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68 lines
1.6 KiB
JavaScript
68 lines
1.6 KiB
JavaScript
import {Scale, LinearScale} from 'chart.js';
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export default class Log2Axis extends Scale {
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constructor(cfg) {
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super(cfg);
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this._startValue = undefined;
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this._valueRange = 0;
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}
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parse(raw, index) {
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const value = LinearScale.prototype.parse.apply(this, [raw, index]);
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return isFinite(value) && value > 0 ? value : null;
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}
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determineDataLimits() {
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const {min, max} = this.getMinMax(true);
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this.min = isFinite(min) ? Math.max(0, min) : null;
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this.max = isFinite(max) ? Math.max(0, max) : null;
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}
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buildTicks() {
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const ticks = [];
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let power = Math.floor(Math.log2(this.min || 1));
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let maxPower = Math.ceil(Math.log2(this.max || 2));
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while (power <= maxPower) {
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ticks.push({value: Math.pow(2, power)});
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power += 1;
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}
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this.min = ticks[0].value;
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this.max = ticks[ticks.length - 1].value;
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return ticks;
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}
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/**
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* @protected
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*/
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configure() {
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const start = this.min;
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super.configure();
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this._startValue = Math.log2(start);
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this._valueRange = Math.log2(this.max) - Math.log2(start);
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}
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getPixelForValue(value) {
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if (value === undefined || value === 0) {
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value = this.min;
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}
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return this.getPixelForDecimal(value === this.min ? 0
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: (Math.log2(value) - this._startValue) / this._valueRange);
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}
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getValueForPixel(pixel) {
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const decimal = this.getDecimalForPixel(pixel);
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return Math.pow(2, this._startValue + decimal * this._valueRange);
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}
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}
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Log2Axis.id = 'log2';
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Log2Axis.defaults = {};
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// The derived axis is registered like this:
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// Chart.register(Log2Axis);
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