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core.interaction.js
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core.interaction.js
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import {_isPointInArea} from '../helpers/helpers.canvas';
import {_lookupByKey, _rlookupByKey} from '../helpers/helpers.collection';
import {getRelativePosition as helpersGetRelativePosition} from '../helpers/helpers.dom';
/**
* @typedef { import("./core.controller").default } Chart
* @typedef { import("../platform/platform.base").ChartEvent } ChartEvent
* @typedef {{axis?: string, intersect?: boolean}} InteractionOptions
* @typedef {{datasetIndex: number, index: number, element: import("./core.element").default}} InteractionItem
*/
/**
* Helper function to get relative position for an event
* @param {Event|ChartEvent} e - The event to get the position for
* @param {Chart} chart - The chart
* @returns {object} the event position
*/
function getRelativePosition(e, chart) {
if ('native' in e) {
return {
x: e.x,
y: e.y
};
}
return helpersGetRelativePosition(e, chart);
}
/**
* Helper function to traverse all of the visible elements in the chart
* @param {Chart} chart - the chart
* @param {function} handler - the callback to execute for each visible item
*/
function evaluateAllVisibleItems(chart, handler) {
const metasets = chart.getSortedVisibleDatasetMetas();
let index, data, element;
for (let i = 0, ilen = metasets.length; i < ilen; ++i) {
({index, data} = metasets[i]);
for (let j = 0, jlen = data.length; j < jlen; ++j) {
element = data[j];
if (!element.skip) {
handler(element, index, j);
}
}
}
}
/**
* Helper function to do binary search when possible
* @param {object} metaset - the dataset meta
* @param {string} axis - the axis mide. x|y|xy
* @param {number} value - the value to find
* @param {boolean} [intersect] - should the element intersect
* @returns {{lo:number, hi:number}} indices to search data array between
*/
function binarySearch(metaset, axis, value, intersect) {
const {controller, data, _sorted} = metaset;
const iScale = controller._cachedMeta.iScale;
if (iScale && axis === iScale.axis && _sorted && data.length) {
const lookupMethod = iScale._reversePixels ? _rlookupByKey : _lookupByKey;
if (!intersect) {
return lookupMethod(data, axis, value);
} else if (controller._sharedOptions) {
// _sharedOptions indicates that each element has equal options -> equal proportions
// So we can do a ranged binary search based on the range of first element and
// be confident to get the full range of indices that can intersect with the value.
const el = data[0];
const range = typeof el.getRange === 'function' && el.getRange(axis);
if (range) {
const start = lookupMethod(data, axis, value - range);
const end = lookupMethod(data, axis, value + range);
return {lo: start.lo, hi: end.hi};
}
}
}
// Default to all elements, when binary search can not be used.
return {lo: 0, hi: data.length - 1};
}
/**
* Helper function to get items using binary search, when the data is sorted.
* @param {Chart} chart - the chart
* @param {string} axis - the axis mode. x|y|xy
* @param {object} position - the point to be nearest to
* @param {function} handler - the callback to execute for each visible item
* @param {boolean} [intersect] - consider intersecting items
*/
function optimizedEvaluateItems(chart, axis, position, handler, intersect) {
const metasets = chart.getSortedVisibleDatasetMetas();
const value = position[axis];
for (let i = 0, ilen = metasets.length; i < ilen; ++i) {
const {index, data} = metasets[i];
const {lo, hi} = binarySearch(metasets[i], axis, value, intersect);
for (let j = lo; j <= hi; ++j) {
const element = data[j];
if (!element.skip) {
handler(element, index, j);
}
}
}
}
/**
* 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) {
const useX = axis.indexOf('x') !== -1;
const useY = axis.indexOf('y') !== -1;
return function(pt1, pt2) {
const deltaX = useX ? Math.abs(pt1.x - pt2.x) : 0;
const deltaY = useY ? Math.abs(pt1.y - pt2.y) : 0;
return Math.sqrt(Math.pow(deltaX, 2) + Math.pow(deltaY, 2));
};
}
/**
* Helper function to get the items that intersect the event position
* @param {Chart} chart - the chart
* @param {object} position - the point to be nearest to
* @param {string} axis - the axis mode. x|y|xy
* @param {boolean} [useFinalPosition] - use the element's animation target instead of current position
* @return {InteractionItem[]} the nearest items
*/
function getIntersectItems(chart, position, axis, useFinalPosition) {
const items = [];
if (!_isPointInArea(position, chart.chartArea, chart._minPadding)) {
return items;
}
const evaluationFunc = function(element, datasetIndex, index) {
if (element.inRange(position.x, position.y, useFinalPosition)) {
items.push({element, datasetIndex, index});
}
};
optimizedEvaluateItems(chart, axis, position, evaluationFunc, true);
return items;
}
/**
* Helper function to get the items nearest to the event position considering all visible items in the chart
* @param {Chart} chart - the chart to look at elements from
* @param {object} position - the point to be nearest to
* @param {string} axis - the axes along which to measure distance
* @param {boolean} [intersect] - if true, only consider items that intersect the position
* @param {boolean} [useFinalPosition] - use the elements animation target instead of current position
* @return {InteractionItem[]} the nearest items
