--- /dev/null
+A short guide to PostScript files created by gnuplot's "postscript" terminal
+
+by Dick Crawford, aka rccrawford@lanl.gov
+
+Before we begin, let me say a few words about PostScript. It is highly ver-
+satile, but with versatility comes complexity. Syntax is extremely important;
+a misplaced command can do unexpected things. Thus the adventurous soul who
+wishes to alter the PostScript but has not been initiated into the arcana of
+PostScript would be well-advised to change only those items (like numerical
+values, font names or heights, or the letters defining symbols) that are
+fairly obvious as to their meaning.
+
+PostScript is stack-oriented and works in Reverse Polish notation:
+'a b add' takes 'a' and 'b' off of the stack and replaces them with 'a+b'.
+
+The 'stroke' command actually draws lines on the page. It uses whatever line
+width and style are currently defined. Thus if we specify a bunch of commands
+like 'LT1 1 2 moveto 3 4 lineto LT3 stroke' [LT1 and LT3 are line type defi-
+nitions, 'x y moveto' moves the (virtual) pen to (x,y) and 'x y lineto' draws
+a line from wherever the pen was to (x,y)], the line connecting points (1,2)
+and (3,4) will be in type LT3.
+
+PostScript is case-sensitive.
+
+The sample file below has been pruned of repeated commands, just to keep its
+length down. Comment lines begin with '%'. Lines beginning with '%%' are
+inserted for "encapsulated PostScript" -- these lines are read by applications
+that import PostScript. Lines beginning with '%#' have been added to the
+sample by me for explanatory purposes.
+
+I have merged files created by the postscript terminal with no options, with
+the "eps" option and with the "enhanced" option. The differences will be
+clearly pointed out when appropriate.
+
+Here we go.
+
+%!PS-Adobe-2.0
+%%Title: psgenh
+%%Creator: gnuplot 3.5 (pre 3.6) patchlevel beta 338
+%%CreationDate: Fri Jan 16 13:18:18 1998
+%%DocumentFonts: (atend)
+%%BoundingBox: 50 50 554 770
+%%Orientation: Landscape
+%# In 'eps' mode, the preceding two lines would look like:
+%# %%BoundingBox: 50 50 410 302
+%# %%Orientation: Portrait
+%%Pages: (atend)
+%%EndComments
+%#
+%# The 'dictionary' contains stuff defined by the user.
+%#
+/gnudict 120 dict def
+gnudict begin
+%#
+%# The following switch toggles between color and monochromatic.
+%#
+/Color false def
+%#
+%# The following switch toggles between solid and dot-dash lines.
+%#
+/Solid false def
+%#
+%# The following parameter scales all linewidths in the plot.
+%#
+/gnulinewidth 5.000 def
+/userlinewidth gnulinewidth def
+%#
+%# The following parameter specifies the vertical displacement of the labels
+%# and titles (it is used in the 'show' commands defined below). It should
+%# be about 1/3 of the font height.
+%#
+/vshift -46 def
+%#
+%# The following parameter scales the lengths of all dot-dash patterns.
+%#
+/dl {10 mul} def
+%#
+%# The following two parameters scale the horizontal and vertical sizes of
+%# the symbols used by 'plot with points'.
+%#
+/hpt_ 31.5 def
+/vpt_ 31.5 def
+/hpt hpt_ def
+/vpt vpt_ def
+%#
+%# The following four commands are aliases of the four 'pen movement'
+%# commands. Use of these aliases significantly shortens the file. Note
+%# that the first two are 'absolute' movements and the latter two are
+%# 'relative'. M and R move to the specified position; L and V draw a
+%# straight line (from the current position) to it.
+%#
+/M {moveto} bind def
+/L {lineto} bind def
+/R {rmoveto} bind def
+/V {rlineto} bind def
+%#
+%# These are a couple more parameters used in plotting symbols. Why
+%# they are here instead of up with 'hpt' and 'vpt' I know not.
+%#
+/vpt2 vpt 2 mul def
+/hpt2 hpt 2 mul def
+%#
+%# The 'show' command writes out a character string. The following three
+%# varieties do so as left-, right-, and center-justified. [Remember,
+%# we're still in the dictionary--the font doesn't need to be specified
+%# until we actually use one of these.]
+%#
+/Lshow { currentpoint stroke M
+ 0 vshift R show } def
+/Rshow { currentpoint stroke M
+ dup stringwidth pop neg vshift R show } def
+/Cshow { currentpoint stroke M
+ dup stringwidth pop -2 div vshift R show } def
+%#
+%# The following commands define the various line types (normal, bold,
+%# dashed, etc.) used by gnuplot.
