.mgc file type 
recognition library library
*  the above mentioned Qt Component (including Extras) with stripped 
plugin *.so
*  cut-down Qt Components theme
*  portrait splashscreen

BTW, the basic package is 6.7, the signing adds about 200 kB overhead in 
this case.

[1] http://hg.microcode.ca/blackberry-py/wiki/Building%20PySide

So that's it! :)

Best wishes
Martin Kolman

PS.: I plan to compile all this to a comprehensive online guide eventually.