chart.js
Version:
Simple HTML5 charts using the canvas element.
568 lines (473 loc) • 15.6 kB
JavaScript
'use strict';
var defaults = require('../core/core.defaults');
var Element = require('../core/core.element');
var helpers = require('../helpers/index');
defaults._set('global', {
legend: {
display: true,
position: 'top',
fullWidth: true,
reverse: false,
weight: 1000,
// a callback that will handle
onClick: function(e, legendItem) {
var index = legendItem.datasetIndex;
var ci = this.chart;
var meta = ci.getDatasetMeta(index);
// See controller.isDatasetVisible comment
meta.hidden = meta.hidden === null ? !ci.data.datasets[index].hidden : null;
// We hid a dataset ... rerender the chart
ci.update();
},
onHover: null,
labels: {
boxWidth: 40,
padding: 10,
// Generates labels shown in the legend
// Valid properties to return:
// text : text to display
// fillStyle : fill of coloured box
// strokeStyle: stroke of coloured box
// hidden : if this legend item refers to a hidden item
// lineCap : cap style for line
// lineDash
// lineDashOffset :
// lineJoin :
// lineWidth :
generateLabels: function(chart) {
var data = chart.data;
return helpers.isArray(data.datasets) ? data.datasets.map(function(dataset, i) {
return {
text: dataset.label,
fillStyle: (!helpers.isArray(dataset.backgroundColor) ? dataset.backgroundColor : dataset.backgroundColor[0]),
hidden: !chart.isDatasetVisible(i),
lineCap: dataset.borderCapStyle,
lineDash: dataset.borderDash,
lineDashOffset: dataset.borderDashOffset,
lineJoin: dataset.borderJoinStyle,
lineWidth: dataset.borderWidth,
strokeStyle: dataset.borderColor,
pointStyle: dataset.pointStyle,
// Below is extra data used for toggling the datasets
datasetIndex: i
};
}, this) : [];
}
}
},
legendCallback: function(chart) {
var text = [];
text.push('<ul class="' + chart.id + '-legend">');
for (var i = 0; i < chart.data.datasets.length; i++) {
text.push('<li><span style="background-color:' + chart.data.datasets[i].backgroundColor + '"></span>');
if (chart.data.datasets[i].label) {
text.push(chart.data.datasets[i].label);
}
text.push('</li>');
}
text.push('</ul>');
return text.join('');
}
});
module.exports = function(Chart) {
var layout = Chart.layoutService;
var noop = helpers.noop;
/**
* Helper function to get the box width based on the usePointStyle option
* @param labelopts {Object} the label options on the legend
* @param fontSize {Number} the label font size
* @return {Number} width of the color box area
*/
function getBoxWidth(labelOpts, fontSize) {
return labelOpts.usePointStyle ?
fontSize * Math.SQRT2 :
labelOpts.boxWidth;
}
Chart.Legend = Element.extend({
initialize: function(config) {
helpers.extend(this, config);
// Contains hit boxes for each dataset (in dataset order)
this.legendHitBoxes = [];
// Are we in doughnut mode which has a different data type
this.doughnutMode = false;
},
// These methods are ordered by lifecycle. Utilities then follow.
// Any function defined here is inherited by all legend types.
