% Feta (not the Font-En-Tja) music font -- draw arrow heads
% This file is part of LilyPond, the GNU music typesetter.
%
% Copyright (C) 2005--2015 Han-Wen Nienhuys <hanwen@xs4all.nl>
%
% The LilyPond font is free software: you can redistribute it and/or modify
% it under the terms of the GNU General Public License as published by
% the Free Software Foundation, either version 3 of the License, or
% (at your option) any later version, or under the SIL Open Font License.
%
% LilyPond is distributed in the hope that it will be useful,
% but WITHOUT ANY WARRANTY; without even the implied warranty of
% MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE.  See the
% GNU General Public License for more details.
%
% You should have received a copy of the GNU General Public License
% along with LilyPond.  If not, see <http://www.gnu.org/licenses/>.

fet_begingroup ("arrowheads");

%
% To consider: we could put arrow heads at their real Unicode locations.
%

%
% Set up paths for upper half of arrow head pointing right.
% CLOSE_PATH is for a closed arrow, OPEN_PATH is for the open arrow.
% OPEN_TENSION sets the tension for the part which forms the path in
% OPEN_PATH.
%

def set_arrow_paths (expr width, height, open_tension, arrowlinethickness) =
	save pat, finalpath;
	save tip_angle_o, tip_angle_c, tip_dir_c, tip_dir_o;
	save indent;
	path pat, open_path, close_path;
	pair tip_dir_o, tip_dir_c;

	pickup pencircle scaled arrowlinethickness;

	indent = linethickness / 2;

	lft x1 = -width;
	x2 = 0;
	top y1 = height;
	y2 = 0;

	z4 = z3;
	y5 = 0;
	x5 = x4 + indent;

	pat := z1
	       ..tension open_tension.. z2{right};
	penpos2 (arrowlinethickness, 90);
	tip_dir_o := direction 0.0 of pat;
	tip_angle_o := angle (tip_dir_o);
	penpos1 (arrowlinethickness, 90 + tip_angle_o);
	z3 = z1;
	penpos3 (arrowlinethickness, tip_angle_o);

	open_path := z1r{tip_dir_o}
		     .. z2r{right}
		     .. z2l{left}
		     .. z1l{-tip_dir_o}
		     .. z3l
		     .. cycle;

	pat := z4
	       .. z5{down};
	tip_dir_c := direction 0.0 of pat;
	tip_angle_c := angle (tip_dir_c);
	penpos4 (arrowlinethickness, 90+ tip_angle_c);
	penpos5 (arrowlinethickness, 0);
	z6 = z5;
	penpos6 (arrowlinethickness, 90);

	close_path := z4l{tip_dir_c}
		      .. z5l{down}
		      .. z6l{right}
		      .. z2l{right}
		      .. z2r{left}
		      ..tension open_tension.. z1r{-tip_dir_o}
		      .. z3l
		      .. cycle;
enddef;


fet_beginchar ("open", "open.01");
	set_char_box (staff_space#, 1.6 linethickness# / 2,
		      0.5 staff_space#, 0.5 staff_space#);
	set_arrow_paths (staff_space, 0.5 staff_space,
			 1.0, 1.6 linethickness);
	fill open_path;
	open_path := open_path yscaled -1;
	fill open_path;

	penlabels (1, 2, 3);
	penlabels (4, 5, 6);
fet_endchar;


fet_beginchar ("open", "open.0M1");
	set_char_box (1.6 linethickness# / 2, staff_space#,
		      0.5 staff_space#, 0.5 staff_space#);
	set_arrow_paths (staff_space, 0.5 staff_space,
			 1.0, 1.6 linethickness);
	fill open_path;
	open_path := open_path yscaled -1;
	fill open_path;
	currentpicture := currentpicture xscaled -1;
fet_endchar;


fet_beginchar ("open", "open.11");
	set_char_box (.5 staff_space#, .5 staff_space#,
		      1.0 staff_space#, 1.6 linethickness# / 2);
	set_arrow_paths (staff_space, 0.5 staff_space,
			 1.0, 1.6 linethickness);
	fill open_path;
	open_path := open_path yscaled -1;
	fill open_path;
	currentpicture := currentpicture rotated 90;
fet_endchar;


fet_beginchar ("open", "open.1M1");
	set_char_box (.5 staff_space#, .5 staff_space#,
		      1.6 linethickness# / 2, 1.0 staff_space#);
	set_arrow_paths (staff_space, 0.5 staff_space,
			 1.0, 1.6 linethickness);
	fill open_path;
	open_path := open_path yscaled -1;
	fill open_path;
	currentpicture := currentpicture rotated 90;
	currentpicture := currentpicture yscaled -1;
fet_endchar;


fet_beginchar ("close", "close.01");
	set_char_box (staff_space#, 0, 0.5 staff_space#, 0.5 staff_space#);
	set_arrow_paths (staff_space, 0.5 staff_space, 1.5, blot_diameter);
	fill close_path;
	close_path := close_path yscaled -1;
	fill close_path;
fet_endchar;


fet_beginchar ("close", "close.0M1");
	set_char_box (0, staff_space#,  0.5 staff_space#, 0.5 staff_space#);
	set_arrow_paths (staff_space, 0.5 staff_space, 1.5, blot_diameter);
	fill close_path;
	close_path := close_path yscaled -1;
	fill close_path;
	currentpicture := currentpicture xscaled -1;
fet_endchar;


fet_beginchar ("close", "close.11");
	set_char_box (.5 staff_space#, .5 staff_space#,
		      1.0 staff_space#, 0.0 staff_space#);
	set_arrow_paths (staff_space, 0.5 staff_space, 1.5, blot_diameter);
	fill close_path;
	close_path := close_path yscaled -1;
	fill close_path;
	currentpicture := currentpicture rotated 90;
fet_endchar;


fet_beginchar ("close", "close.1M1");
	set_char_box (.5 staff_space#, .5 staff_space#,
		      0.0 staff_space#, 1.0 staff_space#);
	set_arrow_paths (staff_space, 0.5 staff_space, 1.5, blot_diameter);
	fill close_path;
	close_path := close_path yscaled -1;
	fill close_path;
	currentpicture := currentpicture rotated -90;
fet_endchar;


fet_endgroup ("arrowheads");