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Diffstat (limited to 'Master/xemtex/gslib/viewjpeg.ps')
-rw-r--r-- | Master/xemtex/gslib/viewjpeg.ps | 153 |
1 files changed, 153 insertions, 0 deletions
diff --git a/Master/xemtex/gslib/viewjpeg.ps b/Master/xemtex/gslib/viewjpeg.ps new file mode 100644 index 00000000000..082c27d2c52 --- /dev/null +++ b/Master/xemtex/gslib/viewjpeg.ps @@ -0,0 +1,153 @@ +%! viewjpeg.ps Copyright (C) 1994 Thomas Merz <tm@pdflib.com> +% +% This program is free software; you can redistribute it and/or modify it +% under the terms of the GNU General Public License as published by the +% Free Software Foundation; either version 2 of the License, or (at your +% option) any later version. +% +% This program is distributed in the hope that it will be useful, but +% WITHOUT ANY WARRANTY; without even the implied warranty of +% MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE. See the GNU General +% Public License for more details. +% +% You should have received a copy of the GNU General Public License along +% with this program; if not, write to the Free Software Foundation, Inc., +% 59 Temple Place, Suite 330, Boston, MA, 02111-1307. + +% $Id: viewjpeg.ps,v 1.1.6.2.2.1 2003/04/12 14:02:39 giles Exp $ +% View JPEG files with Ghostscript +% +% This PostScript code relies on level 2 features. +% +% Only JPEG baseline, extended sequential, and progressive files +% are supported. Note that Adobe PostScript level 2 does not include +% progressive-JPEG support. Ghostscript with IJG JPEG v6 or later +% will decode progressive JPEG, but only if you edit gsjmorec.h to +% enable that feature. +% +% Updated by L. Peter Deutsch 20-May-1997: +% move the usage example to the beginning +% Updates by Tom Lane 6-Sep-1995 + +% Usage example: +% (jpeg-6/testimg.jpg) viewJPEG + +/languagelevel where {pop languagelevel 2 lt}{true} ifelse { + (JPEG needs PostScript Level 2!\n) print flush stop +} if + +/JPEGdict 20 dict def +JPEGdict begin + +/NoParamMarkers [ % JPEG markers without additional parameters + 16#D0 16#D1 16#D2 16#D3 16#D4 16#D5 16#D6 16#D7 16#D8 16#01 +] def + +/NotSupportedMarkers [ % JPEG markers not supported by PostScript level 2 + 16#C3 16#C5 16#C6 16#C7 16#C8 16#C9 16#CA 16#CB 16#CD 16#CE 16#CF +] def + +% Names of color spaces +/ColorSpaceNames << /1 /DeviceGray /3 /DeviceRGB /4 /DeviceCMYK >> def + +% read one byte from file F +% - ==> int --or-- stop context +/NextByte { + F read not { (Read error in ViewJPEG!\n) print flush stop } if +} bind def + +/SkipSegment { % read two bytes and skip that much data + NextByte 8 bitshift NextByte add 2 sub { NextByte pop } repeat +} bind def + +% read width, height, and # of components from JPEG markers +% and store in dict +/readJPEGmarkers { % - ==> dict --or-- stop context + 5 dict begin + + { % loop: read JPEG marker segments until we find SOFn marker or EOF + NextByte + 16#FF eq { % found marker + /markertype NextByte def + % Is it S0F0=baseline, SOF1=extended sequential, SOF2=progressive ? + markertype dup 16#C0 ge exch 16#C2 le and { + NextByte pop NextByte pop % segment length + % Ghostscript and Adobe PS accept only data precision 8 + NextByte 8 ne { + (Error: not 8 bits per component!\n) print flush stop + } if + + % Read crucial image parameters + /height NextByte 8 bitshift NextByte add def + /width NextByte 8 bitshift NextByte add def + /colors NextByte def + + DEBUG { currentdict { exch == == } forall flush } if + exit + } if + + % detect several segment types which are not compatible with PS + NotSupportedMarkers { + markertype eq { + (Marker ) print markertype == + (not supported!\n) print flush stop + } if + } forall + + % Skip segment if marker has parameters associated with it + true NoParamMarkers { markertype eq {pop false exit} if } forall + { SkipSegment } if + } if + } loop + + currentdict dup /markertype undef + end +} bind def + +end % JPEGdict + +% read image parameters from JPEG file and display the image +/viewJPEG { % <file|string> ==> - + save + JPEGdict begin + /saved exch def + /scratch 1 string def + dup type /stringtype eq { (r) file } if + /F exch def + + readJPEGmarkers begin + F 0 setfileposition % reset file pointer + + % We use the whole clipping area for the image (at least in one dimension) + gsave clippath pathbbox grestore + /ury exch def /urx exch def + /lly exch def /llx exch def + + llx lly translate + width height scale + + % use whole width or height, whichever is appropriate + urx llx sub width div ury lly sub height div + 2 copy gt { exch } if pop % min + dup scale + ColorSpaceNames colors scratch cvs get setcolorspace + + % prepare image dictionary + << /ImageType 1 + /Width width + /Height height + /ImageMatrix [ width 0 0 height neg 0 height ] + /BitsPerComponent 8 + % If 4-component (CMYK), assume data is inverted per Adobe Photoshop + colors 4 eq { + /Decode [ colors { 1 0 } repeat ] + } { + /Decode [ colors { 0 1 } repeat ] + } ifelse + /DataSource F /DCTDecode filter + >> image + + end % image parameter dictionary + + saved end restore +} bind def |