179 lines
5.4 KiB
PostScript
179 lines
5.4 KiB
PostScript
% Copyright (C) 1992, 1996 Aladdin Enterprises. All rights reserved.
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%
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% This software is provided AS-IS with no warranty, either express or
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% implied.
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%
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% This software is distributed under license and may not be copied,
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% modified or distributed except as expressly authorized under the terms
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% of the license contained in the file LICENSE in this distribution.
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%
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% For more information about licensing, please refer to
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% http://www.ghostscript.com/licensing/. For information on
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% commercial licensing, go to http://www.artifex.com/licensing/ or
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% contact Artifex Software, Inc., 101 Lucas Valley Road #110,
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% San Rafael, CA 94903, U.S.A., +1(415)492-9861.
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% $Id: impath.ps,v 1.5 2002/02/21 21:49:28 giles Exp $
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% impath.ps
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% Reverse-rasterize a bitmap to produce a Type 1 outline.
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% (This was formerly a Ghostscript operator implemented in C.)
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% <image> <width> <height> <wx> <wy> <ox> <oy> <string>
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% type1imagepath <substring>
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% Converts an image (bitmap) description of a character into
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% a scalable description in Adobe Type 1 format. The
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% current transformation matrix should be the same as the
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% FontMatrix of the font in which this character will be
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% used: this establishes the scaling relationship between
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% image pixels (the image is assumed to be 1 unit high in
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% user space) and the character coordinate system used in
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% the scalable description. wx and wy are the character
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% width, and ox and oy are the character origin relative
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% to the lower left corner of the bitmap, in *pixels*.
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% The image is assumed to be stored in left-to-right,
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% top-to-bottom order. Note that this is not consistent
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% with the `image' operator's interpretation of the CTM.
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% All coordinates in the scalable description are rounded to
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% integers, so the coefficients in the FontMatrix should
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% be on the order of 1/N for some value of N that is
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% either a multiple of the height/width or is large
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% compared to the width and height. (There is a
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% convention, which some PostScript programs rely on, that
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% N=1000.)
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% Note that the encoded description has *not* been subjected
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% to CharString encryption, which is necessary before the
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% description can be given to type1addpath: to do this,
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% follow the type1imagepath with
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% 4330 exch dup .type1encrypt exch pop
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% If the description is too complex to fit into the supplied
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% string, a limitcheck error results. A good rule of
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% thumb is that the size of the string should be about 6
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% times the number of 1-bits in the image that are not
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% completely surrounded by other 1-bits.
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% Import the Type 1 opcodes.
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(type1ops.ps) runlibfile
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100 dict
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dup /type1imagepath_dict exch def
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begin
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/rc { round cvi } bind def
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/moving [/rmoveto /hmoveto /vmoveto] def
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/drawing [/rlineto /hlineto /vlineto] def
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% Convert the current path to a Type 1 token array.
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/putxy % x y ops -> cs_elements
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{ 3 -1 roll dup x sub rc exch /x exch def
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3 -1 roll dup y sub rc exch /y exch def
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% stack: ops dx dy
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dup 0 eq
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{ % dy = 0, use hmoveto/lineto
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pop exch 1 get
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}
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{ 1 index 0 eq
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{ % dx = 0, use vmoveto/lineto
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exch pop exch 2 get
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}
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{ % use rmoveto/rlineto
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3 -1 roll 0 get
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}
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ifelse
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}
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ifelse
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} bind def
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/pathtotype1 % -> charstack
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{ 3 dict begin /x 0 def /y 0 def
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mark
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{ moving putxy
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}
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{ drawing putxy
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}
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{ % Convert curve to relative form
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x y 3
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{ exch neg 7 index add rc
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exch neg 6 index add rc
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8 -2 roll
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}
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repeat /y exch def /x exch def
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1 index 0 eq 5 index 0 eq and % dy1=dx3=0, hv
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{ 5 -1 roll pop exch pop /hvcurveto
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}
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{ dup 0 eq 6 index 0 eq and % dx1=dy3=0, vh
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{ 6 -1 roll pop pop /vhcurveto
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}
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{ /rrcurveto % none of the above
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}
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ifelse
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}
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ifelse
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}
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{ /closepath
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}
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pathforall end
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} bind def
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end % type1imagepath_dict
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% The main program
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/type1imagepath % image width height wx wy ox oy string ->
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% substring
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{ type1imagepath_dict begin
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/tsave save def
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/ostring exch def
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/oy exch def /ox exch def
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/wy exch def /wx exch def
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/height exch def /width exch def
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/data exch def
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/ofilter ostring /NullEncode filter def
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/raster width 7 add 8 idiv def
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% Construct the coordinate transformation.
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height dup scale
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matrix currentmatrix matrix invertmatrix setmatrix
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% Determine the left side bearing.
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/lsbx width
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0 1 width 1 sub
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{ dup dup 8 idiv 0 exch
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raster raster height mul 1 sub
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{ data exch get or }
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for exch 8 mod bitshift 128 and 0 ne
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{ exch pop exit }
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if pop
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}
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for def
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% Compute and encode the origin, width, and side bearing.
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mark
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ox oy dtransform
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rc /opty exch def rc /optx exch def
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wx wy dtransform
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rc /iwy exch def rc /iwx exch def
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lsbx ox sub 0 dtransform
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rc /ilsby exch def rc /ilsbx exch def
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ilsbx
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iwy 0 ne ilsby 0 ne or
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{ ilsby iwx iwy /sbw }
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{ iwx /hsbw }
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ifelse
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ofilter charstack_write
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% Flip over the Y axis, because the image is stored top-to-bottom.
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[1 0 0 -1 0 height] concat
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% Account for the character origin.
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lsbx oy translate
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% Trace the outline.
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newpath
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width height data .imagepath
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gsave matrix setmatrix pathtotype1 grestore
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ofilter charstack_write
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% Terminate the output
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mark /endchar ofilter charstack_write
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ofilter .fileposition ofilter closefile % flush buffers
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ostring 0 3 -1 roll getinterval
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tsave restore
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end
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} bind def
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