Fix Topbar custom component flicker across screens #3864 (#5110)

When a topBar.backgroundComponent is defined, check if a corresponding ReactView has already been created with matching componentName and componentId. If such view is found, reuse it instead of creating another view.

This change will fix a flickering in the TopBar background component when a screen was pushed into a stack with a background component.

lib/android/app/src/main/java/com/reactnativenavigation/parse/params/Text.java

 package com.reactnativenavigation.parse.params;
 
+import android.support.annotation.NonNull;
+
 public class Text extends Param<String> {
     public Text(String value) {
         super(value);
     }
 
+    @NonNull
     @Override
     public String toString() {
         return hasValue() ? value : "No Value";

lib/android/app/src/main/java/com/reactnativenavigation/presentation/StackPresenter.java

 import java.util.List;
 import java.util.Map;
 
-import static com.reactnativenavigation.utils.CollectionUtils.filter;
-import static com.reactnativenavigation.utils.CollectionUtils.forEach;
-import static com.reactnativenavigation.utils.CollectionUtils.keyBy;
-import static com.reactnativenavigation.utils.CollectionUtils.merge;
+import static com.reactnativenavigation.utils.CollectionUtils.*;
 import static com.reactnativenavigation.utils.ObjectUtils.perform;
 
 public class StackPresenter {
         topBar.setBackgroundColor(options.background.color.get(Color.WHITE));
 
         if (options.background.component.hasValue()) {
-            if (backgroundControllers.containsKey(component)) {
-                topBar.setBackgroundComponent(backgroundControllers.get(component).getView());
+            View createdComponent = findBackgroundComponent(options.background.component);
+            if (createdComponent != null) {
+                topBar.setBackgroundComponent(createdComponent);
             } else {
                 TopBarBackgroundViewController controller = new TopBarBackgroundViewController(activity, topBarBackgroundViewCreator);
                 controller.setWaitForRender(options.background.waitForRender);
                 controller.getView().setLayoutParams(new RelativeLayout.LayoutParams(FrameLayout.LayoutParams.MATCH_PARENT, FrameLayout.LayoutParams.MATCH_PARENT));
                 topBar.setBackgroundComponent(controller.getView());
             }
+        } else {
+            topBar.clearBackgroundComponent();
         }
 
         if (options.testId.hasValue()) topBar.setTestId(options.testId.get());
         }
     }
 
+    @Nullable
+    private View findBackgroundComponent(com.reactnativenavigation.parse.Component component) {
+        for (TopBarBackgroundViewController controller : backgroundControllers.values()) {
+            if (ObjectUtils.equalsNotNull(controller.getComponent().name.get(null), component.name.get(null)) &&
+                ObjectUtils.equalsNotNull(controller.getComponent().componentId.get(null), component.componentId.get(null))) {
+                return controller.getView();
+            }
+        }
+        return null;
+    }
+
     private void setInitialTopBarVisibility(TopBarOptions options) {
         if (options.visible.isFalse()) {
             topBar.hide();
             componentRightButtons.put(child, keyBy(rightButtonControllers, TitleBarButtonController::getButtonInstanceId));
             topBar.setRightButtons(rightButtonControllers);
         } else {
-            topBar.setRightButtons(null);
+            topBar.clearRightButtons();
         }
 
         if (leftButtons != null) {
             componentLeftButtons.put(child, keyBy(leftButtonControllers, TitleBarButtonController::getButtonInstanceId));
             topBar.setLeftButtons(leftButtonControllers);
         } else {
-            topBar.setLeftButtons(null);
+            topBar.clearLeftButtons();
         }
 
         if (options.buttons.back.visible.isTrue() && !options.buttons.hasLeftButtons()) {

lib/android/app/src/main/java/com/reactnativenavigation/utils/ObjectUtils.java

     public static boolean notNull(Object o) {
         return o != null;
     }
+
+    public static <T> boolean equalsNotNull(@Nullable T a, @Nullable T b) {
+        return a != null && a.equals(b);
+    }
 }

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

         );
     }
 
-    @Override
-    public void destroy() {
-        topBarController.clear();
-        super.destroy();
-    }
-
-    @Override
-    public void clearOptions() {
-        super.clearOptions();
-        topBarController.clear();
-    }
-
     @Override
     public void onChildDestroyed(Component child) {
         super.onChildDestroyed(child);

lib/android/app/src/main/java/com/reactnativenavigation/viewcontrollers/topbar/TopBarBackgroundViewController.java

     public void setComponent(Component component) {
         this.component = component;
     }
+
+    public Component getComponent() {
+        return component;
+    }
 }

lib/android/app/src/main/java/com/reactnativenavigation/viewcontrollers/topbar/TopBarController.java

         return new TopBar(context, stackLayout);
     }
 
-    public void clear() {
-        if (topBar != null) {
-            topBar.clear();
-        }
-    }
-
     public TopBar getView() {
         return topBar;
     }

