Added on_gain_focus, on_lose_focus, on_show & on_hide handlers on toga.Window

android/src/toga_android/app.py

@@ -4,6 +4,7 @@
 
 import toga
 from android.media import RingtoneManager
+from android.os import Build
 from toga.command import Group
 
 from .libs.activity import IPythonApp, MainActivity
@@ -36,9 +37,17 @@ def onStart(self):
 
     def onResume(self):
         print("Toga app: onResume")
+        if Build.VERSION.SDK_INT < Build.VERSION_CODES.Q:
+            self._impl.interface.on_gain_focus(self._impl.interface)
+            for window in self._impl.interface.windows:
+                window.on_gain_focus(self._impl.interface)
 
     def onPause(self):
         print("Toga app: onPause")
+        if Build.VERSION.SDK_INT < Build.VERSION_CODES.Q:
+            self._impl.interface.on_lose_focus(self._impl.interface)
+            for window in self._impl.interface.windows:
+                window.on_lose_focus(self._impl.interface)
 
     def onStop(self):
         print("Toga app: onStop")
@@ -49,6 +58,17 @@ def onDestroy(self):
     def onRestart(self):
         print("Toga app: onRestart")
 
+    def onTopResumedActivityChanged(self, isTopResumedActivity):
+        print("Toga app: onTopResumedActivityChanged")
+        if isTopResumedActivity:
+            self._impl.interface.on_gain_focus(self._impl.interface)
+            for window in self._impl.interface.windows:
+                window.on_gain_focus(self._impl.interface)
+        else:
+            self._impl.interface.on_lose_focus(self._impl.interface)
+            for window in self._impl.interface.windows:
+                window.on_lose_focus(self._impl.interface)
+
     def onActivityResult(self, requestCode, resultCode, resultData):
         """Callback method, called from MainActivity when an Intent ends.
 

changes/2009.feature.rst

@@ -0,0 +1 @@
+Added `on_gain_focus` and `on_lose_focus` handlers both on the `toga.App` and `toga.Window`.

cocoa/src/toga_cocoa/app.py

@@ -61,6 +61,14 @@ def applicationOpenUntitledFile_(self, sender) -> bool:
         self.impl.select_file()
         return True
 
+    @objc_method
+    def applicationDidBecomeActive_(self, application):
+        self.impl.interface.on_gain_focus(self.interface)
+
+    @objc_method
+    def applicationWillResignActive_(self, application):
+        self.impl.interface.on_lose_focus(self.interface)
+
     @objc_method
     def addDocument_(self, document) -> None:
         # print("Add Document", document)

cocoa/src/toga_cocoa/window.py

@@ -48,6 +48,14 @@ def windowDidResize_(self, notification) -> None:
                 # Set the window to the new size
                 self.interface.content.refresh()
 
+    @objc_method
+    def windowDidBecomeMain_(self, notification):
+        self.impl.interface.on_gain_focus(self.interface)
+
+    @objc_method
+    def windowDidResignMain_(self, notification):
+        self.impl.interface.on_lose_focus(self.interface)
+
     ######################################################################
     # Toolbar delegate methods
     ######################################################################

core/src/toga/app.py

@@ -132,6 +132,8 @@ def __init__(
         minimizable: bool = True,
         factory: None = None,  # DEPRECATED !
         on_close: None = None,
+        on_gain_focus: callable | None = None,
+        on_lose_focus: callable | None = None,
     ) -> None:
         ######################################################################
         # 2022-09: Backwards compatibility
@@ -152,6 +154,8 @@ def __init__(
             closeable=True,
             minimizable=minimizable,
             on_close=on_close,
+            on_gain_focus=on_gain_focus,
+            on_lose_focus=on_lose_focus,
         )
 
     @Window.on_close.setter
@@ -185,6 +189,8 @@ def __init__(
         startup: AppStartupMethod | None = None,
         windows: Iterable[Window] = (),
         on_exit: OnExitHandler | None = None,
+        on_gain_focus: callable | None = None,
+        on_lose_focus: callable | None = None,
         factory: None = None,  # DEPRECATED !
     ):
         """An App is the top level of any GUI program.
@@ -384,6 +390,9 @@ class is defined, and look for a ``.dist-info`` file matching that name.
         self._impl = self._create_impl()
         self.on_exit = on_exit
 
