allow choice of background

latexpic

@@ -2,9 +2,20 @@
 
 set -e
 
+if [ "$#" -ne 2 ]; then
+  echo "Usage: `basename $0` COLOR LATEXSRC"
+  echo  
+  echo "with COLOR being either a single color for text on transparent background or 'color1 on color2'"
+  exit 1
+fi
+
+
 color=$1
 input=$2
 
+fg="${color% on *}"
+bg="${color##* on }"
+
 outpdf="/tmp/latexpic.pdf"
 outpng="/tmp/latexpic.png"
 
@@ -19,12 +30,16 @@ cat <<EOF | pdflatex --output-directory /tmp --jobname latexpic --
 \usepackage{amssymb}
 \usepackage{graphicx}
 
-\color{$1}
+\color{$fg}
 
 \begin{document}
 $input
 \end{document}
 EOF
 
-convert -density 600 "$outpdf" -quality 90 "$outpng"
+if [ "$fg" = "$bg" ]; then
+  convert -density 600 "$outpdf" -quality 90 "$outpng"
+else
+  convert -background "$bg" -flatten -density 600 "$outpdf" -quality 90 "$outpng"
+fi
 xdg-open "$outpng"