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core.helpers.js
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core.helpers.js
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/* global window: false */
/* global document: false */
'use strict';
var color = require('chartjs-color');
var defaults = require('./core.defaults');
var helpers = require('../helpers/index');
var scaleService = require('../core/core.scaleService');
module.exports = function() {
// -- Basic js utility methods
helpers.configMerge = function(/* objects ... */) {
return helpers.merge(helpers.clone(arguments[0]), [].slice.call(arguments, 1), {
merger: function(key, target, source, options) {
var tval = target[key] || {};
var sval = source[key];
if (key === 'scales') {
// scale config merging is complex. Add our own function here for that
target[key] = helpers.scaleMerge(tval, sval);
} else if (key === 'scale') {
// used in polar area & radar charts since there is only one scale
target[key] = helpers.merge(tval, [scaleService.getScaleDefaults(sval.type), sval]);
} else {
helpers._merger(key, target, source, options);
}
}
});
};
helpers.scaleMerge = function(/* objects ... */) {
return helpers.merge(helpers.clone(arguments[0]), [].slice.call(arguments, 1), {
merger: function(key, target, source, options) {
if (key === 'xAxes' || key === 'yAxes') {
var slen = source[key].length;
var i, type, scale;
if (!target[key]) {
target[key] = [];
}
for (i = 0; i < slen; ++i) {
scale = source[key][i];
type = helpers.valueOrDefault(scale.type, key === 'xAxes' ? 'category' : 'linear');
if (i >= target[key].length) {
target[key].push({});
}
if (!target[key][i].type || (scale.type && scale.type !== target[key][i].type)) {
// new/untyped scale or type changed: let's apply the new defaults
// then merge source scale to correctly overwrite the defaults.
helpers.merge(target[key][i], [scaleService.getScaleDefaults(type), scale]);
} else {
// scales type are the same
helpers.merge(target[key][i], scale);
}
}
} else {
helpers._merger(key, target, source, options);
}
}
});
};
helpers.where = function(collection, filterCallback) {
if (helpers.isArray(collection) && Array.prototype.filter) {
return collection.filter(filterCallback);
}
var filtered = [];
helpers.each(collection, function(item) {
if (filterCallback(item)) {
filtered.push(item);
}
});
return filtered;
};
helpers.findIndex = Array.prototype.findIndex ?
function(array, callback, scope) {
return array.findIndex(callback, scope);
} :
function(array, callback, scope) {
scope = scope === undefined ? array : scope;
for (var i = 0, ilen = array.length; i < ilen; ++i) {
if (callback.call(scope, array[i], i, array)) {
return i;
}
}
return -1;
};
helpers.findNextWhere = function(arrayToSearch, filterCallback, startIndex) {
// Default to start of the array
if (helpers.isNullOrUndef(startIndex)) {
startIndex = -1;
}
for (var i = startIndex + 1; i < arrayToSearch.length; i++) {
var currentItem = arrayToSearch[i];
if (filterCallback(currentItem)) {
return currentItem;
}
}
};
helpers.findPreviousWhere = function(arrayToSearch, filterCallback, startIndex) {
// Default to end of the array
if (helpers.isNullOrUndef(startIndex)) {
startIndex = arrayToSearch.length;
}
for (var i = startIndex - 1; i >= 0; i--) {
var currentItem = arrayToSearch[i];
if (filterCallback(currentItem)) {
return currentItem;
}
}
};
// -- Math methods
helpers.isNumber = function(n) {
return !isNaN(parseFloat(n)) && isFinite(n);
};
helpers.almostEquals = function(x, y, epsilon) {
return Math.abs(x - y) < epsilon;
};
helpers.almostWhole = function(x, epsilon) {
var rounded = Math.round(x);
return (((rounded - epsilon) < x) && ((rounded + epsilon) > x));
};
helpers.max = function(array) {
return array.reduce(function(max, value) {
if (!isNaN(value)) {
return Math.max(max, value);
}
return max;
}, Number.NEGATIVE_INFINITY);
};
helpers.min = function(array) {
return array.reduce(function(min, value) {
if (!isNaN(value)) {
return Math.min(min, value);
}
return min;
}, Number.POSITIVE_INFINITY);
};
helpers.sign = Math.sign ?
function(x) {
return Math.sign(x);
} :
function(x) {
x = +x; // convert to a number
if (x === 0 || isNaN(x)) {
return x;
}
return x > 0 ? 1 : -1;
};
helpers.log10 = Math.log10 ?
function(x) {
return Math.log10(x);
} :
function(x) {
var exponent = Math.log(x) * Math.LOG10E; // Math.LOG10E = 1 / Math.LN10.