+        self.on_gain_focus = on_gain_focus
+        self.on_lose_focus = on_lose_focus
+
     def _create_impl(self):
         return self.factory.App(interface=self)
 
@@ -628,6 +637,22 @@ def add_background_task(self, handler: BackgroundTask) -> None:
         """
         self._impl.loop.call_soon_threadsafe(wrapped_handler(self, handler), None)
 
+    @property
+    def on_gain_focus(self) -> callable:
+        return self._on_gain_focus
+
+    @on_gain_focus.setter
+    def on_gain_focus(self, handler):
+        self._on_gain_focus = wrapped_handler(self, handler)
+
+    @property
+    def on_lose_focus(self) -> callable:
+        return self._on_lose_focus
+
+    @on_lose_focus.setter
+    def on_lose_focus(self, handler):
+        self._on_lose_focus = wrapped_handler(self, handler)
+
 
 class DocumentApp(App):
     def __init__(

core/src/toga/window.py

@@ -88,6 +88,8 @@ def __init__(
         minimizable: bool = True,
         factory: None = None,  # DEPRECATED !
         on_close: OnCloseHandler | None = None,
+        on_gain_focus: callable | None = None,
+        on_lose_focus: callable | None = None,
     ) -> None:
         ######################################################################
         # 2022-09: Backwards compatibility
@@ -123,6 +125,9 @@ def __init__(
 
         self.on_close = on_close
 
+        self.on_gain_focus = on_gain_focus
+        self.on_lose_focus = on_lose_focus
+
     @property
     def id(self) -> str:
         """The DOM identifier for the window.
@@ -271,6 +276,22 @@ def close(self) -> None:
         self.app.windows -= self
         self._impl.close()
 
+    @property
+    def on_gain_focus(self) -> callable:
+        return self._on_gain_focus
+
+    @on_gain_focus.setter
+    def on_gain_focus(self, handler):
+        self._on_gain_focus = wrapped_handler(self, handler)
+
+    @property
+    def on_lose_focus(self) -> callable:
+        return self._on_lose_focus
+
+    @on_lose_focus.setter
+    def on_lose_focus(self, handler):
+        self._on_lose_focus = wrapped_handler(self, handler)
+
     ############################################################
     # Dialogs
     ############################################################

examples/window/window/app.py

@@ -122,17 +122,42 @@ def close_handler(self, window, **kwargs):
             return False
         return True
 
+    def on_app_gain_focus(self, widget, **kwargs):
+        self.app_focus_label.text = "App is in focus"
+        print("App is in focus")
+
+    def on_app_lose_focus(self, widget, **kwargs):
+        self.app_focus_label.text = "App is not in focus"
+        print("App is not in focus")
+
+    def on_window_gain_focus(self, widget, **kwargs):
+        self.window_focus_label.text = "MainWindow is in focus"
+        print("MainWindow is in focus")
+
+    def on_window_lose_focus(self, widget, **kwargs):
+        self.window_focus_label.text = "MainWindow is not in focus"
+        print("MainWindow is not in focus")
+
     def startup(self):
         # Track in-app closes
         self.close_count = 0
 
+        self.on_gain_focus = self.on_app_gain_focus
+        self.on_lose_focus = self.on_app_lose_focus
+
         # Set up main window
-        self.main_window = toga.MainWindow(title=self.name)
+        self.main_window = toga.MainWindow(
+            title=self.name,
+            on_gain_focus=self.on_window_gain_focus,
+            on_lose_focus=self.on_window_lose_focus,
+        )
         self.on_exit = self.exit_handler
 
