gtk: implement custom audio for bell

nix/build-support/build-inputs.nix

@@ -28,6 +28,9 @@
   pkgs.glib
   pkgs.gobject-introspection
   pkgs.gsettings-desktop-schemas
+  pkgs.gst_all_1.gst-plugins-base
+  pkgs.gst_all_1.gst-plugins-good
+  pkgs.gst_all_1.gstreamer
   pkgs.gtk4
   pkgs.libadwaita
 ]

nix/devShell.nix

@@ -35,6 +35,7 @@
   gtk4,
   gtk4-layer-shell,
   gobject-introspection,
+  gst_all_1,
   libadwaita,
   blueprint-compiler,
   gettext,
@@ -166,6 +167,9 @@ in
         wayland
         wayland-scanner
         wayland-protocols
+        gst_all_1.gstreamer
+        gst_all_1.gst-plugins-base
+        gst_all_1.gst-plugins-good
       ];
 
     # This should be set onto the rpath of the ghostty binary if you want

nix/package.nix

@@ -127,6 +127,10 @@ in
       mv $out/share/vim/vimfiles "$vim"
       ln -sf "$vim" "$out/share/vim/vimfiles"
       echo "$vim" >> "$out/nix-support/propagated-user-env-packages"
+
+      echo "gst_all_1.gstreamer" >> "$out/nix-support/propagated-user-env-packages"
+      echo "gst_all_1.gst-plugins-base" >> "$out/nix-support/propagated-user-env-packages"
+      echo "gst_all_1.gst-plugins-good" >> "$out/nix-support/propagated-user-env-packages"
     '';
 
     meta = {

src/apprt/gtk/Surface.zig

@@ -2405,6 +2405,47 @@ pub fn ringBell(self: *Surface) !void {
         surface.beep();
     }
 
+    if (features.audio) audio: {
+        // Play a user-specified audio file.
+
+        const pathname, const optional = switch (self.app.config.@"bell-audio-path" orelse break :audio) {
+            .optional => |path| .{ path, true },
+            .required => |path| .{ path, false },
+        };
+
+        const volume: f64 = @min(
+            @max(
+                0.0,
+                self.app.config.@"bell-audio-volume",
+            ),
+            1.0,
+        );
+
+        std.debug.assert(std.fs.path.isAbsolute(pathname));
+        const media_file = gtk.MediaFile.newForFilename(pathname);
+
+        if (!optional) {
+            _ = gobject.Object.signals.notify.connect(
+                media_file,
+                ?*anyopaque,
+                gtkStreamError,
+                null,
+                .{ .detail = "error" },
+            );
+        }
+        _ = gobject.Object.signals.notify.connect(
+            media_file,
+            ?*anyopaque,
+            gtkStreamEnded,
+            null,
+            .{ .detail = "ended" },
+        );
+
+        const media_stream = media_file.as(gtk.MediaStream);
+        media_stream.setVolume(volume);
+        media_stream.play();
+    }
+
     // Mark tab as needing attention
     if (self.container.tab()) |tab| tab: {
         const page = window.notebook.getTabPage(tab) orelse break :tab;
@@ -2413,3 +2454,27 @@ pub fn ringBell(self: *Surface) !void {
         if (page.getSelected() == 0) page.setNeedsAttention(@intFromBool(true));
     }
 }
+
+/// Handle a stream that is in an error state.
+fn gtkStreamError(media_file: *gtk.MediaFile, _: *gobject.ParamSpec, _: ?*anyopaque) callconv(.c) void {
+    const path = path: {
+        const file = media_file.getFile() orelse break :path null;
+        break :path file.getPath();
+    };
+    defer if (path) |p| glib.free(p);
+
+    const media_stream = media_file.as(gtk.MediaStream);
+    const err = media_stream.getError() orelse return;
+
+    log.warn("error playing bell from {s}: {s} {d} {s}", .{
+        path orelse "<<unknown>>",
+        glib.quarkToString(err.f_domain),
+        err.f_code,
+        err.f_message orelse "",
+    });
+}
+
+/// Stream is finished, release the memory.
+fn gtkStreamEnded(media_file: *gtk.MediaFile, _: *gobject.ParamSpec, _: ?*anyopaque) callconv(.c) void {
+    media_file.unref();
+}

src/config/Config.zig

@@ -1890,8 +1890,10 @@ keybind: Keybinds = .{},
 /// open terminals.
 @"custom-shader-animation": CustomShaderAnimation = .true,
 
-/// The list of enabled features that are activated after encountering
+/// Bell features to enable if bell support is available in your runtime. Not
-/// a bell character.
+/// all features are available on all runtimes. The format of this is a list of
+/// features to enable separated by commas. If you prefix a feature with `no-`
+/// then it is disabled. If you omit a feature, its default value is used.
 ///
 /// Valid values are:
 ///
@@ -1901,17 +1903,36 @@ keybind: Keybinds = .{},
 ///    This could result in an audiovisual effect, a notification, or something
 ///    else entirely. Changing these effects require altering system settings:
 ///    for instance under the "Sound > Alert Sound" setting in GNOME,
-///    or the "Accessibility > System Bell" settings in KDE Plasma.
+///    or the "Accessibility > System Bell" settings in KDE Plasma. (GTK only)
 ///
-///    On macOS this has no affect.
+///  * `audio`
+///
+///    Play a custom sound. (GTK only)
+///
+/// Example: `audio`, `no-audio`, `system`, `no-system`:
 ///
 /// On macOS, if the app is unfocused, it will bounce the app icon in the dock
 /// once. Additionally, the title of the window with the alerted terminal
 /// surface will contain a bell emoji (🔔) until the terminal is focused
 /// or a key is pressed. These are not currently configurable since they're
 /// considered unobtrusive.
+///
+/// By default, no bell features are enabled.
 @"bell-features": BellFeatures = .{},
 
+/// If `audio` is an enabled bell feature, this is a path to an audio file. If
+/// the path is not absolute, it is considered relative to the directory of the
+/// configuration file that it is referenced from, or from the current working
+/// directory if this is used as a CLI flag. The path may be prefixed with `~/`
+/// to reference the user's home directory. (GTK only)
+@"bell-audio-path": ?Path = null,
+
+/// If `audio` is an enabled bell feature, this is the volume to play the audio
+/// file at (relative to the system volume). This is a floating point number
+/// ranging from 0.0 (silence) to 1.0 (as loud as possible). The default is 0.5.
+/// (GTK only)
+@"bell-audio-volume": f64 = 0.5,
+
 /// Control the in-app notifications that Ghostty shows.
 ///
 /// On Linux (GTK), in-app notifications show up as toasts. Toasts appear
@@ -5765,6 +5786,7 @@ pub const AppNotifications = packed struct {
 /// See bell-features
 pub const BellFeatures = packed struct {
     system: bool = false,
+    audio: bool = false,
 };
 
 /// See mouse-shift-capture