#How to generate new scale bar thumbnail
#=======================================
#Expects North Carolina dataset. The thumbnail height should be 24 px.
#

export GRASS_RENDER_IMMEDIATE=png
export GRASS_RENDER_TRUECOLOR=TRUE
export GRASS_RENDER_WIDTH=300
export GRASS_RENDER_HEIGHT=300
g.region raster=elevation

#PREFIX=n_arrow_
PREFIX=""

for STYLE in 1a 1b 2 3 4 5 6 7a 7b 8a 8b 9 fancy_compass basic_compass arrow1 arrow2 arrow3 star
do
	echo ${STYLE}
	export GRASS_RENDER_FILE=${PREFIX}${STYLE}.png
	d.northarrow -t style=${STYLE} at=20,20
	mogrify -trim ${PREFIX}${STYLE}.png
	identify -format "%[fx:w]x%[fx:h]" ${PREFIX}${STYLE}.png
	# first resize it to max size and then place it into a bigger rectangle
	mogrify -resize 24x24 -background white -gravity Center -extent 24x24 ${PREFIX}${STYLE}.png
	optipng -o5 ${PREFIX}${STYLE}.png ${PREFIX}${STYLE}.png --quiet
done