Tech Arsenal 1/Tech Arsenal (Arsenal Computer).ISO/tek-04/gs24src.zip/GS_FONTS.PS

Text File | 1992-03-05 | 13KB | 414 lines

%    Copyright (C) 1990, 1992 Aladdin Enterprises.  All rights reserved.
%    Distributed by Free Software Foundation, Inc.
%
% This file is part of Ghostscript.
%
% Ghostscript is distributed in the hope that it will be useful, but
% WITHOUT ANY WARRANTY.  No author or distributor accepts responsibility
% to anyone for the consequences of using it or for whether it serves any
% particular purpose or works at all, unless he says so in writing.  Refer
% to the Ghostscript General Public License for full details.
%
% Everyone is granted permission to copy, modify and redistribute
% Ghostscript, but only under the conditions described in the Ghostscript
% General Public License.  A copy of this license is supposed to have been
% given to you along with Ghostscript so you can know your rights and
% responsibilities.  It should be in a file named COPYING.  Among other
% things, the copyright notice and this notice must be preserved on all
% copies.

% Font initialization for Ghostscript.

% Ghostscript fonts have essentially the same contents as Adobe Type 1 fonts,
% except that the external form doesn't use eexec encryption.
% Someday there will be GNU documentation that describes this format.
% Until then, you'll have to either get a copy of Adobe's book, or read
% the Ghostscript code.  The interpreter for Type 1 fonts, which reveals
% most of their structure, is in the file gstype1.c.


% Define the default font.
/defaultfontname /Ugly def


% Internal procedure to load the font name -> font file name map
% if it isn't loaded already, and push it on the stack.
/Fontmap
 { /FontFileMap where
    { /FontFileMap get }
    { (Fontmap) findlibfile not
       { (Can't find ) print print (!\n) print stop }
      if exch pop

      FontDirectory maxlength dict exch
      2 dict begin
        mark exch 2 index exch
    /;
     { % The stack contains a mark, the dictionary, the font name,
       % the file name, and additional information about the font.
       counttomark 3 sub { pop } repeat put
       1 index
     } bind def
    run
      end
      pop pop        % pop the mark and the copy of the dictionary
      userdict exch /FontFileMap exch put
      FontFileMap
     }
   ifelse
 } bind def


% Ghostscript optionally can load individual CharStrings as they are needed.
% (This is intended primarily for machines with very small memories.)
% This happens if DISKFONTS is true.  In this case, we define another
% dictionary parallel to FontDirectory that retains an open file
% for every font loaded.
DISKFONTS
 { /FontFileDirectory FontDirectory maxlength dict def
 }
if


% Define definefont.  This is a procedure built on an operator that
% does all the error checking and key insertion.
/.buildfontdict 3 dict
    /.buildfont0 where { pop dup 0 /.buildfont0 load put } if
    /.buildfont1 where { pop dup 1 /.buildfont1 load put } if
    /.buildfont3 where { pop dup 3 /.buildfont3 load put } if
def
/definefont
 { 1 dict begin count /d exch def    % save stack depth in case of error
    { dup /FontType get .buildfontdict exch get exec
      DISKFONTS
       { FontFileDirectory 2 index known
          { dup /FontFile FontFileDirectory 4 index get put
      }
     if
       }
      if
      readonly
    }
   stopped
    { count d sub { pop } repeat end /invalidfont signalerror }
    { end dup FontDirectory 4 2 roll put }
   ifelse
 } odef


% Ghostscript optionally can load individual CharStrings as they are needed.
% (This is intended primarily for machines with very small memories.)
% Initially, the character definition is the file position of the definition;
% this gets replaced with the actual CharString.
% Note that if we are loading characters lazily, CharStrings is writable.

% _Cstring must be long enough to hold the longest CharString for
% a character defined using seac.  This is lenIV + 4 * 5 (for the operands
% of sbw, assuming div is not used) + 2 (for sbw) + 3 * 5 (for the operands
% of seac other than the character codes) + 2 * 2 (for the character codes)
% + 2 (for seac), i.e., lenIV + 43.

/_Cstring 60 string def

% When we initially load the font, we call
%    <index|charname> <length> /readstring|/readhexstring skip_C
% to skip over each character definition and return the file position instead.
% This substitutes for the procedure
%    <length> string currentfile exch read[hex]string pop
% What we actually store is fileposition * 1000 + length,
%   negated if the string is stored in binary form.

