chart.js
Version:
Simple HTML5 charts using the canvas element.
531 lines (445 loc) • 16.7 kB
JavaScript
'use strict';
var defaults = require('../core/core.defaults');
var helpers = require('../helpers/index');
var Ticks = require('../core/core.ticks');
module.exports = function(Chart) {
var globalDefaults = defaults.global;
var defaultConfig = {
display: true,
// Boolean - Whether to animate scaling the chart from the centre
animate: true,
position: 'chartArea',
angleLines: {
display: true,
color: 'rgba(0, 0, 0, 0.1)',
lineWidth: 1
},
gridLines: {
circular: false
},
// label settings
ticks: {
// Boolean - Show a backdrop to the scale label
showLabelBackdrop: true,
// String - The colour of the label backdrop
backdropColor: 'rgba(255,255,255,0.75)',
// Number - The backdrop padding above & below the label in pixels
backdropPaddingY: 2,
// Number - The backdrop padding to the side of the label in pixels
backdropPaddingX: 2,
callback: Ticks.formatters.linear
},
pointLabels: {
// Boolean - if true, show point labels
display: true,
// Number - Point label font size in pixels
fontSize: 10,
// Function - Used to convert point labels
callback: function(label) {
return label;
}
}
};
function getValueCount(scale) {
var opts = scale.options;
return opts.angleLines.display || opts.pointLabels.display ? scale.chart.data.labels.length : 0;
}
function getPointLabelFontOptions(scale) {
var pointLabelOptions = scale.options.pointLabels;
var fontSize = helpers.valueOrDefault(pointLabelOptions.fontSize, globalDefaults.defaultFontSize);
var fontStyle = helpers.valueOrDefault(pointLabelOptions.fontStyle, globalDefaults.defaultFontStyle);
var fontFamily = helpers.valueOrDefault(pointLabelOptions.fontFamily, globalDefaults.defaultFontFamily);
var font = helpers.fontString(fontSize, fontStyle, fontFamily);
return {
size: fontSize,
style: fontStyle,
family: fontFamily,
font: font
};
}
function measureLabelSize(ctx, fontSize, label) {
if (helpers.isArray(label)) {
return {
w: helpers.longestText(ctx, ctx.font, label),
h: (label.length * fontSize) + ((label.length - 1) * 1.5 * fontSize)
};
}
return {
w: ctx.measureText(label).width,
h: fontSize
};
}
function determineLimits(angle, pos, size, min, max) {
if (angle === min || angle === max) {
return {
start: pos - (size / 2),
end: pos + (size / 2)
};
} else if (angle < min || angle > max) {
return {
start: pos - size - 5,
end: pos
};
}
return {
start: pos,
end: pos + size + 5
};
}
/**
* Helper function to fit a radial linear scale with point labels
*/
function fitWithPointLabels(scale) {
/*
* Right, this is really confusing and there is a lot of maths going on here
* The gist of the problem is here: https://gist.github.com/nnnick/696cc9c55f4b0beb8fe9
*
* Reaction: https://dl.dropboxusercontent.com/u/34601363/toomuchscience.gif
*
* Solution:
*
* We assume the radius of the polygon is half the size of the canvas at first
* at each index we check if the text overlaps.
*
* Where it does, we store that angle and that index.
*
* After finding the largest index and angle we calculate how much we need to remove
* from the shape radius to move the point inwards by that x.
*
* We average the left and right distances to get the maximum shape radius that can fit in the box
* along with labels.
*
* Once we have that, we can find the centre point for the chart, by taking the x text protrusion
* on each side, removing that from the size, halving it and adding the left x protrusion width.
*
* This will mean we have a shape fitted to the canvas, as large as it can be with the labels
* and position it in the most space efficient manner
*
* https://dl.dropboxusercontent.com/u/34601363/yeahscience.gif
*/
var plFont = getPointLabelFontOptions(scale);
// Get maximum radius of the polygon. Either half the height (minus the text width) or half the width.
