Merge pull request #79 from hecrj/feature/graceful-quit

Add `Game::is_finished` and support graceful quits

src/game.rs

@@ -154,6 +154,15 @@ pub trait Game {
         true
     }
 
+    /// Returns whether the game is finished or not.
+    ///
+    /// If this function returns true, the game will be closed gracefully.
+    ///
+    /// By default, it always returns false.
+    fn is_finished(&self) -> bool {
+        false
+    }
+
     /// Runs the [`Game`] with the given [`WindowSettings`].
     ///
     /// You probably want to call this in your `main` function to run your game!
@@ -181,7 +190,7 @@ pub trait Game {
         let mut timer = Timer::new(Self::TICKS_PER_SECOND);
         let mut alive = true;
 
-        while alive {
+        while alive && !game.is_finished() {
             debug.frame_started();
             timer.update();
 

src/ui.rs

@@ -287,7 +287,7 @@ pub trait UserInterface: Game {
         let mut ui_cache =
             Interface::compute(game.layout(window), &renderer).cache();
 
-        while alive {
+        while alive && !game.is_finished() {
             debug.frame_started();
             timer.update();