// Check for whole powers of 10,
// which due to floating point rounding error should be corrected.
var powerOf10 = Math.round(exponent);
var isPowerOf10 = x === Math.pow(10, powerOf10);
return isPowerOf10 ? powerOf10 : exponent;
};
helpers.toRadians = function(degrees) {
return degrees * (Math.PI / 180);
};
helpers.toDegrees = function(radians) {
return radians * (180 / Math.PI);
};
/**
* Returns the number of decimal places
* i.e. the number of digits after the decimal point, of the value of this Number.
* @param {Number} x - A number.
* @returns {Number} The number of decimal places.
*/
helpers.decimalPlaces = function(x) {
if (!helpers.isFinite(x)) {
return;
}
var e = 1;
var p = 0;
while (Math.round(x * e) / e !== x) {
e *= 10;
p++;
}
return p;
};
// Gets the angle from vertical upright to the point about a centre.
helpers.getAngleFromPoint = function(centrePoint, anglePoint) {
var distanceFromXCenter = anglePoint.x - centrePoint.x;
var distanceFromYCenter = anglePoint.y - centrePoint.y;
var radialDistanceFromCenter = Math.sqrt(distanceFromXCenter * distanceFromXCenter + distanceFromYCenter * distanceFromYCenter);
var angle = Math.atan2(distanceFromYCenter, distanceFromXCenter);
if (angle < (-0.5 * Math.PI)) {
angle += 2.0 * Math.PI; // make sure the returned angle is in the range of (-PI/2, 3PI/2]
}
return {
angle: angle,
distance: radialDistanceFromCenter
};
};
helpers.distanceBetweenPoints = function(pt1, pt2) {
return Math.sqrt(Math.pow(pt2.x - pt1.x, 2) + Math.pow(pt2.y - pt1.y, 2));
};
/**
* Provided for backward compatibility, not available anymore
* @function Chart.helpers.aliasPixel
* @deprecated since version 2.8.0
* @todo remove at version 3
*/
helpers.aliasPixel = function(pixelWidth) {
return (pixelWidth % 2 === 0) ? 0 : 0.5;
};
/**
* Returns the aligned pixel value to avoid anti-aliasing blur
* @param {Chart} chart - The chart instance.
* @param {Number} pixel - A pixel value.
* @param {Number} width - The width of the element.
* @returns {Number} The aligned pixel value.
* @private
*/
helpers._alignPixel = function(chart, pixel, width) {
var devicePixelRatio = chart.currentDevicePixelRatio;
var halfWidth = width / 2;
return Math.round((pixel - halfWidth) * devicePixelRatio) / devicePixelRatio + halfWidth;
};
helpers.splineCurve = function(firstPoint, middlePoint, afterPoint, t) {
// Props to Rob Spencer at scaled innovation for his post on splining between points
// http://scaledinnovation.com/analytics/splines/aboutSplines.html
// This function must also respect "skipped" points
var previous = firstPoint.skip ? middlePoint : firstPoint;
var current = middlePoint;
var next = afterPoint.skip ? middlePoint : afterPoint;
var d01 = Math.sqrt(Math.pow(current.x - previous.x, 2) + Math.pow(current.y - previous.y, 2));
var d12 = Math.sqrt(Math.pow(next.x - current.x, 2) + Math.pow(next.y - current.y, 2));
var s01 = d01 / (d01 + d12);
var s12 = d12 / (d01 + d12);
// If all points are the same, s01 & s02 will be inf
s01 = isNaN(s01) ? 0 : s01;
s12 = isNaN(s12) ? 0 : s12;
var fa = t * s01; // scaling factor for triangle Ta
var fb = t * s12;
return {
previous: {
x: current.x - fa * (next.x - previous.x),
y: current.y - fa * (next.y - previous.y)
},
next: {
x: current.x + fb * (next.x - previous.x),
y: current.y + fb * (next.y - previous.y)
}
};
};
helpers.EPSILON = Number.EPSILON || 1e-14;
helpers.splineCurveMonotone = function(points) {
// This function calculates Bézier control points in a similar way than |splineCurve|,
// but preserves monotonicity of the provided data and ensures no local extremums are added
// between the dataset discrete points due to the interpolation.