*/
function getNearestItems(chart, position, axis, intersect, useFinalPosition) {
const distanceMetric = getDistanceMetricForAxis(axis);
let minDistance = Number.POSITIVE_INFINITY;
let items = [];
if (!_isPointInArea(position, chart.chartArea, chart._minPadding)) {
return items;
}
const evaluationFunc = function(element, datasetIndex, index) {
if (intersect && !element.inRange(position.x, position.y, useFinalPosition)) {
return;
}
const center = element.getCenterPoint(useFinalPosition);
if (!_isPointInArea(center, chart.chartArea, chart._minPadding)) {
return;
}
const distance = distanceMetric(position, center);
if (distance < minDistance) {
items = [{element, datasetIndex, index}];
minDistance = distance;
} else if (distance === minDistance) {
// Can have multiple items at the same distance in which case we sort by size
items.push({element, datasetIndex, index});
}
};
optimizedEvaluateItems(chart, axis, position, evaluationFunc);
return items;
}
function getAxisItems(chart, e, options, useFinalPosition) {
const position = getRelativePosition(e, chart);
const items = [];
const axis = options.axis;
const rangeMethod = axis === 'x' ? 'inXRange' : 'inYRange';
let intersectsItem = false;
evaluateAllVisibleItems(chart, (element, datasetIndex, index) => {
if (element[rangeMethod](position[axis], useFinalPosition)) {
items.push({element, datasetIndex, index});
}
if (element.inRange(position.x, position.y, useFinalPosition)) {
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) {
return [];
}
return items;
}
/**
* Contains interaction related functions
* @namespace Chart.Interaction
*/
export default {
// Helper function for different modes
modes: {
/**
* 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 {Event} e - the event we are find things at
* @param {InteractionOptions} options - options to use
* @param {boolean} [useFinalPosition] - use final element position (animation target)
* @return {InteractionItem[]} - items that are found
*/
index(chart, e, options, useFinalPosition) {
const position = getRelativePosition(e, chart);
// Default axis for index mode is 'x' to match old behaviour
const axis = options.axis || 'x';
const items = options.intersect
? getIntersectItems(chart, position, axis, useFinalPosition)
: getNearestItems(chart, position, axis, false, useFinalPosition);
const elements = [];
if (!items.length) {
return [];
}
chart.getSortedVisibleDatasetMetas().forEach((meta) => {
const index = items[0].index;
const element = meta.data[index];
// don't count items that are skipped (null data)
if (element && !element.skip) {
elements.push({element, datasetIndex: meta.index, index});
}
});
return elements;
},
/**
* 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 {Event} e - the event we are find things at
* @param {InteractionOptions} options - options to use
* @param {boolean} [useFinalPosition] - use final element position (animation target)
* @return {InteractionItem[]} - items that are found
*/
dataset(chart, e, options, useFinalPosition) {
const position = getRelativePosition(e, chart);
const axis = options.axis || 'xy';
let items = options.intersect
? getIntersectItems(chart, position, axis, useFinalPosition) :
getNearestItems(chart, position, axis, false, useFinalPosition);
if (items.length > 0) {
const datasetIndex = items[0].datasetIndex;
const data = chart.getDatasetMeta(datasetIndex).data;
items = [];
for (let i = 0; i < data.length; ++i) {
items.push({element: data[i], datasetIndex, index: i});
}
}
return items;
},
/**
* 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 {Event} e - the event we are find things at
* @param {InteractionOptions} options - options to use
* @param {boolean} [useFinalPosition] - use final element position (animation target)
* @return {InteractionItem[]} - items that are found
*/
point(chart, e, options, useFinalPosition) {
const position = getRelativePosition(e, chart);
const axis = options.axis || 'xy';
return getIntersectItems(chart, position, axis, useFinalPosition);
},
/**
* 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 {Event} e - the event we are find things at
* @param {InteractionOptions} options - options to use
* @param {boolean} [useFinalPosition] - use final element position (animation target)
* @return {InteractionItem[]} - items that are found
*/
nearest(chart, e, options, useFinalPosition) {
const position = getRelativePosition(e, chart);
const axis = options.axis || 'xy';
return getNearestItems(chart, position, axis, options.intersect, useFinalPosition);
},
/**
* 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 {Event} e - the event we are find things at
* @param {InteractionOptions} options - options to use
* @param {boolean} [useFinalPosition] - use final element position (animation target)
* @return {InteractionItem[]} - items that are found
*/
x(chart, e, options, useFinalPosition) {
options.axis = 'x';
return getAxisItems(chart, e, options, useFinalPosition);
},
/**
* 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 {Event} e - the event we are find things at
* @param {InteractionOptions} options - options to use
* @param {boolean} [useFinalPosition] - use final element position (animation target)
* @return {InteractionItem[]} - items that are found
*/
y(chart, e, options, useFinalPosition) {
options.axis = 'y';
return getAxisItems(chart, e, options, useFinalPosition);
}
}
};