[GRASS-dev] Re: [GRASS GIS] #1283: PNG driver and Cairo driver mangle large symbols, XDRIVER doesn't

GRASS GIS trac at osgeo.org
Thu Feb 24 01:16:09 EST 2011

#1283: PNG driver and Cairo driver mangle large symbols, XDRIVER doesn't
 Reporter:  hamish   |       Owner:  grass-dev@…              
     Type:  defect   |      Status:  new                      
 Priority:  major    |   Milestone:  6.4.1                    
Component:  Display  |     Version:  svn-develbranch6         
 Keywords:           |    Platform:  Linux                    
      Cpu:  x86-64   |  

Comment(by glynn):

 Replying to [ticket:1283 hamish]:

 > (note even though it's headless it still needs X.org installed, as a
 dependency of the Cairo driver's X11-output option)

 This depends upon whether GRASS was built --with-x. If USE_X11 is defined
 in the Makefiles, libcairodriver will end up with Xlib as a dependency.

 > In GRASS 7 the situation is a bit better, the PS and one of the
 PNG|cairo* drivers(?) makes nice looking output, only complaint is that
 the closed ring has a sliver where it isn't closed. could a special
 beginning==end test be added to have it code the path?

 This might be an artifact of an attempt at simplifying paths. One of the
 complaints with making d.vect use the driver's polygon filling (instead of
 pre-rasterising paths with G_plot_polygon()) was that rasterising complex
 areas was slow. Some code was added to lib/display in 7.0 (reduce_path(),
 in draw2.c) to merge small, adjacent segments (effectively filtering the
 path), but it can cause problems if you create complex paths (with islands
 /cut-outs) using "cont" instead of "move".

 Or it might be something else entirely. 7.0's lib/display has a specific
 D_close() function for closing paths; writing coincident vertices won't
 cause a path to be closed.

 > [**] should "GRASS_RENDER_IMMEDIATE=cairo" be uppercase or not? the man
 page shows both ways.

 It doesn't matter; the value is compared using G_strcasecmp(). To the
 extent that it matters, the canonical form should be "cairo".

Ticket URL: <https://trac.osgeo.org/grass/ticket/1283#comment:2>
GRASS GIS <http://grass.osgeo.org>

More information about the grass-dev mailing list