Add a soprano recorder tab converter as a Linux AppImage.

The app turns a lead line into Baroque fingering tabs with rhythm kept, ships Twinkle and Ode to Joy, and reads photos locally with oemer when the bundled Python is present.

Co-authored-by: catpersonisme <catpersonisme@gmail.com>

electron/before-build.cjs

@@ -0,0 +1,9 @@
+// The Next standalone server ships its own node_modules as an extra resource.
+// Returning false tells electron-builder to leave the project node_modules out
+// of the AppImage. Those packages are not what the window runs.
+async function beforeBuild() {
+  return false;
+}
+
+module.exports = beforeBuild;
+module.exports.beforeBuild = beforeBuild;

electron/main.cjs

@@ -0,0 +1,126 @@
+const { app, BrowserWindow, dialog } = require("electron");
+const { spawn } = require("node:child_process");
+const fs = require("node:fs");
+const http = require("node:http");
+const net = require("node:net");
+const path = require("node:path");
+
+app.commandLine.appendSwitch("no-sandbox");
+app.commandLine.appendSwitch("disable-dev-shm-usage");
+
+let server;
+
+function freePort() {
+  return new Promise((resolve, reject) => {
+    const probe = net.createServer();
+    probe.listen(0, "127.0.0.1", () => {
+      const address = probe.address();
+      const port = address && typeof address === "object" ? address.port : 0;
+      probe.close(() => resolve(port));
+    });
+    probe.on("error", reject);
+  });
+}
+
+function waitFor(url, timeoutMs) {
+  const started = Date.now();
+  return new Promise((resolve, reject) => {
+    const tick = () => {
+      const request = http.get(url, (response) => {
+        response.resume();
+        if (response.statusCode && response.statusCode < 500) resolve();
+        else retry();
+      });
+      request.on("error", retry);
+    };
+    const retry = () => {
+      if (Date.now() - started > timeoutMs) reject(new Error(`Timed out waiting for ${url}`));
+      else setTimeout(tick, 250);
+    };
+    tick();
+  });
+}
+
+function stopServer() {
+  if (server && !server.killed) server.kill("SIGTERM");
+}
+
+async function open() {
+  const resources = process.resourcesPath;
+  const standalone = path.join(resources, "standalone");
+  const python = path.join(resources, "python", "bin", "python3");
+  const serverJs = path.join(standalone, "server.js");
+  if (!fs.existsSync(serverJs) || !fs.existsSync(python)) {
+    dialog.showErrorBox(
+      "Recorder Tab Converter",
+      "The bundled app or the local reader is missing from this AppImage.",
+    );
+    app.quit();
+    return;
+  }
+
+  const port = await freePort();
+  const logPath = path.join(app.getPath("temp"), "recorder-tab-converter.log");
+  const log = fs.createWriteStream(logPath, { flags: "a" });
+  server = spawn(process.execPath, [serverJs], {
+    cwd: standalone,
+    env: {
+      ...process.env,
+      ELECTRON_RUN_AS_NODE: "1",
+      PORT: String(port),
+      HOSTNAME: "127.0.0.1",
+      OEMER_PYTHON: python,
+      NODE_ENV: "production",
+    },
+    stdio: ["ignore", "pipe", "pipe"],
+  });
+  server.stdout.pipe(log);
+  server.stderr.pipe(log);
+  server.on("exit", (code) => {
+    log.write(`\nserver exit ${code}\n`);
+  });
+
+  const url = `http://127.0.0.1:${port}/`;
+  try {
+    await waitFor(url, 45_000);
+  } catch (error) {
+    dialog.showErrorBox(
+      "Recorder Tab Converter",
+      `${error instanceof Error ? error.message : "The app server did not start."}\nLog: ${logPath}`,
+    );
+    stopServer();
+    app.quit();
+    return;
+  }
+
+  const window = new BrowserWindow({
+    width: 1280,
+    height: 880,
+    minWidth: 390,
+    minHeight: 640,
+    show: false,
+    title: "Recorder Tab Converter",
+    backgroundColor: "#f3ecdf",
+    autoHideMenuBar: true,
+    webPreferences: {
+      contextIsolation: true,
+      nodeIntegration: false,
+      // Renderer sandbox cannot create shared memory here, so the window
+      // fails with ERR_FAILED. The page is the local UI and has no Node access.
+      sandbox: false,
+    },
+  });
+  window.once("ready-to-show", () => window.show());
+  await window.loadURL(url);
+}
+
+app.whenReady().then(open).catch((error) => {
+  dialog.showErrorBox("Recorder Tab Converter", error instanceof Error ? error.message : String(error));
+  app.quit();
+});
+
+app.on("before-quit", stopServer);
+app.on("window-all-closed", () => {
+  stopServer();
+  app.quit();
+});