Initial commit.

android/src/main/java/com/swmansion/rnscreens/ScreenStack.java

@@ -0,0 +1,35 @@
+package com.swmansion.rnscreens;
+
+import android.content.Context;
+
+import java.util.List;
+
+public class ScreenStack extends ScreenContainer {
+
+  private float mTransitioning;
+
+  public ScreenStack(Context context) {
+    super(context);
+  }
+
+  public void setTransitioning(float transitioning) {
+    if (transitioning != mTransitioning) {
+      mTransitioning = transitioning;
+      markUpdated();
+    }
+  }
+
+  @Override
+  protected boolean isScreenActive(Screen screen, List<Screen> allScreens) {
+    int size = allScreens.size();
+    if (size < 1) {
+      return false;
+    }
+    Screen lastScreen = allScreens.get(size - 1);
+    if (mTransitioning != 0 && size > 1) {
+      Screen secondToLast = allScreens.get(size - 2);
+      return screen == lastScreen || screen == secondToLast;
+    }
+    return screen == lastScreen;
+  }
+}