feat: add GamepadVisualizer and compatibility APIs

Introduces `GamepadVisualizer` for rendering Xbox, PlayStation, and Nintendo Switch controller artwork with live button/trigger/stick state updates. Adds `getControllerImagePath()` and `getControllerVisualConfig()` helpers, plus `getCompatibilityIssues()` for surfacing known browser/controller issues (e.g. Firefox + Switch mapping bug). All new APIs are covered by tests.

Author: ReenigneArcher

README.md

@@ -49,6 +49,49 @@ Helper library for Gamepad API. Helps with detecting type of gamepad and mapping
    npm install @lizardbyte/gamepad-helper --ignore-scripts
    ```
 
+## Controller visuals
+
+`GamepadHelper` can render the packaged Xbox, PlayStation, and Nintendo Switch controller artwork and keep its buttons,
+triggers, and sticks synchronized with a browser `Gamepad` object. The consumer controls the asset location, color scheme,
+layout, and theme styling.
+
+```js
+const gamepadHelper = new GamepadHelper();
+const visualizer = gamepadHelper.createVisualizer(
+  document.getElementById('controller-visual'),
+  {
+    assetBasePath: '/assets/img/gamepads/',
+    colorScheme: 'White',
+  },
+);
+
+visualizer.mount(gamepad);
+visualizer.update(navigator.getGamepads()[gamepad.index]);
+
+// Remount the current controller with light-theme artwork.
+visualizer.setColorScheme('Black');
+
+// Remove the generated DOM when the visual is no longer needed.
+visualizer.destroy();
+```
+
+The renderer emits stable `gamepad-visual-*`, `gamepad-trigger-*`, and `gamepad-stick-indicator` classes for consumer
+styles. Custom renderers can use `getControllerVisualConfig()` and `getControllerImagePath()` without duplicating the
+asset-relative metadata.
+
+## Compatibility issues
+
+Use `getCompatibilityIssues()` to keep browser/controller compatibility knowledge in the library while presenting the
+warning in the consumer's own UI.
+
+```js
+const issues = gamepadHelper.getCompatibilityIssues(gamepad);
+
+issues.forEach(issue => {
+  console.warn(issue.message, issue.issueUrl);
+});
+```
+
 ## Attribution
 
 - Button Icons and Controls were created by Zacksly (Licensed under CC BY 3.0 - https://zacksly.itch.io)

src/js/gamepad-helper.js

@@ -3,6 +3,15 @@
  * This module provides a set of utilities for working with gamepads in web applications.
  */
 
+const {
+    GamepadVisualizer,
+    getControllerImagePath,
+    getControllerVisualConfig,
+} = require('./gamepad-visualizer');
+
+const FIREFOX_SWITCH_GAMEPAD_FIXED_VERSION = 155;
+const FIREFOX_SWITCH_GAMEPAD_ISSUE_URL = 'https://bugzilla.mozilla.org/show_bug.cgi?id=1704419';
+
 /**
  * Controller identity metadata used by browser ID lookups.
  * @typedef {Object} GamepadIdentityMapping
@@ -372,6 +381,40 @@ class GamepadHelper {
         return null;
     }
 
+    /**
+     * Get the image path for a full controller visual.
+     * @param {string} controllerType - The type of controller (XBOX, PLAYSTATION, SWITCH)
+     * @param {string} [basePath='/assets/img/gamepads/'] - The base path for the images
+     * @param {string} [colorScheme='White'] - The image color ('Black' or 'White')
+     * @returns {string|null} Encoded controller image path, or null when unavailable
+     */
+    getControllerImagePath(
+        controllerType,
+        basePath = '/assets/img/gamepads/',
+        colorScheme = 'White',
+    ) {
+        return getControllerImagePath(controllerType, basePath, colorScheme);
+    }
+
+    /**
+     * Get a copy of the visual definition for a controller type.
+     * @param {string} controllerType - The type of controller (XBOX, PLAYSTATION, SWITCH)
+     * @returns {Object|null} Controller visual definition, or null when unavailable
+     */
+    getControllerVisualConfig(controllerType) {
+        return getControllerVisualConfig(controllerType);
+    }
+
+    /**
+     * Create a reusable visualizer in a caller-provided DOM container.
+     * @param {Element} container - DOM element that will contain the visual
+     * @param {Object} [options] - Visualizer options
+     * @returns {GamepadVisualizer} Controller visualizer
+     */
+    createVisualizer(container, options = {}) {
+        return new GamepadVisualizer(this, container, options);
+    }
+
     /**
      * Check if the Gamepad API is supported in the current browser
      * @returns {boolean} True if supported, false otherwise
@@ -449,6 +492,55 @@ class GamepadHelper {
         return this.getGamepadInfo(gamepadId).type;
     }
 
+    /**
+     * Extract the major Firefox version from a user-agent string.
+     * @param {string|null} userAgent - Browser user-agent string
+     * @returns {number|null} Firefox major version, or null for other browsers
+     */
+    getFirefoxMajorVersion(userAgent) {
+        if (typeof userAgent !== 'string') {
+            return null;
+        }
+
+        const match = /\bFirefox\/(\d+)/.exec(userAgent);
+        return match ? Number.parseInt(match[1], 10) : null;
+    }
+
+    /**
+     * Get known browser/controller compatibility issues for a gamepad.
+     * @param {Gamepad|null} gamepad - Gamepad to inspect
+     * @param {Object} [options] - Detection options
+     * @param {string} [options.userAgent=navigator.userAgent] - Browser user-agent string
+     * @returns {Object[]} Structured compatibility issues
+     */
+    getCompatibilityIssues(gamepad, options = {}) {
+        if (!gamepad) {
+            return [];
+        }
+
+        const userAgent = options.userAgent ?? globalThis.navigator?.userAgent ?? '';
+        const firefoxVersion = this.getFirefoxMajorVersion(userAgent);
+        const controllerInfo = this.getGamepadInfo(gamepad.id);
+        if (
+            firefoxVersion === null
+            || firefoxVersion >= FIREFOX_SWITCH_GAMEPAD_FIXED_VERSION
+            || controllerInfo.type !== this.CONTROLLER_TYPES.SWITCH
+        ) {
+            return [];
+        }
+
+        return [{
+            code: 'firefox-switch-gamepad-mapping',
+            severity: 'warning',
+            browser: 'firefox',
+            browserVersion: firefoxVersion,
+            controllerType: controllerInfo.type,
+            fixedVersion: FIREFOX_SWITCH_GAMEPAD_FIXED_VERSION,
+            issueUrl: FIREFOX_SWITCH_GAMEPAD_ISSUE_URL,
+            message: `Firefox versions before ${FIREFOX_SWITCH_GAMEPAD_FIXED_VERSION} can report incorrect buttons and axes for Nintendo Switch controllers.`,
+        }];
+    }
+
     /**
      * Get button name for given controller type and button index
      * @param {string} controllerType - The type of controller (XBOX, PLAYSTATION, SWITCH, STANDARD)
@@ -590,5 +682,7 @@ if (globalThis.window) {
     globalThis.GamepadHelper = GamepadHelper;
 }
 
+GamepadHelper.GamepadVisualizer = GamepadVisualizer;
+
 // Export the GamepadHelper class
 module.exports = GamepadHelper;