[Qgis-developer] OSGEO4W vs. Mac OS X Qt version (or ~34 plugins slightly broken)

Larry Shaffer larrys at dakotacarto.com
Wed May 9 10:08:07 PDT 2012

During a recent audit of almost every PyQGIS plugin (casually studying
repetitive design patterns) and helping some users on
gis.stackexhange.com[0] I have come across an issue that may affect
over 30 plugins (for now,
only on Mac).

>From what I can gather, William Kyngesburye's Mac builds (and Unix/Linux,
too?) consistently use a current, stable version of Qt, now at 4.8, while
the OSGEO4W package is at 4.4 [1]. This hasn't been an issue since, I
believe (and assume), the bundled Qt in Mac builds included Qt3 support.
The most recent 1.7.4 Mac version appears to have a bundled Qt with no Qt3
support (is this correct?).

This has caused many PyQGIS plugins to fail to launch on Mac, due to their
use of a Qt3-only QAction signal of activated() in a plugin's initGui()
method. Basically, the plugin does not launch (i.e. does nothing), with no
error. However, for Windows users, the plugin launches fine, causing
problems when trying to offer cross-platform support for plugin issues.

Can someone else verify these findings?

I am slightly surprised Qt3 is still supported, and think dropping its
support sounds like a good idea, especially for QGIS version 1.8 or >, but
certainly don't know all the details on versioning for QGIS distributions.
I understand this may cause problems with the OSGEO4W package. (btw: Why is
it still on Qt 4.4?)

Here are the plugins I have found that use the deprecated activated()
signal, including two core C++ [2] and a ZIP archive of the particular
files that I found to contain that signal [3]. Without a complete
examination of each plugin, I am not entirely certain all of the signals
are of QAction. I tried to include only those that appear to be. (Note:
there may be more uses of Qt3 deprecated methods, etc.)

Please correct me if I am off on my assessment of this situation, or if I
am late to the discussion.

[0] http://gis.stackexchange.com/a/22953/6725 ,
[1] http://trac.osgeo.org/osgeo4w/wiki/pkg-qt4-libs
[2] http://dl.dropbox.com/u/4058089/qgis/plugins_contain-qt3activated.txt
[3] http://dl.dropbox.com/u/4058089/qgis/plugins_contain-qt3activated.zip


Larry Shaffer
Dakota Cartography
Black Hills, South Dakota
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