Create camera wrapper around functions

package.json

@@ -2,7 +2,7 @@
   "name": "web-gphoto2",
   "version": "0.1.0",
   "description": "WebAssembly implementation of gphoto2 and libusb to control DSLR cameras over USB on the Web",
-  "main": "ui/libapi.mjs",
+  "main": "ui/camera.js",
   "types": "ui/libapi.mjs.d.ts",
   "scripts": {
     "test": "echo \"Error: no test specified\" && exit 1"
@@ -23,7 +23,8 @@
   },
   "homepage": "https://github.com/GoogleChromeLabs/web-gphoto2#readme",
   "files": [
-    "ui/libapi.*"
+    "ui/libapi.*",
+    "ui/camera.js"
   ],
   "devDependencies": {
     "@types/emscripten": "^1.39.5",

ui/camera.js

@@ -0,0 +1,114 @@
+/*
+ * Copyright 2021 Google LLC
+ *
+ * This library is free software; you can redistribute it and/or
+ * modify it under the terms of the GNU Lesser General Public
+ * License as published by the Free Software Foundation; either
+ * version 2.1 of the License, or (at your option) any later version.
+ *
+ * This library is distributed in the hope that it will be useful,
+ * but WITHOUT ANY WARRANTY; without even the implied warranty of
+ * MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE. See the GNU
+ * Lesser General Public License for more details.
+ *
+ * You should have received a copy of the GNU Lesser General Public
+ * License along with this library; if not, write to the Free Software
+ * Foundation, Inc., 51 Franklin Street, Fifth Floor, Boston, MA 02110-1301, USA
+ */
+
+
+/** @typedef {import('./libapi.mjs').Context} Context */
+
+// To avoid errors for users who use SSR or Hybrid rendering (e.g. Nuxt.js), we need to check if we're in the browser.
+let initModule;
+
+async function initializeModule() {
+    if (typeof window !== 'undefined') {
+        const module = await import('./libapi.mjs');
+        initModule = module.default;
+        return initModule;
+    } else {
+        console.warn("web-gphoto2 is only available in the browser");
+        return null;
+    }
+}
+
+const ModulePromise = initializeModule().then(initModule => {
+    if (initModule) {
+        return initModule();
+    } else {
+        return null;
+    }
+});
+
+class Camera {
+    constructor() {
+        /** @type {Promise<unknown>} */
+        this.queue = Promise.resolve();
+        this.Module = null;
+        this.context = null;
+    }
+
+    rethrowIfCritical(err) {
+        // If it's precisely Error, it's a custom error; anything else - SyntaxError,
+        // WebAssembly.RuntimeError, TypeError, etc. - is treated as critical here.
+        if (err.constructor !== Error) {
+            throw err;
+        }
+    }
+
+    async connect() {
+        this.Module = await ModulePromise;
+        this.context = await new this.Module.Context();
+    }
+
+    /** Schedules an exclusive async operation on the global context.
+     * @template T
+     * @param {(ctx: Context) => Promise<T>} op
+     * @returns {Promise<T>}
+     */
+    async schedule(op) {
+        let res = this.queue.then(() => op(this.context));
+        this.queue = res.catch(this.rethrowIfCritical);
+        return res;
+    }
+
+    async disconnect() {
+        if (!this.context.isDeleted()) {
+            this.context.delete();
+        }
+    }
+
+    async getConfig() {
+        return this.schedule((context) => context.configToJS());
+    }
+
+    async getSupportedOps() {
+        if (this.context) {
+            return await this.context.supportedOps();
+        }
+        throw new Error("You need to connect to the camera first");
+    }
+
+    async setConfigValue(name, value) {
+        const uiTimeout = new Promise((resolve) => setTimeout(resolve, 800));
+        const setResult = this.schedule((context) => context.setConfigValue(name, value));
+        // wait for both the config set operation and the timeout to complete
+        return Promise.all([setResult, uiTimeout]);
+    }
+
+
+    async capturePreviewAsBlob() {
+        return this.schedule((context) => context.capturePreviewAsBlob());
+    }
+
+    async captureImageAsFile() {
+        return this.schedule((context) => context.captureImageAsFile());
+    }
+
+    async consumeEvents() {
+        return this.schedule((context) => context.consumeEvents());
+    }
+}
+
+export default Camera;

ui/libapi.mjs.d.ts

@@ -29,7 +29,7 @@ export type Config = {
     | { type: 'window'; children: Record<string, Config> }
     | { type: 'section'; children: Record<string, Config> }
     | { type: 'datetime'; value: number }
-);
+  );
 
 declare interface SupportedOps {
   captureImage: boolean;
@@ -41,6 +41,9 @@ declare interface SupportedOps {
 }
 
 declare class Context {
+  context(): Promise<any> {
+    throw new Error('Method not implemented.');
+  }
   configToJS(): Promise<Config & { type: 'window' }>;
   setConfigValue(
     name: string,
@@ -55,6 +58,26 @@ declare class Context {
   isDeleted(): boolean;
 }
 
+export declare class Camera {
+  constructor();
+
+  connect(): Promise<void>;
+  disconnect(): Promise<void>;
+
+  getConfig(): Promise<any>; // replace "any" with the actual type of the config if you have it
+
+  getSupportedOps(): SupportedOps;
+
+  setConfigValue(name: string, value: number | string | boolean): Promise<void>;
+
+  capturePreviewAsBlob(): Promise<Blob>;
+  captureImageAsFile(): Promise<File>;
+  consumeEvents(): Promise<boolean>;
+
+  private rethrowIfCritical(err: any): void;  // any error type can be replaced by more specific if available
+  private schedule<T>(op: (ctx: any) => Promise<T>): Promise<T>;  // ctx and T types can be replaced by more specific if available
+}
+
 export interface Module extends EmscriptenModule {
   Context: typeof Context;
 }