259 lines
7.7 KiB
JavaScript
259 lines
7.7 KiB
JavaScript
// Assumes context is an AudioContext defined outside of this class.
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Polymer('g-spectrogram', {
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// Show the controls UI.
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controls: false,
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// Log mode.
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log: false,
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// Show axis labels, and how many ticks.
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labels: false,
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ticks: 5,
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speed: 2,
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// FFT bin size,
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fftsize: 2048,
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oscillator: false,
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color: false,
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attachedCallback: function() {
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this.tempCanvas = document.createElement('canvas'),
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console.log('Created spectrogram');
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// Get input from the microphone.
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if (navigator.mozGetUserMedia) {
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navigator.mozGetUserMedia({audio: true},
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this.onStream.bind(this),
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this.onStreamError.bind(this));
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} else if (navigator.webkitGetUserMedia) {
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navigator.webkitGetUserMedia({audio: true},
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this.onStream.bind(this),
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this.onStreamError.bind(this));
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}
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this.ctx = this.$.canvas.getContext('2d');
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},
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render: function() {
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//console.log('Render');
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this.width = window.innerWidth;
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this.height = window.innerHeight;
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var didResize = false;
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// Ensure dimensions are accurate.
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if (this.$.canvas.width != this.width) {
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this.$.canvas.width = this.width;
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this.$.labels.width = this.width;
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didResize = true;
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}
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if (this.$.canvas.height != this.height) {
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this.$.canvas.height = this.height;
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this.$.labels.height = this.height;
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didResize = true;
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}
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//this.renderTimeDomain();
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this.renderFreqDomain();
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if (this.labels && didResize) {
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this.renderAxesLabels();
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}
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requestAnimationFrame(this.render.bind(this));
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var now = new Date();
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if (this.lastRenderTime_) {
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this.instantaneousFPS = now - this.lastRenderTime_;
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}
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this.lastRenderTime_ = now;
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},
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renderTimeDomain: function() {
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var times = new Uint8Array(this.analyser.frequencyBinCount);
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this.analyser.getByteTimeDomainData(times);
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for (var i = 0; i < times.length; i++) {
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var value = times[i];
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var percent = value / 256;
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var barHeight = this.height * percent;
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var offset = this.height - barHeight - 1;
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var barWidth = this.width/times.length;
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this.ctx.fillStyle = 'black';
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this.ctx.fillRect(i * barWidth, offset, 1, 1);
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}
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},
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renderFreqDomain: function() {
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var freq = new Uint8Array(this.analyser.frequencyBinCount);
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this.analyser.getByteFrequencyData(freq);
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var ctx = this.ctx;
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// Copy the current canvas onto the temp canvas.
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this.tempCanvas.width = this.width;
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this.tempCanvas.height = this.height;
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//console.log(this.$.canvas.height, this.tempCanvas.height);
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var tempCtx = this.tempCanvas.getContext('2d');
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tempCtx.drawImage(this.$.canvas, 0, 0, this.width, this.height);
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// Iterate over the frequencies.
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for (var i = 0; i < freq.length; i++) {
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var value;
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// Draw each pixel with the specific color.
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if (this.log) {
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logIndex = this.logScale(i, freq.length);
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value = freq[logIndex];
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} else {
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value = freq[i];
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}
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ctx.fillStyle = (this.color ? this.getFullColor(value) : this.getGrayColor(value));
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var percent = i / freq.length;
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var y = Math.round(percent * this.height);
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// draw the line at the right side of the canvas
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ctx.fillRect(this.width - this.speed, this.height - y,
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this.speed, this.speed);
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}
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// Translate the canvas.
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ctx.translate(-this.speed, 0);
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// Draw the copied image.
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ctx.drawImage(this.tempCanvas, 0, 0, this.width, this.height,
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0, 0, this.width, this.height);
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// Reset the transformation matrix.
