Chart.js/src/scales/scale.linear.js

'use strict';

module.exports = function(Chart) {

	var helpers = Chart.helpers;

	var defaultConfig = {
		position: 'left',
		ticks: {
			callback: Chart.Ticks.formatters.linear
		}
	};

	var LinearScale = Chart.LinearScaleBase.extend({

		determineDataLimits: function() {
			var me = this;
			var opts = me.options;
			var chart = me.chart;
			var data = chart.data;
			var datasets = data.datasets;
			var isHorizontal = me.isHorizontal();
			var DEFAULT_MIN = 0;
			var DEFAULT_MAX = 1;

			function IDMatches(meta) {
				return isHorizontal ? meta.xAxisID === me.id : meta.yAxisID === me.id;
			}

			// First Calculate the range
			me.min = null;
			me.max = null;

			var hasStacks = opts.stacked;
			if (hasStacks === undefined) {
				helpers.each(datasets, function(dataset, datasetIndex) {
					if (hasStacks) {
						return;
					}

					var meta = chart.getDatasetMeta(datasetIndex);
					if (chart.isDatasetVisible(datasetIndex) && IDMatches(meta) &&
						meta.stack !== undefined) {
						hasStacks = true;
					}
				});
			}

			if (opts.stacked || hasStacks) {
				var valuesPerStack = {};

				helpers.each(datasets, function(dataset, datasetIndex) {
					var meta = chart.getDatasetMeta(datasetIndex);
					var key = [
						meta.type,
						// we have a separate stack for stack=undefined datasets when the opts.stacked is undefined
						((opts.stacked === undefined && meta.stack === undefined) ? datasetIndex : ''),
						meta.stack
					].join('.');

					if (valuesPerStack[key] === undefined) {
						valuesPerStack[key] = {
							positiveValues: [],
							negativeValues: []
						};
					}

					// Store these per type
					var positiveValues = valuesPerStack[key].positiveValues;
					var negativeValues = valuesPerStack[key].negativeValues;

					if (chart.isDatasetVisible(datasetIndex) && IDMatches(meta)) {
						helpers.each(dataset.data, function(rawValue, index) {
							var value = +me.getRightValue(rawValue);
							if (isNaN(value) || meta.data[index].hidden) {
								return;
							}

							positiveValues[index] = positiveValues[index] || 0;
							negativeValues[index] = negativeValues[index] || 0;

							if (opts.relativePoints) {
								positiveValues[index] = 100;
							} else if (value < 0) {
								negativeValues[index] += value;
							} else {
								positiveValues[index] += value;
							}
						});
					}
				});

				helpers.each(valuesPerStack, function(valuesForType) {
					var values = valuesForType.positiveValues.concat(valuesForType.negativeValues);
					var minVal = helpers.min(values);
					var maxVal = helpers.max(values);
					me.min = me.min === null ? minVal : Math.min(me.min, minVal);
					me.max = me.max === null ? maxVal : Math.max(me.max, maxVal);
				});

			} else {
				helpers.each(datasets, function(dataset, datasetIndex) {
					var meta = chart.getDatasetMeta(datasetIndex);
					if (chart.isDatasetVisible(datasetIndex) && IDMatches(meta)) {
						helpers.each(dataset.data, function(rawValue, index) {
							var value = +me.getRightValue(rawValue);
							if (isNaN(value) || meta.data[index].hidden) {
								return;
							}

							if (me.min === null) {
								me.min = value;
							} else if (value < me.min) {
								me.min = value;
							}

							if (me.max === null) {
								me.max = value;
							} else if (value > me.max) {
								me.max = value;
							}
						});
					}
				});
			}

			me.min = isFinite(me.min) ? me.min : DEFAULT_MIN;
			me.max = isFinite(me.max) ? me.max : DEFAULT_MAX;

			// Common base implementation to handle ticks.min, ticks.max, ticks.beginAtZero
			this.handleTickRangeOptions();
		},
		getTickLimit: function() {
			var maxTicks;
			var me = this;
			var tickOpts = me.options.ticks;

			if (me.isHorizontal()) {
				maxTicks = Math.min(tickOpts.maxTicksLimit ? tickOpts.maxTicksLimit : 11, Math.ceil(me.width / 50));
			} else {
				// The factor of 2 used to scale the font size has been experimentally determined.
				var tickFontSize = helpers.valueOrDefault(tickOpts.fontSize, Chart.defaults.global.defaultFontSize);
				maxTicks = Math.min(tickOpts.maxTicksLimit ? tickOpts.maxTicksLimit : 11, Math.ceil(me.height / (2 * tickFontSize)));
			}

			return maxTicks;
		},
		// Called after the ticks are built. We need
		handleDirectionalChanges: function() {
			if (!this.isHorizontal()) {
				// We are in a vertical orientation. The top value is the highest. So reverse the array
				this.ticks.reverse();
			}
		},
		getLabelForIndex: function(index, datasetIndex) {
			return +this.getRightValue(this.chart.data.datasets[datasetIndex].data[index]);
		},
		// Utils
		getPixelForValue: function(value) {
			// This must be called after fit has been run so that
			// this.left, this.top, this.right, and this.bottom have been defined
			var me = this;
			var start = me.start;

			var rightValue = +me.getRightValue(value);
			var pixel;
			var range = me.end - start;

			if (me.isHorizontal()) {
				pixel = me.left + (me.width / range * (rightValue - start));
				return Math.round(pixel);
			}

			pixel = me.bottom - (me.height / range * (rightValue - start));
			return Math.round(pixel);
		},
		getValueForPixel: function(pixel) {
			var me = this;
			var isHorizontal = me.isHorizontal();
			var innerDimension = isHorizontal ? me.width : me.height;
			var offset = (isHorizontal ? pixel - me.left : me.bottom - pixel) / innerDimension;
			return me.start + ((me.end - me.start) * offset);
		},
		getPixelForTick: function(index) {
			return this.getPixelForValue(this.ticksAsNumbers[index]);
		}
	});
	Chart.scaleService.registerScaleType('linear', LinearScale, defaultConfig);

};