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+% Copyright (C) 1989, 1992, 1993, 1998 Aladdin Enterprises. All rights reserved.
+%
+% This software is provided AS-IS with no warranty, either express or
+% implied.
+%
+% This software is distributed under license and may not be copied,
+% modified or distributed except as expressly authorized under the terms
+% of the license contained in the file LICENSE in this distribution.
+%
+% For more information about licensing, please refer to
+% http://www.ghostscript.com/licensing/. For information on
+% commercial licensing, go to http://www.artifex.com/licensing/ or
+% contact Artifex Software, Inc., 101 Lucas Valley Road #110,
+% San Rafael, CA 94903, U.S.A., +1(415)492-9861.
+
+% $Id: viewgif.ps 6300 2005-12-28 19:56:24Z giles $
+% viewgif.ps
+% Display a GIF file.
+
+/read1 % <file> read1 <int>
+ { read pop
+ } bind def
+/read2 % <file> read2 <int>
+ { dup read1 exch read1 8 bitshift add
+ } bind def
+
+/readGIFheader % <file> readGIFheader <dict>
+ { 20 dict begin
+ dup 6 string readstring pop
+ dup (GIF87a) eq exch (GIF89a) eq or not
+ { (Not a GIF file.\n) print cleartomark stop
+ } if
+ dup read2 /Width exch def
+ dup read2 /Height exch def
+ dup read1
+ dup 128 ge /GlobalColor exch def
+ dup -4 bitshift 7 and 1 add /BitsPerPixel exch def %***BOGUS?***
+ dup 8 and 0 ne /PaletteSorted exch def
+ 7 and 1 add dup /BitsPerPixel exch def
+ 1 exch bitshift /PaletteSize exch def
+ dup read1 /BackgroundIndex exch def
+ dup read1 15 add 64 div /AspectRatio exch def
+ GlobalColor
+ { PaletteSize 3 mul string readstring pop
+ /GlobalPalette exch def
+ } if
+ currentdict end
+ } bind def
+
+/readGIFimageHeader % <file> readGIFimageHeader <dict>
+ % Note: GIF header must be on dict stack
+ { 10 dict begin
+ { dup read1
+ dup (!) 0 get ne { exit } if pop % extension
+ dup read1 pop
+ { dup read1 dup 0 eq { pop exit } if { dup read1 pop } repeat
+ } loop
+ } loop
+ (,) 0 get ne
+ { (Not a GIF image.\n) print stop
+ } if
+ dup read2 /Left exch def
+ dup read2 /Top exch def
+ dup read2 /Width exch def
+ dup read2 /Height exch def
+ dup read1
+ dup 128 ge /LocalColor exch def
+ dup 64 and 0 ne /Interlaced exch def
+ LocalColor
+ { 7 and 1 add /BitsPerPixel exch def
+ 1 BitsPerPixel bitshift 3 mul string readstring pop
+ /Palette exch def
+ }
+ { pop pop /Palette GlobalPalette def
+ }
+ ifelse
+ currentdict end
+ } bind def
+
+/imageGIF % <imagedict> imageGIF
+ { /ImageOut where
+ { pop
+ % We know BitsPerComponent = 8, Decode = [0 255].
+ % and there is only a single data source which is
+ % either a filter or a string whose size is exactly
+ % the width of the row.
+ dup /DataSource get dup type /stringtype eq
+ { ImageOut exch writestring
+ }
+ { pop dup /Width get string
+ 1 index /Height get
+ { 1 index /DataSource get 1 index readstring pop
+ ImageOut exch writestring
+ }
+ repeat pop pop
+ }
+ ifelse
+ }
+ { image
+ }
+ ifelse
+ } bind def
+
+/viewGIF % <file|string> viewGIF -
+ { save 20 dict begin
+ /saved exch def
+ dup type /stringtype eq { (r) file } if
+ /F exch def
+ /ImageOutFile where { /ImageOut ImageOutFile (w) file def } if
+ F readGIFheader /Header exch def
+ currentdict Header end begin begin
+ VGIFDEBUG { Header { exch == == } forall (----------------\n) print flush } if
+ F readGIFimageHeader /ImageHeader exch def
+ currentdict ImageHeader end begin begin
+ VGIFDEBUG { ImageHeader { exch == == } forall (----------------\n) print flush } if
+ /D F
+ << /InitialCodeLength F read1
+ /FirstBitLowOrder true
+ /BlockData true
+ /EarlyChange 0
+ >> /LZWDecode filter def
+
+ [/Indexed /DeviceRGB 1 BitsPerPixel bitshift 1 sub Palette] setcolorspace
+ matrix currentmatrix
+ 0 1 3 { 2 copy get dup 0 ne { dup abs div } if 3 copy put pop pop } for
+ setmatrix
+ << /ImageType 1
+ /ImageMatrix [1 0 0 -1 0 Height]
+ /BitsPerComponent 8
+ /Decode [0 255]
+ Interlaced
+ { /Width Width /Height 1
+ /row Width string def
+ /DataSource row
+ >> /I exch def
+ /inter % <num> <denom> inter -
+ { /denom exch def /num exch def
+ gsave
+ /lines Height denom 1 sub add num sub denom idiv def
+ 0 1 lines 1 sub {
+ Height exch denom mul num add sub
+ I /ImageMatrix get 5 3 -1 roll put
+ D row readstring pop pop
+ I imageGIF
+ } for
+ grestore
+ }
+ bind def
+ 0 8 inter
+ 4 8 inter
+ 2 4 inter
+ 1 2 inter
+ }
+ { /Width Width /Height Height
+ /DataSource D
+ >> imageGIF
+ }
+ ifelse
+ saved end end end restore
+ } bind def