Android: update toolbar after rotation

src/android/toga_android/app.py

@@ -5,8 +5,13 @@
 from toga.command import Group
 
 from .libs.activity import IPythonApp, MainActivity
+from .libs.android import R__id
 from .libs.android.view import Menu, MenuItem
 from .libs.android.graphics import Drawable
+from .libs.android.widget import FrameLayout, LinearLayout, LinearLayout__LayoutParams
+from .libs.android.view import ViewGroup, Window as A_Window
+from .libs.androidx.appcompat import Toolbar
+
 from .window import Window
 
 
@@ -67,7 +72,8 @@ def onActivityResult(self, requestCode, resultCode, resultData):
             print("No intent matching request code {requestCode}")
 
     def onConfigurationChanged(self, new_config):
-        pass
+        if self._impl.toolbar:
+            self._impl.refresh_toolbar()
 
     def onOptionsItemSelected(self, menuitem):
         consumed = False
@@ -161,8 +167,8 @@ def __init__(self, interface):
         self.interface = interface
         self.interface._impl = self
         self._listener = None
-
         self.loop = android_events.AndroidEventLoop()
+        self.toolbar = None
 
     @property
     def native(self):
@@ -172,9 +178,49 @@ def create(self):
         # The `_listener` listens for activity event callbacks. For simplicity,
         # the app's `.native` is the listener's native Java class.
         self._listener = TogaApp(self)
+
+        # Call findViewById on the Window rather than the Activity, to avoid triggering
+        # creation of the default toolbar.
+        self.content_parent = ViewGroup.__cast__(
+            self.native.getWindow().findViewById(R__id.content)
+        )
+        if self.content_parent.getChildCount():
+            # The default toolbar has already been created by the call to setContentView in old
+            # versions of the template, and there's no way to remove it.
+            pass
+        else:
+            # The default toolbar doesn't respond to configuration changes, so disable it
+            # and create our own.
+            self.native.supportRequestWindowFeature(A_Window.FEATURE_NO_TITLE)
+            self.linear_layout = LinearLayout(self.native)
+            self.linear_layout.setOrientation(LinearLayout.VERTICAL)
+            self.native.setContentView(self.linear_layout)
+            self.refresh_toolbar()
+            self.content_parent = FrameLayout(self.native)
+            self.linear_layout.addView(
+                self.content_parent,
+                LinearLayout__LayoutParams.MATCH_PARENT,
+                LinearLayout__LayoutParams.MATCH_PARENT
+            )
+
         # Call user code to populate the main window
         self.interface.startup()
 
+    # See https://developer.android.com/training/appbar/setting-up#add-toolbar
+    def refresh_toolbar(self):
+        if self.toolbar:
+            self.linear_layout.removeView(self.toolbar)
+        self.toolbar = Toolbar(self.native)
+        self.linear_layout.addView(
+            self.toolbar,
+            0,
+            LinearLayout__LayoutParams(
+                LinearLayout__LayoutParams.MATCH_PARENT,
+                LinearLayout__LayoutParams.WRAP_CONTENT
+            )
+        )
+        self.native.setSupportActionBar(self.toolbar)
+
     def open_document(self, fileURL):
         print("Can't open document %s (yet)" % fileURL)
 

src/android/toga_android/libs/android/view.py

@@ -7,9 +7,11 @@
 MotionEvent = JavaClass("android/view/MotionEvent")
 SubMenu = JavaClass("android/view/SubMenu")
 View = JavaClass("android/view/View")
+ViewGroup = JavaClass("android/view/ViewGroup")
 ViewGroup__LayoutParams = JavaClass("android/view/ViewGroup$LayoutParams")
 View__MeasureSpec = JavaClass("android/view/View$MeasureSpec")
 View__OnTouchListener = JavaInterface("android/view/View$OnTouchListener")
 ViewTreeObserver__OnGlobalLayoutListener = JavaInterface(
     "android/view/ViewTreeObserver$OnGlobalLayoutListener"
 )
+Window = JavaClass("android/view/Window")

src/android/toga_android/libs/android/widget.py

@@ -11,6 +11,7 @@
 DatePickerDialog = JavaClass("android/app/DatePickerDialog")
 DatePickerDialog__OnDateSetListener = JavaInterface("android/app/DatePickerDialog$OnDateSetListener")
 EditText = JavaClass("android/widget/EditText")
+FrameLayout = JavaClass("android/widget/FrameLayout")
 HorizontalScrollView = JavaClass("android/widget/HorizontalScrollView")
 ImageView = JavaClass("android/widget/ImageView")
 ImageView__ScaleType = JavaClass("android/widget/ImageView$ScaleType")

src/android/toga_android/libs/androidx/appcompat.py

@@ -0,0 +1,4 @@
+from rubicon.java import JavaClass
+
+
+Toolbar = JavaClass("androidx/appcompat/widget/Toolbar")

src/android/toga_android/window.py

@@ -1,26 +1,25 @@
-from .libs.android import R__id
 from .libs.android.view import ViewTreeObserver__OnGlobalLayoutListener
 
 
 class AndroidViewport:
     # `content_parent` should be the view that will become the parent of the widget passed to
     # `Window.set_content`. This ensures that the viewport `width` and `height` attributes
     # return the usable area of the app, not including the action bar or status bar.
-    def __init__(self, content_parent):
-        self.content_parent = content_parent
-        self.dpi = content_parent.getContext().getResources().getDisplayMetrics().densityDpi
+    def __init__(self, app):
+        self.app = app
+        self.dpi = app.native.getResources().getDisplayMetrics().densityDpi
         # Toga needs to know how the current DPI compares to the platform default,
         # which is 160: https://developer.android.com/training/multiscreen/screendensities
         self.baseline_dpi = 160
         self.scale = float(self.dpi) / self.baseline_dpi
 
     @property
     def width(self):
-        return self.content_parent.getWidth()
+        return self.app.content_parent.getWidth()
 
     @property
     def height(self):
-        return self.content_parent.getHeight()
+        return self.app.content_parent.getHeight()
 
 
 class Window(ViewTreeObserver__OnGlobalLayoutListener):
@@ -34,9 +33,8 @@ def __init__(self, interface, title, position, size):
 
     def set_app(self, app):
         self.app = app
-        content_parent = self.app.native.findViewById(R__id.content).__global__()
-        self.viewport = AndroidViewport(content_parent)
-        content_parent.getViewTreeObserver().addOnGlobalLayoutListener(self)
+        self.viewport = AndroidViewport(app)
+        app.content_parent.getViewTreeObserver().addOnGlobalLayoutListener(self)
 
     def onGlobalLayout(self):
         """This listener is run after each native layout pass. If any view's size or position has
@@ -51,10 +49,11 @@ def onGlobalLayout(self):
     def set_content(self, widget):
         # Set the widget's viewport to be based on the window's content.
         widget.viewport = self.viewport
-        # Set the app's entire contentView to the desired widget. This means that
-        # calling Window.set_content() on any Window object automatically updates
-        # the app, meaning that every Window object acts as the MainWindow.
-        self.app.native.setContentView(widget.native)
+
+        # Set the activity's entire content to the desired widget. This means that
+        # every Window object currently acts as the MainWindow.
+        self.app.content_parent.removeAllViews()
+        self.app.content_parent.addView(widget.native)
 
         # Attach child widgets to widget as their container.
         for child in widget.interface.children: