First sketch of style switcher

README.md

@@ -68,7 +68,7 @@ Read the [CONTRIBUTING.md](CONTRIBUTING.md) guide in order to get familiar with
 
 If you depend on a free software alternative to `mapbox-gl-js`, please consider joining our effort! Anyone with a stake in a healthy community-led fork is welcome to help us figure out our next steps. We welcome contributors and leaders! MapLibre GL JS already represents the combined efforts of a few early fork efforts, and we all benefit from "one project" rather than "our way". If you know of other forks, please reach out to them and direct them here.
 
-> **MapLibre GL JS** is developed following [Semantic Versioning (2.0.0)](https://semver.org/spec/v2.0.0.html).
+> **MapLibre GL JS** is developed following [Semantic Versioning (2.0.0)](https://semver.org/spec/v2.0.0.html).
 
 ### Bounties
 

build/generate-docs.ts

@@ -74,9 +74,45 @@ function generateReadme() {
     fs.rmSync(globalsFile);
 }
 
+/**
+ * Attempts to parse configuration metadata out of the first comment block,
+ * interpreting it JSON.
+ * If JSON parsing succeeds, the comment is removed and the JSON object returned as a configuration object.
+ * Otherwise, the HTML is left intact and the config is null.
+ * @param rawHtml - A raw HTML string to preprocess.
+ * @returns A JSON object with two keys: config and htmlContent. Config may be null.
+ */
+function preprocessHTML(rawHtml: string) {
+    const configPattern = /<!--([\s\S]*?)-->/;
+    const match = rawHtml.match(configPattern);
+
+    if (match) {
+        const configBody = match[1].trim();
+        let config;
+
+        try {
+            config = JSON.parse(configBody);
+            const htmlContent = rawHtml.replace(configPattern, '').trim();
+
+            return {
+                config,
+                htmlContent
+            };
+        } catch (error) {
+            console.info(`Ignoring comment ${configBody} as it does not appear to be JSON.`);
+        }
+    }
+
+    // If no config is found, return the original HTML with no config
+    return {
+        config: null,
+        htmlContent: rawHtml
+    };
+}
+
 /**
  * This takes the examples folder with all the html files and generates a markdown file for each of them.
- * It also create an index file with all the examples and their images.
+ * It also creates an index file with all the examples and their images.
  */
 function generateExamplesFolder() {
     const examplesDocsFolder = path.join('docs', 'examples');
@@ -87,23 +123,51 @@ function generateExamplesFolder() {
     const examplesFolder = path.join('test', 'examples');
     const files = fs.readdirSync(examplesFolder).filter(f => f.endsWith('html'));
     const maplibreUnpkg = `https://unpkg.com/maplibre-gl@${packageJson.version}/`;
+    const styleSwitcherScript = fs.readFileSync(path.join('build', 'style-switcher.js'));
     const indexArray = [] as HtmlDoc[];
+    // TODO: In which cases should we include the MapLibre Demo Tiles? These are only useful for very "zoomed out" maps.
+    const defaultMapStyles = {
+        americana: {name: 'Americana', styleUrl: 'https://americanamap.org/style.json'},
+        maptilerStreets: {name: 'MapTiler Streets', styleUrl: 'https://api.maptiler.com/maps/streets/style.json?key=get_your_own_OpIi9ZULNHzrESv6T2vL'},
+        alidadeSmoothDark: {name: 'Stadia Maps Alidade Smooth Dark', styleUrl: 'https://tiles.stadiamaps.com/styles/alidade_smooth_dark.json'}
+    };
+
     for (const file of files) {
         const htmlFile = path.join(examplesFolder, file);
-        let htmlContent = fs.readFileSync(htmlFile, 'utf-8');
+        let {config, htmlContent} = preprocessHTML(fs.readFileSync(htmlFile, 'utf-8'));
         htmlContent = htmlContent.replace(/\.\.\/\.\.\//g, maplibreUnpkg);
         htmlContent = htmlContent.replace(/-dev.js/g, '.js');
         const htmlContentLines = htmlContent.split('\n');
         const title = htmlContentLines.find(l => l.includes('<title'))?.replace('<title>', '').replace('</title>', '').trim()!;
         const description = htmlContentLines.find(l => l.includes('og:description'))?.replace(/.*content=\"(.*)\".*/, '$1')!;
+
+        const displayedHtmlContent = htmlContent;
+        // Decide whether we want to add the style switcher.
+        // Currently looks for the Americana style, but could be more sophisticated with some effort.
+        const injectStyleSwitcher = htmlContent.indexOf('https://americanamap.org/style.json') !== -1 || config?.availableMapStyles;
+
+        // If possible, inject a style switcher into the HTML.
+        // This will not show up in the copyable example code.
+        if (injectStyleSwitcher) {
+            const sentinel = '</script>';
+            const lastIndex = htmlContent.lastIndexOf(sentinel);
+
+            if (lastIndex !== -1) {
+                const availableMapStyles = JSON.stringify(config?.availableMapStyles || defaultMapStyles);
+                const originalHead = htmlContent.substring(0, lastIndex);
+                const originalTail = htmlContent.substring(lastIndex);
+                htmlContent = `${originalHead}\nconst availableMapStyles = ${availableMapStyles};\n${styleSwitcherScript}\n${originalTail}`;
+            }
+        }
+
         fs.writeFileSync(path.join(examplesDocsFolder, file), htmlContent);
         const mdFileName = file.replace('.html', '.md');
         indexArray.push({
             title,
             description,
             mdFileName
         });
-        const exampleMarkdown = generateMarkdownForExample(title, description, file, htmlContent);
+        const exampleMarkdown = generateMarkdownForExample(title, description, file, displayedHtmlContent);
         fs.writeFileSync(path.join(examplesDocsFolder, mdFileName), exampleMarkdown);
     }
 

