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<li> <a href="global.html#warnBanner">warnBanner</a> </li> </ul> </li> </ul> </div> </div> <div class="row-fluid"> <div class="span12"> <div id="main"> <h1 class="page-title">Source: music21/meter.js</h1> <section> <article> <pre class="sunlight-highlight-javascript linenums">/** * music21j -- Javascript reimplementation of Core music21p features. * music21/meter -- TimeSignature objects * * * Copyright (c) 2013-17, Michael Scott Cuthbert and cuthbertLab * Based on music21 (=music21p), Copyright (c) 2006–17, Michael Scott Cuthbert and cuthbertLab * */ import * as Vex from 'vexflow'; import { base } from './base.js'; import { beam } from './beam.js'; import { common } from './common.js'; import { duration } from './duration.js'; /** * meter module. See {@link music21.meter} namespace for details. * * @exports music21/meter */ /** * Meter and TimeSignature Classes (esp. {@link music21.meter.TimeSignature} ) and methods. * * @namespace music21.meter * @memberof music21 * @requires music21/base * @requires music21/duration */ export const meter = {}; /** * A MUCH simpler version of the music21p TimeSignature object. * * @class TimeSignature * @memberof music21.meter * @param {string} meterString - a string ("4/4", "3/8" etc.) to initialize the TimeSignature. * @property {int} [numerator=4] * @property {int} [denominator=4] * @property {Array<Array<Int>>} beatGroups - groupings of beats; inner arrays are numerator, denominator * @property {string} ratioString - a string like "4/4" * @property {music21.duration.Duration} barDuration - a Duration object representing the expressed total length of the TimeSignature. */ export class TimeSignature extends base.Music21Object { constructor(meterString) { super(); this._numerator = 4; this._denominator = 4; this._beatGroups = []; this._overwrittenBeatCount = undefined; this._overwrittenBeatDuration = undefined; if (typeof meterString === 'string') { this.ratioString = meterString; } } get numerator() { return this._numerator; } set numerator(s) { this._numerator = s; } get denominator() { return this._denominator; } set denominator(s) { this._denominator = s; } get ratioString() { return this.numerator.toString() + '/' + this.denominator.toString(); } set ratioString(meterString) { const meterList = meterString.split('/'); this.numerator = parseInt(meterList[0]); this.denominator = parseInt(meterList[1]); this._beatGroups = []; } get barDuration() { const ql = 4.0 * this._numerator / this._denominator; return new duration.Duration(ql); } get beatGroups() { if (this._beatGroups.length === 0) { this._beatGroups = this.computeBeatGroups(); } return this._beatGroups; } set beatGroups(newGroups) { this._beatGroups = newGroups; } /** * Get the beatCount from the numerator, assuming fast 6/8, etc. * unless .beatCount has been set manually. */ get beatCount() { if (this._overwrittenBeatCount !== undefined) { return this._overwrittenBeatCount; } if (this.numerator > 3 && this.numerator % 3 === 0) { return this.numerator / 3; } else { return this.numerator; } } /** * Manually set the beatCount to an int. */ set beatCount(overwrite) { this._overwrittenBeatCount = overwrite; return overwrite; } /** * Gets a single duration.Duration object representing * the length of a beat in this time signature (using beatCount) * or, if set manually, it can return a list of Durations For * asymmetrical meters. */ get beatDuration() { const dur = this.barDuration; dur.quarterLength /= this.beatCount; return dur; } /** * Set beatDuration to a duration.Duration object or * if the client can handle it, a list of Duration objects... */ set beatDuration(overwrite) { this._overwrittenBeatDuration = overwrite; } /** * Compute the Beat Group according to this time signature. * * @memberof music21.meter.TimeSignature * @returns {Array<Array<Int>>} a list of numerator and denominators, find a list of beat groups. */ computeBeatGroups() { const tempBeatGroups = []; let numBeats = this.numerator; let beatValue = this.denominator; if (beatValue < 8 && numBeats >= 5) { const beatsToEighthNoteRatio = 8 / beatValue; // hopefully Int -- right Brian Ferneyhough? beatValue = 8; numBeats *= beatsToEighthNoteRatio; } if (beatValue >= 8) { while (numBeats >= 5) { tempBeatGroups.push([3, beatValue]); numBeats -= 3; } if (numBeats === 4) { tempBeatGroups.push([2, beatValue]); tempBeatGroups.push([2, beatValue]); } else if (numBeats > 0) { tempBeatGroups.push([numBeats, beatValue]); } } else if (beatValue === 2) { tempBeatGroups.push([1, 2]); } else if (beatValue <= 1) { tempBeatGroups.push([1, 1]); } else { // 4/4, 2/4, 3/4, standard stuff tempBeatGroups.push([2, 8]); } return tempBeatGroups; } /** * Return a span of [start, end] for the current beat/beam grouping */ offsetToSpan(offset) { const beatDuration = this.beatDuration.quarterLength; const beatsFromStart = Math.floor(offset / beatDuration); const start = beatsFromStart * beatDuration; const end = start + beatDuration; return [start, end]; } /** * @param {Iterable} srcStream - a stream of elements. * @param {Object} options - an object with measureStartOffset */ getBeams(srcStream, options) { const params = { measureStartOffset: 0.0 }; common.merge(params, options); const measureStartOffset = params.measureStartOffset; let beamsList = beam.Beams.naiveBeams(srcStream); beamsList = beam.Beams.removeSandwichedUnbeamables(beamsList); const fixBeamsOneElementDepth = (i, el, depth) => { const beams = beamsList[i]; if (!beams || beams === undefined) { return; } const beamNumber = depth + 1; if (!