chart.js
Version:
Simple HTML5 charts using the canvas element.
331 lines (285 loc) • 10.2 kB
JavaScript
;
var helpers = require('../helpers/index');
/**
* Helper function to get relative position for an event
* @param {Event|IEvent} event - The event to get the position for
* @param {Chart} chart - The chart
* @returns {Point} the event position
*/
function getRelativePosition(e, chart) {
if (e.native) {
return {
x: e.x,
y: e.y
};
}
return helpers.getRelativePosition(e, chart);
}
/**
* Helper function to traverse all of the visible elements in the chart
* @param chart {chart} the chart
* @param handler {Function} the callback to execute for each visible item
*/
function parseVisibleItems(chart, handler) {
var datasets = chart.data.datasets;
var meta, i, j, ilen, jlen;
for (i = 0, ilen = datasets.length; i < ilen; ++i) {
if (!chart.isDatasetVisible(i)) {
continue;
}
meta = chart.getDatasetMeta(i);
for (j = 0, jlen = meta.data.length; j < jlen; ++j) {
var element = meta.data[j];
if (!element._view.skip) {
handler(element);
}
}
}
}
/**
* Helper function to get the items that intersect the event position
* @param items {ChartElement[]} elements to filter
* @param position {Point} the point to be nearest to
* @return {ChartElement[]} the nearest items
*/
function getIntersectItems(chart, position) {
var elements = [];
parseVisibleItems(chart, function(element) {
if (element.inRange(position.x, position.y)) {
elements.push(element);
}
});
return elements;
}
/**
* Helper function to get the items nearest to the event position considering all visible items in teh chart
* @param chart {Chart} the chart to look at elements from
* @param position {Point} the point to be nearest to
* @param intersect {Boolean} if true, only consider items that intersect the position
* @param distanceMetric {Function} function to provide the distance between points
* @return {ChartElement[]} the nearest items
*/
function getNearestItems(chart, position, intersect, distanceMetric) {
var minDistance = Number.POSITIVE_INFINITY;
var nearestItems = [];
parseVisibleItems(chart, function(element) {
if (intersect && !element.inRange(position.x, position.y)) {
return;
}
var center = element.getCenterPoint();
var distance = distanceMetric(position, center);
if (distance < minDistance) {
nearestItems = [element];
minDistance = distance;
} else if (distance === minDistance) {
// Can have multiple items at the same distance in which case we sort by size
nearestItems.push(element);
}
});
return nearestItems;
}
/**
* Get a distance metric function for two points based on the
* axis mode setting
* @param {String} axis the axis mode. x|y|xy
*/
function getDistanceMetricForAxis(axis) {
var useX = axis.indexOf('x') !== -1;
var useY = axis.indexOf('y') !== -1;
return function(pt1, pt2) {
var deltaX = useX ? Math.abs(pt1.x - pt2.x) : 0;
var deltaY = useY ? Math.abs(pt1.y - pt2.y) : 0;
return Math.sqrt(Math.pow(deltaX, 2) + Math.pow(deltaY, 2));
};
}
function indexMode(chart, e, options) {
var position = getRelativePosition(e, chart);
// Default axis for index mode is 'x' to match old behaviour
options.axis = options.axis || 'x';
var distanceMetric = getDistanceMetricForAxis(options.axis);
var items = options.intersect ? getIntersectItems(chart, position) : getNearestItems(chart, position, false, distanceMetric);
var elements = [];
if (!items.length) {
return [];
}
chart.data.datasets.forEach(function(dataset, datasetIndex) {
if (chart.isDatasetVisible(datasetIndex)) {
var meta = chart.getDatasetMeta(datasetIndex);
var element = meta.data[items[0]._index];
// don't count items that are skipped (null data)
if (element && !element._view.skip) {
elements.push(element);
}
}
});
return elements;
}
/**
* @interface IInteractionOptions
*/
/**
* If true, only consider items that intersect the point
* @name IInterfaceOptions#boolean
* @type Boolean
*/
/**
* Contains interaction related functions
* @namespace Chart.Interaction
*/
module.exports = {
// Helper function for different modes
modes: {
single: function(chart, e) {
var position = getRelativePosition(e, chart);
var elements = [];
parseVisibleItems(chart, function(element) {
if (element.inRange(position.x, position.y)) {
elements.push(element);
return elements;
}
});
return elements.slice(0, 1);
},
/**
* @function Chart.Interaction.modes.label
* @deprecated since version 2.4.0
* @todo remove at version 3
* @private
*/
label: indexMode,
/**
* Returns items at the same index. If the options.intersect parameter is true, we only return items if we intersect something
* If the options.intersect mode is false, we find the nearest item and return the items at the same index as that item
* @function Chart.Interaction.modes.index
* @since v2.4.0
* @param chart {chart} the chart we are returning items from
* @param e {Event} the event we are find things at
