webview · eliassjogreen · Mar 26, 2022 · Mar 26, 2022 · Mar 26, 2022
diff --git a/.gitignore b/.gitignore
@@ -7,3 +7,4 @@ target/
 
 # plugin cache
 .deno_plugins/
+WebView2Loader.dll
diff --git a/examples/multi-window/main.ts b/examples/multi-window/main.ts
@@ -0,0 +1,113 @@
+import { serve } from "https://deno.land/std@0.132.0/http/server.ts";
+import { preload } from "../../mod.ts";
+await preload();
+
+/**
+ * A window helper class to handle the workers
+ */
+class Window {
+  readonly worker: Worker;
+  #closed = false;
+  get closed() {
+    return this.#closed;
+  }
+
+  constructor(script: string, onclose: () => unknown = () => void 0) {
+    this.worker = new Worker(
+      new URL(script, import.meta.url),
+      {
+        type: "module",
+        deno: { namespace: true, permissions: "inherit" },
+      } as never,
+    );
+
+    this.worker.addEventListener("message", (evt) => {
+      console.log(`[Window "${script}"] Message:`, evt.data);
+      if (evt.data === "close") {
+        this.#closed = true;
+        onclose();
+      }
+    });
+
+    this.worker.addEventListener(
+      "messageerror",
+      (evt) => console.error(`[Window "${script}"] Message Error:`, evt.data),
+    );
+
+    this.worker.addEventListener(
+      "error",
+      (evt) => console.error(`[Window "${script}"] Error:`, evt),
+    );
+  }
+
+  terminate(): Promise<void> {
+    if (this.closed) {
+      return Promise.resolve();
+    }
+
+    return new Promise<void>((res) =>
+      setTimeout(() => {
+        this.worker.postMessage("unload");
+        this.worker.terminate();
+        this.#closed = true;
+        res();
+      }, 25)
+    );
+  }
+}
+
+// The Server
+
+const html = `
+<html>
+<body>
+  <h1>Hello Deno!</h1>
+  <button onclick='fetch("./beep").then(res => res.text()).then(alert)'>
+    Beep
+  </button>
+</body>
+</html>
+`;
+
+const server = serve((req) => {
+  const pathname = new URL(req.url).pathname;
+
+  if (pathname === "/beep") {
+    return new Response("boop");
+  } else if (!pathname || pathname === "/" || pathname === "/index.html") {
+    return new Response(html, {
+      headers: { "Content-Type": "text/html" },
+    });
+  } else {
+    return new Response("Not Found", { status: 404 });
+  }
+}, { port: 8000 });
+
+console.log("[Main] Listening on http://localhost:8000");
+
+// The Windows
+
+// Our cleanup function to help Deno exit when the Windows are closed
+
+let cleaning = false;
+async function cleanup() {
+  if (cleaning) return;
+  cleaning = true;
+
+  await Promise.all(
+    [windowLocal, windowDeno].map((window) => window.terminate()),
+  );
+
+  Deno.exit();
+}
+
+console.log("[Main] Spawning Windows");
+
+const windowLocal = new Window("./window-localhost.ts", cleanup);
+const windowDeno = new Window("./window-denoland.ts", cleanup);
+
+// Window 2
+
+console.log("[Main] Done! Running Server");
+
+await server;
diff --git a/examples/multi-window/window-denoland.ts b/examples/multi-window/window-denoland.ts
@@ -0,0 +1,20 @@
+import { Webview } from "../../mod.ts";
+
+const webview = new Webview();
+
+postMessage("open");
+
+webview.navigate("https://deno.land/");
+
+webview.bind("close", () => {
+  postMessage("close");
+  self.close();
+});
+
+addEventListener(
+  "onmessage",
+  (evt) =>
+    (evt as MessageEvent).data === "unload" ? webview.terminate() : void 0,
+);
+
+webview.run();
diff --git a/examples/multi-window/window-localhost.ts b/examples/multi-window/window-localhost.ts
@@ -0,0 +1,20 @@
+import { Webview } from "../../mod.ts";
+
+const webview = new Webview();
+
+postMessage("open");
+
+webview.navigate("http://localhost:8000");
+
+webview.bind("close", () => {
+  postMessage("close");
+  self.close();
+});
+
+addEventListener(
+  "onmessage",
+  (evt) =>
+    (evt as MessageEvent).data === "unload" ? webview.terminate() : void 0,
+);
+
+webview.run();
diff --git a/mod.ts b/mod.ts
@@ -1,2 +1,2 @@
 export * from "./src/webview.ts";
-export { unload } from "./src/ffi.ts";
+export { preload, unload } from "./src/ffi.ts";
diff --git a/src/ffi.ts b/src/ffi.ts
@@ -7,21 +7,68 @@ const policy = Deno.env.get("PLUGIN_URL") === undefined
 const url = Deno.env.get("PLUGIN_URL") ??
   `https://github.com/webview/webview_deno/releases/download/${version}/`;
 
-if (Deno.build.os === "windows") {
-  const webview2loader = await download(`${url}WebView2Loader.dll`);
-  await Deno.copyFile(webview2loader, "./WebView2Loader.dll");
+/**
+ * Checks for the existence of `./WebView2Loader.dll` for running on Windows
+ *
+ * @returns true if it exists, false if it doesn't
+ */
+async function checkForWebView2Loader(): Promise<boolean> {
+  return await Deno.stat("./WebView2Loader.dll").then(
+    () => true,
+    (e) => e instanceof Deno.errors.NotFound ? false : true,
+  );
+}
+
+// make sure we don't preload twice
+let preloaded = false;
+/**
+ * Loads the `./WebView2Loader.dll` for running on Windows.
+ * Removes old version if it already existed, and only runs once.
+ * Should be run on the main thread so that the `unload` gets hooked in properly, otherwise
+ * make sure `unload` gets called during the `window.onunload` event (after all windows are closed).
+ * 
+ * Does not need to be run on non-windows platforms, but that is subject to change.
+ */
+export async function preload() {
+  if (preloaded) return;
+
+  if (Deno.build.os === "windows") {
+    if (await checkForWebView2Loader()) {
+      await Deno.remove("./WebView2Loader.dll");
+    }
+
+    const webview2loader = await download(`${url}WebView2Loader.dll`);
+    await Deno.copyFile(webview2loader, "./WebView2Loader.dll");
 
-  // deno-lint-ignore no-window-prefix
-  if (typeof window !== "undefined") window.addEventListener("unload", unload);
+    self.addEventListener("unload", unload);
+  }
+
+  preloaded = true;
 }
 
+/**
+ * Unload the library. Should only be run once all windows are closed.
+ * If `preload` was called in the main thread, this will automatically be called
+ * during the `window.onunload` event; otherwise, you may have to call this manually.
+ */
 export function unload() {
   lib.close();
   if (Deno.build.os === "windows") {
     Deno.removeSync("./WebView2Loader.dll");
   }
 }
 
+// Automatically run the preload if we're on windows and on the main thread.
+if (Deno.build.os === "windows") {
+  if ((self as never)["window"]) {
+    await preload();
+  } else if (!await checkForWebView2Loader()) {
+    throw new Error(
+      "WebView2Loader.dll does not exist! Make sure to run preload() from the main thread.",
+    );
+  }
+}
+
 const lib = await prepare({
   name: "webview_deno",
   url,
Original file line number	Diff line number	Diff line change
Expand Up		@@ -7,3 +7,4 @@ target/

		# plugin cache
		.deno_plugins/
		WebView2Loader.dll