How to generate new scale bar thumbnail
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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

for STYLE in classic line solid hollow full_checker part_checker mixed_checker tail_checker up_ticks down_ticks both_ticks arrow_ends
do
	echo ${STYLE}
	export GRASS_RENDER_FILE=${STYLE}.png
	d.barscale style=${STYLE} at=20,20
	mogrify -trim ${STYLE}.png
	identify -format "%[fx:w]x%[fx:h]" ${STYLE}.png
	convert ${STYLE}.png -gravity center -background white -extent 170x24  ${STYLE}.png
	optipng -o5 ${STYLE}.png ${STYLE}.png --quiet
done