public/en/builder/src/echarts/coord/axisTickLabelBuilder.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.
*/
import * as zrUtil from 'zrender/src/core/util';
import * as textContain from 'zrender/src/contain/text';
import { makeInner } from '../util/model';
import { makeLabelFormatter } from './axisHelper';
var inner = makeInner();
/**
 * @param {module:echats/coord/Axis} axis
 * @return {Object} {
 *     labels: [{
 *         formattedLabel: string,
 *         rawLabel: string,
 *         tickValue: number
 *     }, ...],
 *     labelCategoryInterval: number
 * }
 */

export function createAxisLabels(axis) {
  // Only ordinal scale support tick interval
  return axis.type === 'category' ? makeCategoryLabels(axis) : makeRealNumberLabels(axis);
}
/**
 * @param {module:echats/coord/Axis} axis
 * @param {module:echarts/model/Model} tickModel For example, can be axisTick, splitLine, splitArea.
 * @return {Object} {
 *     ticks: Array.<number>
 *     tickCategoryInterval: number
 * }
 */

export function createAxisTicks(axis, tickModel) {
  // Only ordinal scale support tick interval
  return axis.type === 'category' ? makeCategoryTicks(axis, tickModel) : {
    ticks: axis.scale.getTicks()
  };
}

function makeCategoryLabels(axis) {
  var labelModel = axis.getLabelModel();
  var result = makeCategoryLabelsActually(axis, labelModel);
  return !labelModel.get('show') || axis.scale.isBlank() ? {
    labels: [],
    labelCategoryInterval: result.labelCategoryInterval
  } : result;
}

function makeCategoryLabelsActually(axis, labelModel) {
  var labelsCache = getListCache(axis, 'labels');
  var optionLabelInterval = getOptionCategoryInterval(labelModel);
  var result = listCacheGet(labelsCache, optionLabelInterval);

  if (result) {
    return result;
  }

  var labels;
  var numericLabelInterval;

  if (zrUtil.isFunction(optionLabelInterval)) {
    labels = makeLabelsByCustomizedCategoryInterval(axis, optionLabelInterval);
  } else {
    numericLabelInterval = optionLabelInterval === 'auto' ? makeAutoCategoryInterval(axis) : optionLabelInterval;
    labels = makeLabelsByNumericCategoryInterval(axis, numericLabelInterval);
  } // Cache to avoid calling interval function repeatly.


  return listCacheSet(labelsCache, optionLabelInterval, {
    labels: labels,
    labelCategoryInterval: numericLabelInterval
  });
}

function makeCategoryTicks(axis, tickModel) {
  var ticksCache = getListCache(axis, 'ticks');
  var optionTickInterval = getOptionCategoryInterval(tickModel);
  var result = listCacheGet(ticksCache, optionTickInterval);

  if (result) {
    return result;
  }

  var ticks;
  var tickCategoryInterval; // Optimize for the case that large category data and no label displayed,
  // we should not return all ticks.

  if (!tickModel.get('show') || axis.scale.isBlank()) {
    ticks = [];
  }

  if (zrUtil.isFunction(optionTickInterval)) {
    ticks = makeLabelsByCustomizedCategoryInterval(axis, optionTickInterval, true);
  } // Always use label interval by default despite label show. Consider this
  // scenario, Use multiple grid with the xAxis sync, and only one xAxis shows
  // labels. `splitLine` and `axisTick` should be consistent in this case.
  else if (optionTickInterval === 'auto') {
      var labelsResult = makeCategoryLabelsActually(axis, axis.getLabelModel());
      tickCategoryInterval = labelsResult.labelCategoryInterval;
      ticks = zrUtil.map(labelsResult.labels, function (labelItem) {
        return labelItem.tickValue;
      });
    } else {
      tickCategoryInterval = optionTickInterval;
      ticks = makeLabelsByNumericCategoryInterval(axis, tickCategoryInterval, true);
    } // Cache to avoid calling interval function repeatly.


  return listCacheSet(ticksCache, optionTickInterval, {
    ticks: ticks,
    tickCategoryInterval: tickCategoryInterval
  });
}

function makeRealNumberLabels(axis) {
  var ticks = axis.scale.getTicks();
  var labelFormatter = makeLabelFormatter(axis);
  return {
    labels: zrUtil.map(ticks, function (tickValue, idx) {
      return {
        formattedLabel: labelFormatter(tickValue, idx),
        rawLabel: axis.scale.getLabel(tickValue),
        tickValue: tickValue
      };
    })
  };
} // Large category data calculation is performence sensitive, and ticks and label
// probably be fetched by multiple times. So we cache the result.
// axis is created each time during a ec process, so we do not need to clear cache.


function getListCache(axis, prop) {
  // Because key can be funciton, and cache size always be small, we use array cache.
  return inner(axis)[prop] || (inner(axis)[prop] = []);
}

function listCacheGet(cache, key) {
  for (var i = 0; i < cache.length; i++) {
    if (cache[i].key === key) {
      return cache[i].value;
    }
  }
}

function listCacheSet(cache, key, value) {
  cache.push({
    key: key,
    value: value
  });
  return value;
}

function makeAutoCategoryInterval(axis) {
  var result = inner(axis).autoInterval;
  return result != null ? result : inner(axis).autoInterval = axis.calculateCategoryInterval();
}
/**
 * Calculate interval for category axis ticks and labels.
 * To get precise result, at least one of `getRotate` and `isHorizontal`
 * should be implemented in axis.
 */


export function calculateCategoryInterval(axis) {
  var params = fetchAutoCategoryIntervalCalculationParams(axis);
  var labelFormatter = makeLabelFormatter(axis);
  var rotation = (params.axisRotate - params.labelRotate) / 180 * Math.PI;
  var ordinalScale = axis.scale;
  var ordinalExtent = ordinalScale.getExtent(); // Providing this method is for optimization:
  // avoid generating a long array by `getTicks`
  // in large category data case.

