hardcopy.ps

这是一个同样来自贝尔实验室的和UNIX有着渊源的操作系统, 其简洁的设计和实现易于我们学习和理解

%
% Redefiniton of the PostScript file output operators so results go to paper.
% Complicated and slow, but the implementation doesn't place many demands on
% included PostScript. About all that's required is gentle treatment of the
% graphics state between write calls.
%

/#copies 1 store
/aspectratio 1 def
/font /Courier def
/formsperpage 1 def
/landscape false def
/magnification 1 def
/orientation 0 def
/pointsize 10 def
/rotation 1 def
/xoffset .1 def
/yoffset .1 def

/roundpage true def
/useclippath true def
/pagebbox [0 0 612 792] def

/inch {72 mul} def
/min {2 copy gt {exch} if pop} def

/HardcopySetup {
	landscape {/orientation 90 orientation add def} if
	font findfont 1 1.1 div scalefont setfont

	pagedimensions
	xcenter ycenter translate
	orientation rotation mul rotate
	width 2 div neg height 2 div translate
	xoffset inch yoffset inch neg translate
	pointsize 1.1 mul dup scale
	magnification dup aspectratio mul scale
	height width div 1 min dup scale
	0 -1 translate
	0 0 moveto
} def

/pagedimensions {
	useclippath {
		/pagebbox [clippath pathbbox newpath] def
		roundpage currentdict /roundpagebbox known and {roundpagebbox} if
	} if
	pagebbox aload pop
	4 -1 roll exch 4 1 roll 4 copy
	landscape {4 2 roll} if
	sub /width exch def
	sub /height exch def
	add 2 div /xcenter exch def
	add 2 div /ycenter exch def
} def

%
% Unbind the operators in an executable array or packedarray. Leaves the
% unbound array or the original object on the stack.
%

/Unbind {
	0 index xcheck
	1 index type /arraytype eq
	2 index type /packedarraytype eq or and {
		dup length array copy cvx
		dup 0 exch {
			dup type /operatortype eq {
				(                          ) cvs cvn cvx
			} if

			dup type /dicttype eq {
				dup maxlength dict exch {
					Unbind
					3 copy put pop pop
				} forall
			} if

			0 index xcheck
			1 index type /arraytype eq
			2 index type /packedarraytype eq or and {
				Unbind
			} if

			3 copy put pop
			1 add
		} forall
		pop
	} if
} def

%
% New write operator - don't bind the definition! Expands tabs and backspaces,
% wraps long lines, and starts a new page whenever necessary. The code that
% handles newlines assumes lines are separated by one vertical unit.
%

/write {
	true exch

      %%case '\b':
	dup 8#10 eq {
		( ) stringwidth pop neg 0 rmoveto
		currentpoint pop 0 lt {
			currentpoint exch pop 0 exch moveto
		} if
		exch pop false exch
	} if

      %%case '\t':
	dup 8#11 eq {
		currentpoint pop ( ) stringwidth pop div round cvi
		8 mod 8 exch sub {
			2 index 8#40 write
		} repeat
		exch pop false exch
	} if

      %%case '\n':
	dup 8#12 eq {
		currentpoint 0 exch 1 sub moveto pop

		gsave clippath pathbbox pop pop exch pop grestore
		currentpoint exch pop 1 sub ge {
			2 index 8#14 write
		} if
		exch pop false exch
	} if

      %%case '\f':
	dup 8#14 eq {
		gsave showpage grestore
		0 0 moveto
		exch pop false exch
	} if

      %%case '\r':
	dup 8#15 eq {
		currentpoint 0 exch moveto pop
		exch pop false exch
	} if

      %%case EOF:
	dup -1 eq {
		currentpoint 0 ne exch 0 ne or {
			2 index 8#14 write
		} if
		exch pop false exch
	} if

      %%default:
	exch {
		dup
		gsave clippath pathbbox pop 3 1 roll pop pop grestore 
		( ) stringwidth pop currentpoint pop add le {
			2 index 8#12 write
		} if
		( ) dup 0 4 -1 roll put show
	} if

	pop		% the character
	pop		% and file object
} def

%
% All the other file output operators call our redefined write operator.
%

/print {
	(%stdout) (w) file exch {1 index exch write} forall
	pop
} def

/writestring {
	{1 index exch write} forall
	pop
} def

/writehexstring {
	(0123456789ABCDEF) 3 1 roll {
		dup
		3 index exch -4 bitshift 16#F and get 2 index exch write
		2 index exch 16#F and get 1 index exch write
	} forall
	pop pop
} def

%
% Unbind and redefine the remaining file output procedures.
%

/= dup load Unbind def
/== dup load Unbind def
/stack dup load Unbind def
/pstack dup load Unbind def