export function alignScaleTicks()

in src/coord/axisAlignTicks.ts [32:142]

• 87 lines of code
• 24 McCabe index (conditional complexity)

export function alignScaleTicks(
    scale: IntervalScale | LogScale,
    axisModel: AxisBaseModel<Pick<NumericAxisBaseOptionCommon, 'min' | 'max'>>,
    alignToScale: IntervalScale | LogScale
) {

    const intervalScaleProto = IntervalScale.prototype;

    // NOTE: There is a precondition for log scale  here:
    // In log scale we store _interval and _extent of exponent value.
    // So if we use the method of InternalScale to set/get these data.
    // It process the exponent value, which is linear and what we want here.
    const alignToTicks = intervalScaleProto.getTicks.call(alignToScale);
    const alignToNicedTicks = intervalScaleProto.getTicks.call(alignToScale, true);
    const alignToSplitNumber = alignToTicks.length - 1;
    const alignToInterval = intervalScaleProto.getInterval.call(alignToScale);

    const scaleExtent = getScaleExtent(scale, axisModel);
    let rawExtent = scaleExtent.extent;
    const isMinFixed = scaleExtent.fixMin;
    const isMaxFixed = scaleExtent.fixMax;

    if (scale.type === 'log') {
        const logBase = mathLog((scale as LogScale).base);
        rawExtent = [mathLog(rawExtent[0]) / logBase, mathLog(rawExtent[1]) / logBase];
    }

    scale.setExtent(rawExtent[0], rawExtent[1]);
    scale.calcNiceExtent({
        splitNumber: alignToSplitNumber,
        fixMin: isMinFixed,
        fixMax: isMaxFixed
    });
    const extent = intervalScaleProto.getExtent.call(scale);

    // Need to update the rawExtent.
    // Because value in rawExtent may be not parsed. e.g. 'dataMin', 'dataMax'
    if (isMinFixed) {
        rawExtent[0] = extent[0];
    }
    if (isMaxFixed) {
        rawExtent[1] = extent[1];
    }

    let interval = intervalScaleProto.getInterval.call(scale);
    let min: number = rawExtent[0];
    let max: number = rawExtent[1];

    if (isMinFixed && isMaxFixed) {
        // User set min, max, divide to get new interval
        interval = (max - min) / alignToSplitNumber;
    }
    else if (isMinFixed) {
        max = rawExtent[0] + interval * alignToSplitNumber;
        // User set min, expand extent on the other side
        while (max < rawExtent[1] && isFinite(max) && isFinite(rawExtent[1])) {
            interval = increaseInterval(interval);
            max = rawExtent[0] + interval * alignToSplitNumber;
        }
    }
    else if (isMaxFixed) {
        // User set max, expand extent on the other side
        min = rawExtent[1] - interval * alignToSplitNumber;
        while (min > rawExtent[0] && isFinite(min) && isFinite(rawExtent[0])) {
            interval = increaseInterval(interval);
            min = rawExtent[1] - interval * alignToSplitNumber;
        }
    }
    else {
        const nicedSplitNumber = scale.getTicks().length - 1;
        if (nicedSplitNumber > alignToSplitNumber) {
            interval = increaseInterval(interval);
        }

        const range = interval * alignToSplitNumber;
        max = Math.ceil(rawExtent[1] / interval) * interval;
        min = round(max - range);
        // Not change the result that crossing zero.
        if (min < 0 && rawExtent[0] >= 0) {
            min = 0;
            max = round(range);
        }
        else if (max > 0 && rawExtent[1] <= 0) {
            max = 0;
            min = -round(range);
        }

    }

    // Adjust min, max based on the extent of alignTo. When min or max is set in alignTo scale
    const t0 = (alignToTicks[0].value - alignToNicedTicks[0].value) / alignToInterval;
    const t1 = (alignToTicks[alignToSplitNumber].value - alignToNicedTicks[alignToSplitNumber].value) / alignToInterval;

    // NOTE: Must in setExtent -> setInterval -> setNiceExtent order.
    intervalScaleProto.setExtent.call(scale, min + interval * t0, max + interval * t1);
    intervalScaleProto.setInterval.call(scale, interval);
    if (t0 || t1) {
        intervalScaleProto.setNiceExtent.call(scale, min + interval, max - interval);
    }

    if (__DEV__) {
        const ticks = intervalScaleProto.getTicks.call(scale);
        if (ticks[1]
            && (!isValueNice(interval) || getPrecisionSafe(ticks[1].value) > getPrecisionSafe(interval))) {
            warn(
                // eslint-disable-next-line
                `The ticks may be not readable when set min: ${axisModel.get('min')}, max: ${axisModel.get('max')} and alignTicks: true`
            );
        }
    }
}