src/coord/polar/AngleAxis.ts

/*
* 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.
*/

import * as textContain from 'zrender/src/contain/text';
import Axis from '../Axis';
import {makeInner} from '../../util/model';
import Scale from '../../scale/Scale';
import OrdinalScale from '../../scale/Ordinal';
import Polar from './Polar';
import { AngleAxisModel } from './AxisModel';

const inner = makeInner<{
    lastAutoInterval: number
    lastTickCount: number
}, AngleAxisModel>();

interface AngleAxis {
    dataToAngle: Axis['dataToCoord']
    angleToData: Axis['coordToData']
}
class AngleAxis extends Axis {

    polar: Polar;

    model: AngleAxisModel;

    constructor(scale?: Scale, angleExtent?: [number, number]) {
        super('angle', scale, angleExtent || [0, 360]);
    }

    pointToData(point: number[], clamp?: boolean) {
        return this.polar.pointToData(point, clamp)[this.dim === 'radius' ? 0 : 1];
    }

    /**
     * Only be called in category axis.
     * Angle axis uses text height to decide interval
     *
     * @override
     * @return {number} Auto interval for cateogry axis tick and label
     */
    calculateCategoryInterval() {
        const axis = this;
        const labelModel = axis.getLabelModel();

        const ordinalScale = axis.scale as OrdinalScale;
        const ordinalExtent = ordinalScale.getExtent();
        // Providing this method is for optimization:
        // avoid generating a long array by `getTicks`
        // in large category data case.
        const tickCount = ordinalScale.count();

        if (ordinalExtent[1] - ordinalExtent[0] < 1) {
            return 0;
        }

        const tickValue = ordinalExtent[0];
        const unitSpan = axis.dataToCoord(tickValue + 1) - axis.dataToCoord(tickValue);
        const unitH = Math.abs(unitSpan);

        // Not precise, just use height as text width
        // and each distance from axis line yet.
        const rect = textContain.getBoundingRect(
            tickValue == null ? '' : tickValue + '',
            labelModel.getFont(),
            'center',
            'top'
        );
        const maxH = Math.max(rect.height, 7);

        let dh = maxH / unitH;
        // 0/0 is NaN, 1/0 is Infinity.
        isNaN(dh) && (dh = Infinity);
        let interval = Math.max(0, Math.floor(dh));

        const cache = inner(axis.model);
        const lastAutoInterval = cache.lastAutoInterval;
        const lastTickCount = cache.lastTickCount;

        // Use cache to keep interval stable while moving zoom window,
        // otherwise the calculated interval might jitter when the zoom
        // window size is close to the interval-changing size.
        if (lastAutoInterval != null
            && lastTickCount != null
            && Math.abs(lastAutoInterval - interval) <= 1
            && Math.abs(lastTickCount - tickCount) <= 1
            // Always choose the bigger one, otherwise the critical
            // point is not the same when zooming in or zooming out.
            && lastAutoInterval > interval
        ) {
            interval = lastAutoInterval;
        }
        // Only update cache if cache not used, otherwise the
        // changing of interval is too insensitive.
        else {
            cache.lastTickCount = tickCount;
            cache.lastAutoInterval = interval;
        }

        return interval;
    }
}

AngleAxis.prototype.dataToAngle = Axis.prototype.dataToCoord;

AngleAxis.prototype.angleToData = Axis.prototype.coordToData;


export default AngleAxis;