// See : https://en.wikipedia.org/wiki/Monotone_cubic_interpolation
var pointsWithTangents = (points || []).map(function(point) {
return {
model: point._model,
deltaK: 0,
mK: 0
};
});
// Calculate slopes (deltaK) and initialize tangents (mK)
var pointsLen = pointsWithTangents.length;
var i, pointBefore, pointCurrent, pointAfter;
for (i = 0; i < pointsLen; ++i) {
pointCurrent = pointsWithTangents[i];
if (pointCurrent.model.skip) {
continue;
}
pointBefore = i > 0 ? pointsWithTangents[i - 1] : null;
pointAfter = i < pointsLen - 1 ? pointsWithTangents[i + 1] : null;
if (pointAfter && !pointAfter.model.skip) {
var slopeDeltaX = (pointAfter.model.x - pointCurrent.model.x);
// In the case of two points that appear at the same x pixel, slopeDeltaX is 0
pointCurrent.deltaK = slopeDeltaX !== 0 ? (pointAfter.model.y - pointCurrent.model.y) / slopeDeltaX : 0;
}
if (!pointBefore || pointBefore.model.skip) {
pointCurrent.mK = pointCurrent.deltaK;
} else if (!pointAfter || pointAfter.model.skip) {
pointCurrent.mK = pointBefore.deltaK;
} else if (this.sign(pointBefore.deltaK) !== this.sign(pointCurrent.deltaK)) {
pointCurrent.mK = 0;
} else {
pointCurrent.mK = (pointBefore.deltaK + pointCurrent.deltaK) / 2;
}
}
// Adjust tangents to ensure monotonic properties
var alphaK, betaK, tauK, squaredMagnitude;
for (i = 0; i < pointsLen - 1; ++i) {
pointCurrent = pointsWithTangents[i];
pointAfter = pointsWithTangents[i + 1];
if (pointCurrent.model.skip || pointAfter.model.skip) {
continue;
}
if (helpers.almostEquals(pointCurrent.deltaK, 0, this.EPSILON)) {
pointCurrent.mK = pointAfter.mK = 0;
continue;
}
alphaK = pointCurrent.mK / pointCurrent.deltaK;
betaK = pointAfter.mK / pointCurrent.deltaK;
squaredMagnitude = Math.pow(alphaK, 2) + Math.pow(betaK, 2);
if (squaredMagnitude <= 9) {
continue;
}
tauK = 3 / Math.sqrt(squaredMagnitude);
pointCurrent.mK = alphaK * tauK * pointCurrent.deltaK;
pointAfter.mK = betaK * tauK * pointCurrent.deltaK;
}
// Compute control points
var deltaX;
for (i = 0; i < pointsLen; ++i) {
pointCurrent = pointsWithTangents[i];
if (pointCurrent.model.skip) {
continue;
}
pointBefore = i > 0 ? pointsWithTangents[i - 1] : null;
pointAfter = i < pointsLen - 1 ? pointsWithTangents[i + 1] : null;
if (pointBefore && !pointBefore.model.skip) {
deltaX = (pointCurrent.model.x - pointBefore.model.x) / 3;
pointCurrent.model.controlPointPreviousX = pointCurrent.model.x - deltaX;
pointCurrent.model.controlPointPreviousY = pointCurrent.model.y - deltaX * pointCurrent.mK;
}
if (pointAfter && !pointAfter.model.skip) {
deltaX = (pointAfter.model.x - pointCurrent.model.x) / 3;
pointCurrent.model.controlPointNextX = pointCurrent.model.x + deltaX;
pointCurrent.model.controlPointNextY = pointCurrent.model.y + deltaX * pointCurrent.mK;
}
}
};
helpers.nextItem = function(collection, index, loop) {
if (loop) {
return index >= collection.length - 1 ? collection[0] : collection[index + 1];
}
return index >= collection.length - 1 ? collection[collection.length - 1] : collection[index + 1];
};
helpers.previousItem = function(collection, index, loop) {
if (loop) {
return index <= 0 ? collection[collection.length - 1] : collection[index - 1];
}
return index <= 0 ? collection[0] : collection[index - 1];
};
// Implementation of the nice number algorithm used in determining where axis labels will go
helpers.niceNum = function(range, round) {
var exponent = Math.floor(helpers.log10(range));
var fraction = range / Math.pow(10, exponent);
var niceFraction;
if (round) {
if (fraction < 1.5) {
niceFraction = 1;
} else if (fraction < 3) {
niceFraction = 2;
} else if (fraction < 7) {
niceFraction = 5;
} else {
niceFraction = 10;
}
} else if (fraction <= 1.0) {
niceFraction = 1;
} else if (fraction <= 2) {
niceFraction = 2;
} else if (fraction <= 5) {
niceFraction = 5;
} else {
niceFraction = 10;
}
return niceFraction * Math.pow(10, exponent);
};
// Request animation polyfill - http://www.paulirish.com/2011/requestanimationframe-for-smart-animating/
helpers.requestAnimFrame = (function() {
if (typeof window === 'undefined') {
return function(callback) {
callback();
};
}
return window.requestAnimationFrame ||
window.webkitRequestAnimationFrame ||
window.mozRequestAnimationFrame ||
window.oRequestAnimationFrame ||
window.msRequestAnimationFrame ||
function(callback) {
return window.setTimeout(callback, 1000 / 60);
};
}());
// -- DOM methods
helpers.getRelativePosition = function(evt, chart) {
var mouseX, mouseY;
var e = evt.originalEvent || evt;
var canvas = evt.target || evt.srcElement;
var boundingRect = canvas.getBoundingClientRect();
var touches = e.touches;
if (touches && touches.length > 0) {
mouseX = touches[0].clientX;
mouseY = touches[0].clientY;
} else {
mouseX = e.clientX;
mouseY = e.clientY;
}
