Align FAB to screen when BottomTabs are hidden (#1400)

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

 package com.reactnativenavigation.layouts;
 
+import android.annotation.SuppressLint;
 import android.os.Bundle;
 import android.support.annotation.NonNull;
 import android.support.annotation.Nullable;
 import com.reactnativenavigation.params.SideMenuParams;
 import com.reactnativenavigation.params.SlidingOverlayParams;
 import com.reactnativenavigation.params.SnackbarParams;
+import com.reactnativenavigation.params.StyleParams;
 import com.reactnativenavigation.params.TitleBarButtonParams;
 import com.reactnativenavigation.params.TitleBarLeftButtonParams;
 import com.reactnativenavigation.screens.Screen;
 import com.reactnativenavigation.screens.ScreenStack;
+import com.reactnativenavigation.utils.ViewUtils;
 import com.reactnativenavigation.views.BottomTabs;
 import com.reactnativenavigation.views.LightBox;
 import com.reactnativenavigation.views.SideMenu;
 import static android.view.ViewGroup.LayoutParams.MATCH_PARENT;
 import static android.view.ViewGroup.LayoutParams.WRAP_CONTENT;
 
+@SuppressLint("ViewConstructor")
 public class BottomTabsLayout extends BaseLayout implements AHBottomNavigation.OnTabSelectedListener {
 
     private ActivityParams params;
     private void createSnackbarContainer() {
         snackbarAndFabContainer = new SnackbarAndFabContainer(getContext(), this);
         RelativeLayout.LayoutParams lp = new RelativeLayout.LayoutParams(MATCH_PARENT, MATCH_PARENT);
-        lp.addRule(ABOVE, bottomTabs.getId());
+        alignSnackbarContainerWithBottomTabs(lp, getCurrentScreen().getStyleParams());
         snackbarAndFabContainer.setClickable(false);
         getScreenStackParent().addView(snackbarAndFabContainer, lp);
     }
         screenStack.push(params, createScreenLayoutParams(params));
         if (isCurrentStack(screenStack)) {
             bottomTabs.setStyleFromScreen(params.styleParams);
+            alignSnackbarContainerWithBottomTabs((LayoutParams) snackbarAndFabContainer.getLayoutParams(), params.styleParams);
             EventBus.instance.post(new ScreenChangedEvent(params));
         }
     }
 
     @Override
-    public void pop(ScreenParams params) {
+    public void pop(final ScreenParams params) {
         getCurrentScreenStack().pop(params.animateScreenTransitions, new ScreenStack.OnScreenPop() {
             @Override
             public void onScreenPopAnimationEnd() {
                 setBottomTabsStyleFromCurrentScreen();
+                alignSnackbarContainerWithBottomTabs((LayoutParams) snackbarAndFabContainer.getLayoutParams(), params.styleParams);
                 EventBus.instance.post(new ScreenChangedEvent(getCurrentScreenStack().peek().getScreenParams()));
             }
         });
     }
 
     @Override
-    public void popToRoot(ScreenParams params) {
+    public void popToRoot(final ScreenParams params) {
         getCurrentScreenStack().popToRoot(params.animateScreenTransitions, new ScreenStack.OnScreenPop() {
             @Override
             public void onScreenPopAnimationEnd() {
                 setBottomTabsStyleFromCurrentScreen();
+                alignSnackbarContainerWithBottomTabs((LayoutParams) snackbarAndFabContainer.getLayoutParams(), params.styleParams);
                 EventBus.instance.post(new ScreenChangedEvent(getCurrentScreenStack().peek().getScreenParams()));
             }
         });
         screenStack.newStack(params, createScreenLayoutParams(params));
         if (isCurrentStack(screenStack)) {
             bottomTabs.setStyleFromScreen(params.styleParams);
+            alignSnackbarContainerWithBottomTabs((LayoutParams) snackbarAndFabContainer.getLayoutParams(), params.styleParams);
             EventBus.instance.post(new ScreenChangedEvent(params));
         }
     }
 
+    private void alignSnackbarContainerWithBottomTabs(LayoutParams lp, StyleParams styleParams) {
+        if (styleParams.drawScreenAboveBottomTabs || !styleParams.bottomTabsHidden) {
+            lp.addRule(ABOVE, bottomTabs.getId());
+        } else {
+            ViewUtils.removeRuleCompat(lp, ABOVE);
+        }
+    }
+
     @Override
     public void destroy() {
         snackbarAndFabContainer.destroy();

android/app/src/main/java/com/reactnativenavigation/utils/ViewUtils.java

 import android.view.ViewParent;
 import android.view.ViewTreeObserver;
 import android.view.WindowManager;
+import android.widget.RelativeLayout;
 import android.widget.TextView;
 
 import com.reactnativenavigation.NavigationApplication;
     public static void setSpanColor(SpannableString span, int color) {
         span.setSpan(new ForegroundColorSpan(color), 0, span.length(), Spanned.SPAN_EXCLUSIVE_EXCLUSIVE);
     }
+
+    public static void removeRuleCompat(RelativeLayout.LayoutParams layoutParams, int rule) {
+        if (Build.VERSION.SDK_INT >= Build.VERSION_CODES.JELLY_BEAN_MR1) {
+            layoutParams.removeRule(rule);
+        } else {
+            layoutParams.addRule(rule, 0);
+        }
+    }
 }