Move CSS in a separate file to be CSP-compliant (chartjs#6048)

In order to be compatible with any CSP, we need to prevent the automatic creation of the DOM 'style' element and offer our CSS as a separate file that can be manually loaded (`Chart.js` or `Chart.min.js`). Users can now opt-out the style injection using `Chart.platform.disableCSSInjection = true` (note that the style sheet is now injected on the first chart creation).

To prevent duplicating and maintaining the same CSS code at different places, move all these rules in `platform.dom.css` and write a minimal rollup plugin to inject that style as string in `platform.dom.js`. Additionally, this plugin extract the imported style in `./dist/Chart.js` and `./dist/Chart.min.js`.

docs/getting-started/integration.md

@@ -84,3 +84,18 @@ require(['moment'], function() {
     });
 });
 ```
+
+## Content Security Policy
+
+By default, Chart.js injects CSS directly into the DOM. For webpages secured using [Content Security Policy (CSP)](https://developer.mozilla.org/en-US/docs/Web/HTTP/CSP), this requires to allow `style-src 'unsafe-inline'`. For stricter CSP environments, where only `style-src 'self'` is allowed, the following CSS file needs to be manually added to your webpage:
+
+```html
+<link rel="stylesheet" type="text/css" href="path/to/chartjs/dist/Chart.min.css">
+```
+
+And the style injection must be turned off **before creating the first chart**:
+
+```javascript
+// Disable automatic style injection
+Chart.platform.disableCSSInjection = true;
+```

gulpfile.js

@@ -86,7 +86,7 @@ function buildTask() {
 function packageTask() {
   return merge(
       // gather "regular" files landing in the package root
-      gulp.src([outDir + '*.js', 'LICENSE.md']),
+      gulp.src([outDir + '*.js', outDir + '*.css', 'LICENSE.md']),
 
       // since we moved the dist files one folder up (package root), we need to rewrite
       // samples src="../dist/ to src="../ and then copy them in the /samples directory.

package.json

@@ -23,6 +23,7 @@
     "url": "https://github.com/chartjs/Chart.js/issues"
   },
   "devDependencies": {
+    "clean-css": "^4.2.1",
     "coveralls": "^3.0.0",
     "eslint": "^5.9.0",
     "eslint-config-chartjs": "^0.1.0",

rollup.config.js

@@ -4,6 +4,7 @@ const commonjs = require('rollup-plugin-commonjs');
 const resolve = require('rollup-plugin-node-resolve');
 const terser = require('rollup-plugin-terser').terser;
 const optional = require('./rollup.plugins').optional;
+const stylesheet = require('./rollup.plugins').stylesheet;
 const pkg = require('./package.json');
 
 const input = 'src/chart.js';
@@ -23,6 +24,9 @@ module.exports = [
 		plugins: [
 			resolve(),
 			commonjs(),
+			stylesheet({
+				extract: true
+			}),
 			optional({
 				include: ['moment']
 			})
@@ -49,6 +53,10 @@ module.exports = [
 			optional({
 				include: ['moment']
 			}),
+			stylesheet({
+				extract: true,
+				minify: true
+			}),
 			terser({
 				output: {
 					preamble: banner
@@ -76,7 +84,8 @@ module.exports = [
 		input: input,
 		plugins: [
 			resolve(),
-			commonjs()
+			commonjs(),
+			stylesheet()
 		],
 		output: {
 			name: 'Chart',
@@ -91,6 +100,9 @@ module.exports = [
 		plugins: [
 			resolve(),
 			commonjs(),
+			stylesheet({
+				minify: true
+			}),
 			terser({
 				output: {
 					preamble: banner

rollup.plugins.js

@@ -1,4 +1,6 @@
 /* eslint-env es6 */
+const cleancss = require('clean-css');
+const path = require('path');
 
 const UMD_WRAPPER_RE = /(\(function \(global, factory\) \{)((?:\s.*?)*)(\}\(this,)/;
 const CJS_FACTORY_RE = /(module.exports = )(factory\(.*?\))( :)/;
@@ -56,6 +58,51 @@ function optional(config = {}) {
 	};
 }
 
+// https://github.com/chartjs/Chart.js/issues/5208
+function stylesheet(config = {}) {
+	const minifier = new cleancss();
+	const styles = [];
+
+	return {
+		name: 'stylesheet',
+		transform(code, id) {
+			// Note that 'id' can be mapped to a CJS proxy import, in which case
+			// 'id' will start with 'commonjs-proxy', so let's first check if we
+			// are importing an existing css file (i.e. startsWith()).
+			if (!id.startsWith(path.resolve('.')) || !id.endsWith('.css')) {
+				return;
+			}
+
+			if (config.minify) {
+				code = minifier.minify(code).styles;
+			}
+
+			// keep track of all imported stylesheets (already minified)
+			styles.push(code);
+
+			return {
+				code: 'export default ' + JSON.stringify(code)
+			};
+		},
+		generateBundle(opts, bundle) {
+			if (!config.extract) {
+				return;
+			}
+
+			const entry = Object.keys(bundle).find(v => bundle[v].isEntry);
+			const name = (entry || '').replace(/\.js$/i, '.css');
+			if (!name) {
+				this.error('failed to guess the output file name');
+			}
+
+			bundle[name] = {
+				code: styles.filter(v => !!v).join('')
