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[EDIT] FILE: gs_dps2.ps

% Copyright (C) 2001-2019 Artifex Software, Inc.
% 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.
%
% Refer to licensing information at http://www.artifex.com or contact
% Artifex Software, Inc.,  1305 Grant Avenue - Suite 200, Novato,
% CA 94945, U.S.A., +1(415)492-9861, for further information.
%

% Initialization file for basic Display PostScript functions
% that are also included in Level 2.

level2dict begin

% ------ Errors ------ %

% These errors are only defined in Level 2 and DPS.
{ /configurationerror /undefinedresource /unregistered }
{ .registererror } forall

% ------ Halftones ------ %

/.makestackdict
        { { counttomark -1 roll } forall .dicttomark
        } bind def
/currenthalftone		% - currenthalftone <dict>
        { mark .currenthalftone
           { { exch pop }		% halftone
             { /HalftoneType 1		% screen
                { /Frequency /Angle /SpotFunction }
               //.makestackdict exec readonly
             }
             { /HalftoneType 2		% colorscreen
                { /RedFrequency /RedAngle /RedSpotFunction
                  /GreenFrequency /GreenAngle /GreenSpotFunction
                  /BlueFrequency /BlueAngle /BlueSpotFunction
                  /GrayFrequency /GrayAngle /GraySpotFunction
                }
               //.makestackdict exec readonly
             }
           }
          exch get exec
        } odef
currentdict /.makestackdict undef

% Define sethalftone so it converts types 1-4 to type 5.
/.makehalftoneRGBV {	% <dict> <type> <keys> <keysRGBV>
  4 -1 roll exch { 1 index exch get exch } forall 15 1 roll
  14 -2 roll mark 15 1 roll { /Gray /Blue /Green /Red } {
                % stack: v0 v1 v2 type keys comp
    mark
    2 index 0 get 8 -1 roll
    4 index 1 get 9 -1 roll
    6 index 2 get 10 -1 roll
                % stack: type keys comp mark k0 v0 k1 v1 k2 v2
    /HalftoneType 10 index .dicttomark
    counttomark 2 roll
  } forall pop pop
  /Default 1 index .dicttomark exch pop { .sethalftone5 }
} bind def

% The value of each entry in .halftonetypes is a procedure:
%	<setdict> <htdict> <<proc>> <setdict'> <htdict'> <sethalftoneproc>
% This allows us to use these procedures both for actually implementing
% sethalftone and for converting subsidiary dictionaries of HalftoneType 5
% halftones.
systemdict begin
15 dict /.halftonetypes 1 index def begin
  1 {
    mark exch /Default exch .dicttomark { .sethalftone5 }
  } bind def
  2 {
    1 { /Frequency /Angle /SpotFunction } {
      /RedFrequency /RedAngle /RedSpotFunction
      /GreenFrequency /GreenAngle /GreenSpotFunction
      /BlueFrequency /BlueAngle /BlueSpotFunction
      /GrayFrequency /GrayAngle /GraySpotFunction
    } //.makehalftoneRGBV exec
  } bind def
  3 {
    mark exch /Default exch .dicttomark { .sethalftone5 }
  } bind def
  4 {
    3 { /Width /Height /Thresholds } {
      /RedWidth /RedHeight /RedThresholds
      /GreenWidth /GreenHeight /GreenThresholds
      /BlueWidth /BlueHeight /BlueThresholds
      /GrayWidth /GrayHeight /GrayThresholds
    } //.makehalftoneRGBV exec
  } bind def
  5 {
    pop dup length dict copy
    mark 1 index {
                % Even HalftoneType 5 dictionaries have entries other than
                % subsidiary halftone dictionaries.
      dup type /dicttype ne {
        0
      } {
        dup /HalftoneType .knownget not { 0 } if
      } ifelse dup 5 gt {
                % Stack: dict mark ... keyN dictN httypeN
                % Assume that all HalftoneTypes > 5 convert to 5.
        1 index 3 1 roll
        //.halftonetypes exch get exec pop /Default get
                % Stack: dict mark ... keyN setdict'N htdict'N
        counttomark 1 add index 3 index 4 -1 roll put
      } {
        pop
      } ifelse
    } forall .dicttomark { .sethalftone5 }
  } bind def
end
end
currentdict /.makehalftoneRGBV undef

