Apply stack options when stacks are attached to BottomTabs

Currently options are applied when a view is visible. This caused some noticeable flickering when
switching to tabs for the first time.
This commit adds a new callback which ViewController can override - onAttachToParent.
StackController now uses it to apply options which prevents flickering.

lib/android/app/src/main/java/com/reactnativenavigation/viewcontrollers/ViewController.java

@@ -31,6 +31,7 @@ public abstract class ViewController<T extends ViewGroup> implements ViewTreeObs
 
     private Runnable onAppearedListener;
     private boolean appearEventPosted;
+    private boolean isFirstayout = true;
     private Bool waitForRender = new NullBool();
 
     public interface ViewVisibilityListener {
@@ -238,6 +239,10 @@ public abstract class ViewController<T extends ViewGroup> implements ViewTreeObs
 
     @Override
     public void onGlobalLayout() {
+        if (isFirstayout) {
+            onAttachToParent();
+            isFirstayout = false;
+        }
         if (!isShown && isViewShown()) {
             if (!viewVisibilityListener.onViewAppeared(view)) {
                 isShown = true;
@@ -251,6 +256,10 @@ public abstract class ViewController<T extends ViewGroup> implements ViewTreeObs
         }
     }
 
+    protected void onAttachToParent() {
+
+    }
+
     @Override
     public void onChildViewAdded(View parent, View child) {
         yellowBoxDelegate.onChildViewAdded(parent, child);

lib/android/app/src/main/java/com/reactnativenavigation/viewcontrollers/stack/StackController.java

@@ -68,6 +68,13 @@ public class StackController extends ParentController<StackLayout> {
         return stack.peek();
     }
 
+    @Override
+    public void onAttachToParent() {
+        if (!isViewShown() && !isEmpty()) {
+            presenter.applyChildOptions(resolveCurrentOptions(), (Component) getCurrentChild().getView());
+        }
+    }
+
     @Override
     public void mergeOptions(Options options) {
         presenter.mergeOptions(options, (Component) getCurrentChild().getView());
@@ -276,7 +283,7 @@ public class StackController extends ParentController<StackLayout> {
         controller.destroy();
     }
 
-    public ViewController peek() {
+    ViewController peek() {
         return stack.peek();
     }
 
@@ -298,7 +305,7 @@ public class StackController extends ParentController<StackLayout> {
     }
 
     @VisibleForTesting()
-    public boolean canPop() {
+    boolean canPop() {
         return stack.size() > 1;
     }
 

lib/android/app/src/test/java/com/reactnativenavigation/viewcontrollers/stack/StackControllerTest.java

@@ -5,6 +5,7 @@ import android.app.Activity;
 import android.content.Context;
 import android.view.View;
 import android.view.ViewGroup;
+import android.widget.FrameLayout;
 
 import com.reactnativenavigation.BaseTest;
 import com.reactnativenavigation.TestUtils;
@@ -915,6 +916,21 @@ public class StackControllerTest extends BaseTest {
         verify(presenter, times(0)).mergeChildOptions(any(), any(), any());
     }
 
+    @Test
+    public void resolvedOptionsAreAppliedWhenStackIsAttachedToParentAndNotVisible() {
+        FrameLayout parent = new FrameLayout(activity);
+        activity.setContentView(parent);
+
+        ViewController child = new SimpleViewController(activity, childRegistry, "child1", new Options());
+        StackController stack = createStack(Collections.singletonList(child));
+        stack.getView().setVisibility(View.INVISIBLE);
+
+        parent.addView(stack.getView());
+
+        Component component = (Component) child.getView();
+        verify(presenter).applyChildOptions(any(), eq(component));
+    }
+
     @Test
     public void destroy() {
         uut.ensureViewIsCreated();