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% $Id: gs_dpnxt.ps $
% gs_dpnxt.ps
% NeXT Display PostScript extensions

% Define the operation values for compositing.  These must match the values
% in gsdpnext.h, which also are the ones from the NeXT documentation.
% We put them in systemdict, which seems like as good a place as any.
mark
  /Clear /Copy /Sover /Sin /Sout /Satop /Dover /Din /Dout /Datop /Xor
  /PlusD /PlusL /Highlight	% not sure about Highlight
counttomark { counttomark 1 sub def } repeat pop

% We implement readimage and sizeimage using the following 3 otherwise
% undocumented lower-level operators:
%
%	<x> <y> <width> <height> <matrix> .sizeimagebox
%	  <dev_x> <dev_y> <dev_width> <dev_height> <matrix>
%
%	- .sizeimageparams <bits/sample> <multiproc> <ncolors>
%
%	<device> <x> <y> <width> <max_height> <alpha?> <std_depth|null>
%	  <string> .getbitsrect <height> <substring>
%
% NOTE: These operators are subject to change without notice!

% Implement readimage using .getbitsrect.  Experimentation on a NeXT system
% shows that the data is always returned in order of increasing device Y,
% regardless of the CTM.
%
% Note that we can't make stack protection work for this operator,
% because it must remove its operands from the stack before calling
% the supplied procedure(s).

/readimage {		% <x> <y> <width> <height> <proc> [... <procN-1>]
			%   <string> <alpha?> readimage -
  .sizeimageparams exch {
	% multiproc = true.  If N > 1, store the procedures in an array.
    exch pop 1 index { 1 add } if
	% Stack: ... string alpha? nprocs
    dup 1 eq {
      pop false		% only 1 procedure, multiproc is irrelevant
    } {
      dup array 4 1 roll 3 add 2 roll astore 3 1 roll true
    } ifelse
  } {
	% multiproc = false.
    pop pop false
  } ifelse
	% Map the rectangle to device coordinates.
	% Stack: x y w h proc(s) str alpha? multi?
  8 -4 roll matrix .sizeimagebox pop 8 4 roll
	% Make sure we allocate the operand array in local VM
	% to avoid a possible invalidaccess.
  .currentglobal false .setglobal 9 1 roll
  exch { 1 } { 0 } ifelse exch		% alpha is last, if present
  exch 4 1 roll 8 array astore exch .setglobal
  {	% Read out a block of scan lines and pass them to the procedure.
	% Stack: [x y w h alpha? proc(s) str multi?] -- we must consume this.
    dup 3 get 0 eq { pop exit } if
    aload 9 1 roll pop exch pop currentdevice 7 1 roll
	% Always read out the data as standard (not native) pixels.
    .sizeimageparams pop pop exch .getbitsrect
	% Stack: [x y w h alpha? proc(s) str multi?] hread substr
    3 -1 roll
	% Stack: hread substr [x y w h alpha? proc(s) str multi?]
    dup 1 2 copy get 5 index add put
	% Stack: hread substr [x y' w h alpha? proc(s) str multi?]
    dup 3 2 copy get 6 -1 roll sub put
	% Stack: substr [x y' w h' alpha? proc(s) str multi?]
    dup 5 get exch 7 get {
	% multiproc = true, pass each plane to a different procedure.
	% Stack: substr procs
      0 1 2 index length 1 sub {
	% Push 1 plane and its procedure under the top 2 elements.
	% Stack: ... substr procs plane#
	2 index length 2 index length idiv	% bytes per plane
	dup 2 index mul exch
	% Stack: ... substr procs plane# start length
	4 index 3 1 roll getinterval 4 1 roll
	2 copy get 4 1 roll pop
      } for
      exch pop length 2 mul .execn
    } {
	% multiproc = false, just call the procedure.
      exec
    } ifelse
  } //systemdict /exec get 3 packedarray cvx loop
} bind odef

% Implement sizeimage using lower-level operators.

/sizeimage {		% <x> <y> <width> <height> <matrix> sizeimage
			%   <devwidth> <devheight> <bits/sample> <matrix>
			%   <multiproc> <ncolors>
  .sizeimagebox 5 -2 roll pop pop
  .sizeimageparams 3 -1 roll 4 1 roll
} bind odef