Mount all stack children (#6194)

This commit somewhat consolidates how stack children are mounted.

On Android, until now, only the top child in a stack was mounted when the stack became visible or when setStackRoot() was called. When popping the stack the new current child would be mounted when it was attached. This caused flickering when popping the stack as the pop animation started before the child finished mounting.

Now all children will be mounted together after the top child is mounted :)

Co-authored-by: Yogev Ben David <yogev132@gmail.com>

lib/android/app/src/main/java/com/reactnativenavigation/react/ReactView.java

@@ -42,7 +42,7 @@ protected void onAttachedToWindow() {
         start();
     }
 
-    private void start() {
+    public void start() {
         if (isAttachedToReactInstance) return;
         isAttachedToReactInstance = true;
 		final Bundle opts = new Bundle();

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

@@ -9,7 +9,6 @@
 import com.reactnativenavigation.presentation.Presenter;
 import com.reactnativenavigation.utils.StatusBarUtils;
 import com.reactnativenavigation.views.ComponentLayout;
-import com.reactnativenavigation.views.ReactComponent;
 
 import androidx.annotation.NonNull;
 import androidx.core.view.ViewCompat;
@@ -22,10 +21,6 @@ public class ComponentViewController extends ChildController<ComponentLayout> {
     private ComponentPresenter presenter;
     private final ReactViewCreator viewCreator;
 
-    ReactComponent getComponent() {
-        return view;
-    }
-
     public ComponentViewController(final Activity activity,
                                    final ChildControllersRegistry childRegistry,
                                    final String id,
@@ -40,6 +35,11 @@ public ComponentViewController(final Activity activity,
         this.presenter = componentPresenter;
     }
 
+    @Override
+    public void start() {
+        if (!isDestroyed()) getView().start();
+    }
+
     @Override
     public String getCurrentComponentName() {
         return this.componentName;

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

@@ -1,17 +1,16 @@
 package com.reactnativenavigation.viewcontrollers;
 
-import androidx.annotation.NonNull;
-
 import com.reactnativenavigation.utils.StringUtils;
 
 import java.util.ArrayList;
-import java.util.Collection;
 import java.util.HashMap;
 import java.util.Iterator;
+import java.util.List;
 import java.util.Map;
 
-import static com.reactnativenavigation.utils.CollectionUtils.last;
-import static com.reactnativenavigation.utils.CollectionUtils.removeLast;
+import androidx.annotation.NonNull;
+
+import static com.reactnativenavigation.utils.CollectionUtils.*;
 
 public class IdStack<E> implements Iterable<String> {
 
@@ -84,8 +83,8 @@ public Iterator<String> iterator() {
 	}
 
 
-	public Collection<E> values() {
-		return map.values();
+	public List<E> values() {
+		return map(deque, map::get);
 	}
 
     public void remove(Iterator<String> iterator, String id) {

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

@@ -339,6 +339,10 @@ public boolean isRendered() {
         );
     }
 
+    public void start() {
+
+    }
+
     void applyOnController(ViewController controller, Func1<ViewController> task) {
         if (controller != null) task.run(controller);
     }

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

@@ -26,6 +26,7 @@
 import com.reactnativenavigation.views.stack.StackBehaviour;
 import com.reactnativenavigation.views.topbar.TopBar;
 
+import java.util.ArrayList;
 import java.util.Collection;
 import java.util.Iterator;
 import java.util.List;
@@ -214,6 +215,7 @@ public void onSuccess(String childId) {
                             backButtonHelper.addToPushedChild(children.get(i));
                         }
                     }
+                    startChildrenBellowTopChild();
                 }
                 listener.onSuccess(childId);
             }
@@ -360,10 +362,18 @@ private void addInitialChild(StackLayout stackLayout) {
         if (isEmpty()) return;
         ViewGroup child = peek().getView();
         child.setId(CompatUtils.generateViewId());
+        peek().addOnAppearedListener(this::startChildrenBellowTopChild);
         presenter.applyInitialChildLayoutOptions(resolveCurrentOptions());
         stackLayout.addView(child, 0, matchParentWithBehaviour(new StackBehaviour(this)));
     }
 