/skip_C
 { load exch dup 1000 ge 3 index type /nametype ne or
    { % This is a Subrs string, or the string is so long we can't represent
      % its length.  Load it now.
      currentfile 3 1 roll string exch exec pop
    }
    { % Record the position and length, and skip the string.
      dup currentfile fileposition 1000 mul add
      2 index /readstring load eq { neg } if
      3 1 roll
      dup _Cstring length idiv
       { currentfile _Cstring 3 index exec pop pop
       } repeat
      _Cstring length mod _Cstring exch 0 exch getinterval
      currentfile exch 3 -1 roll exec pop pop
    }
   ifelse
 } bind def

% Type1BuildChar calls load_C to actually load the character definition.

/load_C        % charindex fileposandlength ->
 { exch Encoding exch get exch
   read_C type1addpath
 } bind def

/read_C        % charname fileposandlength -> charstring
 { dup abs 1000 idiv FontFile exch setfileposition
   CharStrings 3 1 roll
   dup 0 lt
    { neg 1000 mod string FontFile exch readstring }
    { 1000 mod string FontFile exch readhexstring }
   ifelse pop
   dup 4 1 roll put
% If the character is defined with seac, load its components now.
   dup mark exch seac_C
   counttomark
    { StandardEncoding exch get dup CharStrings exch get
      dup type /integertype eq { read_C } { pop } ifelse pop
    } repeat
   pop        % the mark
 } bind def

/seac_C        % charstring -> achar bchar ..or nothing..
 { dup length _Cstring length le
    { 4330 exch _Cstring type1decrypt exch pop
      dup dup length 2 sub 2 getinterval <0c06> eq    % seac
       { dup length
         Private /lenIV known { Private /lenIV get } { 4 } ifelse
     exch 1 index sub getinterval
% Parse the string just enough to extract the seac information.
% We assume that the only possible operators are hsbw, sbw, and seac,
% and that there are no 5-byte numbers.
     mark 0 3 -1 roll
      { exch
         { { dup 32 lt
              { pop 0 }
          { dup 247 lt
             { 139 sub 0 }
             { dup 251 lt
            { 247 sub 256 mul 108 add 1 1 }
            { 251 sub -256 mul -108 add -1 1 }
               ifelse
             }
            ifelse
          }
         ifelse
           }            % 0
           { mul add 0 }        % 1
         }
        exch get exec
      }
     forall pop
     counttomark 1 add 2 roll cleartomark    % pop all but achar bchar
       }
       { pop    % not seac
       }
      ifelse
    }
    { pop    % punt
    }
   ifelse
 } bind def

% Define an auxiliary procedure for loading a font.
% If DISKFONTS is true:
%    - Prevent the CharStrings from being made read-only.
%    - Substitute a different CharString-reading procedure.
% If the body of the font is encrypted with eexec, this is disabled,
% because the implicit 'systemdict begin' hides the redefinitions.
% We assume that:
%    - The magic procedures (-|, -!, |-, and |) are defined with
%    executeonly or readonly;
%    - The contents of the reading procedures are as defined in bdftops.ps;
%    - The font ends with
%    <font> <Private> <CharStrings>
%    readonly put noaccess|readonly put
4 dict begin
 /dict            % leave room for FontFile
  { 1 add dict
  } bind def
 /executeonly        % for reading procedures
  { readonly
  } def
 /noaccess        % for Subrs strings and Private dictionary
  { readonly
  } def
 /readonly        % for procedures and CharStrings dictionary
  {    % We want to take the following non-standard actions here:
      %   - If the operand is the CharStrings dictionary, do nothing;
    %   - If the operand is a number (a file position replacing the
    %    actual CharString), do nothing;
    %   - If the operand is either of the reading procedures (-| or -!),
    %    substitute a different one.
    dup type /dicttype eq        % CharStrings or Private
     { 1 index /CharStrings ne { readonly } if }
     { dup type /arraytype eq        % procedure or data array
        { dup length 5 eq 1 index xcheck and
       { dup 0 get /string eq
         1 index 1 get /currentfile eq and
         1 index 2 get /exch eq and
         1 index 3 get dup /readstring eq exch /readhexstring eq or and
         1 index 4 get /pop eq and
          { 3 get cvlit /skip_C cvx 2 packedarray cvx
          }
          { readonly
          }
         ifelse
       }
       { readonly
       }
      ifelse
    }
    { dup type /stringtype eq    % must be a Subr string
       { readonly }
      if
    }
       ifelse
     }
    ifelse
  } bind def
currentdict end /.loadfontdict exch def
/.loadfont        % <file> .loadfont ->
 { mark exch systemdict begin
   DISKFONTS { .loadfontdict begin } if
    % We can't just use `run', because we want to check for
    % .PFB files.  We can't save the packing status anywhere,
    % so we need two separate control paths.
   currentpacking
    { false setpacking
       { dup read not { -1 } if
         2 copy unread 16#80 eq { /PFBDecode filter } if
     cvx exec
       } stopped    % split up `execute'
      true setpacking
      $error /newerror get and {handleerror} if
    }
    {  { dup read not { -1 } if
         2 copy unread 16#80 eq { /PFBDecode filter } if
     cvx exec
       } execute
    }
   ifelse
   DISKFONTS { end } if
   end cleartomark
 } bind def