// Scale mouse coordinates into canvas coordinates
// by following the pattern laid out by 'jerryj' in the comments of
// http://www.html5canvastutorials.com/advanced/html5-canvas-mouse-coordinates/
var paddingLeft = parseFloat(helpers.getStyle(canvas, 'padding-left'));
var paddingTop = parseFloat(helpers.getStyle(canvas, 'padding-top'));
var paddingRight = parseFloat(helpers.getStyle(canvas, 'padding-right'));
var paddingBottom = parseFloat(helpers.getStyle(canvas, 'padding-bottom'));
var width = boundingRect.right - boundingRect.left - paddingLeft - paddingRight;
var height = boundingRect.bottom - boundingRect.top - paddingTop - paddingBottom;
// We divide by the current device pixel ratio, because the canvas is scaled up by that amount in each direction. However
// the backend model is in unscaled coordinates. Since we are going to deal with our model coordinates, we go back here
mouseX = Math.round((mouseX - boundingRect.left - paddingLeft) / (width) * canvas.width / chart.currentDevicePixelRatio);
mouseY = Math.round((mouseY - boundingRect.top - paddingTop) / (height) * canvas.height / chart.currentDevicePixelRatio);
return {
x: mouseX,
y: mouseY
};
};
// Private helper function to convert max-width/max-height values that may be percentages into a number
function parseMaxStyle(styleValue, node, parentProperty) {
var valueInPixels;
if (typeof styleValue === 'string') {
valueInPixels = parseInt(styleValue, 10);
if (styleValue.indexOf('%') !== -1) {
// percentage * size in dimension
valueInPixels = valueInPixels / 100 * node.parentNode[parentProperty];
}
} else {
valueInPixels = styleValue;
}
return valueInPixels;
}
/**
* Returns if the given value contains an effective constraint.
* @private
*/
function isConstrainedValue(value) {
return value !== undefined && value !== null && value !== 'none';
}
// Private helper to get a constraint dimension
// @param domNode : the node to check the constraint on
// @param maxStyle : the style that defines the maximum for the direction we are using (maxWidth / maxHeight)
// @param percentageProperty : property of parent to use when calculating width as a percentage
// @see http://www.nathanaeljones.com/blog/2013/reading-max-width-cross-browser
function getConstraintDimension(domNode, maxStyle, percentageProperty) {
var view = document.defaultView;
var parentNode = helpers._getParentNode(domNode);
var constrainedNode = view.getComputedStyle(domNode)[maxStyle];
var constrainedContainer = view.getComputedStyle(parentNode)[maxStyle];
var hasCNode = isConstrainedValue(constrainedNode);
var hasCContainer = isConstrainedValue(constrainedContainer);
var infinity = Number.POSITIVE_INFINITY;
if (hasCNode || hasCContainer) {
return Math.min(
hasCNode ? parseMaxStyle(constrainedNode, domNode, percentageProperty) : infinity,
hasCContainer ? parseMaxStyle(constrainedContainer, parentNode, percentageProperty) : infinity);
}
return 'none';
}
// returns Number or undefined if no constraint
helpers.getConstraintWidth = function(domNode) {
return getConstraintDimension(domNode, 'max-width', 'clientWidth');
};
// returns Number or undefined if no constraint
helpers.getConstraintHeight = function(domNode) {
return getConstraintDimension(domNode, 'max-height', 'clientHeight');
};
/**
* @private
*/
helpers._calculatePadding = function(container, padding, parentDimension) {
padding = helpers.getStyle(container, padding);
return padding.indexOf('%') > -1 ? parentDimension * parseInt(padding, 10) / 100 : parseInt(padding, 10);
};
/**
* @private
*/
helpers._getParentNode = function(domNode) {
var parent = domNode.parentNode;
if (parent && parent.toString() === '[object ShadowRoot]') {
parent = parent.host;
}
return parent;
};
helpers.getMaximumWidth = function(domNode) {
var container = helpers._getParentNode(domNode);
if (!container) {
return domNode.clientWidth;
}
var clientWidth = container.clientWidth;
var paddingLeft = helpers._calculatePadding(container, 'padding-left', clientWidth);
var paddingRight = helpers._calculatePadding(container, 'padding-right', clientWidth);
var w = clientWidth - paddingLeft - paddingRight;
var cw = helpers.getConstraintWidth(domNode);
return isNaN(cw) ? w : Math.min(w, cw);
};
helpers.getMaximumHeight = function(domNode) {
var container = helpers._getParentNode(domNode);
if (!container) {
return domNode.clientHeight;
}
var clientHeight = container.clientHeight;
var paddingTop = helpers._calculatePadding(container, 'padding-top', clientHeight);
var paddingBottom = helpers._calculatePadding(container, 'padding-bottom', clientHeight);
var h = clientHeight - paddingTop - paddingBottom;
var ch = helpers.getConstraintHeight(domNode);
return isNaN(ch) ? h : Math.min(h, ch);
};
helpers.getStyle = function(el, property) {
return el.currentStyle ?
