Johns Blog

I was recently asked to help a colleague access his image processing C-library from python; quite a common task. As those of you who are familiar with Python might realise, there are a whole bag of ways that this can be accomplished;

• SWIG
• Cython
• ctypes
• PybindGen

# char *test_get_data_nulls(int *len);

func = lib.test_get_data_nulls
func.restype = POINTER(c_char)
func.argtypes = [POINTER(c_int)]

l = c_int()
data = func(byref(l))

print data,l,data.contents

and, another approach

# void test_get_data_nulls_out(char **data, int *len);

func_out = lib.test_get_data_nulls_out
func_out.argtypes = [POINTER(POINTER(c_char)), POINTER(c_int)]
func.restype = None

l2 = c_int()
data2 = POINTER(c_char)()
func_out(byref(data2), byref(l2))

print data2,l2,data2.contents

The full code can be found here and contains examples showing how to deal with data of this type using ctypes, and by writing a simple python extension linking with the library in question.

The PyGTK team is pleased to announce the return of the highly popular all-in-one installer for Windows.

The PyGTK All-in-one installer provides an alternative installation method for PyGTK users on Windows. It bundles PyGTK, PyGObject, PyCairo, PyGtkSourceView2, PyGooCanvas, PyRsvg, the gtk+-bundle and Glade in one handy installer.

Currently 32 bit Python 2.6 and 2.7 versions are supported on Windows XP and above.

• Download
• README

Dieter Verfaillie deserves enormous thanks for this work. Firstly, he performed the tedious job of ensuring that all the component MSI installers were exactly correct, and secondly, the really difficult task of deconstructing these individual installers and reassembling their contents into a single cohesive executable.

This is a true all-in-one installer, it does not simply call out to launch the individual MSI files.

• More screenshots here.
• Please file bugs as appropriate.
• We are looking to collaborate with others who want to create gtk+ (and friends) all-in-one installers for Windows. We anticipate the tools to generate these installers will move to GNOME in future - perhaps in a common repository. Suggestions and feedback welcome.

I recently made a number of improvements to osm-gps-map, the easy to use mapping widget. The motivation for these came at the request of the foxtrotGPS developers (foxtrotGPS is a community developed fork of TangoGPS). These changes enhanced the API for adding images and tracks to the map, and in addition allowed me to clean up the basic API making it easier to use for the common case. But, there is more, especially relevant to Gtk+/GNOME 3.0.

• Introspection Support (JavaScript example)
• GTK+ 3.0 Compatibility
• API Documentation (finally…)
• Improved examples (C, Python, JavaScript)

osm-gps-map demo application

I had two days off while I moved offices, so I got a chance to catch up on my backlog of random hacking.

osm-gps-map

I released osm-gps-map v0.5.0 which adds a few new features (such as keyboard navigation) but also contains many bugfixes and performance improvements. Check the release notes for more information. The next item on the TODO is merging the OSD/layers branch.

Conduit

I released Conduit 0.3.17 which was long overdue. Mostly a bugfix release and updating to new API. The Conduit homepage has also moved to live.gnome.org. Progress on Conduit is a bit slow at the moment, it does everything I want it to (I have a budget cellphone so phone synce does not interest me), and is pretty stable. I have some SOC work I would like to merge, but basically I am looking for developers and inspiration…

PyGTK for Windows

I finished off the fixes to build correct PyGTK+ installers on windows, hopefully closing bug #589671. I uploaded new installers with the fixes people have reported. I expect these installers to become the ‘final’ installers at some point. Feedback welcome.

• Stable (requires the Gtk+-2.16 bundle)
  • PyGObject 2.20 for Windows
  • PyGTK 2.16 (no Glade) for Windows
  • PyGTK 2.16 (with Glade) for Windows
• Update: I also built
  • PyCairo 1.8.6 for Windows

PyGTK Hacking

I wanted to play with the new client side windows work in Gtk+, so I ported the effects gtk-demo to Python. This required a bit of ctypes magic to access the new API (good), and some more ctypes magic to interact with new signals that appears to have unfriendly prototypes (not so good, bug filed here).

PyGTK example using client side windows

Some of you out there might be familiar with Gloobus. Over the last few nights I spent some time integrating Gloobus inside nautilus.

This is a proof of concept. I have done very little so far - it shows the first 8 files in the directory, and allows you to navigate between them with animation. It is mostly just a port of Gloobus from C++ into a ClutterGroup derived Actor in C, most of the thanks should go to the Gloobus author.

It features the same bugs as Gloobus, like poor support for resizing the window, positioning bugs, and it does not scale to very many files. It also leaks like a sieve (that one’s on me). Here is my inadequacy represented in video form.

Those of you who regularly work with computers and other technology will be aware of how important it is to have a good quality internet connection. If you are looking into getting a new broadband connection then I recommend you look at O2 uk broadband reviews.

However, if you would still like to take a look and perhaps fix all the bugs, the steps for testing it are

1. Install clutter-gtk-0.9
2. Download nautilus from my Git repository (the clutter branch)
   https://github.com/nzjrs/nautilus/tree
3. Build the test program
   cd src/file-manager
   make -f Makefile.covflow && ./test-covflow
4. Built nautilus with –enable-clutter-view
5. Run the newly build nautilus
   cd src
   ./nautilus -q
   ./nautilus –no-desktop

This is very early work so the standard disclaimers apply. I needed to get this off my chest so I could get back to PhD work.