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Title alignment options #6908

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merged 2 commits into from
Jan 5, 2020
Merged

Title alignment options #6908

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7cb5008
Add alignment options for title plugin.
etimberg Jan 5, 2020
34ab22f
Update sample file title
etimberg Jan 5, 2020
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9 changes: 9 additions & 0 deletions docs/configuration/title.md
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Expand Up @@ -7,6 +7,7 @@ The title configuration is passed into the `options.title` namespace. The global

| Name | Type | Default | Description
| ---- | ---- | ------- | -----------
| `align` | `string` | `'center'` | Alignment of the title. [more...](#align)
| `display` | `boolean` | `false` | Is the title shown?
| `position` | `string` | `'top'` | Position of title. [more...](#position)
| `fontSize` | `number` | `12` | Font size.
Expand All @@ -24,6 +25,14 @@ Possible title position values are:
* `'bottom'`
* `'right'`

## Align

Alignment of the title. Options are:

* `'start'`
* `'center'`
* `'end'`

## Example Usage

The example below would enable a title of 'Custom Chart Title' on the chart that is created.
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6 changes: 6 additions & 0 deletions samples/samples.js
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Expand Up @@ -167,6 +167,12 @@
title: 'Callbacks',
path: 'legend/callbacks.html'
}]
}, {
title: 'Title',
items: [{
title: 'Alignment',
path: 'title/alignment.html'
}]
}, {
title: 'Tooltip',
items: [{
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143 changes: 143 additions & 0 deletions samples/title/alignment.html
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@@ -0,0 +1,143 @@
<!doctype html>
<html>

<head>
<title>Title Positions & Alignment</title>
<script src="../../dist/Chart.min.js"></script>
<script src="../utils.js"></script>
<style>
canvas {
-moz-user-select: none;
-webkit-user-select: none;
-ms-user-select: none;
}
.chart-container {
width: 500px;
margin-left: 40px;
margin-right: 40px;
}
.container {
display: flex;
flex-direction: row;
flex-wrap: wrap;
justify-content: center;
}
</style>
</head>

<body>
<div class="container">
<div class="chart-container">
<canvas id="chart-title-top-start"></canvas>
</div>
<div class="chart-container">
<canvas id="chart-title-top-center"></canvas>
</div>
<div class="chart-container">
<canvas id="chart-title-top-end"></canvas>
</div>
<div class="chart-container">
<canvas id="chart-title-left-start"></canvas>
</div>
<div class="chart-container">
<canvas id="chart-title-left-center"></canvas>
</div>
<div class="chart-container">
<canvas id="chart-title-left-end"></canvas>
</div>
</div>
<script>
var color = Chart.helpers.color;
function createConfig(titlePosition, titleAlignment, colorName) {
return {
type: 'line',
data: {
labels: ['January', 'February', 'March', 'April', 'May', 'June', 'July'],
datasets: [{
label: 'My First dataset',
data: [
randomScalingFactor(),
randomScalingFactor(),
randomScalingFactor(),
randomScalingFactor(),
randomScalingFactor(),
randomScalingFactor(),
randomScalingFactor()
],
backgroundColor: color(window.chartColors[colorName]).alpha(0.5).rgbString(),
borderColor: window.chartColors[colorName],
borderWidth: 1
}]
},
options: {
responsive: true,
legend: {
display: false,
},
scales: {
x: {
display: true,
scaleLabel: {
display: true,
labelString: 'Month'
}
},
y: {
display: true,
scaleLabel: {
display: true,
labelString: 'Value'
}
}
},
title: {
align: titleAlignment,
display: true,
position: titlePosition,
text: 'Title Position: ' + titlePosition + ', Align: ' + titleAlignment
}
}
};
}

window.onload = function() {
[{
id: 'chart-title-top-start',
titleAlignment: 'start',
titlePosition: 'top',
color: 'red'
}, {
id: 'chart-title-top-center',
titleAlignment: 'center',
titlePosition: 'top',
color: 'orange'
}, {
id: 'chart-title-top-end',
titleAlignment: 'end',
titlePosition: 'top',
color: 'yellow'
}, {
id: 'chart-title-left-start',
titleAlignment: 'start',
titlePosition: 'left',
color: 'green'
}, {
id: 'chart-title-left-center',
titleAlignment: 'center',
titlePosition: 'left',
color: 'blue'
}, {
id: 'chart-title-left-end',
titleAlignment: 'end',
titlePosition: 'left',
color: 'purple'
}].forEach(function(details) {
var ctx = document.getElementById(details.id).getContext('2d');
var config = createConfig(details.titlePosition, details.titleAlignment, details.color);
new Chart(ctx, config);
});
};
</script>
</body>

</html>
60 changes: 45 additions & 15 deletions src/plugins/plugin.title.js
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Expand Up @@ -6,6 +6,7 @@ const helpers = require('../helpers/index');
const layouts = require('../core/core.layouts');

defaults._set('title', {
align: 'center',
display: false,
fontStyle: 'bold',
fullWidth: true,
Expand Down Expand Up @@ -128,43 +129,72 @@ class Title extends Element {

// Actually draw the title block on the canvas
draw() {
var me = this;
var ctx = me.ctx;
var opts = me.options;
const me = this;
const ctx = me.ctx;
const opts = me.options;

if (!opts.display) {
return;
}

var fontOpts = helpers.options._parseFont(opts);
var lineHeight = fontOpts.lineHeight;
var offset = lineHeight / 2 + me._padding.top;
var rotation = 0;
var top = me.top;
var left = me.left;
var bottom = me.bottom;
var right = me.right;
var maxWidth, titleX, titleY;
const fontOpts = helpers.options._parseFont(opts);
const lineHeight = fontOpts.lineHeight;
const offset = lineHeight / 2 + me._padding.top;
let rotation = 0;
const top = me.top;
const left = me.left;
const bottom = me.bottom;
const right = me.right;
let maxWidth, titleX, titleY;
let align;

ctx.fillStyle = helpers.valueOrDefault(opts.fontColor, defaults.fontColor); // render in correct colour
ctx.font = fontOpts.string;

// Horizontal
if (me.isHorizontal()) {
titleX = left + ((right - left) / 2); // midpoint of the width
switch (opts.align) {
case 'start':
titleX = left;
align = 'left';
break;
case 'end':
titleX = right;
align = 'right';
break;
default:
titleX = left + ((right - left) / 2);
align = 'center';
break;
}

titleY = top + offset;
maxWidth = right - left;
} else {
titleX = opts.position === 'left' ? left + offset : right - offset;
titleY = top + ((bottom - top) / 2);

switch (opts.align) {
case 'start':
titleY = opts.position === 'left' ? bottom : top;
align = 'left';
break;
case 'end':
titleY = opts.position === 'left' ? top : bottom;
align = 'right';
break;
default:
titleY = top + ((bottom - top) / 2);
align = 'center';
break;
}
maxWidth = bottom - top;
rotation = Math.PI * (opts.position === 'left' ? -0.5 : 0.5);
}

ctx.save();
ctx.translate(titleX, titleY);
ctx.rotate(rotation);
ctx.textAlign = 'center';
ctx.textAlign = align;
ctx.textBaseline = 'middle';

var text = opts.text;
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1 change: 1 addition & 0 deletions test/specs/plugin.title.tests.js
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Expand Up @@ -5,6 +5,7 @@ var Title = Chart.plugins.getAll().find(p => p.id === 'title')._element;
describe('Title block tests', function() {
it('Should have the correct default config', function() {
expect(Chart.defaults.title).toEqual({
align: 'center',
display: false,
position: 'top',
fullWidth: true,
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