build/style-switcher.js

@@ -0,0 +1,115 @@
+// Style switcher for embedding into example pages.
+// Note that there are several uses of `window.parent` throughout this file.
+// This is because the code is executing from an example
+// that is embedded into the page via an iframe.
+// As these are served from the same origin, this is allowed by JavaScript.
+
+/**
+ * Gets a list of nodes whose text content includes the given string.
+ *
+ * @param searchText The text to look for in the element text node.
+ * @param root The root node to start traversing from.
+ * @returns A list of DOM nodes matching the search.
+ */
+function getNodesByTextContent(searchText, root = window.parent.document.body) {
+    const matchingNodes = [];
+
+    function traverse(node) {
+        if (node.nodeType === Node.ELEMENT_NODE) {
+            node.childNodes.forEach(traverse);
+        } else if (node.nodeType === Node.TEXT_NODE) {
+            if (node.nodeValue.includes(searchText)) {
+                matchingNodes.push(node);
+            }
+        }
+    }
+
+    traverse(root);
+
+    return matchingNodes.map(node => node.parentNode); // Return parent nodes of the matching text nodes
+}
+
+/**
+ * Gets the current map style slug from the query string.
+ * @returns {string}
+ */
+function getMapStyleQueryParam() {
+    const url = new URL(window.parent.location.href);
+    return url.searchParams.get('mapStyle');
+}
+
+/**
+ * Sets the map style slug in the browser's query string
+ * (ex: when the user selects a new style).
+ * @param styleKey
+ */
+function setMapStyleQueryParam(styleKey) {
+    const url = new URL(window.parent.location.href);
+    if (url.searchParams.get('mapStyle') !== styleKey) {
+        url.searchParams.set('mapStyle', styleKey);
+        // TODO: Observe URL changes ex: forward and back
+        // Manipulates the window history so that the page doesn't reload.
+        window.parent.history.pushState(null, '', url);
+    }
+}
+
+class StyleSwitcherControl {
+    constructor () {
+        this.el = document.createElement('div');
+    }
+
+    onAdd (_) {
+        this.el.className = 'maplibregl-ctrl';
+
+        const select = document.createElement('select');
+        select.oninput = (event) => {
+            const styleKey = event.target.value;
+            const style = availableMapStyles[styleKey];
+            this.setStyle(styleKey, style);
+        };
+
+        const mapStyleKey = getMapStyleQueryParam();
+
+        for (const key in availableMapStyles) {
+            if (availableMapStyles.hasOwnProperty(key)) {
+                const style = availableMapStyles[key];
+                let selected = '';
+
+                // As we go through the styles, look for it in the rendered example.
+                if (this.styleURLNode === undefined && getNodesByTextContent(style.styleUrl)) {
+                    this.styleURLNode = getNodesByTextContent(style.styleUrl)[0];
+                }
+
+                if (key === mapStyleKey) {
+                    selected = ' selected';
+                    this.setStyle(key, style);
+                }
+
+                select.insertAdjacentHTML('beforeend', `<option value="${key}"${selected}>${style.name}</option>`);
+            }
+        }
+
+        // Add the select to the element
+        this.el.append(select);
+
+        return this.el;
+    }
+
+    onRemove (_) {
+        // Remove all children
+        this.el.replaceChildren()
+    }
+
+    setStyle(styleKey, style) {
+        // Change the map style
+        map.setStyle(style.styleUrl)
+
+        // Update the example
+        this.styleURLNode.innerText = `'${style.styleUrl}'`;
+
+        // Update the URL
+        setMapStyleQueryParam(styleKey);
+    }
+}
+
+map.addControl(new StyleSwitcherControl(), 'top-left');

