How to draw or edit curved lines in free GIS?

Question

I'm searching informations about drawing simple curved arrow lines into free GIS like QGIS, in this problem data geometry is CIRCULARSTRING ( a type which exists in latest postgis version)

It seems GIS like QGIS doesn't actually support editing (and drawing?) of this type of geometry, so i'm searching a plugin like cadtools to draw this lines, but without transformation into simple LINESTRINGS, and try to using directly curve lines drawing function into QGIS API (or other free gis) , if it's possible ..

Any idea ? Thanks a lot! SR.

Answer 1

It's not possible to develop a simple plugin for QGIS that will add the functionality you are looking for. Many underlying core classes in QGIS will have to be adjusted to fit curved features in.

Quoting Andreas Neumann (http://lists.osgeo.org/pipermail/qgis-user/2011-July/012760.html):

QGIS only supports the Simple Features Geometry.

The CAD tools plugin can help to draw arcs, but since QGIS cannot store and edit them, the CAD tool will segmentize the arcs and calculate a lot of vertices.

If this is acceptable to you, you can use the CAD tools. Otherwise, you have to wait until arcs are supported in QGIS (no concrete plans yet).