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| -rw-r--r-- | contrib/eqn2graph/eqn2graph.sh | 108 |
1 files changed, 108 insertions, 0 deletions
diff --git a/contrib/eqn2graph/eqn2graph.sh b/contrib/eqn2graph/eqn2graph.sh new file mode 100644 index 0000000..3e9c374 --- /dev/null +++ b/contrib/eqn2graph/eqn2graph.sh @@ -0,0 +1,108 @@ +#! /bin/sh +# +# eqn2graph -- compile EQN equation descriptions to bitmap images +# +# by Eric S. Raymond <esr@thyrsus.com>, July 2002 +# +# In Unixland, the magic is in knowing what to string together... +# +# Take an eqn equation on stdin, emit cropped bitmap on stdout. +# The eqn markup should *not* be wrapped in .EQ/.EN, this script will do that. +# A -format FOO option changes the image output format to any format +# supported by convert(1). All other options are passed to convert(1). +# The default format is PNG. +# +# This is separate from pic2graph because pic processing has some weird +# clipping effect on the output, mangling equations that are very wide +# or deep. Besides, this tool can supply its own delimiters. +# + +# Requires the groff suite and the ImageMagick tools. Both are open source. +# This code is released to the public domain. +# +# Here are the assumptions behind the option processing: +# +# 1. None of the options of eqn(1) are relevant. +# +# 2. Many options of convert(1) are potentially relevant, (especially +# -density, -interlace, -transparency, -border, and -comment). +# +# Thus, we pass everything except -format to convert(1). +# +convert_opts="" +convert_trim_arg="-trim" +format="png" + +while [ "$1" ] +do + case $1 in + -format) + format=$2 + shift;; + -v | --version) + echo "GNU eqn2graph (groff) version @VERSION@" + exit 0;; + --help) + echo "usage: eqn2graph [ option ...] < in > out" + exit 0;; + *) + convert_opts="$convert_opts $1";; + esac + shift +done + +# create temporary directory +tmp= +for d in "$GROFF_TMPDIR" "$TMPDIR" "$TMP" "$TEMP" /tmp +do + test -n "$d" && break +done + +if ! test -d "$d" +then + echo "$0: error: temporary directory \"$d\" does not exist or is" \ + "not a directory" >&2 + exit 1 +fi + +if ! tmp=`(umask 077 && mktemp -d -q "$d/eqn2graph-XXXXXX") 2> /dev/null` +then + # mktemp failed--not installed or is a version that doesn't support those + # flags? Fall back to older method which uses more predictable naming. + # + # $RANDOM is a Bashism. The fallback of $PPID is not good pseudorandomness, + # but is supported by the stripped-down dash shell, for instance. + tmp="$d/eqn2graph$$-${RANDOM:-$PPID}" + (umask 077 && mkdir "$tmp") 2> /dev/null +fi + +if ! test -d "$tmp" +then + echo "$0: error: cannot create temporary directory \"$tmp\"" >&2 + exit 1 +fi + +# See if the installed version of convert(1) is new enough to support the -trim +# option. Versions that didn't were described as "old" as early as 2008. +is_convert_recent=`convert -help | grep -e -trim` +if test -z "$is_convert_recent" +then + echo "$0: warning: falling back to old '-crop 0x0' trim method" >&2 + convert_trim_arg="-crop 0x0" +fi + +trap 'exit_status=$?; rm -rf "$tmp" && exit $exit_status' EXIT INT TERM + +# Here goes: +# 1. Add .EQ/.EN. +# 2. Process through eqn(1) to emit troff markup. +# 3. Process through groff(1) to emit Postscript. +# 4. Use convert(1) to crop the Postscript and turn it into a bitmap. +read equation +(echo ".EQ"; echo 'delim $$'; echo ".EN"; echo '$'"$equation"'$') | \ + groff -e -Tps -P-pletter > "$tmp"/eqn2graph.ps \ + && convert $convert_trim_arg $convert_opts "$tmp"/eqn2graph.ps \ + "$tmp"/eqn2graph.$format \ + && cat "$tmp"/eqn2graph.$format + +# End |