d.vect.thematic doesn't re-run upon zoom in the GUI

[voncasec]

Hi everyone, I have noticed what seems to me to be a bug with displaying thematic map layers in Grass 6.4 RC4 using Ubuntu 8.10.

When a thematic layer is displayed based on the attributes of a point file, the initial thematic map display seems fine (i.e. the graduated point symbols correspond with the locations of the point data in x,y space). However, if I zoom in or out of the data or pan to a different region, the thematic map layer does not zoom or pan with the the vector layers or raster layers also being displayed, the graduated symbols seem fixed to the display not associated with the point file that was used to create it.

[hamish]

which GUI? wxPython or gis.m?

[yytsui]

It's wxPython. I tried Grass7.0 trunk today Rev:38333, it also does not work.

[yytsui]

I spent sometime to look into this issue and consider using FloatCanvas ​http://trac.paulmcnett.com/floatcanvas/wiki to fixed this bug. However, If we use FloatCanvas to display maps, that means probably a lot of codes in gui/wxpython/gui_modules/mapdisp.py, mapdisp_windows.py ,wxgui_utils and render.py has to be change. Anyone know how much effort this might cause? And I just sent an email to FloatCanvas mailing list to ask whether does FloatCanavas support multilayer. Any suggestion? Thanks

[martinl]

Replying to yytsui:

I spent sometime to look into this issue and consider using FloatCanvas ​http://trac.paulmcnett.com/floatcanvas/wiki to fixed this bug. However, If we use FloatCanvas to display maps, that means probably a lot of codes in gui/wxpython/gui_modules/mapdisp.py, mapdisp_windows.py ,wxgui_utils and render.py has to be change. Anyone know how much effort this might cause? And I just sent an email to

probably quite a lot of work. If you start I would suggest to make a fork of wxGUI in grass-addons and later to merge it into trunk.

[cmbarton]

I looked at FloatCanvas quite a while ago. It is nice, but it is much simpler that we need for GRASS. The GRASS canvas does what FloatCanvas does, but a lot more.

d.vect.thematic was written (by me and enhanced by others) as a shell script wrapper around d.vect. When it was written, all GRASS displays still used d.mon via an xterm. It still works in the display environment of TclTk and wxPython canvases, but not as well.

We could add the newer module d.thematic.area to the layer tree selections. I've done that for GRASS 7. I don't know if that would be permitted for GRASS 6.4 as it is sort of a feature change (though it shouldn't break anything). We could also enhance d.vect.thematic by 'Pythonizing' it. Glynn has done that for GRASS 7, but I haven't yet had the chance to test it.

Ultimately, we are aware that we need to create a new and improved Python script or an extended C module. As of a few days ago, I think that the C module seems to be the direction we are headed. Any help would be appreciated.

Michael