Implement overrideBackPress

android/app/src/main/java/com/reactnativenavigation/layouts/BottomTabsLayout.java

 
     @Override
     public boolean onBackPressed() {
+        if (getCurrentScreenStack().handleBackPressInJs()) {
+            return true;
+        }
+
         if (getCurrentScreenStack().canPop()) {
             getCurrentScreenStack().pop(true);
             setBottomTabsStyleFromCurrentScreen();

android/app/src/main/java/com/reactnativenavigation/layouts/SingleScreenLayout.java

 
     @Override
     public boolean onBackPressed() {
+        if (stack.handleBackPressInJs()) {
+            return true;
+        }
+
         if (stack.canPop()) {
             stack.pop(true);
             return true;

android/app/src/main/java/com/reactnativenavigation/params/ScreenParams.java

     public String screenId;
     public List<TitleBarButtonParams> rightButtons;
     public TitleBarLeftButtonParams leftButton;
+    public boolean overrideBackPressInJs;
     public String title;
     public StyleParams styleParams;
     public List<TopTabParams> topTabParams;

android/app/src/main/java/com/reactnativenavigation/params/TitleBarLeftButtonParams.java

 
 public class TitleBarLeftButtonParams extends TitleBarButtonParams {
     public MaterialMenuDrawable.IconState iconState;
+    public boolean overrideBackPressInJs;
 
     public TitleBarLeftButtonParams(TitleBarButtonParams params) {
         icon = params.icon;
     public boolean isBackButton() {
         return eventId.equals("back");
     }
+
+    public void setOverrideBackPressInJs(boolean overrideBackPressInJs) {
+        this.overrideBackPressInJs = overrideBackPressInJs;
+    }
 }

android/app/src/main/java/com/reactnativenavigation/params/parsers/ScreenParamsParser.java

     private static final String TOP_TABS = "topTabs";
     private static final String FRAGMENT_CREATOR_CLASS_NAME = "fragmentCreatorClassName";
     private static final String FRAGMENT_CREATOR_PASS_PROPS = "fragmentCreatorPassProps";
+    public static final String OVERRIDE_BACK_PRESS = "overrideBackPress";
 
     @SuppressWarnings("ConstantConditions")
     public static ScreenParams parse(Bundle params) {
 
         result.title = params.getString(KEY_TITLE);
         result.rightButtons = parseRightButton(params);
+        result.overrideBackPressInJs = params.getBoolean(OVERRIDE_BACK_PRESS, false);
         result.leftButton = parseLeftButton(params);
 
         result.topTabParams = parseTopTabs(params);

android/app/src/main/java/com/reactnativenavigation/screens/Screen.java

         if (screenParams.leftButton != null) {
             screenParams.leftButton.setColorFromScreenStyle(screenParams.styleParams.titleBarButtonColor);
         }
-        topBar.addTitleBarAndSetButtons(screenParams.rightButtons, screenParams.leftButton,
-                leftButtonOnClickListener, screenParams.navigatorEventId);
+        topBar.addTitleBarAndSetButtons(screenParams.rightButtons,
+                screenParams.leftButton,
+                leftButtonOnClickListener,
+                screenParams.navigatorEventId,
+                screenParams.overrideBackPressInJs);
     }
 
     private void createTopBar() {
 
     public void setTitleBarLeftButton(String navigatorEventId, LeftButtonOnClickListener backButtonListener,
                                       TitleBarLeftButtonParams titleBarLeftButtonParams) {
-        topBar.setTitleBarRightButton(navigatorEventId, backButtonListener, titleBarLeftButtonParams);
+        topBar.setTitleBarLeftButton(navigatorEventId,
+                backButtonListener,
+                titleBarLeftButtonParams,
+                screenParams.overrideBackPressInJs);
     }
 
     public StyleParams getStyleParams() {

android/app/src/main/java/com/reactnativenavigation/screens/ScreenStack.java

 import android.view.View;
 import android.widget.RelativeLayout;
 
+import com.reactnativenavigation.NavigationApplication;
 import com.reactnativenavigation.params.ScreenParams;
 import com.reactnativenavigation.params.StyleParams;
 import com.reactnativenavigation.params.TitleBarButtonParams;
         return stack.peek().getStyleParams();
     }
 
+    public boolean handleBackPressInJs() {
+        ScreenParams currentScreen = stack.peek().screenParams;
+        if (currentScreen.overrideBackPressInJs) {
+            NavigationApplication.instance.sendNavigatorEvent("backPress", currentScreen.navigatorEventId);
+            return true;
+        }
+        return false;
+    }
+
     private void performOnScreen(String screenInstanceId, Task<Screen> task) {
         if (stack.isEmpty()) {
             return;

android/app/src/main/java/com/reactnativenavigation/views/LeftButton.java

     private TitleBarLeftButtonParams params;
     private final LeftButtonOnClickListener onClickListener;
     private final String navigatorEventId;
+    private final boolean overrideBackPressInJs;
 
     public LeftButton(Context context,
                       TitleBarLeftButtonParams params,
                       LeftButtonOnClickListener onClickListener,
-                      String navigatorEventId) {
+                      String navigatorEventId,
+                      boolean overrideBackPressInJs) {
         super(context, getColor(params), Stroke.THIN);
         this.params = params;
         this.onClickListener = onClickListener;
         this.navigatorEventId = navigatorEventId;
+        this.overrideBackPressInJs = overrideBackPressInJs;
         setInitialState();
     }
 
