lib/scripts/lyxpreview2bitmap.sh

   1 #! /bin/sh
   2
   3 # file lyxpreview2bitmap.sh
   4 # This file is part of LyX, the document processor.
   5 # Licence details can be found in the file COPYING.
   6 #
   7 # author Angus Leeming
   8 # with much advice from David Kastrup, david.kastrup@t-online.de.
   9 #
  10 # Full author contact details are available in file CREDITS
  11
  12 # This script takes a LaTeX file and generates bitmap image files,
  13 # one per page.
  14
  15 # The idea is to use it with preview.sty from the preview-latex project
  16 # (http://preview-latex.sourceforge.net/) to create small bitmap
  17 # previews of things like math equations.
  18
  19 # preview.sty can be obtained from
  20 # CTAN/macros/latex/contrib/supported/preview.
  21
  22 # This script takes three arguments:
  23 # TEXFILE:       the name of the .tex file to be converted.
  24 # SCALEFACTOR:   a scale factor, used to ascertain the resolution of the
  25 #                generated image which is then passed to gs.
  26 # OUTPUTFORMAT:  the format of the output bitmap image files.
  27 #                Two formats are recognised: "ppm" and "png".
  28
  29 # If successful, this script will leave in dir ${DIR}:
  30 # a (possibly large) number of image files with names like
  31 #         ${BASE}\([0-9]*\).${SUFFIX} where SUFFIX is ppm or png.
  32 # a file containing info needed by LyX to position the images correctly
  33 # on the screen.
  34 #         ${BASE}.metrics
  35 # All other files ${BASE}* will be deleted.
  36
  37 # A quick note on the choice of OUTPUTFORMAT:
  38
  39 # In general files in PPM format are 10-100 times larger than the
  40 # equivalent files in PNG format. Larger files results in longer
  41 # reading and writing times as well as greater disk usage.
  42
  43 # However, whilst the Qt image loader can load files in PNG format
  44 # without difficulty, the xforms image loader cannot. They must first
  45 # be converted to a loadable format (eg PPM!). Thus, previews will take
  46 # longer to appear if the xforms loader is used to load snippets in
  47 # PNG format.
  48
  49 # You can always experiment by adding a line to your
  50 # ${LYXUSERDIR}/preferences file
  51 #        \converter lyxpreview ${FORMAT} "lyxpreview2bitmap.sh" ""
  52 # where ${FORMAT} is either ppm or png.
  53
  54 # Three helper functions.
  55 FIND_IT ()
  56 {
  57         test $# -eq 1 || exit 1
  58
  59         type $1 > /dev/null || {
  60                 echo "Unable to find \"$1\". Please install."
  61                 exit 1
  62         }
  63 }
  64
  65 BAIL_OUT ()
  66 {
  67         # Remove everything except the original .tex file.
  68         FILES=`ls ${BASE}* | sed -e "/${BASE}.tex/d"`
  69         rm -f ${FILES} texput.log
  70         echo "Leaving ${BASE}.tex in ${DIR}"
  71         exit 1
  72 }
  73
  74 REQUIRED_VERSION ()
  75 {
  76         echo "We require preview.sty version 0.73 or newer. You're using"
  77         grep 'Package: preview' ${LOGFILE}
  78 }
  79
  80 # Preliminary check.
  81 if [ $# -ne 3 ]; then
  82         exit 1
  83 fi
  84
  85 # Extract the params from the argument list.
  86 DIR=`dirname $1`
  87 BASE=`basename $1 .tex`
  88
  89 SCALEFACTOR=$2
  90
  91 if [ "$3" = "ppm" ]; then
  92         GSDEVICE=pnmraw
  93         GSSUFFIX=ppm
  94 elif [ "$3" = "png" ]; then
  95         GSDEVICE=png16m
  96         GSSUFFIX=png
  97 else
  98         echo "Unrecognised output format ${OUTPUTFORMAT}."
  99         echo "Expected either \"ppm\" or \"png\"."
 100         BAIL_OUT
 101 fi
 102
 103 # We use latex, dvips and gs, so check that they're all there.
 104 FIND_IT latex
 105 FIND_IT dvips
 106 FIND_IT gs
 107
 108 # Initialise some variables.
 109 TEXFILE=${BASE}.tex
 110 LOGFILE=${BASE}.log
 111 DVIFILE=${BASE}.dvi
 112 PSFILE=${BASE}.ps
 113 METRICSFILE=${BASE}.metrics
 114
 115 # LaTeX -> DVI.
 116 cd ${DIR}
 117 latex ${TEXFILE} ||
 118 {
 119         echo "Failed: latex ${TEXFILE}"
 120         BAIL_OUT
 121 }
 122
 123 # Parse ${LOGFILE} to obtain bounding box info to output to
 124 # ${METRICSFILE}.
