GUI application development for GTA02 - Which framework?

[Matthias Keller]

Hi Nicola

> Debian and gentoo offers qmake natively on the platform, mkspec does
> not need to be specialized for GTA02, but only for arm platform. OE
> offers a nice cross-compile environments for QT apps. So may you
> explain better what kind of problem do you have in developing with qt?

I was following the instructions on 
http://wiki.openmoko.org/wiki/Development_with_Eclipse

At first I found out that I had to add another source to my "opkg.conf" 
on my development platform:

-- 8< --
arch gstreamer 51
src/gz gstreamer 
http://www.angstrom-distribution.org/feeds/2008/ipk/glibc/armv4t/gstreamer
-- >8 --

Building from Eclipse was ok for projects that didn't contain any UI 
designer files.

However, as I think that the UI designer is really helpful, I checked 
the suggestions of the last paragraph "workaround to deal with .ui files 
from Qt-Designer".

Invoking a build within Eclipse, this ended up in:

-- 8< --
/usr/local/openmoko/arm/arm-angstrom-linux-gnueabi/bin/g++ 
-L/usr/local/openmoko
/arm/arm-angstrom-linux-gnueabi/usr/lib -o"OpenmokoTest"  ./MainWindow.o 
./QtTes
t.o   -lQtGui -lQtCore -lQtDBus
./MainWindow.o: In function `myMainWindow::myMainWindow(QMainWindow*)':
MainWindow.cpp:(.text+0x64): undefined reference to `vtable for 
myMainWindow'
./MainWindow.o: In function `myMainWindow::myMainWindow(QMainWindow*)':
MainWindow.cpp:(.text+0xd0): undefined reference to `vtable for myMainWindow
-- >8 --

It's pretty clear why this happened: The generated file 
"moc_MainWindow.cpp" had still been compiled for the host platform of 
the development machine (Linux i686). Eclipse is just not checking that 
there is another dependency when re-compiling anything else for ARM.

After re-compiling "moc_MainWindow.cpp" for ARM by hand everything was ok.

The problem of this approach is that "qmake" isn't set to the target 
platform and can't be used in the way as it is supposed. Invoking 
"moc-qt4" and recompiling "moc_*.cpp" by hand is definitely not the idea 
of the qmake build system.

However, I was no longer sure if it is really reasonable to use Qt for 
Openmoko development. In particular, this wiki page doesn't look like if 
anyone really uses it.


> I started a wiki page at
> http://wiki.openmoko.org/wiki/Developing_with_C%2B%2B_and_Qt , I will
> happy to add some hints for your needs.

This is really great! I just checked out the devshell, it basically 
worked out-of-the-box (the only minor change was to replace "alias 
./configure=.." with "alias configure=.." in the devshell script on 
Ubuntu 8.10).

I guess that "http://wiki.openmoko.org/wiki/Development_with_Eclipse" 
definitely should be updated. Your solution is working, however, I could 
not distinguish from the beginning which of the different pages about Qt 
development is the best/the working one. This should be pointed out more.

Having an improved script for UI designer files is just another hack, 
maybe it would be best to recommend that the people should install the 
devshell first and then include this in their Eclipse profile if they 
want to use it?!

By now, I did not dare to change anything in the wiki as I've no clue 
about the policies that are in place. Is it ok to just change things, or 
should I contact someone like the owner of a particular document first?


Cheers,

Matthias

-- 
ETH Zürich, Matthias Keller, Institute TIK
ETZ G 76, Gloriastrasse 35, 8092 Zürich
Tel +41 44 632 70 41, http://www.tik.ee.ethz.ch/~kellmatt