#!/usr/bin/env bash
# ---------------------------------------------------
# Preview of Graphviz .DOT files
#
# Procedure :
#   http://bernaerts.dyndns.org/linux/76-gnome/333-gnome-shell-graphviz-viewer-thumbnailer
# Depends on :
#   * dot (graphviz package)
#   * eog
# Parameters :
#   $1 - full path of DOT file
# Revision history :
#   24/04/2015, V1.0 - Creation by N. Bernaerts
# ---------------------------------------------------

# check tools availability
command -v dot >/dev/null 2>&1 || { zenity --error --text="Please install dot [graphviz package]"; exit 1; }
command -v eog >/dev/null 2>&1 || { zenity --error --text="Please install eog [eye of gnome]"; exit 1; }

# select graphviz file if not given as parameter
[ "$1" != "" ] && DOT_FILE="$1" || DOT_FILE="$(zenity --file-selection --file-filter='Graphviz files (dot)|*.dot' --title='Select file to preview')"

# if no file selected, exit
[ "${DOT_FILE}" == "" ] && exit 0

# retrieve file parameters
DOT_DIR=$(dirname "${DOT_FILE}")
DOT_NAME=$(basename "${DOT_FILE}")
DOT_BASE="${DOT_NAME%.*}"

# generate temporary local filename
TMP_DIR=$(mktemp -d -t preview-XXXXXXXX)
TMP_PIX="${TMP_DIR}/${DOT_BASE}.png"

# convert graphviz DOT file to PNG
cd "${DOT_DIR}" 
dot -Tpng "${DOT_FILE}" > "${TMP_PIX}"

# preview display
eog "${TMP_PIX}"

# remove temporary files
rm "${TMP_PIX}"
rmdir "${TMP_DIR}"