tolead.js

// abc2svg - tolead.js - convert ABC to lead sheet
//
// Copyright (C) 2014-2018 Jean-Francois Moine
//
// This file is part of abc2svg.
//
// abc2svg 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.
//
// abc2svg 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 abc2svg.  If not, see <http://www.gnu.org/licenses/>.

var	BASE_LEN = 1536

function lead(tsfirst, voice_tb, music_types, info) {
	var	s, beat, cur_beat, i,
		line = '';

	function get_beat(s) {
		if (s.a_meter[0].top[0] == 'C' || !s.a_meter[0].bot) {
			beat = BASE_LEN / 4
		} else {
			beat = BASE_LEN / s.a_meter[0].bot[0] |0
			if (isNaN(beat)) {
				abc2svg.print('** Cannot get the beat')
				return
			}
			if (s.a_meter[0].bot[0] == 8
			 && s.a_meter[0].top[0] % 3 == 0)
				beat = BASE_LEN / 8 * 3
		}
	} // get_beat()

	abc2svg.print('-- ' + info.T + ' --');

	// get the beat
	get_beat(voice_tb[0].meter)
	if (beat == undefined)
		return

	// treat only the first voice
	cur_beat = 0
	for (s = voice_tb[0].sym; s; s = s.next) {
		while (s.time > cur_beat) {
			line += '/ ';
			cur_beat += beat
		}
		switch (music_types[s.type]) {
		case 'note':
		case 'rest':
			if (s.a_gch) {		// search a chord symbol
				for (i = 0; i < s.a_gch.length; i++) {
					if (s.a_gch[i].type == 'g') {
						line += s.a_gch[i].text + ' ';
						cur_beat = s.time + beat
						break
					}
				}
			}
			break
		case 'bar':
			if (s.eoln) {
				if (s.bar_type == '::')
					line += ':|\n|: '
				else
					line += s.bar_type +'\n'
			} else {
				if (s.bar_type == '::')
					line += ':|: '
				else
					line += s.bar_type + ' '
			}
			cur_beat = s.time	// re-synchronize
			break
		case 'meter':
			get_beat(s)
			break
		}
	}
	abc2svg.print(line)
}

// -- local functions
abc2svg.abort = function(e) {
	abc2svg.abc_end()
	abc2svg.print(e.message + "\n*** Abort ***\n" + e.stack);
	abc2svg.quit()
}

abc2svg.abc_init = function() {
	user.get_abcmodel = lead
}
abc2svg.abc_end = function() {
	if (user.errtxt)
		abc2svg.print("Errors:\n" + user.errtxt)
}