         # Label to show responses.
         self.label = toga.Label("Ready.")
 
+        self.app_focus_label = toga.Label("App focus status")
+        self.window_focus_label = toga.Label("Window focus status")
         # Buttons
         btn_style = Pack(flex=1, padding=5)
         btn_do_origin = toga.Button(
@@ -175,6 +200,8 @@ def startup(self):
         self.inner_box = toga.Box(
             children=[
                 self.label,
+                self.app_focus_label,
+                self.window_focus_label,
                 btn_do_origin,
                 btn_do_left,
                 btn_do_right,

gtk/src/toga_gtk/window.py

@@ -20,6 +20,8 @@ def __init__(self, interface, title, position, size):
         self.native._impl = self
 
         self.native.connect("delete-event", self.gtk_delete_event)
+        self.native.connect("focus-in-event", self.window_on_gain_focus)
+        self.native.connect("focus-out-event", self.window_on_lose_focus)
 
         self.native.set_default_size(size[0], size[1])
 
@@ -138,3 +140,11 @@ def set_full_screen(self, is_full_screen):
             self.native.fullscreen()
         else:
             self.native.unfullscreen()
+
+    def window_on_gain_focus(self, sender, event):
+        self.interface.app.on_gain_focus(self.interface)
+        self.interface.on_gain_focus(self.interface)
+
+    def window_on_lose_focus(self, sender, event):
+        self.interface.app.on_lose_focus(self.interface)
+        self.interface.on_lose_focus(self.interface)

iOS/src/toga_iOS/app.py

@@ -15,10 +15,16 @@ class PythonAppDelegate(UIResponder):
     @objc_method
     def applicationDidBecomeActive_(self, application) -> None:
         print("App became active.")
+        App.app.interface.on_gain_focus(App.app.interface)
+        for window in App.app.interface.windows:
+            window.on_gain_focus(App.app.interface)
 
     @objc_method
     def applicationWillResignActive_(self, application) -> None:
         print("App about to leave foreground.", flush=True)
+        App.app.interface.on_lose_focus(App.app.interface)
+        for window in App.app.interface.windows:
+            window.on_lose_focus(App.app.interface)
 
     @objc_method
     def applicationDidEnterBackground_(self, application) -> None:

web/src/toga_web/window.py

@@ -16,6 +16,8 @@ def __init__(self, interface, title, position, size):
         app_placeholder = js.document.getElementById("app-placeholder")
         app_placeholder.appendChild(self.native)
 
+        js.document.body.onfocus = self.window_on_gain_focus
+        js.document.body.onblur = self.window_on_lose_focusS
         self.set_title(title)
 
     def get_title(self):
@@ -77,3 +79,11 @@ def set_size(self, size):
 
     def set_full_screen(self, is_full_screen):
         self.interface.factory.not_implemented("Window.set_full_screen()")
+
+    def window_on_gain_focus(self, sender, event):
+        self.interface.app.on_gain_focus(self.interface)
+        self.interface.on_gain_focus(self.interface)
+
+    def window_on_lose_focus(self, sender, event):
+        self.interface.app.on_lose_focus(self.interface)
+        self.interface.on_lose_focus(self.interface)

winforms/src/toga_winforms/window.py

@@ -43,6 +43,9 @@ def __init__(self, interface, title, position, size):
             self.native.FormBorderStyle = self.native.FormBorderStyle.FixedSingle
             self.native.MaximizeBox = False
 
+        self.native.Activated += self.window_on_gain_focus
+        self.native.Deactivate += self.window_on_lose_focus
+
     def create_toolbar(self):
         if self.interface.toolbar:
             if self.toolbar_native:
@@ -173,3 +176,13 @@ def resize_content(self):
             self.native.ClientSize.Width,
             self.native.ClientSize.Height - vertical_shift,
         )
+
+    def window_on_gain_focus(self, sender, event):
+        if self.interface.app is not None:
+            self.interface.app.on_gain_focus(self.interface)
+        self.interface.on_gain_focus(self.interface)
+
+    def window_on_lose_focus(self, sender, event):
+        if self.interface.app is not None:
+            self.interface.app.on_lose_focus(self.interface)
+        self.interface.on_lose_focus(self.interface)