+%#
+%# UP, DL, and UL are busywork commands used by others here
+%#
+/UP { dup vpt_ mul /vpt exch def hpt_ mul /hpt exch def
+ /hpt2 hpt 2 mul def /vpt2 vpt 2 mul def } def
+/DL { Color {setrgbcolor Solid {pop []} if 0 setdash }
+ {pop pop pop Solid {pop []} if 0 setdash} ifelse } def
+/BL { stroke gnulinewidth 2 mul setlinewidth } def %# twice the linewidth
+/AL { stroke gnulinewidth 2 div setlinewidth } def %# half the linewidth
+/UL { gnulinewidth mul /userlinewidth exch def } def
+/PL { stroke userlinewidth setlinewidth } def %# normal linewidth
+/LTb { BL [] 0 0 0 DL } def
+/LTa { AL [1 dl 2 dl] 0 setdash 0 0 0 setrgbcolor } def
+/LT0 { PL [] 0 1 0 DL } def
+/LT1 { PL [4 dl 2 dl] 0 0 1 DL } def
+%#
+%# ...and a bunch more.
+%# In the LT's, the first command ('PL' for LT1) sets the linewidth,
+%# the stuff in [...] defines the dot-dash pattern, and the three numbers
+%# define the rgb color.
+%#
+%# The following commands define the symbols used to plot data points.
+%#
+/Pnt { stroke [] 0 setdash
+ gsave 1 setlinecap M 0 0 V stroke grestore } def
+/Dia { stroke [] 0 setdash 2 copy vpt add M
+ hpt neg vpt neg V hpt vpt neg V
+ hpt vpt V hpt neg vpt V closepath stroke
+ Pnt } def
+%#
+%# ...and a bunch (dozens) more.
+%#
+%# The 'MF...' commands are used to handle the 'enhanced' syntax. If the
+%# 'enhanced' mode is not invoked, these commands won't appear in the file.
+%#
+/MFshow {{dup dup 0 get findfont exch 1 get scalefont setfont
+ [ currentpoint ] exch dup 2 get 0 exch rmoveto dup dup 5 get exch 4 get
+ {show} {stringwidth pop 0 rmoveto}ifelse dup 3 get
+ {2 get neg 0 exch rmoveto pop} {pop aload pop moveto}ifelse} forall} bind def
+/MFwidth {0 exch {dup 3 get{dup dup 0 get findfont exch 1 get scalefont setfont
+ 5 get stringwidth pop add}
+ {pop} ifelse} forall} bind def
+/MLshow { currentpoint stroke M
+ 0 exch R MFshow } bind def
+/MRshow { currentpoint stroke M
+ exch dup MFwidth neg 3 -1 roll R MFshow } def
+/MCshow { currentpoint stroke M
+ exch dup MFwidth -2 div 3 -1 roll R MFshow } def
+end
+%#
+%# The dictionary is now complete. We activate it, save what went before
+%# (the 'gsave' command saves everything on a different stack) and begin.
+%#
+%%EndProlog
+%%Page: 1 1
+gnudict begin
+gsave
+%#
+%# First we position the plot on the page and scale it.
+%#
+%# The 'translate' command moves the origin to the specified position.
+%# [The PostScript default origin is near the lower left-hand corner.]
+%# The 'scale' command changes the units used in the plot.
+%# [The PostScript default unit is the point: 72 points equal one inch.]
+%# The 'rotation' command rotates the coordinates clockwise through the
+%# specified angle (degrees).
+%# [The PostScript default orientation is profile.]
+%#
+%# This sample changes the orientation to landscape (the gnuplot default)
+%# and the unit to tenths of a point. Note that if the first two commands
+%# were interchanged, the translation would be only five points in each
+%# direction, instead of fifty.
+%#
+%# If this had been generated in 'eps' mode, the "90 rotate" and "0 -5040
+%# translate" commands would not appear and the units would be 0.050 instead
+%# of 0.100.
+%#
+%# If you want to change the size or the position of the plot, this is where
+%# to do it.
+%#
+50 50 translate
+0.100 0.100 scale
+90 rotate
+0 -5040 translate
+0 setgray
+newpath
+%#
+%# Define the default font. The number is the height. As usual, fonts
+%# used primarily for text have characters only about 70% the specified
+%# height, because spacing between lines is built-in. The Symbol font and
+%# others that are normally not used for text produce characters that are
+%# more nearly the specified height. Thus if you want to intersperse, for
+%# example, Greek and Roman letters (as you might when writing an equation),
+%# you'll need to play with the heights of the two fonts in order for them
+%# to look reasonably proportioned.
