Android modal life cycle screen events added, Fixes #1144 (#1200)

android/app/src/main/java/com/reactnativenavigation/controllers/NavigationActivity.java

@@ -35,6 +35,7 @@ import com.reactnativenavigation.params.SnackbarParams;
 import com.reactnativenavigation.params.TitleBarButtonParams;
 import com.reactnativenavigation.params.TitleBarLeftButtonParams;
 import com.reactnativenavigation.react.ReactGateway;
+import com.reactnativenavigation.screens.Screen;
 import com.reactnativenavigation.utils.OrientationHelper;
 import com.reactnativenavigation.views.SideMenu.Side;
 
@@ -235,15 +236,24 @@ public class NavigationActivity extends AppCompatActivity implements DefaultHard
     }
 
     void showModal(ScreenParams screenParams) {
+        Screen previousScreen = layout.getCurrentScreen();
+        NavigationApplication.instance.getEventEmitter().sendScreenChangedEvent("willDisappear", previousScreen.getNavigatorEventId());
+        NavigationApplication.instance.getEventEmitter().sendScreenChangedEvent("didDisappear", previousScreen.getNavigatorEventId());
         modalController.showModal(screenParams);
     }
 
     void dismissTopModal() {
         modalController.dismissTopModal();
+        Screen previousScreen = layout.getCurrentScreen();
+        NavigationApplication.instance.getEventEmitter().sendScreenChangedEvent("willAppear", previousScreen.getNavigatorEventId());
+        NavigationApplication.instance.getEventEmitter().sendScreenChangedEvent("didAppear", previousScreen.getNavigatorEventId());
     }
 
     void dismissAllModals() {
         modalController.dismissAllModals();
+        Screen previousScreen = layout.getCurrentScreen();
+        NavigationApplication.instance.getEventEmitter().sendScreenChangedEvent("willAppear", previousScreen.getNavigatorEventId());
+        NavigationApplication.instance.getEventEmitter().sendScreenChangedEvent("didAppear", previousScreen.getNavigatorEventId());
     }
 
     public void showLightBox(LightBoxParams params) {