(function() {
var onDOMContentLoaded = function() {
window.AudioContext = window.AudioContext || window.webkitAudioContext;
try {
// Create the instance of AudioContext
var context = new AudioContext();
} catch (error) {
window.alert(error.message + ' : Please use Chrome or Safari.');
return;
}
// Create the instance of OscillatorNode
var oscillator = context.createOscillator();
// Parameters for the instance of OscillatorNode
var type = oscillator.type;
var detune = oscillator.detune.value;
// for legacy browsers
context.createGain = context.createGain || context.createGainNode;
// Create the instance of GainNode
var gain = context.createGain();
// Flag for starting or stopping sound
var isStop = true;
// Parameters for Glide
var startFrequency = -1; // Abnormal value
var time = document.getElementById('range-glide').valueAsNumber;
var glideType = document.getElementById('form-glide-type').elements['radio-glide-type'][0].value;
/*
* Event Listener
*/
// Start or Stop sound
var PIANO_88S = [
'A-4', 'A-4h', 'B-4',
'C-3', 'C-3h', 'D-3', 'D-3h', 'E-3', 'F-3', 'F-3h', 'G-3', 'G-3h', 'A-3', 'A-3h', 'B-3',
'C-2', 'C-2h', 'D-2', 'D-2h', 'E-2', 'F-2', 'F-2h', 'G-2', 'G-2h', 'A-2', 'A-2h', 'B-2',
'C-1', 'C-1h', 'D-1', 'D-1h', 'E-1', 'F-1', 'F-1h', 'G-1', 'G-1h', 'A-1', 'A-1h', 'B-1',
'C', 'Ch', 'D', 'Dh', 'E', 'F', 'Fh', 'G', 'Gh', 'A', 'Ah', 'B',
'C1', 'C1h', 'D1', 'D1h', 'E1', 'F1', 'F1h', 'G1', 'G1h', 'A1', 'A1h', 'B1',
'C2', 'C2h', 'D2', 'D2h', 'E2', 'F2', 'F2h', 'G2', 'G2h', 'A2', 'A2h', 'B2',
'C3', 'C3h', 'D3', 'D3h', 'E3', 'F3', 'F3h', 'G3', 'G3h', 'A3', 'A3h', 'B3',
'C4'
];
var pianoKeys = Array.prototype.slice.call(document.querySelectorAll('#piano ul li'), 0);
var convertIndex = function(index) {
//
// The 12 equal temparement
//
// Min -> A 27.5Hz, Max -> C 4186 Hz
//
// Example :
// A * 1.059463 -> A# (half up)
//
var FREQUENCY_RATIO = Math.pow(2, (1 / 12)); // about 1.059463;
var MIN_A = 27.5;
return (MIN_A * Math.pow(FREQUENCY_RATIO, index));
};
pianoKeys.forEach(function(element, index, array) {
// Start sound
element.addEventListener(EventWrapper.START, function(event) {
if (!isStop) {
oscillator.stop(0);
}
var pianoIndex = PIANO_88S.indexOf(this.id);
var endFrequency = convertIndex(pianoIndex);
// Create the instance of OscillatorNode
oscillator = context.createOscillator();
// for legacy browsers
oscillator.start = oscillator.start || oscillator.noteOn;
oscillator.stop = oscillator.stop || oscillator.noteOff;
// OscillatorNode (Input) -> GainNode (Volume) -> AudioDestinationNode (Output)
oscillator.connect(gain);
gain.connect(context.destination);
// Set parameters
oscillator.type = type;
oscillator.detune.value = detune;
// for scheduling
var t0 = context.currentTime;
var t1 = t0 + time;
// Scheduling for Glide
oscillator.frequency.cancelScheduledValues(t0);
// The 1st sound ?
if (startFrequency === -1) {
oscillator.frequency.setValueAtTime(endFrequency, t0);
} else {
oscillator.frequency.setValueAtTime(startFrequency, t0);
}
switch (glideType) {
case 'linear' :
oscillator.frequency.linearRampToValueAtTime(endFrequency, t1);
break;
case 'exponential' :
oscillator.frequency.exponentialRampToValueAtTime(endFrequency, t1);
break;
default :
break;
}
// Start sound at t0
oscillator.start(t0);
// Update
startFrequency = endFrequency;
isStop = false;
this.classList.remove('key-off');
this.classList.add('key-on');
}, false);
// Stop sound
element.addEventListener(EventWrapper.END, function() {
if (isStop) {
return;
}
oscillator.stop(0);
isStop = true;
this.classList.remove('key-on');
this.classList.add('key-off');
}, false);
});
// Control Volume
document.getElementById('range-volume').addEventListener('input', function() {
var min = gain.gain.minValue || 0;
var max = gain.gain.maxValue || 1;
if ((this.valueAsNumber >= min) && (this.valueAsNumber <= max)) {
gain.gain.value = this.valueAsNumber;
document.getElementById('output-volume').textContent = this.value;
}
}, false);
// Select type
document.getElementById('form-wave-type').addEventListener('change', function() {
for (var i = 0, len = this.elements['radio-wave-type'].length; i < len; i++) {
if (this.elements['radio-wave-type'][i].checked) {
oscillator.type = type = (typeof oscillator.type === 'string') ? this.elements['radio-wave-type'][i].value : i;
break;
}
}
}, false);
// Control detune
document.getElementById('range-detune').addEventListener('input', function() {
var min = oscillator.detune.minValue || -4800;
var max = oscillator.detune.maxValue || 4800;
if ((this.valueAsNumber >= min) && (this.valueAsNumber <= max)) {
oscillator.detune.value = detune = this.valueAsNumber;
document.getElementById('output-detune').textContent = this.value;
}
}, false);
// Control Glide Time
document.getElementById('range-glide').addEventListener('input', function() {
if (this.valueAsNumber >= 0) {
time = this.valueAsNumber / 5;
document.getElementById('output-glide').textContent = this.value;
}
}, false);
};
if ((document.readyState === 'interactive') || (document.readyState === 'complete')) {
onDOMContentLoaded();
} else {
document.addEventListener('DOMContentLoaded', onDOMContentLoaded, true);
}
})();
function EventWrapper(){
}
(function(){
var click = '';
var start = '';
var move = '';
var end = '';
// Touch Panel ?
if (/iPhone|iPad|iPod|Android/.test(navigator.userAgent)) {
click = 'click';
start = 'touchstart';
move = 'touchmove';
end = 'touchend';
} else {
click = 'click';
start = 'mousedown';
move = 'mousemove';
end = 'mouseup';
}
EventWrapper.CLICK = click;
EventWrapper.START = start;
EventWrapper.MOVE = move;
EventWrapper.END = end;
})();