// Any function can be extended by the legend type
beforeUpdate: noop,
update: function(maxWidth, maxHeight, margins) {
var me = this;
// Update Lifecycle - Probably don't want to ever extend or overwrite this function ;)
me.beforeUpdate();
// Absorb the master measurements
me.maxWidth = maxWidth;
me.maxHeight = maxHeight;
me.margins = margins;
// Dimensions
me.beforeSetDimensions();
me.setDimensions();
me.afterSetDimensions();
// Labels
me.beforeBuildLabels();
me.buildLabels();
me.afterBuildLabels();
// Fit
me.beforeFit();
me.fit();
me.afterFit();
//
me.afterUpdate();
return me.minSize;
},
afterUpdate: noop,
//
beforeSetDimensions: noop,
setDimensions: function() {
var me = this;
// Set the unconstrained dimension before label rotation
if (me.isHorizontal()) {
// Reset position before calculating rotation
me.width = me.maxWidth;
me.left = 0;
me.right = me.width;
} else {
me.height = me.maxHeight;
// Reset position before calculating rotation
me.top = 0;
me.bottom = me.height;
}
// Reset padding
me.paddingLeft = 0;
me.paddingTop = 0;
me.paddingRight = 0;
me.paddingBottom = 0;
// Reset minSize
me.minSize = {
width: 0,
height: 0
};
},
afterSetDimensions: noop,
//
beforeBuildLabels: noop,
buildLabels: function() {
var me = this;
var labelOpts = me.options.labels || {};
var legendItems = helpers.callback(labelOpts.generateLabels, [me.chart], me) || [];
if (labelOpts.filter) {
legendItems = legendItems.filter(function(item) {
return labelOpts.filter(item, me.chart.data);
});
}
if (me.options.reverse) {
legendItems.reverse();
}
me.legendItems = legendItems;
},
afterBuildLabels: noop,
//
beforeFit: noop,
fit: function() {
var me = this;
var opts = me.options;
var labelOpts = opts.labels;
var display = opts.display;
var ctx = me.ctx;
var globalDefault = defaults.global;
var valueOrDefault = helpers.valueOrDefault;
var fontSize = valueOrDefault(labelOpts.fontSize, globalDefault.defaultFontSize);
var fontStyle = valueOrDefault(labelOpts.fontStyle, globalDefault.defaultFontStyle);
var fontFamily = valueOrDefault(labelOpts.fontFamily, globalDefault.defaultFontFamily);
var labelFont = helpers.fontString(fontSize, fontStyle, fontFamily);
// Reset hit boxes
var hitboxes = me.legendHitBoxes = [];
var minSize = me.minSize;
var isHorizontal = me.isHorizontal();
if (isHorizontal) {
minSize.width = me.maxWidth; // fill all the width
minSize.height = display ? 10 : 0;
} else {
minSize.width = display ? 10 : 0;
minSize.height = me.maxHeight; // fill all the height
}
// Increase sizes here
if (display) {
ctx.font = labelFont;
if (isHorizontal) {
// Labels
// Width of each line of legend boxes. Labels wrap onto multiple lines when there are too many to fit on one
var lineWidths = me.lineWidths = [0];
var totalHeight = me.legendItems.length ? fontSize + (labelOpts.padding) : 0;
ctx.textAlign = 'left';
ctx.textBaseline = 'top';
helpers.each(me.legendItems, function(legendItem, i) {
var boxWidth = getBoxWidth(labelOpts, fontSize);
var width = boxWidth + (fontSize / 2) + ctx.measureText(legendItem.text).width;
if (lineWidths[lineWidths.length - 1] + width + labelOpts.padding >= me.width) {
totalHeight += fontSize + (labelOpts.padding);
lineWidths[lineWidths.length] = me.left;
}
// Store the hitbox width and height here. Final position will be updated in `draw`
hitboxes[i] = {
left: 0,
top: 0,
width: width,
height: fontSize
};
lineWidths[lineWidths.length - 1] += width + labelOpts.padding;
});
minSize.height += totalHeight;
} else {
var vPadding = labelOpts.padding;
var columnWidths = me.columnWidths = [];
var totalWidth = labelOpts.padding;
