desktop: fast redraws and resizes (GPU on, batched output, throttled resize) (0.2.4)

desktop/main.js

@@ -10,6 +10,31 @@ const path = require("node:path");
 if (process.platform === "linux") app.commandLine.appendSwitch("no-sandbox");
 app.setName("hqterm");
 
+// Speed: xterm 6 draws fast only through WebGL, so the GPU has to be on.
+// Chromium blocklists many Linux GPU/driver combinations and then every pane
+// falls back to the DOM renderer, where redraws and resizes crawl. Opt out of
+// the blocklist and run natively on Wayland.
+// `"gpu": false` in ~/.config/hqterm/desktop.json turns all of this off.
+const GPU_OFF = (() => {
+  try {
+    const p = require("node:path").join(process.env.XDG_CONFIG_HOME || require("node:path").join(require("node:os").homedir(), ".config"), "hqterm", "desktop.json");
+    return JSON.parse(require("node:fs").readFileSync(p, "utf8")).gpu === false;
+  } catch {
+    return false;
+  }
+})();
+if (GPU_OFF) {
+  app.disableHardwareAcceleration();
+} else {
+  // Only the blocklist: forcing GPU rasterization/zero-copy breaks the
+  // compositor where there is no real GPU (UnknownVizError under Xvfb).
+  app.commandLine.appendSwitch("ignore-gpu-blocklist");
+  if (process.platform === "linux" && (process.env.WAYLAND_DISPLAY || process.env.XDG_SESSION_TYPE === "wayland")) {
+    app.commandLine.appendSwitch("ozone-platform-hint", "auto");
+    app.commandLine.appendSwitch("enable-features", "WaylandWindowDecorations");
+  }
+}
+
 const VERSION = require("./package.json").version;
 const HOST_RE = /^[A-Za-z0-9._@:\-\[\]]+$/;
 const SESSION_RE = /^[A-Za-z0-9][A-Za-z0-9._-]*$/;
@@ -33,6 +58,7 @@ function loadConfig() {
     fontSize: Number.isFinite(c.fontSize) && c.fontSize >= 6 && c.fontSize <= 72 ? c.fontSize : 14,
     theme: c.theme && typeof c.theme === "object" ? c.theme : undefined,
     restore: c.restore !== false,
+    gpu: c.gpu !== false,
   };
 }
 
@@ -194,10 +220,28 @@ ipcMain.handle("pty:spawn", (e, { spec, cols, rows }) => {
   });
   ptys.set(id, p);
   const sender = e.sender;
+  // Coalesce output: one IPC message per pane every few ms, not one per read.
+  // A full-screen redraw arrives as dozens of small reads; sent one by one
+  // they each cost a renderer task and a partial repaint you can watch.
+  let pending = "";
+  let timer = null;
+  const flush = () => {
+    timer = null;
+    if (pending && !sender.isDestroyed()) sender.send("pty:data", id, pending);
+    pending = "";
+  };
   p.onData((data) => {
-    if (!sender.isDestroyed()) sender.send("pty:data", id, data);
+    pending += data;
+    if (pending.length >= 256 * 1024) {
+      if (timer) clearTimeout(timer);
+      flush();
+    } else if (!timer) {
+      timer = setTimeout(flush, 4);
+    }
   });
   p.onExit(({ exitCode, signal }) => {
+    if (timer) clearTimeout(timer);
+    flush();
     ptys.delete(id);
     if (!sender.isDestroyed()) sender.send("pty:exit", id, exitCode, signal);
   });
@@ -252,6 +296,17 @@ if (!app.requestSingleInstanceLock()) {
     // No menu: Ctrl+W, Ctrl+R and friends belong to the shell.
     Menu.setApplicationMenu(null);
     createWindow();
+    // What the GPU is doing, for "why is it slow": ~/.config/hqterm/desktop.log.
+    try {
+      fs.mkdirSync(configDir(), { recursive: true });
+      const st = app.getGPUFeatureStatus();
+      fs.writeFileSync(
+        path.join(configDir(), "desktop.log"),
+        `${new Date().toISOString()} hqterm desktop ${VERSION}\n` +
+          `gpu: ${GPU_OFF ? "off (desktop.json)" : "on"}; webgl=${st.webgl} webgl2=${st.webgl2} rasterization=${st.gpu_compositing}/${st.rasterization}\n` +
+          `session: ${process.env.XDG_SESSION_TYPE || "?"} wayland=${process.env.WAYLAND_DISPLAY ? "yes" : "no"}\n`,
+      );
+    } catch {}
     if (process.env.HQTERM_DESKTOP_SMOKE) {
       // CI: prove the window and a PTY come up, draw emoji and an iTerm2
       // inline image, optionally screenshot it ($HQTERM_DESKTOP_SMOKE_SHOT), exit.

