gtk-ng: show on-screen keyboard on LMB release (#8224)

include/ghostty.h

@@ -757,6 +757,7 @@ typedef enum {
   GHOSTTY_ACTION_OPEN_URL,
   GHOSTTY_ACTION_SHOW_CHILD_EXITED,
   GHOSTTY_ACTION_PROGRESS_REPORT,
+  GHOSTTY_ACTION_SHOW_ON_SCREEN_KEYBOARD,
 } ghostty_action_tag_e;
 
 typedef union {

src/Surface.zig

@@ -4804,6 +4804,12 @@ pub fn performBindingAction(self: *Surface, action: input.Binding.Action) !bool
             {},
         ),
 
+        .show_on_screen_keyboard => return try self.rt_app.performAction(
+            .{ .surface = self },
+            .show_on_screen_keyboard,
+            {},
+        ),
+
         .select_all => {
             const sel = self.io.terminal.screen.selectAll();
             if (sel) |s| {

src/apprt/action.zig

@@ -291,6 +291,9 @@ pub const Action = union(Key) {
     /// Show a native GUI notification about the progress of some TUI operation.
     progress_report: terminal.osc.Command.ProgressReport,
 
+    /// Show the on-screen keyboard.
+    show_on_screen_keyboard,
+
     /// Sync with: ghostty_action_tag_e
     pub const Key = enum(c_int) {
         quit,
@@ -345,6 +348,7 @@ pub const Action = union(Key) {
         open_url,
         show_child_exited,
         progress_report,
+        show_on_screen_keyboard,
     };
 
     /// Sync with: ghostty_action_u

src/apprt/gtk-ng/class/application.zig

@@ -618,6 +618,7 @@ pub const Application = extern struct {
             .toggle_window_decorations => return Action.toggleWindowDecorations(target),
             .toggle_command_palette => return Action.toggleCommandPalette(target),
             .toggle_split_zoom => return Action.toggleSplitZoom(target),
+            .show_on_screen_keyboard => return Action.showOnScreenKeyboard(target),
 
             // Unimplemented but todo on gtk-ng branch
             .inspector,
@@ -2146,6 +2147,21 @@ const Action = struct {
         }
     }
 
+    pub fn showOnScreenKeyboard(target: apprt.Target) bool {
+        switch (target) {
+            .app => {
+                log.warn("show_on_screen_keyboard to app is unexpected", .{});
+                return false;
+            },
+            // NOTE: Even though `activateOsk` takes a gdk.Event, it's currently
+            // unused by all implementations of `activateOsk` as of GTK 4.18.
+            // The commit that introduced the method (ce6aa73c) clarifies that
+            // the event *may* be used by other IM backends, but for Linux desktop
+            // environments this doesn't matter.
+            .surface => |v| return v.rt_surface.surface.showOnScreenKeyboard(null),
+        }
+    }
+
     fn getQuickTerminalWindow() ?*Window {
         // Find a quick terminal window.
         const list = gtk.Window.listToplevels();

src/apprt/gtk-ng/class/surface.zig

@@ -573,6 +573,11 @@ pub const Surface = extern struct {
         return self.as(gtk.Widget).activateAction("win.toggle-command-palette", null) != 0;
     }
 
+    pub fn showOnScreenKeyboard(self: *Self, event: ?*gdk.Event) bool {
+        const priv = self.private();
+        return priv.im_context.as(gtk.IMContext).activateOsk(event) != 0;
+    }
+
     /// Set the current progress report state.
     pub fn setProgressReport(
         self: *Self,
@@ -1946,18 +1951,29 @@ pub const Surface = extern struct {
         const event = gesture.as(gtk.EventController).getCurrentEvent() orelse return;
 
         const priv = self.private();
-        if (priv.core_surface) |surface| {
-            const gtk_mods = event.getModifierState();
-            const button = translateMouseButton(gesture.as(gtk.GestureSingle).getCurrentButton());
-            const mods = gtk_key.translateMods(gtk_mods);
-            _ = surface.mouseButtonCallback(
-                .release,
-                button,
-                mods,
-            ) catch |err| {
-                log.warn("error in key callback err={}", .{err});
-                return;
-            };
+        const surface = priv.core_surface orelse return;
+        const gtk_mods = event.getModifierState();
+        const button = translateMouseButton(gesture.as(gtk.GestureSingle).getCurrentButton());
+
+        const mods = gtk_key.translateMods(gtk_mods);
+        const consumed = surface.mouseButtonCallback(
+            .release,
+            button,
+            mods,
+        ) catch |err| {
+            log.warn("error in key callback err={}", .{err});
+            return;
+        };
+
+        // Trigger the on-screen keyboard if we have no selection,
+        // and that the mouse event hasn't been intercepted by the callback.
+        //
+        // It's better to do this here rather than within the core callback
+        // since we have direct access to the underlying gdk.Event here.
+        if (!consumed and button == .left and !surface.hasSelection()) {
+            if (!self.showOnScreenKeyboard(event)) {
+                log.warn("failed to activate the on-screen keyboard", .{});
+            }
         }
     }
 

src/apprt/gtk/App.zig

@@ -539,6 +539,7 @@ pub fn performAction(
         .check_for_updates,
         .undo,
         .redo,
+        .show_on_screen_keyboard,
         => {
             log.warn("unimplemented action={}", .{action});
             return false;

src/input/Binding.zig

@@ -524,6 +524,14 @@ pub const Action = union(enum) {
     /// Has no effect on macOS.
     show_gtk_inspector,
 
+    /// Show the on-screen keyboard if one is present.
+    ///
+    /// Only implemented on Linux (GTK). On GNOME, the "Screen Keyboard"
+    /// accessibility feature must be turned on, which can be found under
+    /// Settings > Accessibility > Typing. Other platforms are as of now
+    /// untested.
+    show_on_screen_keyboard,
+
     /// Open the configuration file in the default OS editor.
     ///
     /// If your default OS editor isn't configured then this will fail.
@@ -1051,6 +1059,7 @@ pub const Action = union(enum) {
             .toggle_window_float_on_top,
             .toggle_secure_input,
             .toggle_command_palette,
+            .show_on_screen_keyboard,
             .reset_window_size,
             .crash,
             => .surface,

src/input/command.zig

@@ -369,6 +369,12 @@ fn actionCommands(action: Action.Key) []const Command {
             .description = "Show the GTK inspector.",
         }},
 
+        .show_on_screen_keyboard => comptime &.{.{
+            .action = .show_on_screen_keyboard,
+            .title = "Show On-Screen Keyboard",
+            .description = "Show the on-screen keyboard if present.",
+        }},
+
         .open_config => comptime &.{.{
             .action = .open_config,
             .title = "Open Config",