Add window states API

android/src/toga_android/app.py

@@ -11,6 +11,7 @@
 
 import toga
 from toga.command import Group, Separator
+from toga.constants import WindowState
 from toga.dialogs import InfoDialog
 
 from .libs import events
@@ -314,14 +315,18 @@ def set_current_window(self, window):
         pass
 
     ######################################################################
-    # Full screen control
+    # Presentation mode controls
     ######################################################################
 
-    def enter_full_screen(self, windows):
-        pass
+    def enter_presentation_mode(self, screen_window_dict):
+        for screen, window in screen_window_dict.items():
+            window._impl._before_presentation_mode_screen = window.screen
+            window.screen = screen
+            window._impl.set_window_state(WindowState.PRESENTATION)
 
-    def exit_full_screen(self, windows):
-        pass
+    def exit_presentation_mode(self):
+        # There is only a single window on android.
+        self.interface.main_window._impl.set_window_state(WindowState.NORMAL)
 
     ######################################################################
     # Platform-specific APIs

android/src/toga_android/window.py

@@ -10,6 +10,7 @@
 from java import dynamic_proxy
 from java.io import ByteArrayOutputStream
 
+from toga.constants import WindowState
 from toga.types import Position, Size
 
 from .container import Container
@@ -36,6 +37,9 @@ def __init__(self, interface, title, position, size):
         self.interface = interface
         self.interface._impl = self
         self._initial_title = title
+        # Use a shadow variable since the presence of ActionBar is not
+        # a reliable indicator for confirmation of presentation mode.
+        self._in_presentation_mode = False
 
     ######################################################################
     # Window properties
@@ -47,6 +51,11 @@ def get_title(self):
     def set_title(self, title):
         self.app.native.setTitle(title)
 
+    def show_actionbar(self, show):  # pragma: no cover
+        # The testbed can't create a simple window, so we can't test this.
+        # ActionBar is always hidden on Window.
+        pass
+
     ######################################################################
     # Window lifecycle
     ######################################################################
@@ -137,8 +146,68 @@ def get_visible(self):
     # Window state
     ######################################################################
 
-    def set_full_screen(self, is_full_screen):
-        self.interface.factory.not_implemented("Window.set_full_screen()")
+    def get_window_state(self):
+        # `window.state` is called in `_close()`, which itself is
+        # sometimes called during certain stages when the app
+        # attribute may not exist. In such cases, return NORMAL.
+        if getattr(self, "app", None) is None:
+            return WindowState.NORMAL
+        decor_view = self.app.native.getWindow().getDecorView()
+        system_ui_flags = decor_view.getSystemUiVisibility()
+        if system_ui_flags & (
+            decor_view.SYSTEM_UI_FLAG_FULLSCREEN
+            | decor_view.SYSTEM_UI_FLAG_HIDE_NAVIGATION
+            | decor_view.SYSTEM_UI_FLAG_IMMERSIVE
+        ):
+            if self._in_presentation_mode:
+                return WindowState.PRESENTATION
+            else:
+                return WindowState.FULLSCREEN
+        return WindowState.NORMAL
+
+    def set_window_state(self, state):
+        current_state = self.get_window_state()
+        decor_view = self.app.native.getWindow().getDecorView()
+
+        if current_state == state:
+            return
+
+        elif current_state != WindowState.NORMAL:
+            if current_state == WindowState.FULLSCREEN:
+                decor_view.setSystemUiVisibility(0)
+
+            else:  # current_state == WindowState.PRESENTATION:
+                decor_view.setSystemUiVisibility(0)
+                self.show_actionbar(True)
+                self._in_presentation_mode = False
+
+            self.set_window_state(state)
+
+        else:  # current_state == WindowState.NORMAL:
+            if state == WindowState.MAXIMIZED:
+                # no-op on Android.
+                pass
+
+            elif state == WindowState.MINIMIZED:
+                # no-op on Android.
+                pass
+
+            elif state == WindowState.FULLSCREEN:
+                decor_view.setSystemUiVisibility(
+                    # These constants are all marked as deprecated as of API 30.
+                    decor_view.SYSTEM_UI_FLAG_FULLSCREEN
+                    | decor_view.SYSTEM_UI_FLAG_HIDE_NAVIGATION
+                    | decor_view.SYSTEM_UI_FLAG_IMMERSIVE
+                )
+
+            else:  # state == WindowState.PRESENTATION:
+                decor_view.setSystemUiVisibility(
+                    decor_view.SYSTEM_UI_FLAG_FULLSCREEN
+                    | decor_view.SYSTEM_UI_FLAG_HIDE_NAVIGATION
+                    | decor_view.SYSTEM_UI_FLAG_IMMERSIVE
+                )
+                self.show_actionbar(False)
+                self._in_presentation_mode = True
 
