shade.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

%
% Shading support - primarily for ASCII file translators.
%

/grays [0.98 0.9 0.75 0.6] def

/setshade {
	/level exch def
	level 0 le {
		/textgray 0 def
		/backgray 1 def
	}{
		/backgray level grays length gt
			{/textgray 1 def 0}
			{/textgray 0 def grays level 1 sub get}
		ifelse def
	} ifelse
	textgray setgray
	/dY1 0 def
	/dY2 0 def
} bind def

/drawrvbox {
	/x2 exch charwidth mul def
	/x1 exch charwidth mul def

	x1 x2 lt {
		dup		% expects y on top
		/y1 exch linespace mul def
		/y2 y1 def

		dY1 0 eq dY2 0 eq and {
			currentfont /FontBBox get aload pop
			160 sub
			currentfont /FontMatrix get dtransform /dY2 exch def pop
			100 add
			currentfont /FontMatrix get dtransform /dY1 exch def pop
		} if

		/y1 y1 dY1 add def
		/y2 y2 dY2 add def

		backgray setgray
		newpath
		x1 y1 moveto
		x2 y1 lineto
		x2 y2 lineto
		x1 y2 lineto
		closepath fill
	} if
	textgray setgray
} bind def