(beams.getNumbers().includes(beamNumber))) { return; } const dur = el.duration; const pos = el.offset + measureStartOffset; const start = pos; // opFrac const end = pos + dur.quarterLength; // opFrac; const startNext = end; const isLast = (i === srcStream.length - 1); const isFirst = (i === 0); let beamNext; let beamPrevious; if (!isFirst) { beamPrevious = beamsList[i - 1]; } if (!isLast) { beamNext = beamsList[i + 1]; } const [archetypeSpanStart, archetypeSpanEnd] = this.offsetToSpan(start); let archetypeSpanNextStart = 0.0; if (beamNext !== undefined) { archetypeSpanNextStart = this.offsetToSpan(startNext)[0]; } if (start === archetypeSpanStart && end === archetypeSpanEnd) { beamsList[i] = undefined; return; } let beamType; if (isFirst) { beamType = 'start'; if (beamNext === undefined || !(beamNext.getNumbers().includes(beamNumber))) { beamType = 'partial-right'; } } else if (isLast) { beamType = 'start'; if (beamPrevious === undefined || !beamPrevious.getNumbers().includes(beamNumber)) { beamType = 'partial-left'; } } else if (beamPrevious === undefined || !beamPrevious.getNumbers().includes(beamNumber)) { if (beamNumber === 1 && beamNext === undefined) { beamsList[i] = undefined; return; } else if (beamNext === undefined && beamNumber > 1) { beamType = 'partial-left'; } else if (startNext >= archetypeSpanEnd) { beamType = 'partial-left'; } else if (beamNext === undefined || !(beamNext.getNumbers().includes(beamNumber))) { beamType = 'partial-right'; } else { beamType = 'start'; } } else if (beamPrevious !== undefined && beamPrevious.getNumbers().includes(beamNumber) && ['stop', 'partial-left'].includes(beamPrevious.getTypeByNumber(beamNumber)) ) { if (beamNext !== undefined) { beamType = 'start'; } else { beamType = 'partial-left'; } } else if (beamNext === undefined || !beamNext.getNumbers().includes(beamNumber)) { beamType = 'stop'; } else if (startNext < archetypeSpanEnd) { beamType = 'continue'; } else if (startNext >= archetypeSpanNextStart) { beamType = 'stop'; } else { console.warn('Cannot match beamType'); return; } beams.setByNumber(beamNumber, beamType); }; for (let depth = 0; depth < beam.beamableDurationTypes.length; depth++) { let i = 0; for (const el of srcStream) { fixBeamsOneElementDepth(i, el, depth); i += 1; } } beamsList = beam.Beams.sanitizePartialBeams(beamsList); beamsList = beam.Beams.mergeConnectingPartialBeams(beamsList); return beamsList; } /** * Compute the Beat Group according to this time signature for VexFlow. For beaming. * * @memberof music21.meter.TimeSignature * @param {Vex} Vex - a reference to the Vex object * @returns {Array<Vex.Flow.Fraction>} a list of numerator and denominator groups, for VexFlow */ vexflowBeatGroups() { const tempBeatGroups = this.beatGroups; // console.log(tempBeatGroups); const vfBeatGroups = []; for (let i = 0; i < tempBeatGroups.length; i++) { const bg = tempBeatGroups[i]; vfBeatGroups.push(new Vex.Flow.Fraction(bg[0], bg[1])); } return vfBeatGroups; // if (numBeats % 3 == 0 && beatValue < 4) { // // 6/8, 3/8, 9/8, etc. // numBeats = numBeats / 3; // beatValue = beatValue / 3; // } } } meter.TimeSignature = TimeSignature; </pre> </article> </section> </div> <div class="clearfix"></div> <footer> <span class="copyright"> Music21j, Copyright © 2013-2018 Michael Scott Cuthbert and cuthbertLab. </span> <br /> <span class="jsdoc-message"> Documentation generated by <a href="https://github.com/jsdoc3/jsdoc">JSDoc 3.5.5</a> on Wed Jul 4th 2018 using the <a href="https://github.com/terryweiss/docstrap">DocStrap template</a>. </span> </footer> </div> <br clear="both"> </div> </div>  <script src="scripts/docstrap.lib.js"></script> <script src="scripts/bootstrap-dropdown.js"></script> <script src="scripts/toc.js"></script> <script> $( function () { $( "[id*='$']" ).each( function () { var $this = $( this ); $this.attr( "id", $this.attr( "id" ).replace( "$", "__" ) ); } ); $( "#toc" ).toc( { anchorName : function ( i, heading, prefix ) { return $( heading ).attr( "id" ) || ( prefix + i ); }, selectors : "h1,h2,h3,h4", showAndHide : false, scrollTo : "100px" } ); $( "#toc>ul" ).addClass( "nav nav-pills nav-stacked" ); $( "#main span[id^='toc']" ).addClass( "toc-shim" ); $( '.dropdown-toggle' ).dropdown(); // $( ".tutorial-section pre, .readme-section pre" ).addClass( "sunlight-highlight-javascript" ).addClass( "linenums" ); $( ".tutorial-section pre, .readme-section pre" ).each( function () { var $this = $( this ); var example = $this.find( "code" ); exampleText = example.html(); var lang = /{@lang (.*?)}/.exec( exampleText ); if ( lang && lang[1] ) { exampleText = exampleText.replace( lang[0], "" ); example.html( exampleText ); lang = lang[1]; } else { lang = "javascript"; } if ( lang ) { $this .addClass( "sunlight-highlight-" + lang ) .addClass( "linenums" ) .html( example.html() ); } } ); Sunlight.highlightAll( { lineNumbers : true, showMenu : true, enableDoclinks : true } ); } ); </script>   </body> </html>