pictures.sr

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

.de PI	\" Picture Include
.	\" $1=file(page) $2=height,width,yoff,xoff $3=flags
.	\" Height, width, xoff, and yoff are for the frame, flags is for the
.	\" picture. Default dimensions are inches.
\\X'PI:\\n(.o:\\n(.i:\\n(.l:\\n(.t:\\$1:\\$2:\\$3:'\\c
..
.nr FT 0
.de BP	\" Begin a Picture
.	\"
.	\" $1=file(page) $2=height $3=width $4=position $5=offset $6=flags $7=label
.	\"
.	\" Height, width, position, and offset are for the frame, flags is for
.	\" the picture. The postion flag should be l, c, r, or "". Omitting the
.	\" position argument is also allowed for compatibility with the original
.	\" version of the macro. In that case offset is taken relative to your
.	\" left margin.
.if \\n(FT>1 .EP
.	\" Need these when we switch environments.
.nr Ov \\n(.v
.nr Oi \\n(.i
.nr Ol \\n(.l
.	\" Remember the arguments - sometimes as both a string and number register.
.nr $2 \\$2i
.nr $3 \\$3i
.nr $4 \\$4i
.ds $4 \\$4
.nr $5 \\$5i
.ds $5 \\$6
.ds $6 \\$7
.	\" Accept a few unadvertised position flags.
.if '\\*($4'L' .ds $4 l
.if '\\*($4'C' .ds $4 c
.if '\\*($4'R' .ds $4 r
.	\" A null with more than three arguments means l.
.if \\n(.$>3 .if '\\*($4'' .ds $4 l
.	\" Default frame dimensions if missing, zero, or null.
.if !\\n($2>0 .nr $2 3.0i
.if !\\n($3>0 .nr $3 \\n(.lu-\\n(.iu-\\n($4u
.if !\\n($3>0 .nr $3 \\n($2u
.	\" Figure out the offset that will be used the rest of the way.
.if '\\*($4'l' .nr $4 \\n($5u
.if '\\*($4'c' .nr $4 (\\n(.lu-\\n(.iu-\\n($3u)/2u+\\n($5u
.if '\\*($4'r' .nr $4 \\n(.lu-\\n(.iu-\\n($3u+\\n($5u
.	\" If we haven't recognized the position flag assume it wasn't given and
.	\" treat argument four as an offset from the left.
.if !'\\*($4'l' .if !'\\*($4'c' .if !'\\*($4'r' .ds $5 \\$5
.if !'\\*($4'l' .if !'\\*($4'c' .if !'\\*($4'r' .ds $6 \\$6
.	\" Set increments for line length and indent.
.nr Ii \\n($3u+\\n($4u+.1i
.nr Il \\n(.lu-\\n(.iu-\\n($4u+.1i
.	\" Set the frame type to one of:
.	\"	0 - frame is as wide as a line of text - skip over it.
.	\"	1 - fits in left or right margins
.	\"	2 - fill with text on the right
.	\"	3 - on the left
.	\"	4 - or on both sides of the frame
.	\"	5 - only set in EP if FT was 4 and now filling on the right.
.	\" Assume the frame is as wide as a line of text, then check dimensions
.	\" to see what's really true. The order of these tests is important!
.nr FT 0
.if \\n($4u>1.0i .nr FT 3
.if \\n($4u+\\n(.iu>=\\n(.lu .nr FT 1
.if \\n($3u+\\n($4u+\\n(.iu+1.0i<\\n(.lu .nr FT 2
.if \\n($3u+\\n($4u<=0 .nr FT 1
.if \\n(FT=2 .if \\n($4u>1.0i .nr FT 4
.	\" Ask for some vertical space - labeled pictures need a little extra,
.	\" margin pictures a little less.
.if \\n(FT=1 .if '\\*($6'' .ne \\n($2u
.if \\n(FT=1 .if !'\\*($6'' .ne \\n($2u+2v
.if !\\n(FT=1 .if '\\*($6'' .ne \\n($2u+3v
.if !\\n(FT=1 .if !'\\*($6'' .ne \\n($2u+5v
.	\" Save our place, draw the picture, label it, and return. Need precise
.	\" control of when \X'...' is put out - thus the new environment.
.mk Oh
.ev 1
.in \\n(Oiu
.ll \\n(Olu
.vs \\n(Ovu
.if \\n(FT=1 .sp -1v
.if \\n(FT=1 .PI \\$1 \\n($2u,\\n($3u,\\n(.vu,\\n($4u t\\*($5
.if !\\n(FT=1 .PI \\$1 \\n($2u,\\n($3u,\\n(.vu,\\n($4u \\*($5
.in
.ll
.vs
.ev
.lt \\n($3u
.tl \(ts\(ts\\h'\\n($4u+\\n(.iu'\\v'\\n($2u+1.5v'\\*($6\\v'-\\n($2u-1.5v'\\h'-\\n($4u-\\n(.iu'\(ts\(ts
.lt
'sp |\\n(Ohu
.	\" Figure out what to do with the text that follows.
.if !'\\*($6'' .nr $2 +2v
.if \\n(FT=0 .sp \\n($2u+2v
.if \\n(FT=1 .nr FT 0
.if \\n(FT=2 'in +\\n(Iiu
.if \\n(FT>2 .ll -\\n(Ilu
.if \\n(FT>1 .di BB
.if \\n(FT>1 .dt \\n($2u+2v+1u EP
.	\" Clean things up.
.rr $2
.rr $3
.rr $4
.rm $4
.rr $5
.rm $5
.rm $6
.rr Oh
.rr Oi
.rr Ol
.rr Ov
.if \\n(FT=0 .EP
..
.de EP	\" End the Picture - Normally called from a trap, although it can be used
.	\" on its own to mark the end of a picture.
.nr Ot 0
.if \\n(.tu<\\n(.pu .nr Ot \\n(.tu
.if \\n(Ot>0 .if \\n(FT=4 .nr FT 3
.if \\n(FT<2 .nr Ot 0
.if \\n(Ot>0 .br
.if \\n(FT=5 .nr Ot 0
.if \\n(FT>1 \{\
.	ev 1
.	eo
.	br
.	di
.	nf
.	in 0
.	BB
.	in
.	fi
.	ec
.	ev
.	rm BB\}
.if \\n(FT=5 \{\
.	nr FT 2
'	sp |\\n(Nhu+1v\}
.if \\n(FT=4 \{\
.	mk Nh
.	nr Nh -1v
.	nr FT 5
'	sp -\\n(dnu+1v
'	in +\\n(Iiu
.	ll +\\n(Ilu
.	di BB
.	dt \\n(dnu-2v+1u EP\}
.if \\n(FT=2 'in -\\n(Iiu
.if \\n(FT=3 .ll +\\n(Ilu
.if \\n(FT<4 .nr FT 0
.if \\n(Ot>0 .sp \\n(Otu
.rr Ot
.if \\n(FT=0 \{\
.	rr Nh
.	rr Ii
.	rr Il\}
..