// Use this to calculate the offset + change. - Make sure L/R protrusion is at least 0 to stop issues with centre points
var largestPossibleRadius = Math.min(scale.height / 2, scale.width / 2);
var furthestLimits = {
r: scale.width,
l: 0,
t: scale.height,
b: 0
};
var furthestAngles = {};
var i, textSize, pointPosition;
scale.ctx.font = plFont.font;
scale._pointLabelSizes = [];
var valueCount = getValueCount(scale);
for (i = 0; i < valueCount; i++) {
pointPosition = scale.getPointPosition(i, largestPossibleRadius);
textSize = measureLabelSize(scale.ctx, plFont.size, scale.pointLabels[i] || '');
scale._pointLabelSizes[i] = textSize;
// Add quarter circle to make degree 0 mean top of circle
var angleRadians = scale.getIndexAngle(i);
var angle = helpers.toDegrees(angleRadians) % 360;
var hLimits = determineLimits(angle, pointPosition.x, textSize.w, 0, 180);
var vLimits = determineLimits(angle, pointPosition.y, textSize.h, 90, 270);
if (hLimits.start < furthestLimits.l) {
furthestLimits.l = hLimits.start;
furthestAngles.l = angleRadians;
}
if (hLimits.end > furthestLimits.r) {
furthestLimits.r = hLimits.end;
furthestAngles.r = angleRadians;
}
if (vLimits.start < furthestLimits.t) {
furthestLimits.t = vLimits.start;
furthestAngles.t = angleRadians;
}
if (vLimits.end > furthestLimits.b) {
furthestLimits.b = vLimits.end;
furthestAngles.b = angleRadians;
}
}
scale.setReductions(largestPossibleRadius, furthestLimits, furthestAngles);
}
/**
* Helper function to fit a radial linear scale with no point labels
*/
function fit(scale) {
var largestPossibleRadius = Math.min(scale.height / 2, scale.width / 2);
scale.drawingArea = Math.round(largestPossibleRadius);
scale.setCenterPoint(0, 0, 0, 0);
}
function getTextAlignForAngle(angle) {
if (angle === 0 || angle === 180) {
return 'center';
} else if (angle < 180) {
return 'left';
}
return 'right';
}
function fillText(ctx, text, position, fontSize) {
if (helpers.isArray(text)) {
var y = position.y;
var spacing = 1.5 * fontSize;
for (var i = 0; i < text.length; ++i) {
ctx.fillText(text[i], position.x, y);
y += spacing;
}
} else {
ctx.fillText(text, position.x, position.y);
}
}
function adjustPointPositionForLabelHeight(angle, textSize, position) {
if (angle === 90 || angle === 270) {
position.y -= (textSize.h / 2);
} else if (angle > 270 || angle < 90) {
position.y -= textSize.h;
}
}
function drawPointLabels(scale) {
var ctx = scale.ctx;
var valueOrDefault = helpers.valueOrDefault;
var opts = scale.options;
var angleLineOpts = opts.angleLines;
var pointLabelOpts = opts.pointLabels;
ctx.lineWidth = angleLineOpts.lineWidth;
ctx.strokeStyle = angleLineOpts.color;
var outerDistance = scale.getDistanceFromCenterForValue(opts.ticks.reverse ? scale.min : scale.max);
// Point Label Font
var plFont = getPointLabelFontOptions(scale);
ctx.textBaseline = 'top';
for (var i = getValueCount(scale) - 1; i >= 0; i--) {
if (angleLineOpts.display) {
var outerPosition = scale.getPointPosition(i, outerDistance);
ctx.beginPath();
ctx.moveTo(scale.xCenter, scale.yCenter);
ctx.lineTo(outerPosition.x, outerPosition.y);
ctx.stroke();
ctx.closePath();
}
if (pointLabelOpts.display) {
// Extra 3px out for some label spacing
var pointLabelPosition = scale.getPointPosition(i, outerDistance + 5);
// Keep this in loop since we may support array properties here
var pointLabelFontColor = valueOrDefault(pointLabelOpts.fontColor, globalDefaults.defaultFontColor);
ctx.font = plFont.font;
ctx.fillStyle = pointLabelFontColor;
var angleRadians = scale.getIndexAngle(i);
var angle = helpers.toDegrees(angleRadians);
ctx.textAlign = getTextAlignForAngle(angle);
adjustPointPositionForLabelHeight(angle, scale._pointLabelSizes[i], pointLabelPosition);
fillText(ctx, scale.pointLabels[i] || '', pointLabelPosition, plFont.size);
}
}
}
function drawRadiusLine(scale, gridLineOpts, radius, index) {
var ctx = scale.ctx;
ctx.strokeStyle = helpers.valueAtIndexOrDefault(gridLineOpts.color, index - 1);
ctx.lineWidth = helpers.valueAtIndexOrDefault(gridLineOpts.lineWidth, index - 1);
if (scale.options.gridLines.circular) {
// Draw circular arcs between the points
ctx.beginPath();
ctx.arc(scale.xCenter, scale.yCenter, radius, 0, Math.PI * 2);
ctx.closePath();
ctx.stroke();