var currentColWidth = 0;
var currentColHeight = 0;
var itemHeight = fontSize + vPadding;
helpers.each(me.legendItems, function(legendItem, i) {
var boxWidth = getBoxWidth(labelOpts, fontSize);
var itemWidth = boxWidth + (fontSize / 2) + ctx.measureText(legendItem.text).width;
// If too tall, go to new column
if (currentColHeight + itemHeight > minSize.height) {
totalWidth += currentColWidth + labelOpts.padding;
columnWidths.push(currentColWidth); // previous column width
currentColWidth = 0;
currentColHeight = 0;
}
// Get max width
currentColWidth = Math.max(currentColWidth, itemWidth);
currentColHeight += itemHeight;
// Store the hitbox width and height here. Final position will be updated in `draw`
hitboxes[i] = {
left: 0,
top: 0,
width: itemWidth,
height: fontSize
};
});
totalWidth += currentColWidth;
columnWidths.push(currentColWidth);
minSize.width += totalWidth;
}
}
me.width = minSize.width;
me.height = minSize.height;
},
afterFit: noop,
// Shared Methods
isHorizontal: function() {
return this.options.position === 'top' || this.options.position === 'bottom';
},
// Actually draw the legend on the canvas
draw: function() {
var me = this;
var opts = me.options;
var labelOpts = opts.labels;
var globalDefault = defaults.global;
var lineDefault = globalDefault.elements.line;
var legendWidth = me.width;
var lineWidths = me.lineWidths;
if (opts.display) {
var ctx = me.ctx;
var valueOrDefault = helpers.valueOrDefault;
var fontColor = valueOrDefault(labelOpts.fontColor, globalDefault.defaultFontColor);
var fontSize = valueOrDefault(labelOpts.fontSize, globalDefault.defaultFontSize);
var fontStyle = valueOrDefault(labelOpts.fontStyle, globalDefault.defaultFontStyle);
var fontFamily = valueOrDefault(labelOpts.fontFamily, globalDefault.defaultFontFamily);
var labelFont = helpers.fontString(fontSize, fontStyle, fontFamily);
var cursor;
// Canvas setup
ctx.textAlign = 'left';
ctx.textBaseline = 'middle';
ctx.lineWidth = 0.5;
ctx.strokeStyle = fontColor; // for strikethrough effect
ctx.fillStyle = fontColor; // render in correct colour
ctx.font = labelFont;
var boxWidth = getBoxWidth(labelOpts, fontSize);
var hitboxes = me.legendHitBoxes;
// current position
var drawLegendBox = function(x, y, legendItem) {
if (isNaN(boxWidth) || boxWidth <= 0) {
return;
}
// Set the ctx for the box
ctx.save();
ctx.fillStyle = valueOrDefault(legendItem.fillStyle, globalDefault.defaultColor);
ctx.lineCap = valueOrDefault(legendItem.lineCap, lineDefault.borderCapStyle);
ctx.lineDashOffset = valueOrDefault(legendItem.lineDashOffset, lineDefault.borderDashOffset);
ctx.lineJoin = valueOrDefault(legendItem.lineJoin, lineDefault.borderJoinStyle);
ctx.lineWidth = valueOrDefault(legendItem.lineWidth, lineDefault.borderWidth);
ctx.strokeStyle = valueOrDefault(legendItem.strokeStyle, globalDefault.defaultColor);
var isLineWidthZero = (valueOrDefault(legendItem.lineWidth, lineDefault.borderWidth) === 0);
if (ctx.setLineDash) {
// IE 9 and 10 do not support line dash
ctx.setLineDash(valueOrDefault(legendItem.lineDash, lineDefault.borderDash));
}
if (opts.labels && opts.labels.usePointStyle) {
// Recalculate x and y for drawPoint() because its expecting
// x and y to be center of figure (instead of top left)
var radius = fontSize * Math.SQRT2 / 2;
var offSet = radius / Math.SQRT2;
var centerX = x + offSet;
var centerY = y + offSet;
// Draw pointStyle as legend symbol
helpers.canvas.drawPoint(ctx, legendItem.pointStyle, radius, centerX, centerY);
} else {
// Draw box as legend symbol
if (!isLineWidthZero) {
ctx.strokeRect(x, y, boxWidth, fontSize);
}
