Some fixes regarding the joystic PR

doc/examples/joystick/.gitignore

@@ -0,0 +1,44 @@
+# Miscellaneous
+*.class
+*.log
+*.pyc
+*.swp
+.DS_Store
+.atom/
+.buildlog/
+.history
+.svn/
+
+# IntelliJ related
+*.iml
+*.ipr
+*.iws
+.idea/
+
+# The .vscode folder contains launch configuration and tasks you configure in
+# VS Code which you may wish to be included in version control, so this line
+# is commented out by default.
+#.vscode/
+
+# Flutter/Dart/Pub related
+**/doc/api/
+**/ios/Flutter/.last_build_id
+.dart_tool/
+.flutter-plugins
+.flutter-plugins-dependencies
+.packages
+.pub-cache/
+.pub/
+/build/
+
+# Web related
+lib/generated_plugin_registrant.dart
+
+# Symbolication related
+app.*.symbols
+
+# Obfuscation related
+app.*.map.json
+
+# Exceptions to above rules.
+!/packages/flutter_tools/test/data/dart_dependencies_test/**/.packages

doc/examples/joystick/lib/player.dart

@@ -12,7 +12,7 @@ class Player extends Component implements JoystickListener {
   final _greenPaint = Paint()..color = const Color(0xFF00FF00);
   final double speed = 159;
   double currentSpeed = 0;
-  double radAngle;
+  double radAngle = 0;
   bool _move = false;
   Paint _paint;
 

lib/components/joystick/joystick_directional.dart

@@ -72,7 +72,7 @@ class JoystickDirectional {
         Offset(margin.left, _screenSize.height - margin.bottom);
     _backgroundRect = Rect.fromCircle(center: osBackground, radius: size / 2);
 
-    Offset osKnob =
+    final Offset osKnob =
         Offset(_backgroundRect.center.dx, _backgroundRect.center.dy);
     _knobRect = Rect.fromCircle(center: osKnob, radius: size / 4);