+    private void startChildrenBellowTopChild() {
+        ArrayList<ViewController> children = new ArrayList(getChildControllers());
+        for (int i = children.size() - 2; i >= 0; i--) {
+            children.get(i).start();
+        }
+    }
+
     private void onNavigationButtonPressed(String buttonId) {
         if (Constants.BACK_BUTTON_ID.equals(buttonId)) {
             pop(Options.EMPTY, new CommandListenerAdapter());

lib/android/app/src/main/java/com/reactnativenavigation/views/ComponentLayout.java

@@ -45,6 +45,10 @@ public void destroy() {
         reactView.destroy();
     }
 
+    public void start() {
+        reactView.start();
+    }
+
 	public void sendComponentStart() {
 		reactView.sendComponentStart(ComponentType.Component);
 	}

lib/android/app/src/test/java/com/reactnativenavigation/viewcontrollers/IdStackTest.java

@@ -109,6 +109,6 @@ public void values() {
         assertThat(uut.values()).isNotNull().isEmpty();
         uut.push("123", 123);
         uut.push("456", 456);
-        assertThat(uut.values()).isNotNull().containsExactlyInAnyOrder(123, 456);
+        assertThat(uut.values()).isNotNull().containsSequence(123, 456);
     }
 }

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

@@ -12,9 +12,9 @@
 import com.reactnativenavigation.anim.NavigationAnimator;
 import com.reactnativenavigation.mocks.ImageLoaderMock;
 import com.reactnativenavigation.mocks.SimpleViewController;
+import com.reactnativenavigation.mocks.TitleBarButtonCreatorMock;
 import com.reactnativenavigation.mocks.TitleBarReactViewCreatorMock;
 import com.reactnativenavigation.mocks.TopBarBackgroundViewCreatorMock;
-import com.reactnativenavigation.mocks.TitleBarButtonCreatorMock;
 import com.reactnativenavigation.parse.AnimationOptions;
 import com.reactnativenavigation.parse.NestedAnimationsOptions;
 import com.reactnativenavigation.parse.Options;
@@ -59,6 +59,7 @@
 
 import androidx.coordinatorlayout.widget.CoordinatorLayout;
 
+import static com.reactnativenavigation.utils.ObjectUtils.take;
 import static com.reactnativenavigation.utils.ViewUtils.topMargin;
 import static org.assertj.core.api.Java6Assertions.assertThat;
 import static org.mockito.ArgumentMatchers.any;
@@ -82,6 +83,7 @@ public class StackControllerTest extends BaseTest {
     private ViewController child1a;
     private ViewController child2;
     private ViewController child3;
+    private SimpleViewController.SimpleView child3View;
     private ViewController child4;
     private NavigationAnimator animator;
     private TopBarController topBarController;
@@ -108,13 +110,22 @@ public void beforeEach() {
                     new Options()
                 )
         );
+        createChildren();
+        uut = createStack();
+        activity.setContentView(uut.getView());
+    }
+
+    private void createChildren() {
         child1 = spy(new SimpleViewController(activity, childRegistry, "child1", new Options()));
         child1a = spy(new SimpleViewController(activity, childRegistry, "child1", new Options()));
         child2 = spy(new SimpleViewController(activity, childRegistry, "child2", new Options()));
-        child3 = spy(new SimpleViewController(activity, childRegistry, "child3", new Options()));
+        child3 = spy(new SimpleViewController(activity, childRegistry, "child3", new Options()) {
+            @Override
+            protected SimpleView createView() {
+                return take(child3View, super.createView());
+            }
+        });
         child4 = spy(new SimpleViewController(activity, childRegistry, "child4", new Options()));
-        uut = createStack();
-        activity.setContentView(uut.getView());
     }
 
     @Test
@@ -394,6 +405,19 @@ public void setRoot_doesNotCrashWhenCalledWithSameId() {
         assertContainsOnlyId(child1a.getId());
     }
 
+    @Test
+    public void setRoot_topScreenIsStartedThenTheRest() {
+        disablePushAnimation(child1, child2, child3);
+        child3View = spy(new SimpleViewController.SimpleView(activity));
+
+        uut.setRoot(Arrays.asList(child1, child2, child3), new CommandListenerAdapter());
+        ShadowLooper.idleMainLooper();
+        InOrder inOrder = inOrder(child3View, child2, child1);
+        inOrder.verify(child3View).start();
+        inOrder.verify(child2).start();
+        inOrder.verify(child1).start();
+    }
+
     @Test
     public synchronized void pop() {
         disablePushAnimation(child1, child2);