core: add keyEventIsBinding

This API can be used to determine if the next key event, if given as-is,
would result in a key binding being triggered.

include/ghostty.h

@@ -714,6 +714,7 @@ void ghostty_surface_set_color_scheme(ghostty_surface_t,
 ghostty_input_mods_e ghostty_surface_key_translation_mods(ghostty_surface_t,
                                                           ghostty_input_mods_e);
 void ghostty_surface_key(ghostty_surface_t, ghostty_input_key_s);
+bool ghostty_surface_key_is_binding(ghostty_surface_t, ghostty_input_key_s);
 void ghostty_surface_text(ghostty_surface_t, const char*, uintptr_t);
 bool ghostty_surface_mouse_captured(ghostty_surface_t);
 bool ghostty_surface_mouse_button(ghostty_surface_t,

src/Surface.zig

@@ -1637,13 +1637,38 @@ pub fn preeditCallback(self: *Surface, preedit_: ?[]const u8) !void {
     try self.queueRender();
 }
 
+/// Returns true if the given key event would trigger a keybinding
+/// if it were to be processed. This is useful for determining if
+/// a key event should be sent to the terminal or not.
+///
+/// Note that this function does not check if the binding itself
+/// is performable, only if the key event would trigger a binding.
+/// If a performable binding is found and the event is not performable,
+/// then Ghosty will act as though the binding does not exist.
+pub fn keyEventIsBinding(
+    self: *Surface,
+    event: input.KeyEvent,
+) bool {
+    switch (event.action) {
+        .release => return false,
+        .press, .repeat => {},
+    }
+
+    // Our keybinding set is either our current nested set (for
+    // sequences) or the root set.
+    const set = self.keyboard.bindings orelse &self.config.keybind.set;
+
+    // If we have a keybinding for this event then we return true.
+    return set.getEvent(event) != null;
+}
+
 /// Called for any key events. This handles keybindings, encoding and
 /// sending to the terminal, etc.
 pub fn keyCallback(
     self: *Surface,
     event: input.KeyEvent,
 ) !InputEffect {
-    // log.debug("text keyCallback event={}", .{event});
+    log.debug("text keyCallback event={}", .{event});
 
     // Crash metadata in case we crash in here
     crash.sentry.thread_state = self.crashThreadState();

src/apprt/embedded.zig

@@ -147,12 +147,12 @@ pub const App = struct {
         self.core_app.focusEvent(focused);
     }
 
-    /// See CoreApp.keyEvent.
-    pub fn keyEvent(
+    /// Convert a C key event into a Zig key event.
+    fn coreKeyEvent(
         self: *App,
         target: KeyTarget,
         event: KeyEvent,
-    ) !bool {
+    ) !?input.KeyEvent {
         const action = event.action;
         const keycode = event.keycode;
         const mods = event.mods;
@@ -243,7 +243,7 @@ pub const App = struct {
                         result.text,
                     ) catch |err| {
                         log.err("error in preedit callback err={}", .{err});
-                        return false;
+                        return null;
                     },
                 }
             } else {
@@ -251,7 +251,7 @@ pub const App = struct {
                     .app => {},
                     .surface => |surface| surface.core_surface.preeditCallback(null) catch |err| {
                         log.err("error in preedit callback err={}", .{err});
-                        return false;
+                        return null;
                     },
                 }
 
@@ -335,7 +335,7 @@ pub const App = struct {
         } else .invalid;
 
         // Build our final key event
-        const input_event: input.KeyEvent = .{
+        return .{
             .action = action,
             .key = key,
             .physical_key = physical_key,
@@ -345,24 +345,39 @@ pub const App = struct {
             .utf8 = result.text,
             .unshifted_codepoint = unshifted_codepoint,
         };
+    }
+
+    /// See CoreApp.keyEvent.
+    pub fn keyEvent(
+        self: *App,
+        target: KeyTarget,
+        event: KeyEvent,
+    ) !bool {
+        // Convert our C key event into a Zig one.
+        const input_event: input.KeyEvent = (try self.coreKeyEvent(
+            target,
+            event,
+        )) orelse return false;
 
         // Invoke the core Ghostty logic to handle this input.
         const effect: CoreSurface.InputEffect = switch (target) {
             .app => if (self.core_app.keyEvent(
                 self,
                 input_event,
-            ))
-                .consumed
-            else
-                .ignored,
+            )) .consumed else .ignored,
 
-            .surface => |surface| try surface.core_surface.keyCallback(input_event),
+            .surface => |surface| try surface.core_surface.keyCallback(
+                input_event,
+            ),
         };
 
         return switch (effect) {
             .closed => true,
             .ignored => false,
             .consumed => consumed: {
+                const is_down = input_event.action == .press or
+                    input_event.action == .repeat;
+
                 if (is_down) {
                     // If we consume the key then we want to reset the dead
                     // key state.
@@ -1601,6 +1616,28 @@ pub const CAPI = struct {
         };
     }
 
+    /// Returns true if the given key event would trigger a binding
+    /// if it were sent to the surface right now. The "right now"
+    /// is important because things like trigger sequences are only
+    /// valid until the next key event.
+    export fn ghostty_surface_key_is_binding(
+        surface: *Surface,
+        event: KeyEvent,
+    ) bool {
+        const core_event = surface.app.coreKeyEvent(
+            .{ .surface = surface },
+            event.keyEvent(),
+        ) catch |err| {
+            log.warn("error processing key event err={}", .{err});
+            return false;
+        } orelse {
+            log.warn("error processing key event", .{});
+            return false;
+        };
+
+        return surface.core_surface.keyEventIsBinding(core_event);
+    }
+
     /// Send raw text to the terminal. This is treated like a paste
     /// so this isn't useful for sending escape sequences. For that,
     /// individual key input should be used.