} else {
// Draw straight lines connecting each index
var valueCount = getValueCount(scale);
if (valueCount === 0) {
return;
}
ctx.beginPath();
var pointPosition = scale.getPointPosition(0, radius);
ctx.moveTo(pointPosition.x, pointPosition.y);
for (var i = 1; i < valueCount; i++) {
pointPosition = scale.getPointPosition(i, radius);
ctx.lineTo(pointPosition.x, pointPosition.y);
}
ctx.closePath();
ctx.stroke();
}
}
function numberOrZero(param) {
return helpers.isNumber(param) ? param : 0;
}
var LinearRadialScale = Chart.LinearScaleBase.extend({
setDimensions: function() {
var me = this;
var opts = me.options;
var tickOpts = opts.ticks;
// Set the unconstrained dimension before label rotation
me.width = me.maxWidth;
me.height = me.maxHeight;
me.xCenter = Math.round(me.width / 2);
me.yCenter = Math.round(me.height / 2);
var minSize = helpers.min([me.height, me.width]);
var tickFontSize = helpers.valueOrDefault(tickOpts.fontSize, globalDefaults.defaultFontSize);
me.drawingArea = opts.display ? (minSize / 2) - (tickFontSize / 2 + tickOpts.backdropPaddingY) : (minSize / 2);
},
determineDataLimits: function() {
var me = this;
var chart = me.chart;
var min = Number.POSITIVE_INFINITY;
var max = Number.NEGATIVE_INFINITY;
helpers.each(chart.data.datasets, function(dataset, datasetIndex) {
if (chart.isDatasetVisible(datasetIndex)) {
var meta = chart.getDatasetMeta(datasetIndex);
helpers.each(dataset.data, function(rawValue, index) {
var value = +me.getRightValue(rawValue);
if (isNaN(value) || meta.data[index].hidden) {
return;
}
min = Math.min(value, min);
max = Math.max(value, max);
});
}
});
me.min = (min === Number.POSITIVE_INFINITY ? 0 : min);
me.max = (max === Number.NEGATIVE_INFINITY ? 0 : max);
// Common base implementation to handle ticks.min, ticks.max, ticks.beginAtZero
me.handleTickRangeOptions();
},
getTickLimit: function() {
var tickOpts = this.options.ticks;
var tickFontSize = helpers.valueOrDefault(tickOpts.fontSize, globalDefaults.defaultFontSize);
return Math.min(tickOpts.maxTicksLimit ? tickOpts.maxTicksLimit : 11, Math.ceil(this.drawingArea / (1.5 * tickFontSize)));
},
convertTicksToLabels: function() {
var me = this;
Chart.LinearScaleBase.prototype.convertTicksToLabels.call(me);
// Point labels
me.pointLabels = me.chart.data.labels.map(me.options.pointLabels.callback, me);
},
getLabelForIndex: function(index, datasetIndex) {
return +this.getRightValue(this.chart.data.datasets[datasetIndex].data[index]);
},
fit: function() {
if (this.options.pointLabels.display) {
fitWithPointLabels(this);
} else {
fit(this);
}
},
/**
* Set radius reductions and determine new radius and center point
* @private
*/
setReductions: function(largestPossibleRadius, furthestLimits, furthestAngles) {
var me = this;
var radiusReductionLeft = furthestLimits.l / Math.sin(furthestAngles.l);
var radiusReductionRight = Math.max(furthestLimits.r - me.width, 0) / Math.sin(furthestAngles.r);
var radiusReductionTop = -furthestLimits.t / Math.cos(furthestAngles.t);
var radiusReductionBottom = -Math.max(furthestLimits.b - me.height, 0) / Math.cos(furthestAngles.b);
radiusReductionLeft = numberOrZero(radiusReductionLeft);
radiusReductionRight = numberOrZero(radiusReductionRight);
radiusReductionTop = numberOrZero(radiusReductionTop);
radiusReductionBottom = numberOrZero(radiusReductionBottom);
me.drawingArea = Math.min(
Math.round(largestPossibleRadius - (radiusReductionLeft + radiusReductionRight) / 2),
Math.round(largestPossibleRadius - (radiusReductionTop + radiusReductionBottom) / 2));
me.setCenterPoint(radiusReductionLeft, radiusReductionRight, radiusReductionTop, radiusReductionBottom);
},
setCenterPoint: function(leftMovement, rightMovement, topMovement, bottomMovement) {
var me = this;
var maxRight = me.width - rightMovement - me.drawingArea;
var maxLeft = leftMovement + me.drawingArea;
var maxTop = topMovement + me.drawingArea;
var maxBottom = me.height - bottomMovement - me.drawingArea;
me.xCenter = Math.round(((maxLeft + maxRight) / 2) + me.left);
me.yCenter = Math.round(((maxTop + maxBottom) / 2) + me.top);
},
getIndexAngle: function(index) {
var angleMultiplier = (Math.PI * 2) / getValueCount(this);
var startAngle = this.chart.options && this.chart.options.startAngle ?
