% abcm2ps format file to provide guitar chord diagrams
%
% Version 1.0
% Copyright Gek S. Low, 31 July 2006
%
% Required fonts: FretQwik.ttf and FretQwikC.ttf (free guitar construction fonts)
% Postscript fontmap names: FretQwik and FretQwikC
%
% I wrote this format file because I didn't like the approach used by the abcm2ps examples to add guitar chord diagrams.
% The examples use user-defined decorations, which are limited to a max of 128, and is way too much programming.
% My method is to "hook" into the gcshow abcm2ps postscript routine to draw the diagrams.
% And because I'm lazy, I'm using the excellent and free FretQwik fonts by Robert Allgeyer.
% I suggest using FretQwikC for guitar chords and FretQwik for mandolin/ukulele chords.
% I'm sure you can draw better diagrams with custom Postscript routines, but I'm not going to try... :-)
%
% Please look for the fonts yourself. I will not provide the fonts and I will not entertain requests for them.
%
% DISCLAIMER: This abcm2ps format file is provided as is, is written for my personal use.
% I tested this format file with abcm2ps 4.12.22 at the time of writing. It is always possible that it may not
% work with future versions of abcm2ps. Use at your own risk. Contributions and suggestions are welcome.
%
% Free for personal and non-commercial use only.

% -- Layout section
staffsep   100 % need more space to fit in the chord diagrams

% -- Postscript section
beginps

% This sets up the chord library
% abcm2ps will encode sharp accidentals as octal 201, and flat accidentals as octal 201
% Each chord is an array of 2 elements: the fret position and a string describing the frets relative to that position
% If fret position is zero, then it is not printed
/chorddict 10 dict def
/createchords {
	chorddict begin
		% major chords
		(C) [0 (032010)] def
		(D) [0 (xx0232)] def
		(E) [0 (022100)] def
		(F) [0 (133211)] def
		(G) [3 (320003)] def
		(A) [0 (002220)] def
		(B) [0 (x24442)] def
		(B\202) [0 (x13331)] def
		% minor chords
		(Dm) [0 (xx0231)] def
		% 7th chords
		(C7) [0 (x32310)] def
		(G7) [3 (131211)] def
		% m7 chords
		%(Dm7) [0 (xx0211)] def
		(Dm7) [5 (x13121)] def
		(Em7) [7 (x13121)] def
		(Am7) [5 (131111)] def
		% maj7 chords
		(Cmaj7) [3 (x13231)] def
		(Gmaj7) [3 (1x221x)] def
		% dim7 chords
		(C\201dim7) [3 (x23131)] def
		(D\201dim7) [5 (x23131)] def
		% m7b5 chords
		(Dm7\2025) [5 (x1212x)] def
	end
} def

createchords	

% the drawing routines
/fretboard {(\320) show}! % empty fretboard, no nut

/showgchord { % array showgchord
	% first element - fret number, if any
	dup 0 get
	dup 0 ne { % there's a fret position number
		-4 0 RM % move everything left
		dup 10 lt {
			177 add ( ) dup 0 4 -1 roll
			put show (\240) show}
			{
				dup 10 idiv 177 add ( ) dup 0 4 -1 roll put show (\240) show
				10 mod 177 add
				dup 177 eq {22 add} if % digit 0 is stored somewhere else
				( ) dup 0 4 -1 roll put show (\240) show
			} % greater than 10, must display two digits
			ifelse
			fretboard} % draw fretboard without nut
		{ pop (\260) show } ifelse
	% second element, the chord
	1 get
	{ dup 120 eq { pop (\300\240) show } %x
		{ dup 48 eq { pop (\241\240) show } %0
		{ dup 49 eq { pop (\261\240) show } %1
		{ dup 50 eq { pop (\301\240) show } %2
		{ dup 51 eq { pop (\321\240) show } %3
		{ dup 52 eq { pop (\341\240) show } %4
		{ dup 53 eq { pop (\361\240) show } %5
		if} ifelse} ifelse} ifelse} ifelse} ifelse} ifelse
	} forall}!

/gcshow { % str gcshow
	0 0 RM currentpoint gsave M -1 24 RM /FretQwikC 12 selectfont
	dup chorddict exch known {
		dup chorddict exch get showgchord} 
		{fretboard} ifelse
	grestore
	/gchshow load cshow
}!

endps