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88 lines
2.4 KiB
88 lines
2.4 KiB
const VF = Vex.Flow;
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const numBeats = 7;
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const beatValue = 8;
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const widthPerBeat = 40;
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let numBars = 0;
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// Create an SVG renderer and attach it to the DIV element named "boo".
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const musicSection = document.querySelector("#music");
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const renderer = new VF.Renderer(musicSection, VF.Renderer.Backends.SVG);
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// Size our SVG:
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renderer.resize(4*numBeats*widthPerBeat+2, musicSection.offsetHeight);
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// And get a drawing context:
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const context = renderer.getContext();
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const randomArrayElement = (array) => {
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const randomIndex = Math.floor(Math.random()*array.length);
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return array[randomIndex];
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}
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const randomNote = () => {
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const pitch = randomArrayElement(['a', 'b', 'c', 'd', 'e', 'f', 'g']);
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const octave = randomArrayElement(['4', '5']);
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return `${pitch}/${octave}`;
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}
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const returnNewNote = () => {
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const newNote = new VF.StaveNote({clef: "treble", keys: [randomNote()], duration: "8" })
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if(Math.random() > 0.6){
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const accidentals = ['b', '#'];
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const randomAccidentalIndex = Math.floor(Math.random()*accidentals.length);
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const accidental = accidentals[randomAccidentalIndex];
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newNote.addAccidental(0, new VF.Accidental(accidental));
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}
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return newNote;
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}
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const createBar = () => {
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const staveWidth = numBeats*widthPerBeat;
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const stave = new VF.Stave(numBars*staveWidth, 40, staveWidth);
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// Add a clef and time signature.
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if(numBars === 0){
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stave.addClef("treble").addTimeSignature("7/8");
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}
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// Connect it to the rendering context and draw!
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stave.setContext(context).draw();
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const notes = [
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returnNewNote(),
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returnNewNote(),
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];
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const notes2 = [
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returnNewNote(),
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returnNewNote(),
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];
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const notes3 = [
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returnNewNote(),
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returnNewNote(),
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returnNewNote(),
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];
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const allNotes = notes.concat(notes2).concat(notes3);
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const beams = [
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new VF.Beam(notes),
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new VF.Beam(notes2),
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new VF.Beam(notes3)
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]
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// Create a voice in 4/4 and add the notes from above
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const voice = new VF.Voice({num_beats: numBeats, beatValue: 8});
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voice.addTickables(notes);
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// Format and justify the notes to 400 pixels.
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Vex.Flow.Formatter.FormatAndDraw(context, stave, allNotes);
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beams.forEach(function(b) {b.setContext(context).draw()})
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numBars++;
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}
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for(let i = 0; i < 4; i++){
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createBar();
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}
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