gs_fform.ps

来自「遗传算法工具箱 希望高手指点 GATOOLS」· PS 代码 · 共 111 行

%    Copyright (C) 1995, 1996 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.

% gs_fform.ps
% Monochrome Form caching implemented in PostScript.

% This implementation is pretty unreasonable:
%	- It doesn't remember transparent pixels.
%	- It reduces everything to black and white.
%	- It doesn't handle halftone or Pattern phasing.
% However, it's good enough to produce some useful output.

% In order to prevent restore from clearing the cache, we explicitly
% push the cache entries on the stack before a restore and reinstall them.
/formcachedict 20 dict def
currentglobal true setglobal
/restore
 { mark formcachedict { } forall
   counttomark 1 add index { restore } .internalstopped
    { cleartomark restore }
    { counttomark 2 idiv { formcachedict 3 1 roll put } repeat pop pop }
   ifelse
 } bind odef

/.form.buffer 65000 string def
/execform
 { dup /Implementation known not
    { dup /FormType get 1 ne { /rangecheck signalerror } if
      formcachedict 1 index .knownget not
       { currentglobal true setglobal
		% Stack: form global
         10 dict
	   dup /ImageType 1 put
	   dup /ImageMatrix [0 0 0 0 0 0] put
	   dup /DataSource
	    {	% Stack: y (impl is on dict stack)
	      Height 1 index sub
	      //.form.buffer length Width 7 add 8 idiv idiv .min
              1 index add exch
	      Device exch //.form.buffer copyscanlines
	    }
	   put
	   dup /BitsPerComponent 1 put
	   dup /Decode [0 1] put
	   dup /Device null put
		% Stack: form global impl
	 formcachedict 3 index 2 index put
         exch setglobal
       }
      if 1 index /Implementation 3 -1 roll put
    }
   if
   gsave dup /Matrix get concat
   dup /Implementation get
		% Check whether we can use the cached value.
		% Stack: form implementation
   dup /ImageMatrix get matrix currentmatrix
   true 0 1 3
    {		% Stack: form impl cachemat curmat true index
      3 index 1 index get exch 3 index exch get ne { pop false exit } if
    }
   for		% Stack: form impl cachemat curmat valid
   exch pop exch pop not
    {		% Cache is invalid.  Execute the Form and save the bits.
      gsave begin
      currentglobal exch true setglobal
      ImageMatrix currentmatrix pop
      dup /BBox get aload pop
      exch 3 index sub exch 2 index sub rectclip
		% Make the cache device.
      clippath gsave matrix setmatrix pathbbox grestore
		% We now have the bounding box in device space.
      2 { 4 -1 roll floor cvi } repeat
      2 { 4 -1 roll ceiling cvi } repeat
      2 index sub /Height exch def
      2 index sub /Width exch def
      ImageMatrix aload pop
      exch 7 index sub exch 6 index sub
      6 array astore
      3 1 roll pop pop
      dup ImageMatrix copy pop
      Width Height <00 ff> makeimagedevice
      /Device 1 index def
      nulldevice setdevice initgraphics
      exch setglobal
      dup dup /PaintProc get exec
      nulldevice grestore currentdict end
    }
   if
		% Now paint the bits.
		% Stack: form implementation
   /DeviceGray setcolorspace dup begin 0 exch image end pop
   pop grestore
 } odef

setglobal