Log.js
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/**
* Log scale
* @module echarts/scale/Log
*/
define(function (require) {
var zrUtil = require('zrender/core/util');
var Scale = require('./Scale');
var numberUtil = require('../util/number');
// Use some method of IntervalScale
var IntervalScale = require('./Interval');
var scaleProto = Scale.prototype;
var intervalScaleProto = IntervalScale.prototype;
var mathFloor = Math.floor;
var mathCeil = Math.ceil;
var mathPow = Math.pow;
var LOG_BASE = 10;
var mathLog = Math.log;
var LogScale = Scale.extend({
type: 'log',
/**
* @return {Array.<number>}
*/
getTicks: function () {
return zrUtil.map(intervalScaleProto.getTicks.call(this), function (val) {
return numberUtil.round(mathPow(LOG_BASE, val));
});
},
/**
* @param {number} val
* @return {string}
*/
getLabel: intervalScaleProto.getLabel,
/**
* @param {number} val
* @return {number}
*/
scale: function (val) {
val = scaleProto.scale.call(this, val);
return mathPow(LOG_BASE, val);
},
/**
* @param {number} start
* @param {number} end
*/
setExtent: function (start, end) {
start = mathLog(start) / mathLog(LOG_BASE);
end = mathLog(end) / mathLog(LOG_BASE);
intervalScaleProto.setExtent.call(this, start, end);
},
/**
* @return {number} end
*/
getExtent: function () {
var extent = scaleProto.getExtent.call(this);
extent[0] = mathPow(LOG_BASE, extent[0]);
extent[1] = mathPow(LOG_BASE, extent[1]);
return extent;
},
/**
* @param {Array.<number>} extent
*/
unionExtent: function (extent) {
extent[0] = mathLog(extent[0]) / mathLog(LOG_BASE);
extent[1] = mathLog(extent[1]) / mathLog(LOG_BASE);
scaleProto.unionExtent.call(this, extent);
},
/**
* Update interval and extent of intervals for nice ticks
* @param {number} [approxTickNum = 10] Given approx tick number
*/
niceTicks: function (approxTickNum) {
approxTickNum = approxTickNum || 10;
var extent = this._extent;
var span = extent[1] - extent[0];
if (span === Infinity || span <= 0) {
return;
}
var interval = mathPow(10, mathFloor(mathLog(span / approxTickNum) / Math.LN10));
var err = approxTickNum / span * interval;
// Filter ticks to get closer to the desired count.
if (err <= 0.5) {
interval *= 10;
}
var niceExtent = [
numberUtil.round(mathCeil(extent[0] / interval) * interval),
numberUtil.round(mathFloor(extent[1] / interval) * interval)
];
this._interval = interval;
this._niceExtent = niceExtent;
},
/**
* Nice extent.
* @param {number} [approxTickNum = 10] Given approx tick number
* @param {boolean} [fixMin=false]
* @param {boolean} [fixMax=false]
*/
niceExtent: intervalScaleProto.niceExtent
});
zrUtil.each(['contain', 'normalize'], function (methodName) {
LogScale.prototype[methodName] = function (val) {
val = mathLog(val) / mathLog(LOG_BASE);
return scaleProto[methodName].call(this, val);
};
});
LogScale.create = function () {
return new LogScale();
};
return LogScale;
});