Show and hide title with animation on collapse

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

     public StyleParams.Color scrimColor;
     public CollapseBehaviour collapseBehaviour;
     public boolean expendOnTopTabChange;
+    public boolean showTitleWhenCollapsed;
 
     public boolean hasBackgroundImage() {
         return imageUri != null;

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

     private Bundle params;
     private boolean titleBarHideOnScroll;
     private boolean drawBelowTopBar;
+    private final boolean hasReactView;
+    private final boolean hasBackgroundImage;
 
     CollapsingTopBarParamsParser(Bundle params, boolean titleBarHideOnScroll, boolean drawBelowTopBar) {
         this.params = params;
         this.titleBarHideOnScroll = titleBarHideOnScroll;
         this.drawBelowTopBar = drawBelowTopBar;
+        hasReactView = params.containsKey("collapsingToolBarComponent");
+        hasBackgroundImage = params.containsKey("collapsingToolBarImage");
     }
 
     public CollapsingTopBarParams parse() {
         result.reactViewHeight = params.getInt("collapsingToolBarComponentHeight");
         result.expendOnTopTabChange = params.getBoolean("expendCollapsingToolBarOnTopTabChange");
         result.scrimColor = getColor(params, "collapsingToolBarCollapsedColor", new StyleParams.Color(Color.WHITE));
+        result.showTitleWhenCollapsed = hasReactView;
         result.collapseBehaviour = getCollapseBehaviour();
         return result;
     }
         return titleBarHideOnScroll || hasImageOrReactView();
     }
 
-    private boolean hasImageOrReactView() {
-        return hasBackgroundImage() || hasReactView();
-    }
-
     private CollapseBehaviour getCollapseBehaviour() {
-        if (hasBackgroundImage() || hasReactView()) {
+        if (hasImageOrReactView()) {
             return new CollapseTopBarBehaviour();
         }
         if (titleBarHideOnScroll && drawBelowTopBar) {
         return new TitleBarHideOnScrollBehaviour();
     }
 
-    private boolean hasBackgroundImage() {
-        return params.containsKey("collapsingToolBarImage");
-    }
-
-    private boolean hasReactView() {
-        return params.containsKey("collapsingToolBarComponent");
+    private boolean hasImageOrReactView() {
+        return hasBackgroundImage || hasReactView;
     }
 }

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

 import android.view.View;
 import android.view.animation.AccelerateDecelerateInterpolator;
 import android.view.animation.AccelerateInterpolator;
+import android.widget.TextView;
 
 import com.reactnativenavigation.params.BaseTitleBarButtonParams;
 import com.reactnativenavigation.params.StyleParams;
 import java.util.List;
 
 public class TitleBar extends Toolbar {
-
+    private static final int TITLE_VISIBILITY_ANIMATION_DURATION = 320;
     private LeftButton leftButton;
     private ActionMenuView actionMenuView;
 
                     }
                 });
     }
+
+    public void showTitle() {
+        animateTitle(1);
+    }
+
+    public void hideTitle() {
+        animateTitle(0);
+    }
+
+    private void animateTitle(int alpha) {
+        getTitleView().animate()
+                .alpha(alpha)
+                .setDuration(TITLE_VISIBILITY_ANIMATION_DURATION);
+    }
+
+    private View getTitleView() {
+        return getChildAt(0) instanceof TextView ? getChildAt(0) : getChildAt(1);
+    }
 }

android/app/src/main/java/com/reactnativenavigation/views/collapsingToolbar/CollapsingTitleBar.java

 
 import com.reactnativenavigation.params.CollapsingTopBarParams;
 import com.reactnativenavigation.params.StyleParams;
+import com.reactnativenavigation.utils.ViewUtils;
 import com.reactnativenavigation.views.TitleBar;
 
 public class CollapsingTitleBar extends TitleBar implements View.OnTouchListener {
         this.params = params;
         addCollapsingTitle();
         setOnTouchListener(this);
+        hideTitle(params);
+    }
+
+    private void hideTitle(CollapsingTopBarParams params) {
+        if (params.showTitleWhenCollapsed) {
+            ViewUtils.runOnPreDraw(this, new Runnable() {
+                @Override
+                public void run() {
+                    hideTitle();
+                }
+            });
+        }
     }
 
     private void addCollapsingTitle() {

android/app/src/main/java/com/reactnativenavigation/views/collapsingToolbar/CollapsingTopBar.java

     private final CollapsingTopBarParams params;
     private final ViewCollapser viewCollapser;
     private final int topBarHeight;
-    private String title;
 
     public CollapsingTopBar(Context context, final StyleParams params) {
         super(context);
         this.scrollListener = scrollListener;
     }
 
-    @Override
-    public void setTitle(String title) {
-        if (params.hasReactView()) {
-            this.title = title;
-        } else {
-            super.setTitle(title);
-        }
-    }
-
     private void createBackgroundImage() {
         if (params.hasBackgroundImage()) {
             collapsingTopBarBackground = new CollapsingTopBarBackground(getContext(), params);
             header.setOnHiddenListener(new CollapsingTopBarReactHeaderAnimator.OnHiddenListener() {
                 @Override
                 public void onHidden() {
-                    titleBar.setTitle(title);
+                    titleBar.showTitle();
                 }
             });
             header.setOnVisibleListener(new CollapsingTopBarReactHeaderAnimator.OnVisibleListener() {
                 @Override
                 public void onVisible() {
-                    titleBar.setTitle("");
+                    titleBar.hideTitle();
                 }
             });
         }