docs/index.md

@@ -34,7 +34,18 @@ This documentation is divided into several sections:
 
 Each section describes classes or objects as well as their **properties**, **parameters**, **instance members**, and associated **events**. Many sections also include inline code examples and related resources.
 
-In the examples, we use vector tiles from our [Demo tiles repository](https://github.com/maplibre/demotiles) and from [MapTiler](https://maptiler.com). Get your own API key if you want to use MapTiler data in your project.
+In the examples, we use vector tiles from our [Demo tiles repository](https://github.com/maplibre/demotiles)
+and the following other providers (presented in alphabetical order).
+
+|                                          |                                                                                                                                                            |
+|------------------------------------------|------------------------------------------------------------------------------------------------------------------------------------------------------------|
+| [Americana OSM](https://tile.ourmap.us/) | A community tile server run by (amazingly dedicated) volunteers. Consult their [tile usage policy](https://tile.ourmap.us/usage.html) for acceptable uses. |
+| [MapTiler](https://maptiler.com)         | A commercial tile provider; requires an API key for use.                                                                                                   |
+| [Stadia Maps](https://stadiamaps.com/)   | A commercial tile provider; requires an API key or domain registration for use.                                                                            |
+
+You can find a list of other tile providers on the
+[Awesome MapLibre](https://github.com/maplibre/awesome-maplibre?tab=readme-ov-file#maptile-providers) tile provider section,
+or on the [OSM Wiki](https://wiki.openstreetmap.org/wiki/Vector_tiles#Providers).
 
 ## NPM
 

test/examples/add-3d-model-babylon.html

@@ -21,7 +21,7 @@
 
     const map = (window.map = new maplibregl.Map({
         container: 'map',
-        style: 'https://api.maptiler.com/maps/basic/style.json?key=get_your_own_OpIi9ZULNHzrESv6T2vL',
+        style: 'https://americanamap.org/style.json',
         zoom: 18,
         center: [148.9819, -35.3981],
         pitch: 60,

