gs_dps2.ps

GhostScript的源代码

%    Copyright (C) 1990, 1996, 1997 Aladdin Enterprises.  All rights reserved.
% 
% This file is part of Aladdin Ghostscript.
% 
% Aladdin Ghostscript is distributed with NO WARRANTY OF ANY KIND.  No author
% or distributor accepts any responsibility for the consequences of using it,
% or for whether it serves any particular purpose or works at all, unless he
% or she says so in writing.  Refer to the Aladdin Ghostscript Free Public
% License (the "License") for full details.
% 
% Every copy of Aladdin Ghostscript must include a copy of the License,
% normally in a plain ASCII text file named PUBLIC.  The License grants you
% the right to copy, modify and redistribute Aladdin Ghostscript, but only
% under certain conditions described in the License.  Among other things, the
% License requires that the copyright notice and this notice be preserved on
% all copies.

% $Id: gs_dps2.ps $
% Initialization file for basic Display PostScript functions
% that are also included in Level 2.

level2dict begin

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

/.makestackdict
	{ { counttomark -1 roll } forall .dicttomark
	} bind def
/currenthalftone		% - currenthalftone <dict>
	{ mark .currenthalftone
	   { { exch pop }		% halftone
	     { /HalftoneType 1		% screen
		{ /Frequency /Angle /SpotFunction }
	       .makestackdict
	     }
	     { /HalftoneType 2		% colorscreen
		{ /RedFrequency /RedAngle /RedSpotFunction
		  /GreenFrequency /GreenAngle /GreenSpotFunction
		  /BlueFrequency /BlueAngle /BlueSpotFunction
		  /GrayFrequency /GrayAngle /GraySpotFunction
		}
	       .makestackdict
	     }
	   }
	  exch get exec
	} odef
% Define sethalftone so it converts all other types to type 5.
/.sethalftoneRGBV	% <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 .sethalftone5
	} bind def
/sethalftone {		% <dict> sethalftone -
		% We must create the new dictionary in the same VM as the
		% operand; otherwise, invalidaccess errors may occur.
	.currentglobal 1 index dup gcheck .setglobal
	dup /HalftoneType get 1 sub {
	      { mark /Default 2 index .dicttomark .sethalftone5
	      }
	      { 1 { /Frequency /Angle /SpotFunction }
		{ /RedFrequency /RedAngle /RedSpotFunction
		  /GreenFrequency /GreenAngle /GreenSpotFunction
		  /BlueFrequency /BlueAngle /BlueSpotFunction
		  /GrayFrequency /GrayAngle /GraySpotFunction
		} .sethalftoneRGBV
	      }
	      { mark /Default 2 index .dicttomark .sethalftone5
	      }
	      { 3 { /Width /Height /Thresholds }
		{ /RedWidth /RedHeight /RedThresholds
		  /GreenWidth /GreenHeight /GreenThresholds
		  /BlueWidth /BlueHeight /BlueThresholds
		  /GrayWidth /GrayHeight /GrayThresholds
		} .sethalftoneRGBV
	      }
	      { dup .sethalftone5
	      }
	} exch get exec .setglobal pop
} 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 .copydict } if
      dup /Frequency 5 index put
      dup /Angle 4 index put
    }
   if
 } bind def
/setscreen		% <ignore*2> <dict> setscreen -
	{ dup type /dicttype eq
	   { .fixsethalftonescreen sethalftone pop pop pop }
	   { //setscreen }
	  ifelse
	} odef
/setcolorscreen		% <ignore*11> <dict> setcolorscreen -
	{ dup type /dicttype eq
	   { .fixsethalftonescreen sethalftone 12 { pop } repeat }
	   { //setcolorscreen }
	  ifelse
	} odef
% 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 }
   ifelse 3 2 roll
 } bind def
/currentscreen		% - currentscreen 60 0 <dict>
	{ .currenthalftone
	   { { .fixcurrenthalftonescreen }	% halftone
	     { }				% screen
	     { 12 3 roll 9 { pop } repeat	% colorscreen
	       dup type /dicttype eq { .fixcurrenthalftonescreen } if
	     }
	   }
	  exch get exec
	} odef
/currentcolorscreen	% - currentcolorscreen (60 0 <dict>)*4
	{ .currenthalftone
	   { { .fixcurrenthalftonescreen 3 copy 6 copy }	% halftone
	     { 3 copy 6 copy }			% screen
	     { }				% colorscreen
	   }
	  exch get exec
	} odef

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

/.localarray where {
  pop
} {
  /.localarray {
    currentglobal false setglobal
    exch array exch setglobal
  } bind def
} ifelse
/.UserObjects {
  .userdict /UserObjects
} 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 -
  .UserObjects .knownget {
    length dup 3 index le {
		% Stack: index value len
      2 index eq { 1 index 2 mul } { 1 index 1 add } ifelse
      .localarray .UserObjects get
      1 index copy pop
      .UserObjects 3 -1 roll put
    } {
      pop
    } ifelse
  } {
    .UserObjects 3 index 1 add 10 .max .localarray put
  } ifelse
  .UserObjects get 2 index 2 index put pop pop
} odef
/execuserobject {		% <index> execuserobject -
  .UserObjects get 1 index get exch pop exec
} odef
/undefineuserobject {		% <index> undefineuserobject -
  .UserObjects get 1 index null put pop
} odef

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

% Dummy definitions for cache control operators

/ucachestatus {			% - ucachestatus -mark- ? ? ? ? <size>
	mark 0 0 0 0 .userdict /.ucachesize .knownget not { 0 } if
} odef
/setucacheparams {		% -mark- ... <size> setucacheparams -
		% Provoke an appropriate error if needed.
	counttomark 1 lt { () 0 get } if
	0 or .userdict /.ucachesize 2 index 0 .max put cleartomark
} odef

end				% level2dict