plan9fox/sys/lib/ghostscript/viewmiff.ps

%    Copyright (C) 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: viewmiff.ps,v 1.4 2002/02/21 21:49:28 giles Exp $
% viewmiff.ps
% Display a MIFF file.  You would think the 'display' command would do this,
% but many versions of 'display' either core-dump or require unacceptably
% large amounts of memory.

% Recognize MIFF keywords.
/miffwords mark
  /class { cvn /class exch def }
  /colors { cvi /colors exch def }
  /columns { cvi /Width exch def }
  /compression { cvn /compression exch def }
  /depth { cvi /depth exch def }
  /packets { cvi /packets exch def }
  /rows { cvi /Height exch def }
.dicttomark readonly def

% Recognize MIFF image classes.
/miffclasses mark
  /DirectClass {
    /DeviceRGB setcolorspace
    /BitsPerComponent depth def
    /Decode [ 0 1 0 1 0 1 ] def
  }
  /PseudoClass {
    [ /Indexed
		% The MIFF documentation lies about the size of pixels
		% for this case: the pixel size is determined only by
		% the number of colors, and is not affected by the image
		% depth.  Specifically, if there are 256 or fewer colors
		% but the depth (of color map entries) is 16, each pixel
		% is still only 1 byte, not 2.
      currentdict /colors known {
	/DeviceRGB colors 1 sub
	/BitsPerComponent colors 256 le { 8 } { 16 } ifelse def
	colors 3 mul string depth 8 eq {
	  f exch readstring pop
	} {
		% 16-bit color map entries: take only the high-order byte.
	  0 1 2 index length 1 sub {
	    f read pop 2 index 3 1 roll put f read pop pop
	  } for
	} ifelse
      } {
	/colors 256 def
	/DeviceGray 255
	256 string 0 1 255 { 1 index exch dup put } for
      } ifelse
    ] setcolorspace
    /Decode [ 0 1 BitsPerComponent bitshift 1 sub ] def
  }
.dicttomark readonly def

% Recognize MIFF compression methods.
/rlstring 768 string def
/rlread {
		% packets is not reliable -- disregard it.
  dup rlstring 0 3 getinterval readstring {
    pop read pop 3 mul 3 3 2 index {
      rlstring exch rlstring 0 3 getinterval putinterval
    } for
    rlstring 0 3 -1 roll 3 add getinterval
  } {
    pop pop ()
  } ifelse
} bind def
/miffcompress mark
  /Uncompressed { f }
  /RunLengthEncoded { { f rlread } }
  /Zip { [ f /FlateDecode filter cvlit /rlread cvx ] cvx }
.dicttomark readonly def

% Read a MIFF file and display the image.
/viewmiff {		% <filename> viewmiff -
  50 dict begin
  /fname 1 index def
  /f exch (r) file def
		% Set defaults.
  /ImageType 1 def
  /class /DirectClass def
  /compression /Uncompressed def
  /depth 8 def
  /packets 16#7fffffff def
		% Read and parse the header.
  { f token pop
    dup (:) eq { pop exit } if
    dup type /nametype eq {
      .namestring (=) search {
	exch pop miffwords exch .knownget { exec } { pop } ifelse
      } {
	pop	% who knows?
      } ifelse
    } {
      pop	% probably a comment in braces
    } ifelse
  } loop
		% Read and display the image.
  miffclasses class get exec
  /DataSource miffcompress compression get exec def
  /ImageMatrix [Width 0 0 Height neg 0 Height] def
  currentpagedevice /PageSize get
    dup 0 get exch 1 get scale
  gsave 0.8 setgray 0 0 1 1 rectfill grestore	% provide background
  currentdict image
  showpage
		% Clean up.
  f closefile
  end
} bind def