+			};
+		}
+	};
+}
+
 module.exports = {
-	optional
+	optional,
+	stylesheet
 };

samples/advanced/content-security-policy.css

@@ -0,0 +1,20 @@
+.content {
+	max-width: 640px;
+	margin: auto;
+	padding: 1rem;
+}
+
+.note {
+	font-family: sans-serif;
+	color: #5050a0;
+	line-height: 1.4;
+	margin-bottom: 1rem;
+	padding: 1rem;
+}
+
+code {
+	background-color: #f5f5ff;
+	border: 1px solid #d0d0fa;
+	border-radius: 4px;
+	padding: 0.05rem 0.25rem;
+}

samples/advanced/content-security-policy.html

@@ -0,0 +1,27 @@
+<!DOCTYPE html>
+<html lang="en-US">
+<head>
+	<meta charset="utf-8">
+	<meta http-equiv="X-UA-Compatible" content="IE=Edge">
+	<meta name="viewport" content="width=device-width, initial-scale=1">
+	<meta http-equiv="Content-Security-Policy" content="default-src 'self'">
+	<title>Scriptable > Bubble | Chart.js sample</title>
+	<link rel="stylesheet" type="text/css" href="../../dist/Chart.min.css">
+	<link rel="stylesheet" type="text/css" href="./content-security-policy.css">
+	<script src="../../dist/Chart.min.js"></script>
+	<script src="../utils.js"></script>
+	<script src="content-security-policy.js"></script>
+</head>
+<body>
+	<div class="content">
+		<div class="note">
+			In order to support a strict content security policy (<code>default-src 'self'</code>),
+			this page manually loads <code>Chart.min.css</code> and turns off the automatic style
+			injection by setting <code>Chart.platform.disableCSSInjection = true;</code>.
+		</div>
+		<div class="wrapper">
+			<canvas id="chart-0"></canvas>
+		</div>
+	</div>
+</body>
+</html>

samples/advanced/content-security-policy.js

@@ -0,0 +1,54 @@
+var utils = Samples.utils;
+
+// CSP: disable automatic style injection
+Chart.platform.disableCSSInjection = true;
+
+utils.srand(110);
+
+function generateData() {
+	var DATA_COUNT = 16;
+	var MIN_XY = -150;
+	var MAX_XY = 100;
+	var data = [];
+	var i;
+
+	for (i = 0; i < DATA_COUNT; ++i) {
+		data.push({
+			x: utils.rand(MIN_XY, MAX_XY),
+			y: utils.rand(MIN_XY, MAX_XY),
+			v: utils.rand(0, 1000)
+		});
+	}
+
+	return data;
+}
+
+window.addEventListener('load', function() {
+	new Chart('chart-0', {
+		type: 'bubble',
+		data: {
+			datasets: [{
+				backgroundColor: utils.color(0),
+				data: generateData()
+			}, {
+				backgroundColor: utils.color(1),
+				data: generateData()
+			}]
+		},
+		options: {
+			aspectRatio: 1,
+			legend: false,
+			tooltip: false,
+			elements: {
+				point: {
+					radius: function(context) {
+						var value = context.dataset.data[context.dataIndex];
+						var size = context.chart.width;
+						var base = Math.abs(value.v) / 1000;
+						return (size / 24) * base;
+					}
+				}
+			}
+		}
+	});
+});

samples/samples.js

@@ -187,6 +187,9 @@
 		items: [{
 			title: 'Progress bar',
 			path: 'advanced/progress-bar.html'
+		}, {
+			title: 'Content Security Policy',
+			path: 'advanced/content-security-policy.html'
 		}]
 	}];
 

samples/style.css

@@ -1,4 +1,3 @@
-@import url('https://maxcdn.bootstrapcdn.com/font-awesome/4.7.0/css/font-awesome.min.css');
 @import url('https://fonts.googleapis.com/css?family=Lato:100,300,400,700,900');
 
 body, html {

scripts/deploy.sh

@@ -41,7 +41,7 @@ cd $TARGET_DIR
 git checkout $TARGET_BRANCH
 
 # Copy dist files
-deploy_files '../dist/*.js' './dist'
+deploy_files '../dist/*.css ../dist/*.js' './dist'
 
 # Copy generated documentation
 deploy_files '../dist/docs/*' './docs'

scripts/release.sh

@@ -21,7 +21,7 @@ git remote add auth-origin https://$GITHUB_AUTH_TOKEN@github.com/$TRAVIS_REPO_SL
 git config --global user.email "$GITHUB_AUTH_EMAIL"
 git config --global user.name "Chart.js"
 git checkout --detach --quiet
-git add -f dist/*.js bower.json
+git add -f dist/*.css dist/*.js bower.json
 git commit -m "Release $VERSION"
 git tag -a "v$VERSION" -m "Version $VERSION"
 git push -q auth-origin refs/tags/v$VERSION 2>/dev/null

src/platforms/platform.dom.css

@@ -0,0 +1,46 @@
+/*
+ * DOM element rendering detection
+ * https://davidwalsh.name/detect-node-insertion
+ */
+@keyframes chartjs-render-animation {
+	from { opacity: 0.99; }
+	to { opacity: 1; }
+}
+
+.chartjs-render-monitor {
+	animation: chartjs-render-animation 0.001s;
+}
+
+/*
+ * DOM element resizing detection
+ * https://github.com/marcj/css-element-queries
+ */
+.chartjs-size-monitor,
+.chartjs-size-monitor-expand,
+.chartjs-size-monitor-shrink {
+	position: absolute;
+	left: 0;
+	top: 0;
+	right: 0;
+	bottom: 0;
+	overflow: hidden;
+	pointer-events: none;
+	visibility: hidden;
+	z-index: -1;
+}
+
+.chartjs-size-monitor-expand > div {
+	position: absolute;
+	width: 1000000px;
+	height: 1000000px;
+	left: 0;
+	top: 0;
+}
+
+.chartjs-size-monitor-shrink > div {
+	position: absolute;
+	width: 200%;
+	height: 200%;
+	left: 0;
+	top: 0;
+}