scale.financialLinear.js

'use strict';

module.exports = function(Chart) {

	var helpers = Chart.helpers;

	var defaultConfig = {
		position: 'left',
		ticks: {
			// Copied from Ticks.formatters.linear
			callback: function(tickValue, index, ticks) {
				// If we have lots of ticks, don't use the ones
				var delta = ticks.length > 3 ? ticks[2] - ticks[1] : ticks[1] - ticks[0];

				// If we have a number like 2.5 as the delta, figure out how many decimal places we need
				if (Math.abs(delta) > 1) {
					if (tickValue !== Math.floor(tickValue)) {
						// not an integer
						delta = tickValue - Math.floor(tickValue);
					}
				}

				var logDelta = helpers.log10(Math.abs(delta));
				var tickString = '';

				if (tickValue !== 0) {
					var numDecimal = -1 * Math.floor(logDelta);
					numDecimal = Math.max(Math.min(numDecimal, 20), 0); // toFixed has a max of 20 decimal places
					tickString = tickValue.toFixed(numDecimal);
				} else {
					tickString = '0'; // never show decimal places for 0
				}

				return tickString;
			}
		}
	};

	var FinancialLinearScale = Chart.scaleService.getScaleConstructor('linear').extend({

		determineDataLimits: function() {
			var me = this;
			var chart = me.chart;
			var data = chart.data;
			var datasets = data.datasets;
			var isHorizontal = me.isHorizontal();

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

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

			// Regular charts use x, y values
			// For the financial chart we have rawValue.h (hi) and rawValue.l (low) for each point
			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 high = rawValue.h;
						var low = rawValue.l;
			
						if (me.min === null) {
							me.min = low;
						} else if (low < me.min) {
							me.min = low;
						}
		
						if (me.max === null) {
							me.max = high;
						} else if (high > me.max) {
							me.max = high;
						}
					});
				}
			});

			// Add whitespace around bars. Axis shouldn't go exactly from min to max
			me.min = me.min - me.min * 0.05;
			me.max = me.max + me.max * 0.05;

			// Common base implementation to handle ticks.min, ticks.max, ticks.beginAtZero
			this.handleTickRangeOptions();
		}
	});
	Chart.scaleService.registerScaleType('financialLinear', FinancialLinearScale, defaultConfig);

};