* @param options {IInteractionOptions} options to use during interaction
* @return {Chart.Element[]} Array of elements that are under the point. If none are found, an empty array is returned
*/
index: indexMode,
/**
* Returns items in the same dataset. If the options.intersect parameter is true, we only return items if we intersect something
* If the options.intersect is false, we find the nearest item and return the items in that dataset
* @function Chart.Interaction.modes.dataset
* @param chart {chart} the chart we are returning items from
* @param e {Event} the event we are find things at
* @param options {IInteractionOptions} options to use during interaction
* @return {Chart.Element[]} Array of elements that are under the point. If none are found, an empty array is returned
*/
dataset: function(chart, e, options) {
var position = getRelativePosition(e, chart);
options.axis = options.axis || 'xy';
var distanceMetric = getDistanceMetricForAxis(options.axis);
var items = options.intersect ? getIntersectItems(chart, position) : getNearestItems(chart, position, false, distanceMetric);
if (items.length > 0) {
items = chart.getDatasetMeta(items[0]._datasetIndex).data;
}
return items;
},
/**
* @function Chart.Interaction.modes.x-axis
* @deprecated since version 2.4.0. Use index mode and intersect == true
* @todo remove at version 3
* @private
*/
'x-axis': function(chart, e) {
return indexMode(chart, e, {intersect: false});
},
/**
* Point mode returns all elements that hit test based on the event position
* of the event
* @function Chart.Interaction.modes.intersect
* @param chart {chart} the chart we are returning items from
* @param e {Event} the event we are find things at
* @return {Chart.Element[]} Array of elements that are under the point. If none are found, an empty array is returned
*/
point: function(chart, e) {
var position = getRelativePosition(e, chart);
return getIntersectItems(chart, position);
},
/**
* nearest mode returns the element closest to the point
* @function Chart.Interaction.modes.intersect
* @param chart {chart} the chart we are returning items from
* @param e {Event} the event we are find things at
* @param options {IInteractionOptions} options to use
* @return {Chart.Element[]} Array of elements that are under the point. If none are found, an empty array is returned
*/
nearest: function(chart, e, options) {
var position = getRelativePosition(e, chart);
options.axis = options.axis || 'xy';
var distanceMetric = getDistanceMetricForAxis(options.axis);
var nearestItems = getNearestItems(chart, position, options.intersect, distanceMetric);
// We have multiple items at the same distance from the event. Now sort by smallest
if (nearestItems.length > 1) {
nearestItems.sort(function(a, b) {
var sizeA = a.getArea();
var sizeB = b.getArea();
var ret = sizeA - sizeB;
if (ret === 0) {
// if equal sort by dataset index
ret = a._datasetIndex - b._datasetIndex;
}
return ret;
});
}
// Return only 1 item
return nearestItems.slice(0, 1);
},
/**
* x mode returns the elements that hit-test at the current x coordinate
* @function Chart.Interaction.modes.x
* @param chart {chart} the chart we are returning items from
* @param e {Event} the event we are find things at
* @param options {IInteractionOptions} options to use
* @return {Chart.Element[]} Array of elements that are under the point. If none are found, an empty array is returned
*/
x: function(chart, e, options) {
var position = getRelativePosition(e, chart);
var items = [];
var intersectsItem = false;
parseVisibleItems(chart, function(element) {
if (element.inXRange(position.x)) {
items.push(element);
}
if (element.inRange(position.x, position.y)) {
intersectsItem = true;
}
});
// If we want to trigger on an intersect and we don't have any items
// that intersect the position, return nothing
if (options.intersect && !intersectsItem) {
items = [];
}
return items;
},
/**
* y mode returns the elements that hit-test at the current y coordinate
* @function Chart.Interaction.modes.y
* @param chart {chart} the chart we are returning items from
* @param e {Event} the event we are find things at
* @param options {IInteractionOptions} options to use
* @return {Chart.Element[]} Array of elements that are under the point. If none are found, an empty array is returned
*/
y: function(chart, e, options) {
var position = getRelativePosition(e, chart);
var items = [];
var intersectsItem = false;
parseVisibleItems(chart, function(element) {
if (element.inYRange(position.y)) {
items.push(element);
}
if (element.inRange(position.x, position.y)) {
intersectsItem = true;
}
});
// If we want to trigger on an intersect and we don't have any items
// that intersect the position, return nothing
if (options.intersect && !intersectsItem) {
items = [];
}
return items;
}
}
};