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ctx.setTransform(1, 0, 0, 1, 0, 0);
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},
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/**
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* Given an index and the total number of entries, return the
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* log-scaled value.
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*/
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logScale: function(index, total, opt_base) {
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var base = opt_base || 2;
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var logmax = this.logBase(total + 1, base);
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var exp = logmax * index / total;
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return Math.round(Math.pow(base, exp) - 1);
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},
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logBase: function(val, base) {
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return Math.log(val) / Math.log(base);
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},
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renderAxesLabels: function() {
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var canvas = this.$.labels;
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canvas.width = this.width;
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canvas.height = this.height;
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var ctx = canvas.getContext('2d');
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var startFreq = 440;
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var nyquist = context.sampleRate/2;
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var endFreq = nyquist - startFreq;
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var step = (endFreq - startFreq) / this.ticks;
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var yLabelOffset = 5;
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// Render the vertical frequency axis.
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for (var i = 0; i <= this.ticks; i++) {
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var freq = startFreq + (step * i);
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// Get the y coordinate from the current label.
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var index = this.freqToIndex(freq);
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var percent = index / this.getFFTBinCount();
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var y = (1-percent) * this.height;
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var x = this.width - 60;
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// Get the value for the current y coordinate.
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var label;
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if (this.log) {
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// Handle a logarithmic scale.
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var logIndex = this.logScale(index, this.getFFTBinCount());
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// Never show 0 Hz.
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freq = Math.max(1, this.indexToFreq(logIndex));
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}
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var label = this.formatFreq(freq);
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var units = this.formatUnits(freq);
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ctx.font = '16px Inconsolata';
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// Draw the value.
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ctx.textAlign = 'right';
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ctx.fillText(label, x, y + yLabelOffset);
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// Draw the units.
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ctx.textAlign = 'left';
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ctx.fillText(units, x + 10, y + yLabelOffset);
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// Draw a tick mark.
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ctx.fillRect(x + 40, y, 30, 2);
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}
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},
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clearAxesLabels: function() {
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var canvas = this.$.labels;
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var ctx = canvas.getContext('2d');
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ctx.clearRect(0, 0, this.width, this.height);
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},
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formatFreq: function(freq) {
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return (freq >= 1000 ? (freq/1000).toFixed(1) : Math.round(freq));
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},
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formatUnits: function(freq) {
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return (freq >= 1000 ? 'KHz' : 'Hz');
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},
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indexToFreq: function(index) {
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var nyquist = context.sampleRate/2;
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return nyquist/this.getFFTBinCount() * index;
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},
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freqToIndex: function(frequency) {
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var nyquist = context.sampleRate/2;
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return Math.round(frequency/nyquist * this.getFFTBinCount());
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},
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getFFTBinCount: function() {
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return this.fftsize / 2;
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},
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onStream: function(stream) {
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var input = context.createMediaStreamSource(stream);
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var analyser = context.createAnalyser();
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analyser.smoothingTimeConstant = 0;
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analyser.fftSize = this.fftsize;
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// Connect graph.
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input.connect(analyser);
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this.analyser = analyser;
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// Setup a timer to visualize some stuff.
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this.render();
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},
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onStreamError: function(e) {
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console.error(e);
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},
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getGrayColor: function(value) {
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return 'rgb(V, V, V)'.replace(/V/g, 255 - value);
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},
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getFullColor: function(value) {
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var fromH = 62;
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var toH = 0;
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var percent = value / 255;
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var delta = percent * (toH - fromH);
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var hue = fromH + delta;
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return 'hsl(H, 100%, 50%)'.replace(/H/g, hue);
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},
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logChanged: function() {
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if (this.labels) {
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this.renderAxesLabels();
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}
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},
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ticksChanged: function() {
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if (this.labels) {
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this.renderAxesLabels();
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}
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},
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labelsChanged: function() {
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if (this.labels) {
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this.renderAxesLabels();
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} else {
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this.clearAxesLabels();
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}
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}
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});
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