Interval.js

/*
* Licensed to the Apache Software Foundation (ASF) under one
* or more contributor license agreements.  See the NOTICE file
* distributed with this work for additional information
* regarding copyright ownership.  The ASF licenses this file
* to you under the Apache License, Version 2.0 (the
* "License"); you may not use this file except in compliance
* with the License.  You may obtain a copy of the License at
*
*   http://www.apache.org/licenses/LICENSE-2.0
*
* Unless required by applicable law or agreed to in writing,
* software distributed under the License is distributed on an
* "AS IS" BASIS, WITHOUT WARRANTIES OR CONDITIONS OF ANY
* KIND, either express or implied.  See the License for the
* specific language governing permissions and limitations
* under the License.
*/

/**
 * Interval scale
 * @module echarts/scale/Interval
 */


import * as numberUtil from '../util/number';
import * as formatUtil from '../util/format';
import Scale from './Scale';
import * as helper from './helper';

var roundNumber = numberUtil.round;

/**
 * @alias module:echarts/coord/scale/Interval
 * @constructor
 */
var IntervalScale = Scale.extend({

    type: 'interval',

    _interval: 0,

    _intervalPrecision: 2,

    setExtent: function (start, end) {
        var thisExtent = this._extent;
        //start,end may be a Number like '25',so...
        if (!isNaN(start)) {
            thisExtent[0] = parseFloat(start);
        }
        if (!isNaN(end)) {
            thisExtent[1] = parseFloat(end);
        }
    },

    unionExtent: function (other) {
        var extent = this._extent;
        other[0] < extent[0] && (extent[0] = other[0]);
        other[1] > extent[1] && (extent[1] = other[1]);

        // unionExtent may called by it's sub classes
        IntervalScale.prototype.setExtent.call(this, extent[0], extent[1]);
    },
    /**
     * Get interval
     */
    getInterval: function () {
        return this._interval;
    },

    /**
     * Set interval
     */
    setInterval: function (interval) {
        this._interval = interval;
        // Dropped auto calculated niceExtent and use user setted extent
        // We assume user wan't to set both interval, min, max to get a better result
        this._niceExtent = this._extent.slice();

        this._intervalPrecision = helper.getIntervalPrecision(interval);
    },

    /**
     * @return {Array.<number>}
     */
    getTicks: function () {
        return helper.intervalScaleGetTicks(
            this._interval, this._extent, this._niceExtent, this._intervalPrecision
        );
    },

    /**
     * @param {number} data
     * @param {Object} [opt]
     * @param {number|string} [opt.precision] If 'auto', use nice presision.
     * @param {boolean} [opt.pad] returns 1.50 but not 1.5 if precision is 2.
     * @return {string}
     */
    getLabel: function (data, opt) {
        if (data == null) {
            return '';
        }

        var precision = opt && opt.precision;

        if (precision == null) {
            precision = numberUtil.getPrecisionSafe(data) || 0;
        }
        else if (precision === 'auto') {
            // Should be more precise then tick.
            precision = this._intervalPrecision;
        }

        // (1) If `precision` is set, 12.005 should be display as '12.00500'.
        // (2) Use roundNumber (toFixed) to avoid scientific notation like '3.5e-7'.
        data = roundNumber(data, precision, true);

        return formatUtil.addCommas(data);
    },

    /**
     * Update interval and extent of intervals for nice ticks
     *
     * @param {number} [splitNumber = 5] Desired number of ticks
     * @param {number} [minInterval]
     * @param {number} [maxInterval]
     */
    niceTicks: function (splitNumber, minInterval, maxInterval) {
        splitNumber = splitNumber || 5;
        var extent = this._extent;
        var span = extent[1] - extent[0];
        if (!isFinite(span)) {
            return;
        }
        // User may set axis min 0 and data are all negative
        // FIXME If it needs to reverse ?
        if (span < 0) {
            span = -span;
            extent.reverse();
        }

        var result = helper.intervalScaleNiceTicks(
            extent, splitNumber, minInterval, maxInterval
        );

        this._intervalPrecision = result.intervalPrecision;
        this._interval = result.interval;
        this._niceExtent = result.niceTickExtent;
    },

    /**
     * Nice extent.
     * @param {Object} opt
     * @param {number} [opt.splitNumber = 5] Given approx tick number
     * @param {boolean} [opt.fixMin=false]
     * @param {boolean} [opt.fixMax=false]
     * @param {boolean} [opt.minInterval]
     * @param {boolean} [opt.maxInterval]
     */
    niceExtent: function (opt) {
        var extent = this._extent;
        // If extent start and end are same, expand them
        if (extent[0] === extent[1]) {
            if (extent[0] !== 0) {
                // Expand extent
                var expandSize = extent[0];
                // In the fowllowing case
                //      Axis has been fixed max 100
                //      Plus data are all 100 and axis extent are [100, 100].
                // Extend to the both side will cause expanded max is larger than fixed max.
                // So only expand to the smaller side.
                if (!opt.fixMax) {
                    extent[1] += expandSize / 2;
                    extent[0] -= expandSize / 2;
                }
                else {
                    extent[0] -= expandSize / 2;
                }
            }
            else {
                extent[1] = 1;
            }
        }
        var span = extent[1] - extent[0];
        // If there are no data and extent are [Infinity, -Infinity]
        if (!isFinite(span)) {
            extent[0] = 0;
            extent[1] = 1;
        }

        this.niceTicks(opt.splitNumber, opt.minInterval, opt.maxInterval);

        // var extent = this._extent;
        var interval = this._interval;

        if (!opt.fixMin) {
            extent[0] = roundNumber(Math.floor(extent[0] / interval) * interval);
        }
        if (!opt.fixMax) {
            extent[1] = roundNumber(Math.ceil(extent[1] / interval) * interval);
        }
    }
});

/**
 * @return {module:echarts/scale/Time}
 */
IntervalScale.create = function () {
    return new IntervalScale();
};

export default IntervalScale;