%!
%
% PostScript source - print blank chord diagrams for fretted instruments
%
% Author: A.W. Rogers
% This PostScript program generates one or more pages of blank chord diagrams
% for fretted string instruments.  It is set up for guitar chords, but the
% parameters can easily be modified for other instruments - for example, to
% print mandolin chord diagrams, define /nstrings as 4 and /nfrets as 5.
% 
% The user specifies the desired fret and string spacing (in inches), and
% the program automatically determines how many diagrams can fit on each
% page (ensuring that the row/column spacing is at least half the diagram
% width/height).  This supersedes an earlier version where the user specified
% the number of rows and columns per page and the program scaled the diagrams
% accordingly.
% 
% Andrew

% user-tweakable parameters
/nstrings 6 def				% number of strings
/nfrets 4 def				% number of frets (not including nut)
/stringspace 0.15 def			% spacing between strings (inches)
/fretspace 0.25 def			% spacing between frets (inches)
/pagemargin 0.5 def			% page margin (inches)
/linewidth 0.5 def			% fret/string line width (points)
/nutlinewidth 1.5 def			% nut line width (points)

% draw chord diagram (lower left corner at current point)
/drawbox {
	/x linewidth -0.5 mul def
	/xx boxwidth linewidth add def
	gsave
	currentpoint translate
	linewidth setlinewidth
	1 1 nstrings {				% draw strings
		/n exch 1 sub def
		n stringspace mul 0 moveto
		0 boxheight rlineto
		stroke
	} for
	1 1 nfrets {				% draw frets
		/n exch 1 sub def
		x n fretspace mul moveto
		xx 0 rlineto
		stroke
	} for
	nutlinewidth setlinewidth		% draw nut
	x boxheight moveto
	xx 0 rlineto
	stroke
	grestore
} def

% initial setup
/inch {72 mul} def
/stringspace stringspace inch def
/fretspace fretspace inch def
/pagemargin pagemargin inch def
/boxheight nfrets fretspace mul def
/boxwidth nstrings 1 sub stringspace mul def
pagemargin pagemargin translate
/pageheight 11 inch pagemargin 2 mul sub def
/pagewidth 8.5 inch pagemargin 2 mul sub def

% determine how many fit on a page - minimum spacing 1/2 {height|width}
/ncolumns pagewidth 2 mul boxwidth 3 mul div 0.34 add cvi def
/nrows pageheight 2 mul boxheight 3 mul div 0.34 add cvi def
/X pagewidth boxwidth ncolumns mul sub ncolumns 1 sub div boxwidth add def
/Y pageheight boxheight nrows mul sub nrows 1 sub div boxheight add def

% print them

0 1 nrows 1 sub {
	/y exch Y mul def
	0 1 ncolumns 1 sub {
		X mul y moveto
		drawbox
	} for
} for

showpage
.