[GRASS-dev] in trunk png/cairo d.vect overwrites previous images?

Moritz Lennert mlennert at club.worldonline.be
Tue Jan 31 05:15:47 EST 2012

On 31/01/12 11:01, Patrice Dumas wrote:
> On Tue, Jan 31, 2012 at 10:36:01AM +0100, Moritz Lennert wrote:
>> This behaviour is controlled by the GRASS_PNG_READ environment variable.
>> If you set it to TRUE, then GRASS will lay the new d.vect on top of the
>> already drawn vectors, otherwise it overwrites with the new. See
>> http://grass.osgeo.org/grass70/manuals/html70_user/cairodriver.html.
> Thanks.  I was pretty sure I missed something although I did read the
> Fine Manual before asking...  Maybe the GRASS_PNG_READ description
> could be enhanced by adding
>    Otherwise the GRASS_PNGFILE file content is overwritten each time
>    a new display command is used.

Will do, thanks for the suggestion.

> Also I think that the Example should also set
> otherwise it doesn't really make sense as the elevation raster will not
> appear on map.png.

Here's what I see as example on the page:

export GRASS_PNGFILE=nc_spm.png
export GRASS_WIDTH=800
export GRASS_HEIGHT=800

g.region rast=elevation
d.rast map=elevation
d.vect map=streams width=1 color=blue fcolor=aqua type=area,line
d.vect map=roadsmajor width=2

i.e. GRASS_PNG_READ is set... :-)


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