test/examples/add-3d-model.html

@@ -19,8 +19,7 @@
 <script>
     const map = (window.map = new maplibregl.Map({
         container: 'map',
-        style:
-            'https://api.maptiler.com/maps/basic/style.json?key=get_your_own_OpIi9ZULNHzrESv6T2vL',
+        style: 'https://americanamap.org/style.json',
         zoom: 18,
         center: [148.9819, -35.3981],
         pitch: 60,
@@ -142,4 +141,4 @@
     });
 </script>
 </body>
-</html>
+</html>

test/examples/add-a-marker.html

@@ -18,8 +18,7 @@
 <script>
     const map = new maplibregl.Map({
         container: 'map',
-        style:
-            'https://api.maptiler.com/maps/streets/style.json?key=get_your_own_OpIi9ZULNHzrESv6T2vL',
+        style: 'https://americanamap.org/style.json',
         center: [12.550343, 55.665957],
         zoom: 8
     });
@@ -29,4 +28,4 @@
         .addTo(map);
 </script>
 </body>
-</html>
+</html>

test/examples/add-image-animated.html

@@ -18,8 +18,7 @@
 <script>
     const map = new maplibregl.Map({
         container: 'map',
-        style:
-            'https://api.maptiler.com/maps/streets/style.json?key=get_your_own_OpIi9ZULNHzrESv6T2vL'
+        style: 'https://americanamap.org/style.json'
     });
 
     const size = 200;
@@ -92,7 +91,7 @@
         }
     };
 
-    map.on('load', () => {
+    map.on('styledata', () => {
         map.addImage('pulsing-dot', pulsingDot, {pixelRatio: 2});
 
         map.addSource('points', {
@@ -121,4 +120,4 @@
     });
 </script>
 </body>
-</html>
+</html>

test/examples/add-image-generated.html

@@ -18,8 +18,7 @@
 <script>
     const map = new maplibregl.Map({
         container: 'map',
-        style:
-            'https://api.maptiler.com/maps/streets/style.json?key=get_your_own_OpIi9ZULNHzrESv6T2vL'
+        style: 'https://americanamap.org/style.json'
     });
 
     map.on('load', () => {
@@ -65,4 +64,4 @@
     });
 </script>
 </body>
-</html>
+</html>

test/examples/add-image-missing-generated.html

@@ -18,8 +18,7 @@
 <script>
     const map = new maplibregl.Map({
         container: 'map',
-        style:
-            'https://api.maptiler.com/maps/streets/style.json?key=get_your_own_OpIi9ZULNHzrESv6T2vL'
+        style: 'https://americanamap.org/style.json'
     });
 
     map.on('styleimagemissing', (e) => {
@@ -100,4 +99,4 @@
     });
 </script>
 </body>
-</html>
+</html>

test/examples/add-image-stretchable.html

@@ -18,8 +18,7 @@
 <script>
     const map = new maplibregl.Map({
         container: 'map',
-        style:
-            'https://api.maptiler.com/maps/streets/style.json?key=get_your_own_OpIi9ZULNHzrESv6T2vL',
+        style: 'https://americanamap.org/style.json',
         zoom: 0.1
     });
 
@@ -153,4 +152,4 @@
     });
 </script>
 </body>
-</html>
+</html>

test/examples/add-image.html

@@ -18,8 +18,7 @@
 <script>
     const map = new maplibregl.Map({
         container: 'map',
-        style:
-            'https://api.maptiler.com/maps/streets/style.json?key=get_your_own_OpIi9ZULNHzrESv6T2vL'
+        style: 'https://americanamap.org/style.json'
     });
 
     map.on('load', async () => {
@@ -52,4 +51,4 @@
     });
 </script>
 </body>
-</html>
+</html>

test/examples/animate-a-line.html

@@ -33,8 +33,7 @@
 <script>
     const map = new maplibregl.Map({
         container: 'map',
-        style:
-            'https://api.maptiler.com/maps/streets/style.json?key=get_your_own_OpIi9ZULNHzrESv6T2vL',
+        style: 'https://americanamap.org/style.json',
         center: [0, 0],
         zoom: 0.5
     });