linebender · futurepaul · May 31, 2020 · Apr 16, 2020 · May 26, 2020 · May 31, 2020
diff --git a/.github/workflows/ci.yml b/.github/workflows/ci.yml
@@ -223,6 +223,16 @@ jobs:
       - name: wasm-pack build examples
         run: wasm-pack build --dev --target web druid/examples/wasm
 
+      # Clippy and build the hello_wasm_web example
+      - name: cargo clippy hello_wasm_web example
+        uses: actions-rs/cargo@v1
+        with:
+          command: clippy
+          args: --manifest-path=druid/examples/hello_wasm_web/Cargo.toml --target wasm32-unknown-unknown -- -D warnings
+
+      - name: wasm-pack build hello_wasm_web example
+        run: wasm-pack build --target web druid/examples/hello_wasm_web
+
   test-nightly:
     runs-on: ${{ matrix.os }}
     strategy:

diff --git a/Cargo.toml b/Cargo.toml
@@ -5,4 +5,5 @@ members = [
     "druid-derive",
     "docs/book_examples",
     "druid/examples/wasm",
+    "druid/examples/hello_wasm_web",
 ]
diff --git a/druid/examples/hello_wasm_web/Cargo.toml b/druid/examples/hello_wasm_web/Cargo.toml
@@ -0,0 +1,16 @@
+[package]
+name = "hello-wasm-web"
+version = "0.1.0"
+license = "Apache-2.0"
+description = "Minimal wasm example for web"
+repository = "https://github.com/xi-editor/druid"
+edition = "2018"
+publish = false
+
+[lib]
+crate-type = ["cdylib", "rlib"]
+
+[dependencies]
+druid = { path="../.."}
+wasm-bindgen = "0.2.60"
+console_error_panic_hook = { version = "0.1.6" }
diff --git a/druid/examples/hello_wasm_web/README.md b/druid/examples/hello_wasm_web/README.md
@@ -0,0 +1,29 @@
+# druid WASM hello world
+
+This is a minimal example of building a single druid application for the web. To build all the druid examples as wasm, check out the main wasm example.
+
+## Building
+
+You will need `cargo` and `wasm-pack` for building the code and a simple
+server like [`http`](https://crates.io/crates/https) for serving the web page.
+
+First build with.
+
+```
+> wasm-pack build --target web --dev
+```
+
+This generates a JavaScript module that exports the `wasm_main` function that's been annotated with the `#[wasm_bindgen]` macro. Leave off the `--dev` flag if you're doing a release build.
+
+Now run
+
+```
+> http
+```
+
+which should start serving this folder.
+
+Finally, point your browser to the appropriate localhost url (usually http://localhost:8000) and you
+should see your app.
+
+When you make changes to the project, re-run `wasm-pack build --target web --dev` and you can see the changes in your browser when you refresh -- no need to restart `http`.
diff --git a/druid/examples/hello_wasm_web/index.html b/druid/examples/hello_wasm_web/index.html
@@ -0,0 +1,27 @@
+<!DOCTYPE html>
+<html lang="en">
+
+<head>
+    <meta charset="utf-8">
+    <title>Druid WASM example</title>
+    <style>
+        html,
+        body,
+        canvas {
+            margin: 0px;
+            padding: 0px;
+            width: 100%;
+            height: 100%;
+            overflow: hidden;
+        }
+    </style>
+</head>
+
+<body>
+    <noscript>This page contains webassembly and javascript content, please enable javascript in your
+        browser.</noscript>
+    <canvas id="canvas"></canvas>
+    <script type="module" src="./index.js" type="application/javascript"></script>
+</body>
+
+</html>
diff --git a/druid/examples/hello_wasm_web/index.js b/druid/examples/hello_wasm_web/index.js
@@ -0,0 +1,8 @@
+import init, { wasm_main } from "./pkg/hello_wasm_web.js";
+
+async function run() {
+  await init();
+  wasm_main();
+}
+
+run();
diff --git a/druid/examples/hello_wasm_web/src/lib.rs b/druid/examples/hello_wasm_web/src/lib.rs
@@ -0,0 +1,72 @@
+// Copyright 2020 The xi-editor Authors.
+//
+// Licensed under the Apache License, Version 2.0 (the "License");
+// you may not use this file except in compliance with the License.
+// You may obtain a copy of the License at
+//
+//     http://www.apache.org/licenses/LICENSE-2.0
+//
+// Unless required by applicable law or agreed to in writing, software
+// distributed under the License is distributed on an "AS IS" BASIS,
+// WITHOUT WARRANTIES OR CONDITIONS OF ANY KIND, either express or implied.
+// See the License for the specific language governing permissions and
+// limitations under the License.
+
+use druid::widget::{Align, Flex, Label, TextBox};
+use druid::{AppLauncher, Data, Env, Lens, Widget, WidgetExt, WindowDesc};
+
+use wasm_bindgen::prelude::*;
+
+const VERTICAL_WIDGET_SPACING: f64 = 20.0;
+const TEXT_BOX_WIDTH: f64 = 200.0;
+
+#[derive(Clone, Data, Lens)]
+struct HelloState {
+    name: String,
+}
+
+// This wrapper function is the primary modification we're making to the vanilla
+// hello.rs example.
+#[wasm_bindgen]
+pub fn wasm_main() {
+    // This hook is necessary to get panic messages on wasm32
+    std::panic::set_hook(Box::new(console_error_panic_hook::hook));
+    main()
+}
+
+pub fn main() {
+    // describe the main window
+    //
+    // Window title is set in index.html and window size is ignored on the web,
+    // so can we leave those off.
+    let main_window = WindowDesc::new(build_root_widget);
+
+    // create the initial app state
+    let initial_state = HelloState {
+        name: "World".into(),
+    };
+
+    // start the application
+    AppLauncher::with_window(main_window)
+        .launch(initial_state)
+        .expect("Failed to launch application");
+}
+
+fn build_root_widget() -> impl Widget<HelloState> {
+    // a label that will determine its text based on the current app data.
+    let label = Label::new(|data: &HelloState, _env: &Env| format!("Hello {}!", data.name));
+    // a textbox that modifies `name`.
+    let textbox = TextBox::new()
+        .with_placeholder("Who are we greeting?")
+        .fix_width(TEXT_BOX_WIDTH)
+        .lens(HelloState::name);
+
+    // arrange the two widgets vertically, with some padding
+    let layout = Flex::column()
+        .with_child(label)
+        .with_spacer(VERTICAL_WIDGET_SPACING)
+        .with_child(textbox);
+
+    // center the two widgets in the available space
+    Align::centered(layout)
+}