Merge branch 'KeepScreenStackViews'

android/app/src/main/java/com/reactnativenavigation/activities/BottomTabActivity.java

@@ -21,8 +21,6 @@ import java.util.ArrayList;
 import java.util.HashMap;
 import java.util.Map;
 
-import static android.view.ViewGroup.LayoutParams.MATCH_PARENT;
-
 /**
  * Created by guyc on 02/04/16.
  */
@@ -42,7 +40,7 @@ public class BottomTabActivity extends BaseReactActivity implements AHBottomNavi
     private AHBottomNavigation mBottomNavigation;
     private FrameLayout mContentFrame;
     private ArrayList<ScreenStack> mScreenStacks;
-    private int mCurrentStackPosition = 0;
+    private int mCurrentStackPosition = -1;
 
     @Override
     protected void handleOnCreate() {
@@ -177,8 +175,15 @@ public class BottomTabActivity extends BaseReactActivity implements AHBottomNavi
         if (wasSelected) {
             return;
         }
-        mContentFrame.removeAllViews();
-        mContentFrame.addView(mScreenStacks.get(position), new FrameLayout.LayoutParams(MATCH_PARENT, MATCH_PARENT));
+
+        // Remove current ScreenStack
+        if (mCurrentStackPosition >= 0) {
+            mScreenStacks.get(mCurrentStackPosition).removeFromScreen(mContentFrame);
+        }
+
+        // Add new ScreenStack
+        mScreenStacks.get(position).addToScreen(mContentFrame);
+
         mCurrentStackPosition = position;
         StyleHelper.updateStyles(mToolbar, getCurrentScreen());
 

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

@@ -3,9 +3,11 @@ package com.reactnativenavigation.views;
 import android.animation.LayoutTransition;
 import android.content.Context;
 import android.util.AttributeSet;
+import android.view.ViewGroup;
 import android.widget.FrameLayout;
 
 import com.facebook.react.ReactInstanceManager;
+import com.facebook.react.ReactRootView;
 import com.reactnativenavigation.activities.BaseReactActivity;
 import com.reactnativenavigation.core.RctManager;
 import com.reactnativenavigation.core.objects.Screen;
@@ -30,8 +32,7 @@ public class ScreenStack extends FrameLayout {
     }
 
     private final Stack<ScreenView> mStack = new Stack<>();
-    private final ReactInstanceManager mReactInstanceManager =
-            RctManager.getInstance().getReactInstanceManager();
+    private final ReactInstanceManager mReactInstanceManager = RctManager.getInstance().getReactInstanceManager();
     private BaseReactActivity mReactActivity;
 
     public ScreenStack(BaseReactActivity context) {
@@ -145,4 +146,24 @@ public class ScreenStack extends FrameLayout {
     public Screen peek() {
         return mStack.peek().screen;
     }
+
+    /**
+     * Remove the ScreenStack from {@code parent} while preventing all child react views from getting unmounted
+     */
+    public void removeFromScreen(ViewGroup parent) {
+        ReactRootView view = mStack.peek().view.getReactRootView();
+        ReflectionUtils.setBooleanField(view, "mAttachScheduled", true);
+
+        parent.removeView(this);
+    }
+
+    /**
+     * Add ScreenStack to {@code parent}
+     */
+    public void addToScreen(ViewGroup parent) {
+        ReactRootView view = mStack.peek().view.getReactRootView();
+        ReflectionUtils.setBooleanField(view, "mAttachScheduled", false);
+
+        parent.addView(this, new FrameLayout.LayoutParams(MATCH_PARENT, MATCH_PARENT));
+    }
 }