el.currentStyle[property] :
document.defaultView.getComputedStyle(el, null).getPropertyValue(property);
};
helpers.retinaScale = function(chart, forceRatio) {
var pixelRatio = chart.currentDevicePixelRatio = forceRatio || (typeof window !== 'undefined' && window.devicePixelRatio) || 1;
if (pixelRatio === 1) {
return;
}
var canvas = chart.canvas;
var height = chart.height;
var width = chart.width;
canvas.height = height * pixelRatio;
canvas.width = width * pixelRatio;
chart.ctx.scale(pixelRatio, pixelRatio);
// If no style has been set on the canvas, the render size is used as display size,
// making the chart visually bigger, so let's enforce it to the "correct" values.
// See https://github.com/chartjs/Chart.js/issues/3575
if (!canvas.style.height && !canvas.style.width) {
canvas.style.height = height + 'px';
canvas.style.width = width + 'px';
}
};
// -- Canvas methods
helpers.fontString = function(pixelSize, fontStyle, fontFamily) {
return fontStyle + ' ' + pixelSize + 'px ' + fontFamily;
};
helpers.longestText = function(ctx, font, arrayOfThings, cache) {
cache = cache || {};
var data = cache.data = cache.data || {};
var gc = cache.garbageCollect = cache.garbageCollect || [];
if (cache.font !== font) {
data = cache.data = {};
gc = cache.garbageCollect = [];
cache.font = font;
}
ctx.font = font;
var longest = 0;
helpers.each(arrayOfThings, function(thing) {
// Undefined strings and arrays should not be measured
if (thing !== undefined && thing !== null && helpers.isArray(thing) !== true) {
longest = helpers.measureText(ctx, data, gc, longest, thing);
} else if (helpers.isArray(thing)) {
// if it is an array lets measure each element
// to do maybe simplify this function a bit so we can do this more recursively?
helpers.each(thing, function(nestedThing) {
// Undefined strings and arrays should not be measured
if (nestedThing !== undefined && nestedThing !== null && !helpers.isArray(nestedThing)) {
longest = helpers.measureText(ctx, data, gc, longest, nestedThing);
}
});
}
});
var gcLen = gc.length / 2;
if (gcLen > arrayOfThings.length) {
for (var i = 0; i < gcLen; i++) {
delete data[gc[i]];
}
gc.splice(0, gcLen);
}
return longest;
};
helpers.measureText = function(ctx, data, gc, longest, string) {
var textWidth = data[string];
if (!textWidth) {
textWidth = data[string] = ctx.measureText(string).width;
gc.push(string);
}
if (textWidth > longest) {
longest = textWidth;
}
return longest;
};
helpers.numberOfLabelLines = function(arrayOfThings) {
var numberOfLines = 1;
helpers.each(arrayOfThings, function(thing) {
if (helpers.isArray(thing)) {
if (thing.length > numberOfLines) {
numberOfLines = thing.length;
}
}
});
return numberOfLines;
};
helpers.color = !color ?
function(value) {
console.error('Color.js not found!');
return value;
} :
function(value) {
/* global CanvasGradient */
if (value instanceof CanvasGradient) {
value = defaults.global.defaultColor;
}
return color(value);
};
helpers.getHoverColor = function(colorValue) {
/* global CanvasPattern */
return (colorValue instanceof CanvasPattern || colorValue instanceof CanvasGradient) ?
colorValue :
helpers.color(colorValue).saturate(0.5).darken(0.1).rgbString();
};
};