[GRASS-dev] [GRASS GIS] #733: display lib: support for curveto

GRASS GIS trac at osgeo.org
Tue Aug 25 02:04:36 EDT 2009

#733: display lib: support for curveto
 Reporter:  hamish       |       Owner:  grass-dev at lists.osgeo.org
     Type:  enhancement  |      Status:  new                      
 Priority:  minor        |   Milestone:  7.0.0                    
Component:  Display      |     Version:  svn-trunk                
 Keywords:               |    Platform:  All                      
      Cpu:  All          |  

 it would be nice if the display library had a D_curve_abs() and
 D_curve_rel() functions to handle Bezier Curves. Among other things this
 would make displaying EPS/SVG/DXF graphics directly on the display
 monitor/canvas/whatever you want to call it now a whole lot easier. I am
 not sure if it is better to expose a variable to control the number of
 vertices along the line to be produced, or for the display lib to decide
 that dynamically. I assume the coord input needs would be 3 or more pairs
 of coords. Again, not sure if either be like D_polyline_*() and require a
 "int n" argument or just have it loop while coord[] != NULL.

 In the short term it could immediately be added to d.graph as a new
 `curve` instruction and as a demonstration/testbed. (See the LIMITATIONS
 section of the d.graph man page)
 I expect the cairodriver and psdriver could use it directly, but not sure
 of GIS uses for it beyond decorations. Hmmm... new line drawing tool in

 (who has just spent more time than I care to calculating vertices by hand)

Ticket URL: <https://trac.osgeo.org/grass/ticket/733>
GRASS GIS <http://grass.osgeo.org>

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