desktop/package.json

@@ -1,7 +1,7 @@
 {
   "name": "hqterm-desktop",
   "productName": "hqterm",
-  "version": "0.2.3",
+  "version": "0.2.4",
   "description": "hqterm desktop: a terminal window that shows hqtui/qc images and HD emoji (xterm.js + node-pty).",
   "license": "MIT",
   "author": "Profullstack, Inc. <hello@profullstack.com>",

desktop/src/app.js

@@ -106,7 +106,13 @@
       if (rt.ptyId !== undefined) hq.write(rt.ptyId, d);
     });
     term.onBinary((d) => rt.ptyId !== undefined && hq.write(rt.ptyId, d));
-    term.onResize(({ cols, rows }) => rt.ptyId !== undefined && hq.resize(rt.ptyId, cols, rows));
+    // Tell the shell the new size only once it has settled: every PTY resize
+    // makes a full-screen program (and hqsh's remote side) redraw everything,
+    // so resizing per frame while dragging floods it with redraws.
+    term.onResize(({ cols, rows }) => {
+      clearTimeout(rt.ptyResizeTimer);
+      rt.ptyResizeTimer = setTimeout(() => rt.ptyId !== undefined && hq.resize(rt.ptyId, cols, rows), 80);
+    });
     term.onTitleChange((t) => {
       rt.title = t;
       renderBar();
@@ -124,20 +130,7 @@
     if (rt.opened) return;
     rt.opened = true;
     rt.term.open(rt.el);
-    if (webglCount < MAX_WEBGL) {
-      try {
-        const gl = new WebglAddon.WebglAddon();
-        gl.onContextLoss(() => {
-          gl.dispose();
-          webglCount--;
-        });
-        rt.term.loadAddon(gl);
-        webglCount++;
-        rt.webgl = gl;
-      } catch {
-        // DOM renderer it is.
-      }
-    }
+    loadWebgl(rt);
     // After the renderer, so images draw on top of it.
     const images = new ImageAddon.ImageAddon({ iipSupport: true, sixelSupport: true, enableSizeReports: true });
     rt.term.loadAddon(images);
@@ -146,6 +139,35 @@
     spawn(rt);
   }
 
+  /**
+   * The fast renderer. Without it xterm falls back to the DOM, where redraws
+   * are visibly slow, so say so once instead of silently crawling, and after a
+   * lost GPU context try WebGL again rather than staying on the slow path.
+   */
+  function loadWebgl(rt) {
+    if (rt.disposed || webglCount >= MAX_WEBGL) return slowRenderer(rt);
+    try {
+      const gl = new WebglAddon.WebglAddon();
+      gl.onContextLoss(() => {
+        gl.dispose();
+        webglCount--;
+        rt.webgl = undefined;
+        setTimeout(() => loadWebgl(rt), 1000);
+      });
+      rt.term.loadAddon(gl);
+      webglCount++;
+      rt.webgl = gl;
+    } catch {
+      slowRenderer(rt);
+    }
+  }
+
+  function slowRenderer(rt) {
+    if (rt.warnedSlow) return;
+    rt.warnedSlow = true;
+    rt.term.write("\x1b[2mhqterm: GPU rendering is unavailable here, so this pane uses the slower renderer (see ~/.config/hqterm/desktop.log).\x1b[0m\r\n");
+  }
+
   /**
    * iTerm2, WezTerm and kitty leave the cursor just right of an inline image,
    * and hqtui's emoji art relies on it ("hi " + art + " there"). addon-image
@@ -182,17 +204,32 @@
     } catch {}
   }
 
+  /**
+   * Refit after a size change, at most every FIT_EVERY ms while a window or
+   * divider is being dragged, plus once when it stops. A fit reflows the whole
+   * scrollback; doing it on every frame is what made resizing judder.
+   */
+  const FIT_EVERY = 50;
   function fitSoon(rt) {
     if (rt.fitQueued) return;
     rt.fitQueued = true;
-    requestAnimationFrame(() => {
-      rt.fitQueued = false;
-      fit(rt);
-    });
+    const wait = Math.max(0, FIT_EVERY - (performance.now() - (rt.lastFit || 0)));
+    setTimeout(() => {
+      requestAnimationFrame(() => {
+        rt.fitQueued = false;
+        rt.lastFit = performance.now();
+        fit(rt);
+        // The trailing fit, in case the size kept changing after this one.
+        clearTimeout(rt.fitTrail);
+        rt.fitTrail = setTimeout(() => fit(rt), FIT_EVERY * 2);
+      });
+    }, wait);
   }
 
   function disposeRuntime(rt) {
     rt.disposed = true;
+    clearTimeout(rt.ptyResizeTimer);
+    clearTimeout(rt.fitTrail);
     if (rt.ptyId !== undefined) {
       hq.kill(rt.ptyId);
       byPty.delete(rt.ptyId);

package.json

@@ -1,6 +1,6 @@
 {
   "name": "hqterm",
-  "version": "0.2.3",
+  "version": "0.2.4",
   "description": "Terminal session manager: persistent hqsh sessions with images and HD emoji, built on hqtui.",
   "license": "MIT",
   "private": true,