 125 # This extracts lines starting "Preview: Tightpage" and
 126 # "Preview: Snippet".
 127 grep -E 'Preview: [ST]' ${LOGFILE} > ${METRICSFILE} ||
 128 {
 129         echo "Failed: grep -E 'Preview: [ST]' ${LOGFILE}"
 130         REQUIRED_VERSION
 131         BAIL_OUT
 132 }
 133
 134 # Parse ${LOGFILE} to obtain ${RESOLUTION} for the gs process to follow.
 135 # 1. Extract font size from a line like "Preview: Fontsize 20.74pt"
 136 # Use grep for speed and because it gives an error if the line is
 137 # not found.
 138 LINE=`grep 'Preview: Fontsize' ${LOGFILE}` ||
 139 {
 140         echo "Failed: grep 'Preview: Fontsize' ${LOGFILE}"
 141         REQUIRED_VERSION
 142         BAIL_OUT
 143 }
 144 # The sed script strips out everything that won't form a decimal number
 145 # from the line. It bails out after the first match has been made in
 146 # case there are multiple lines "Preview: Fontsize". (There shouldn't
 147 # be.)
 148 # Note: use "" quotes in the echo to preserve newlines.
 149 LATEXFONT=`echo "${LINE}" | sed 's/[^0-9\.]//g; 1q'`
 150
 151 # 2. Extract magnification from a line like
 152 # "Preview: Magnification 2074"
 153 # If no such line found, default to MAGNIFICATION=1000.
 154 LINE=`grep 'Preview: Magnification' ${LOGFILE}`
 155 if LINE=`grep 'Preview: Magnification' ${LOGFILE}`; then
 156         # Strip out everything that won't form an /integer/.
 157         MAGNIFICATION=`echo "${LINE}" | sed 's/[^0-9]//g; 1q'`
 158 else
 159         MAGNIFICATION=1000
 160 fi
 161
 162 # 3. Compute resolution.
 163 # "bc" allows floating-point arithmetic, unlike "expr" or "dc".
 164 RESOLUTION=`echo "scale=2; \
 165         ${SCALEFACTOR} * (10/${LATEXFONT}) * (1000/${MAGNIFICATION})" \
 166         | bc`
 167
 168 # DVI -> PostScript
 169 dvips -o ${PSFILE} ${DVIFILE} ||
 170 {
 171         echo "Failed: dvips -o ${PSFILE} ${DVIFILE}"
 172         BAIL_OUT
 173 }
 174
 175 # PostScript -> Bitmap files
 176 # Older versions of gs have problems with a large degree of
 177 # anti-aliasing at high resolutions
 178
 179 # test expects integer arguments.
 180 # ${RESOLUTION} may be a float. Truncate it.
 181 INT_RESOLUTION=`echo "${RESOLUTION} / 1" | bc`
 182
 183 ALPHA=4
 184 if [ ${INT_RESOLUTION} -gt 150 ]; then
 185         ALPHA=2
 186 fi
 187
 188 gs -q -dNOPAUSE -dBATCH -dSAFER \
 189         -sDEVICE=${GSDEVICE} -sOutputFile=${BASE}%d.${GSSUFFIX} \
 190         -dGraphicsAlphaBit=${ALPHA} -dTextAlphaBits=${ALPHA} \
 191         -r${RESOLUTION} ${PSFILE} ||
 192 {
 193         echo "Failed: gs ${PSFILE}"
 194         BAIL_OUT
 195 }
 196
 197 # All has been successful, so remove everything except the bitmap files
 198 # and the metrics file.
 199 FILES=`ls ${BASE}* | sed -e "/${BASE}.metrics/d" \
 200                          -e "/${BASE}\([0-9]*\).${GSSUFFIX}/d"`
 201 rm -f ${FILES} texput.log
 202
 203 # The bitmap files can have large amounts of whitespace to the left and
 204 # right. This can be cropped if so desired.
 205 CROP=1
 206 type pnmcrop > /dev/null || CROP=0
 207
 208 # There's no point cropping the image if using PNG images. If you want to
 209 # crop, use PPM.
 210 # Apparently dvipng will support cropping at some stage in the future...
 211 if [ ${CROP} -eq 1 -a "${GSDEVICE}" = "pnmraw" ]; then
 212         for FILE in ${BASE}*.${GSSUFFIX}
 213         do
 214                 if pnmcrop -left ${FILE} 2> /dev/null |\
 215                    pnmcrop -right  2> /dev/null > ${BASE}.tmp; then
 216                         mv ${BASE}.tmp ${FILE}
 217                 else
 218                         rm -f ${BASE}.tmp
 219                 fi
 220         done
 221         rm -f ${BASE}.tmp
 222 fi
 223
 224 echo "Previews generated!"