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

 import com.reactnativenavigation.views.titlebar.TitleBar;
 import com.reactnativenavigation.views.toptabs.TopTabs;
 
+import java.util.Collections;
 import java.util.List;
 
 import static android.view.ViewGroup.LayoutParams.MATCH_PARENT;
     }
 
     public void setBackgroundComponent(View component) {
+        if (this.component == component || component.getParent() != null) return;
         this.component = component;
         root.addView(component, 0);
     }
         titleBar.setLeftButtons(leftButtons);
     }
 
+    public void clearLeftButtons() {
+        titleBar.setLeftButtons(Collections.emptyList());
+    }
+
     public void setRightButtons(List<TitleBarButtonController> rightButtons) {
         titleBar.setRightButtons(rightButtons);
     }
 
+    public void clearRightButtons() {
+        titleBar.setRightButtons(Collections.emptyList());
+    }
+
     public void setElevation(Double elevation) {
         if (Build.VERSION.SDK_INT >= Build.VERSION_CODES.LOLLIPOP && getElevation() != elevation.floatValue()) {
             this.elevation = UiUtils.dpToPx(getContext(), elevation.floatValue());
         animator.hide(options, onAnimationEnd);
     }
 
-    public void clear() {
+    public void clearBackgroundComponent() {
         if (component != null) {
             root.removeView(component);
             component = null;
         }
-        titleBar.clear();
     }
 
     public void clearTopTabs() {

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

 import org.json.JSONObject;
 import org.junit.Test;
 import org.mockito.ArgumentCaptor;
+import org.mockito.Mockito;
 
 import java.util.ArrayList;
 import java.util.Collection;
         assertThat(leftCaptor.getValue().get(0)).isNotEqualTo(leftButton);
     }
 
+    @Test
+    public void applyTopBarOptions_backgroundComponentIsCreatedOnceIfNameAndIdAreEqual() {
+        Options o = new Options();
+        o.topBar.background.component.name = new Text("comp");
+        o.topBar.background.component.componentId = new Text("compId");
+
+        uut.applyChildOptions(o, Mockito.mock(com.reactnativenavigation.views.Component.class));
+        assertThat(uut.getBackgroundComponents().size()).isOne();
+
+        uut.applyChildOptions(o, Mockito.mock(com.reactnativenavigation.views.Component.class));
+        assertThat(uut.getBackgroundComponents().size()).isOne();
+    }
+
     @Test
     public void mergeChildOptions_buttonColorIsResolvedFromAppliedOptions() {
         Options appliedOptions = new Options();

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

-package com.reactnativenavigation.viewcontrollers;
-
-import android.app.Activity;
-import android.content.Context;
-import android.support.annotation.NonNull;
-
-import com.reactnativenavigation.BaseTest;
-import com.reactnativenavigation.viewcontrollers.topbar.TopBarController;
-import com.reactnativenavigation.views.StackLayout;
-import com.reactnativenavigation.views.titlebar.TitleBar;
-import com.reactnativenavigation.views.topbar.TopBar;
-
-import org.junit.Test;
-import org.mockito.Mockito;
-
-import static org.mockito.Mockito.mock;
-import static org.mockito.Mockito.spy;
-import static org.mockito.Mockito.times;
-import static org.mockito.Mockito.verify;
-
-public class TopBarControllerTest extends BaseTest {
-
-    private TopBarController uut;
-
-    @Override
-    public void beforeEach() {
-        uut = new TopBarController();
-    }
-
-    @Test
-    public void clear() {
-        final TitleBar[] titleBar = new TitleBar[1];
-        uut = new TopBarController() {
-            @NonNull
-            @Override
-            protected TopBar createTopBar(Context context, StackLayout stackLayout) {
-                return new TopBar(context, stackLayout) {
-                    @Override
-                    protected TitleBar createTitleBar(Context context) {
-                        titleBar[0] = spy(super.createTitleBar(context));
-                        return titleBar[0];
-                    }
-                };
-            }
-        };
-        Activity activity = newActivity();
-        uut.createView(activity, Mockito.mock(StackLayout.class));
-        uut.clear();
-        verify(titleBar[0], times(1)).clear();
-    }
-
-    @Test
-    public void destroy() {
-        uut.createView(newActivity(), mock(StackLayout.class));
-        uut.clear();
-    }
-
-    @Test
-    public void destroy_canBeCalledBeforeViewIsCreated() {
-        uut.clear();
-    }
-}

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

         verify(presenter).applyChildOptions(any(), eq(component));
     }
 
-    @Test
-    public void destroy() {
-        uut.destroy();
-        verify(topBarController, times(1)).clear();
-    }
-
     private void assertContainsOnlyId(String... ids) {
         assertThat(uut.size()).isEqualTo(ids.length);
         assertThat(uut.getChildControllers()).extracting((Extractor<ViewController, String>) ViewController::getId).containsOnly(ids);