this.chart.options.startAngle :
0;
var startAngleRadians = startAngle * Math.PI * 2 / 360;
// Start from the top instead of right, so remove a quarter of the circle
return index * angleMultiplier + startAngleRadians;
},
getDistanceFromCenterForValue: function(value) {
var me = this;
if (value === null) {
return 0; // null always in center
}
// Take into account half font size + the yPadding of the top value
var scalingFactor = me.drawingArea / (me.max - me.min);
if (me.options.ticks.reverse) {
return (me.max - value) * scalingFactor;
}
return (value - me.min) * scalingFactor;
},
getPointPosition: function(index, distanceFromCenter) {
var me = this;
var thisAngle = me.getIndexAngle(index) - (Math.PI / 2);
return {
x: Math.round(Math.cos(thisAngle) * distanceFromCenter) + me.xCenter,
y: Math.round(Math.sin(thisAngle) * distanceFromCenter) + me.yCenter
};
},
getPointPositionForValue: function(index, value) {
return this.getPointPosition(index, this.getDistanceFromCenterForValue(value));
},
getBasePosition: function() {
var me = this;
var min = me.min;
var max = me.max;
return me.getPointPositionForValue(0,
me.beginAtZero ? 0 :
min < 0 && max < 0 ? max :
min > 0 && max > 0 ? min :
0);
},
draw: function() {
var me = this;
var opts = me.options;
var gridLineOpts = opts.gridLines;
var tickOpts = opts.ticks;
var valueOrDefault = helpers.valueOrDefault;
if (opts.display) {
var ctx = me.ctx;
var startAngle = this.getIndexAngle(0);
// Tick Font
var tickFontSize = valueOrDefault(tickOpts.fontSize, globalDefaults.defaultFontSize);
var tickFontStyle = valueOrDefault(tickOpts.fontStyle, globalDefaults.defaultFontStyle);
var tickFontFamily = valueOrDefault(tickOpts.fontFamily, globalDefaults.defaultFontFamily);
var tickLabelFont = helpers.fontString(tickFontSize, tickFontStyle, tickFontFamily);
helpers.each(me.ticks, function(label, index) {
// Don't draw a centre value (if it is minimum)
if (index > 0 || tickOpts.reverse) {
var yCenterOffset = me.getDistanceFromCenterForValue(me.ticksAsNumbers[index]);
// Draw circular lines around the scale
if (gridLineOpts.display && index !== 0) {
drawRadiusLine(me, gridLineOpts, yCenterOffset, index);
}
if (tickOpts.display) {
var tickFontColor = valueOrDefault(tickOpts.fontColor, globalDefaults.defaultFontColor);
ctx.font = tickLabelFont;
ctx.save();
ctx.translate(me.xCenter, me.yCenter);
ctx.rotate(startAngle);
if (tickOpts.showLabelBackdrop) {
var labelWidth = ctx.measureText(label).width;
ctx.fillStyle = tickOpts.backdropColor;
ctx.fillRect(
-labelWidth / 2 - tickOpts.backdropPaddingX,
-yCenterOffset - tickFontSize / 2 - tickOpts.backdropPaddingY,
labelWidth + tickOpts.backdropPaddingX * 2,
tickFontSize + tickOpts.backdropPaddingY * 2
);
}
ctx.textAlign = 'center';
ctx.textBaseline = 'middle';
ctx.fillStyle = tickFontColor;
ctx.fillText(label, 0, -yCenterOffset);
ctx.restore();
}
}
});
if (opts.angleLines.display || opts.pointLabels.display) {
drawPointLabels(me);
}
}
}
});
Chart.scaleService.registerScaleType('radialLinear', LinearRadialScale, defaultConfig);
};