     @Override
     public void onClick(View v) {
         if (isBackButton()) {
-            onClickListener.onTitleBarBackButtonClick();
+            handleBackButtonClick();
         } else if (isSideMenuButton()) {
             onClickListener.onSideMenuButtonClick();
         } else {
         }
     }
 
+    private void handleBackButtonClick() {
+        if (overrideBackPressInJs) {
+            NavigationApplication.instance.sendNavigatorEvent("backPress", navigatorEventId);
+        } else {
+            onClickListener.onTitleBarBackButtonClick();
+        }
+    }
+
     private void setInitialState() {
         if (params != null) {
             setIconState(params.iconState);

android/app/src/main/java/com/reactnativenavigation/views/TitleBar.java

     }
 
     public void setLeftButton(TitleBarLeftButtonParams leftButtonParams,
-                              LeftButtonOnClickListener leftButtonOnClickListener, String navigatorEventId) {
+                              LeftButtonOnClickListener leftButtonOnClickListener, String navigatorEventId, boolean overrideBackPressInJs) {
         if (shouldSetLeftButton(leftButtonParams)) {
-            createAndSetLeftButton(leftButtonParams, leftButtonOnClickListener, navigatorEventId);
+            createAndSetLeftButton(leftButtonParams, leftButtonOnClickListener, navigatorEventId, overrideBackPressInJs);
         } else if (hasLeftButton()) {
             updateLeftButton(leftButtonParams);
         }
         return leftButton == null && leftButtonParams != null;
     }
 
-    private void createAndSetLeftButton(TitleBarLeftButtonParams leftButtonParams, LeftButtonOnClickListener leftButtonOnClickListener, String navigatorEventId) {
-        leftButton = new LeftButton(getContext(), leftButtonParams, leftButtonOnClickListener, navigatorEventId);
+    private void createAndSetLeftButton(TitleBarLeftButtonParams leftButtonParams,
+                                        LeftButtonOnClickListener leftButtonOnClickListener,
+                                        String navigatorEventId,
+                                        boolean overrideBackPressInJs) {
+        leftButton = new LeftButton(getContext(), leftButtonParams, leftButtonOnClickListener, navigatorEventId,
+                overrideBackPressInJs);
         setNavigationOnClickListener(leftButton);
         setNavigationIcon(leftButton);
     }

android/app/src/main/java/com/reactnativenavigation/views/TopBar.java

     public void addTitleBarAndSetButtons(List<TitleBarButtonParams> rightButtons,
                                          TitleBarLeftButtonParams leftButton,
                                          LeftButtonOnClickListener leftButtonOnClickListener,
-                                         String navigatorEventId) {
+                                         String navigatorEventId, boolean overrideBackPressInJs) {
         titleBar = new TitleBar(getContext());
         addView(titleBar);
         titleBar.setRightButtons(rightButtons, navigatorEventId);
-        titleBar.setLeftButton(leftButton, leftButtonOnClickListener, navigatorEventId);
+        titleBar.setLeftButton(leftButton, leftButtonOnClickListener, navigatorEventId, overrideBackPressInJs);
     }
 
     public void setTitle(String title) {
         return topTabs;
     }
 
-    public void setTitleBarRightButton(String navigatorEventId,
-                                       LeftButtonOnClickListener leftButtonOnClickListener,
-                                       TitleBarLeftButtonParams titleBarLeftButtonParams) {
-        titleBar.setLeftButton(titleBarLeftButtonParams, leftButtonOnClickListener, navigatorEventId);
+    public void setTitleBarLeftButton(String navigatorEventId,
+                                      LeftButtonOnClickListener leftButtonOnClickListener,
+                                      TitleBarLeftButtonParams titleBarLeftButtonParams,
+                                      boolean overrideBackPressInJs) {
+        titleBar.setLeftButton(titleBarLeftButtonParams, leftButtonOnClickListener, navigatorEventId,
+                overrideBackPressInJs);
     }
 
     private void setTopTabsStyle(StyleParams style) {

src/deprecated/platformSpecificDeprecated.android.js

   params.screen = adaptNavigationParams(screen);
   params.appStyle = convertStyleParams(params.appStyle);
   params.sideMenu = convertDrawerParamsToSideMenuParams(params.drawer);
+  params.overrideBackPress = screen.overrideBackPress;
 
   newPlatformSpecific.startApp(params);
 }
   params.screenId = params.screen;
   let adapted = adaptNavigationStyleToScreenStyle(params);
   adapted = adaptNavigationParams(adapted);
-
+  adapted.overrideBackPress = params.overrideBackPress;
+  
   newPlatformSpecific.push(adapted);
 }
 
 
     let newtab = adaptNavigationStyleToScreenStyle(tab);
     newtab = adaptNavigationParams(tab);
+    newtab.overrideBackPress = tab.overrideBackPress;
     newTabs.push(newtab);
   });
   params.tabs = newTabs;
   params.screenId = params.screen;
   let adapted = adaptNavigationStyleToScreenStyle(params);
   adapted = adaptNavigationParams(adapted);
+  adapted.overrideBackPress = params.overrideBackPress;
 
   newPlatformSpecific.showModal(adapted);
 }