/sethalftone {		% <dict> sethalftone -
        % We must create the new dictionary in the same VM as the
        % operand; otherwise, invalidaccess errors may occur.
  .currentglobal 1 .argindex dup gcheck .setglobal
  dup //.halftonetypes 1 index /HalftoneType get
  dup type /integertype ne {
    /sethalftone .systemvar /typecheck signalerror
  } if
  .knownget not {
    /sethalftone .systemvar /rangecheck signalerror
  } if
  exec exec
  .setglobal pop
} .bind odef
% Redefine setscreen and setcolorscreen to recognize halftone dictionaries,
% and to insert the Frequency and Angle into Type 1 halftones, per
% Adobe TN 5085.
/.fixsethalftonescreen		% <freq> <angle> <dict> .fix...screen
                                %   <freq> <angle> <dict> <dict'>
 { dup dup /HalftoneType get 1 eq
    { dup wcheck not { dup length dict .copydict } if
      dup /Frequency 5 index put
      dup /Angle 4 index put
      languagelevel 3 ge { dup /AccurateScreens dup getuserparam put } if
    }
   if
 } bind def
/setscreen		% <ignore*2> <dict> setscreen -
        { dup type /dicttype eq
           { //.fixsethalftonescreen exec sethalftone pop pop pop }
           { //setscreen }
          ifelse
        } .bind odef
/setcolorscreen		% <ignore*11> <dict> setcolorscreen -
        { dup type /dicttype eq
           { //.fixsethalftonescreen exec sethalftone 12 { pop } repeat }
           { //setcolorscreen }
          ifelse
        } .bind odef
currentdict /.fixsethalftonescreen undef

% Redefine currentscreen and currentcolorscreen to extract the Frequency
% and Angle from Type 1 halftones, per Adobe TN 5085.
/.fixcurrenthalftonescreen	% <dict> .fix... <freq> <angle> <proc>
 { dup /HalftoneType get 1 eq
    { dup /Frequency get 1 index /Angle get }
    { 60.0 0.0 }	% Adobe returns these as reals
   ifelse 3 2 roll
 } bind def
/currentscreen		% - currentscreen 60 0 <dict>
        { .currenthalftone
           { { //.fixcurrenthalftonescreen exec }% halftone
             { }				% screen
             { 12 3 roll 9 { pop } repeat	% colorscreen
               dup type /dicttype eq { //.fixcurrenthalftonescreen exec } if
             }
           }
          exch get exec
        } odef
/currentcolorscreen	% - currentcolorscreen (60 0 <dict>)*4
{ .currenthalftone
   { { //.fixcurrenthalftonescreen exec 3 copy 6 copy }	% halftone
     {					% screen
         % The procedure might not be readable....
         dup rcheck { dup length array copy cvx } if
         3 copy 6 copy
     }
     { }				% colorscreen
   }
  exch get exec
} odef
currentdict /.fixcurrenthalftonescreen undef

% ------ User objects ------ %

/.UserObjects {
  .userdict /UserObjects
} bind executeonly odef
% In order to get proper error recovery behavior, we need to be careful
% not to pop any operands from the stack until we're done.
% The code below faithfully duplicates the apparent array-growing
% behavior of Adobe interpreters.
/defineuserobject {		% <index> <value> defineuserobject -
  1 index 65535 gt {
    % .localvmarray throws limitcheck but CET 31-02 wants rangecheck
    /defineuserobject .systemvar /rangecheck signalerror
  } if
  .UserObjects .knownget {
    length dup 3 .argindex le {
                % Stack: index value len
      2 index eq { 1 index 2 mul } { 1 index 1 add } ifelse
      .localvmarray .UserObjects get
      1 index copy pop
      .UserObjects 3 -1 roll put
    } {
      pop
    } ifelse
  } {
    .UserObjects 3 .argindex 1 add 10 .max .localvmarray put
  } ifelse
  .UserObjects get 2 .argindex 2 index put pop pop
} bind odef
/execuserobject {		% <index> execuserobject -
  dup type /integertype ne {
    % Adobe validates the argument before accessing UserObjects - CET 31-03
    /execuserobject .systemvar /typecheck signalerror
  } if
  .UserObjects get 1 .argindex get exch pop exec
} bind odef
/undefineuserobject {		% <index> undefineuserobject -
  dup type /integertype ne {
    % Adobe validates the argument before accessing UserObjects - CET 31-11
    /undefineuserobject .systemvar /typecheck signalerror
  } if
  .UserObjects get 1 .argindex //null put pop
} bind odef
currentdict /.UserObjects undef

% ------ Cache control ------ %

% Dummy definitions for cache control operators

/ucachestatus {			% - ucachestatus -mark- ? ? ? ? <size>
        mark 0 0 0 0 /MaxUPathItem getuserparam
} odef
/setucacheparams {		% -mark- ... <size> setucacheparams -
                % Provoke an appropriate error if needed.
        counttomark 1 lt { () 0 get } if
        dup 0 or /MaxUPathItem getuserparam .max
        1 dict dup /MaxUPathItem 4 -1 roll put setuserparams cleartomark
} odef

end				% level2dict

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