% Define findfont so it tries to load a font if it's not found.
/findfont
 {
    % If the key is a string, convert it to a name for lookup.
    dup type /stringtype eq { cvn } if

    % If the font isn't in FontDirectory already, load it.
    dup FontDirectory exch known
     { FontDirectory exch get
     }
     { dup        % save the font name on the stack

       % Push the font name -> font file name map on the stack,
       % loading it if necessary.
       Fontmap

       % Read the file name from the map.
       % (The stack contains the font name and the font file map.)
       1 index known not
        { QUIET not
           { (Substituting ) print defaultfontname cvx =only
             ( for unknown font ) print == flush
           } { pop } ifelse
          pop defaultfontname findfont
        }
        { dup Fontmap exch get

          % If we can't find the file, substitute for the font.
          findlibfile
           { DISKFONTS
              { 1 index (r) file
            FontFileDirectory exch 4 index exch put
          }
             if
             QUIET not
          { (Loading ) print 2 index =only
            ( font from ) print exch print (... ) print flush }
          { exch pop }
         ifelse exch pop
         .loadfont
         QUIET not
          { vmstatus 3 { =only ( ) print } repeat
            (done.\n) print flush
          } if
         % Check to make sure the font was actually loaded.
         dup FontDirectory exch known
          { findfont
          }
          { (Loading ) print cvx =only
            ( font failed, substituting )print defaultfontname cvx =only
            (.\n) print flush
            defaultfontname findfont
          }
         ifelse
           }
           { 1 index defaultfontname eq
          { (Can't find default font!\n) print
            pop pop NullFont
          }
          { (Can't find font file ) print print
            (, substituting ) print defaultfontname cvx =only
            (.\n) print flush
            pop pop defaultfontname findfont
          }
         ifelse
           }
          ifelse
        }
       ifelse

     } ifelse

 } odef % bind def


% The CharStrings for a Ghostscript font are a dictionary in which
% the key is the character name, and the value is a compressed
% representation of a path, as produced by type1imagepath.
% For detailed information, see the book
% "Adobe Type 1 Font Format", published by Adobe Systems Inc.

% Here is the BuildChar implementation
% for Type 1 (Ghostscript standard) fonts.
% The name Type1BuildChar is known to the interpreter.

/Type1BuildChar
 { exch begin
    dup Encoding exch get
    dup CharStrings exch known not
     { QUIET not
        { (Substituting .notdef for ) print = flush
    } { pop } ifelse
       /.notdef
     } if
    currentdict /Metrics known
     { dup Metrics exch known
        { dup Metrics exch get .setmetrics } if
     } if
    CharStrings exch get
    PaintType 0 ne
     { 1 setmiterlimit 1 setlinejoin 1 setlinecap
       currentdict /StrokeWidth known { StrokeWidth } { 0 } ifelse
       setlinewidth
     } if
    dup type /stringtype eq        % encoded outline
     { type1addpath pop }        % does a fill or stroke
     { dup type /integertype eq        % file position for lazy loading
        { load_C
    }
    { currentdict end systemdict begin begin
      exec
      end
    }
       ifelse
     }
    ifelse
   end
 } bind def



% Define a procedure to load all known fonts.
% This isn't likely to be very useful.
/loadallfonts
 { Fontmap { pop findfont pop } forall
 } bind def