lib/app: intro `AppComponent` to react to application life-cycle in app.nit

Signed-off-by: Alexis Laferrière <alexis.laf@xymus.net>

diff --git a/lib/app/app_base.nit b/lib/app/app_base.nit
index 76fbd09..e709e84 100644 (file)
--- a/lib/app/app_base.nit
+++ b/lib/app/app_base.nit
@@ -14,6 +14,7 @@
 # See the License for the specific language governing permissions and
 # limitations under the License.
 
+# Base of the _app.nit_ framework, defines `App`
 module app_base is
        new_annotation app_name
        new_annotation app_namespace
@@ -22,9 +23,11 @@ end
 
 # App subclasses are cross-platform applications
 #
-# This class is redefed by plateform modules and so
-# App can be specialized directly in the user app.
+# This class is refined by platform modules and so
+# App can be specialized directly in the user application code.
 class App
+       super AppComponent
+
        protected init do end
 
        # Starts the internal setup of graphical and other stuff
@@ -33,14 +36,47 @@ class App
 
        # Main entry point of your application
        fun run do end
+end
+
+# An element of an application that is notified of the application life cycle
+#
+# Most users of _app.nit_ need only to implement `on_create` to setup the application.
+#
+# On mobile devices, the application can be stopped a anytime when another application takes the foreground.
+# Implement the callbacks `on_save_state` and `on_load_state` to keep the state of the application between execution,
+# for an illusion of continuous execution.
+abstract class AppComponent
+
+       # The application is being created
+       #
+       # You should build the UI at this time.
+       fun on_create do end
 
-       # Main init method for graphical stuff
-       # Is called when display is ready so graphical assets
-       # can be loaded at this time.
-       fun window_created do end
+       # The application is starting or restarting, it is visible to the user
+       fun on_start do end
 
-       # Called before destroying the window
-       fun window_closing do end
+       # The application enters the active state, it is in the foreground and interactive
+       fun on_resume do end
+
+       # The application leaves the active state but is still partially visible
+       #
+       # It may still be visible in the background.
+       # It may then go back to `on_resume` or `on_stop`.
+       fun on_pause do end
+
+       # The application is completely hidden from the user
+       #
+       # It may then be destroyed (`on_destroy`) or go back to `on_start`.
+       fun on_stop do end
+
+       # The application is being destroyed
+       fun on_destroy do end
+
+       # The application may be destroyed soon, save its state for a future `on_restore_state`
+       fun on_save_state do end
+
+       # The application is launching, restore its state from a previous `on_save_state`
+       fun on_restore_state do end
 end
 
 # Print a warning
@@ -52,5 +88,6 @@ end
 
 # The running `App`
 fun app: App do return once new App
+
 app.setup
 app.run