ctx.fillRect(x, y, boxWidth, fontSize);
}
ctx.restore();
};
var fillText = function(x, y, legendItem, textWidth) {
var halfFontSize = fontSize / 2;
var xLeft = boxWidth + halfFontSize + x;
var yMiddle = y + halfFontSize;
ctx.fillText(legendItem.text, xLeft, yMiddle);
if (legendItem.hidden) {
// Strikethrough the text if hidden
ctx.beginPath();
ctx.lineWidth = 2;
ctx.moveTo(xLeft, yMiddle);
ctx.lineTo(xLeft + textWidth, yMiddle);
ctx.stroke();
}
};
// Horizontal
var isHorizontal = me.isHorizontal();
if (isHorizontal) {
cursor = {
x: me.left + ((legendWidth - lineWidths[0]) / 2),
y: me.top + labelOpts.padding,
line: 0
};
} else {
cursor = {
x: me.left + labelOpts.padding,
y: me.top + labelOpts.padding,
line: 0
};
}
var itemHeight = fontSize + labelOpts.padding;
helpers.each(me.legendItems, function(legendItem, i) {
var textWidth = ctx.measureText(legendItem.text).width;
var width = boxWidth + (fontSize / 2) + textWidth;
var x = cursor.x;
var y = cursor.y;
if (isHorizontal) {
if (x + width >= legendWidth) {
y = cursor.y += itemHeight;
cursor.line++;
x = cursor.x = me.left + ((legendWidth - lineWidths[cursor.line]) / 2);
}
} else if (y + itemHeight > me.bottom) {
x = cursor.x = x + me.columnWidths[cursor.line] + labelOpts.padding;
y = cursor.y = me.top + labelOpts.padding;
cursor.line++;
}
drawLegendBox(x, y, legendItem);
hitboxes[i].left = x;
hitboxes[i].top = y;
// Fill the actual label
fillText(x, y, legendItem, textWidth);
if (isHorizontal) {
cursor.x += width + (labelOpts.padding);
} else {
cursor.y += itemHeight;
}
});
}
},
/**
* Handle an event
* @private
* @param {IEvent} event - The event to handle
* @return {Boolean} true if a change occured
*/
handleEvent: function(e) {
var me = this;
var opts = me.options;
var type = e.type === 'mouseup' ? 'click' : e.type;
var changed = false;
if (type === 'mousemove') {
if (!opts.onHover) {
return;
}
} else if (type === 'click') {
if (!opts.onClick) {
return;
}
} else {
return;
}
// Chart event already has relative position in it
var x = e.x;
var y = e.y;
if (x >= me.left && x <= me.right && y >= me.top && y <= me.bottom) {
// See if we are touching one of the dataset boxes
var lh = me.legendHitBoxes;
for (var i = 0; i < lh.length; ++i) {
var hitBox = lh[i];
if (x >= hitBox.left && x <= hitBox.left + hitBox.width && y >= hitBox.top && y <= hitBox.top + hitBox.height) {
// Touching an element
if (type === 'click') {
// use e.native for backwards compatibility
opts.onClick.call(me, e.native, me.legendItems[i]);
changed = true;
break;
} else if (type === 'mousemove') {
// use e.native for backwards compatibility
opts.onHover.call(me, e.native, me.legendItems[i]);
changed = true;
break;
}
}
}
}
return changed;
}
});
function createNewLegendAndAttach(chart, legendOpts) {
var legend = new Chart.Legend({
ctx: chart.ctx,
options: legendOpts,
chart: chart
});
layout.configure(chart, legend, legendOpts);
layout.addBox(chart, legend);
chart.legend = legend;
}
return {
id: 'legend',
beforeInit: function(chart) {
var legendOpts = chart.options.legend;
if (legendOpts) {
createNewLegendAndAttach(chart, legendOpts);
}
},
beforeUpdate: function(chart) {
var legendOpts = chart.options.legend;
var legend = chart.legend;
if (legendOpts) {
helpers.mergeIf(legendOpts, defaults.global.legend);
if (legend) {
layout.configure(chart, legend, legendOpts);
legend.options = legendOpts;
} else {
createNewLegendAndAttach(chart, legendOpts);
}
} else if (legend) {
layout.removeBox(chart, legend);
delete chart.legend;
}
},
afterEvent: function(chart, e) {
var legend = chart.legend;
if (legend) {
legend.handleEvent(e);
}
}
};
};