  var tickCount = ordinalScale.count();

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

  var step = 1; // Simple optimization. Empirical value: tick count should less than 40.

  if (tickCount > 40) {
    step = Math.max(1, Math.floor(tickCount / 40));
  }

  var tickValue = ordinalExtent[0];
  var unitSpan = axis.dataToCoord(tickValue + 1) - axis.dataToCoord(tickValue);
  var unitW = Math.abs(unitSpan * Math.cos(rotation));
  var unitH = Math.abs(unitSpan * Math.sin(rotation));
  var maxW = 0;
  var maxH = 0; // Caution: Performance sensitive for large category data.
  // Consider dataZoom, we should make appropriate step to avoid O(n) loop.

  for (; tickValue <= ordinalExtent[1]; tickValue += step) {
    var width = 0;
    var height = 0; // Not precise, do not consider align and vertical align
    // and each distance from axis line yet.

    var rect = textContain.getBoundingRect(labelFormatter(tickValue), params.font, 'center', 'top'); // Magic number

    width = rect.width * 1.3;
    height = rect.height * 1.3; // Min size, void long loop.

    maxW = Math.max(maxW, width, 7);
    maxH = Math.max(maxH, height, 7);
  }

  var dw = maxW / unitW;
  var dh = maxH / unitH; // 0/0 is NaN, 1/0 is Infinity.

  isNaN(dw) && (dw = Infinity);
  isNaN(dh) && (dh = Infinity);
  var interval = Math.max(0, Math.floor(Math.min(dw, dh)));
  var cache = inner(axis.model);
  var lastAutoInterval = cache.lastAutoInterval;
  var 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;
}

function fetchAutoCategoryIntervalCalculationParams(axis) {
  var labelModel = axis.getLabelModel();
  return {
    axisRotate: axis.getRotate ? axis.getRotate() : axis.isHorizontal && !axis.isHorizontal() ? 90 : 0,
    labelRotate: labelModel.get('rotate') || 0,
    font: labelModel.getFont()
  };
}

function makeLabelsByNumericCategoryInterval(axis, categoryInterval, onlyTick) {
  var labelFormatter = makeLabelFormatter(axis);
  var ordinalScale = axis.scale;
  var ordinalExtent = ordinalScale.getExtent();
  var labelModel = axis.getLabelModel();
  var result = []; // TODO: axisType: ordinalTime, pick the tick from each month/day/year/...

  var step = Math.max((categoryInterval || 0) + 1, 1);
  var startTick = ordinalExtent[0];
  var tickCount = ordinalScale.count(); // Calculate start tick based on zero if possible to keep label consistent
  // while zooming and moving while interval > 0. Otherwise the selection
  // of displayable ticks and symbols probably keep changing.
  // 3 is empirical value.

  if (startTick !== 0 && step > 1 && tickCount / step > 2) {
    startTick = Math.round(Math.ceil(startTick / step) * step);
  } // (1) Only add min max label here but leave overlap checking
  // to render stage, which also ensure the returned list
  // suitable for splitLine and splitArea rendering.
  // (2) Scales except category always contain min max label so
  // do not need to perform this process.


  var showMinMax = {
    min: labelModel.get('showMinLabel'),
    max: labelModel.get('showMaxLabel')
  };

  if (showMinMax.min && startTick !== ordinalExtent[0]) {
    addItem(ordinalExtent[0]);
  } // Optimize: avoid generating large array by `ordinalScale.getTicks()`.


  var tickValue = startTick;

  for (; tickValue <= ordinalExtent[1]; tickValue += step) {
    addItem(tickValue);
  }

  if (showMinMax.max && tickValue !== ordinalExtent[1]) {
    addItem(ordinalExtent[1]);
  }

  function addItem(tVal) {
    result.push(onlyTick ? tVal : {
      formattedLabel: labelFormatter(tVal),
      rawLabel: ordinalScale.getLabel(tVal),
      tickValue: tVal
    });
  }

  return result;
} // When interval is function, the result `false` means ignore the tick.
// It is time consuming for large category data.


function makeLabelsByCustomizedCategoryInterval(axis, categoryInterval, onlyTick) {
  var ordinalScale = axis.scale;
  var labelFormatter = makeLabelFormatter(axis);
  var result = [];
  zrUtil.each(ordinalScale.getTicks(), function (tickValue) {
    var rawLabel = ordinalScale.getLabel(tickValue);

    if (categoryInterval(tickValue, rawLabel)) {
      result.push(onlyTick ? tickValue : {
        formattedLabel: labelFormatter(tickValue),
        rawLabel: rawLabel,
        tickValue: tickValue
      });
    }
  });
  return result;
} // Can be null|'auto'|number|function


function getOptionCategoryInterval(model) {
  var interval = model.get('interval');
  return interval == null ? 'auto' : interval;
}