+%#
+%# The font defined here is used for the tick labels first, then the axis
+%# labels and plot titles, and finally the key. If you want to change the
+%# font, simply insert the modified line after you are done with the old one
+%# (i.e. the last 'show' command to use it) but before the new one is needed.
+%# Note that if you change the font height, you'll also want to change the
+%# value of 'vshift' (it's near the top of the dictionary). I'll give an
+%# example of this later on...
+%#
+(Helvetica) findfont 140 scalefont setfont
+LTb
+%#
+%# Label and draw the ticks along the y-axis. I've given you three
+%# y-tics in different formats...
+%#
+%# The tick length is 63 units.
+%#
+%# This first y-tic is in 'normal' mode:
+%#
+728 560 M
+63 0 V
+6325 0 R
+-63 0 V
+644 560 M
+(-10) Rshow
+%#
+%# This y-tic is in 'enhanced' mode:
+%#
+728 1645 M
+63 0 V
+6325 0 R
+-63 0 V
+ stroke
+644 1645 M
+[ [(Helvetica) 140.0 0.0 true true (-5)]
+] -46.7 MRshow
+%#
+%# This one is in 'normal' mode, but is rotated:
+%#
+434 2730 M
+63 0 V
+6619 0 R
+-63 0 V
+-6759 0 R
+currentpoint gsave translate 90 rotate 0 0 M
+(0) Cshow
+grestore
+%#
+%# Now the x-tics. Here's one:
+%#
+728 560 M
+0 63 V
+0 4277 R
+0 -63 V
+ stroke
+728 420 M
+[ [(Helvetica) 140.0 0.0 true true (-10)]
+] -46.7 MCshow
+LTb
+%#
+%# Now draw the left and lower axes. Were this drawn by 'splot'
+%# instead of 'plot', there might be some other axes drawn.
+%#
+728 560 M
+6388 0 V
+0 4340 V
+-6388 0 V
+728 560 L
+ stroke
+%# Now come labels (both for the axes and those on "set label" commands)
+%# and other titles. I just give you axis labels here, in 'enhanced' mode:
+%#
+140 2730 M
+currentpoint gsave translate 90 rotate 0 0 moveto
+[ [(Helvetica) 140.0 0.0 true true (ylabel)]
+] -46.7 MCshow
+grestore
+3922 210 M
+[ [(Helvetica) 140.0 0.0 true true (xlabel)]
+] -46.7 MCshow
+%#
+%# We're finally ready to plot functions and/or data.
+%#
+%# The key is drawn just before the applicable data.
+%#
+%# Choose a line type and write the key.
+%# In this sample, it is drawn with lines.
+%#
+1.000 UL
+LT0
+6465 4767 M (x) Rshow %# the function label in the key
+6549 4767 M %# the sample line in the key
+399 0 V
+%#
+%# Now the data (this is drawn with some combination of absolute and
+%# relative lineto's and moveto's):
+%#
+728 560 M
+2043 560 V
+4926 911 L
+2043 560 V
+7116 4900 L
+%#
+%# ...and more.
+%#
+%# We don't need to eplicitly 'stroke' to draw the lines for each function
+%# because the 'stroke' command is included in the line-type definition
+%# commands. Thus switching line types automatically 'strokes' previous
+%# lines. Clever program, that gnuplot...
+%#
+%# We can now repeat commands for the key and data for as many items
+%# as were specified on the "plot" or "splot" command.
+%#
+%# Here's a second function, plotted with dots:
+%#
+LT1
+6486 4486 M
+(function 2) Rshow
+6654 4486 Pnt
+%#
+%# The data:
+%#
+840 911 Pnt
+2883 2030 Pnt
+4926 2590 Pnt
+6969 3710 Pnt
+%#
+%# ...and more.
+%#
+%# Since we're now done, we 'stroke' the last lines, close the dictionary
+%# and restore the previous settings (those saved by the 'gsave' at the top).
+%# [The 'gsave'/'grestore' pair is included so that if this file is embedded
+%# in another PostScript file, this patch won't mess up the other parts of
+%# the picture. It's considered good PostScript style to do this.]
+%#
+stroke
+grestore
+end
+%#
+%# And, finally, we send the page to the printer. [If we do embed this
+%# file into another PostScript file, we'd remove this 'showpage'. Unless,
+%# of course, this was appended to the other file, in which case we'd
+%# remove the 'showpage' from the end of that file.]
+%#
+%#
+showpage
+%%Trailer
+%%DocumentFonts: Helvetica
+%%Pages: 1
projects / gnuplot / blobdiff