     ######################################################################
     # Window capabilities
@@ -168,3 +237,10 @@ def create_toolbar(self):
         # Toolbar items are configured as part of onPrepareOptionsMenu; trigger that
         # handler.
         self.app.native.invalidateOptionsMenu()
+
+    def show_actionbar(self, show):
+        actionbar = self.app.native.getSupportActionBar()
+        if show:
+            actionbar.show()
+        else:
+            actionbar.hide()

android/tests_backend/window.py

@@ -1,17 +1,26 @@
 from androidx.appcompat import R as appcompat_R
 
+from toga.constants import WindowState
+
 from .dialogs import DialogsMixin
 from .probe import BaseProbe
 
 
 class WindowProbe(BaseProbe, DialogsMixin):
+    supports_fullscreen = True
+    supports_presentation = True
+
     def __init__(self, app, window):
         super().__init__(app)
         self.native = self.app._impl.native
         self.window = window
 
-    async def wait_for_window(self, message, minimize=False, full_screen=False):
-        await self.redraw(message)
+    async def wait_for_window(
+        self, message, minimize=False, full_screen=False, rapid_state_switching=False
+    ):
+        await self.redraw(
+            message, delay=0.1 if (full_screen or rapid_state_switching) else 0
+        )
 
     @property
     def content_size(self):
@@ -20,6 +29,22 @@ def content_size(self):
             self.root_view.getHeight() / self.scale_factor,
         )
 
+    def get_window_state(self):
+        decor_view = self.native.getWindow().getDecorView()
+        system_ui_flags = decor_view.getSystemUiVisibility()
+        if system_ui_flags & (
+            decor_view.SYSTEM_UI_FLAG_FULLSCREEN
+            | decor_view.SYSTEM_UI_FLAG_HIDE_NAVIGATION
+            | decor_view.SYSTEM_UI_FLAG_IMMERSIVE
+        ):
+            if self.window._impl._in_presentation_mode:
+                current_state = WindowState.PRESENTATION
+            else:
+                current_state = WindowState.FULLSCREEN
+        else:
+            current_state = WindowState.NORMAL
+        return current_state
+
     def _native_menu(self):
         return self.native.findViewById(appcompat_R.id.action_bar).getMenu()
 

changes/1857.feature.rst

@@ -0,0 +1 @@
+Toga apps can now detect and set their window states including maximized, minimized, normal, full screen and presentation states.

changes/1857.removal.rst

@@ -0,0 +1 @@
+"Full screen mode" on an app has been renamed "Presentation mode" to avoid the ambiguity with "full screen mode" on a window. The ``toga.App.enter_full_screen`` and ``toga.App.exit_full_screen`` APIs have been renamed ``toga.App.enter_presentation_mode`` and ``toga.App.exit_presentation_mode``, respectively. ```

cocoa/src/toga_cocoa/app.py

@@ -13,6 +13,7 @@
 
 import toga
 from toga.command import Command, Group, Separator
+from toga.constants import WindowState
 from toga.handlers import NativeHandler
 
 from .command import Command as CommandImpl, submenu_for_group
@@ -369,34 +370,37 @@ def set_current_window(self, window):
         window._impl.native.makeKeyAndOrderFront(window._impl.native)
 
     ######################################################################
-    # Full screen control
+    # Presentation mode controls
     ######################################################################
 
-    def enter_full_screen(self, windows):
+    def enter_presentation_mode(self, screen_window_dict):
         opts = NSMutableDictionary.alloc().init()
         opts.setObject(
             NSNumber.numberWithBool(True), forKey="NSFullScreenModeAllScreens"
         )
 
-        for window, screen in zip(windows, NSScreen.screens):
+        for screen, window in screen_window_dict.items():
             # The widgets are actually added to window._impl.container.native, instead of
             # window.content._impl.native. And window._impl.native.contentView is
             # window._impl.container.native. Hence, we need to go fullscreen on
             # window._impl.container.native instead.
-            window._impl.container.native.enterFullScreenMode(screen, withOptions=opts)
-            # Going full screen causes the window content to be re-homed
-            # in a NSFullScreenWindow; teach the new parent window
-            # about its Toga representations.
+            window._impl.container.native.enterFullScreenMode(
+                screen._impl.native, withOptions=opts
+            )
+            # Going presentation mode causes the window content to be re-homed
+            # in a NSFullScreenWindow; teach the new parent window about its
+            # Toga representations.
             window._impl.container.native.window._impl = window._impl
             window._impl.container.native.window.interface = window
             window.content.refresh()
 
-    def exit_full_screen(self, windows):
+    def exit_presentation_mode(self):
         opts = NSMutableDictionary.alloc().init()
         opts.setObject(
             NSNumber.numberWithBool(True), forKey="NSFullScreenModeAllScreens"
         )
 
-        for window in windows:
-            window._impl.container.native.exitFullScreenModeWithOptions(opts)
-            window.content.refresh()
+        for window in self.interface.windows:
+            if window.state == WindowState.PRESENTATION:
+                window._impl.container.native.exitFullScreenModeWithOptions(opts)
+                window.content.refresh()