Add PopRootControllerMode to address Android 12 back button behavior (#663)

README.md

@@ -20,27 +20,27 @@ Conductor is architecture-agnostic and does not try to force any design decision
 ## Installation
 
 ```gradle
-implementation 'com.bluelinelabs:conductor:3.1.2'
+implementation 'com.bluelinelabs:conductor:3.1.3'
 
 // AndroidX Transition change handlers:
-implementation 'com.bluelinelabs:conductor-androidx-transition:3.1.2'
+implementation 'com.bluelinelabs:conductor-androidx-transition:3.1.3'
 
 // ViewPager PagerAdapter:
-implementation 'com.bluelinelabs:conductor-viewpager:3.1.2'
+implementation 'com.bluelinelabs:conductor-viewpager:3.1.3'
 
 // ViewPager2 Adapter:
-implementation 'com.bluelinelabs:conductor-viewpager2:3.1.2'
+implementation 'com.bluelinelabs:conductor-viewpager2:3.1.3'
 
 // RxJava2 Autodispose support:
-implementation 'com.bluelinelabs:conductor-autodispose:3.1.2'
+implementation 'com.bluelinelabs:conductor-autodispose:3.1.3'
 
 // Lifecycle-aware Controllers (architecture components):
-implementation 'com.bluelinelabs:conductor-archlifecycle:3.1.2'
+implementation 'com.bluelinelabs:conductor-archlifecycle:3.1.3'
 ```
 
 **SNAPSHOT**
 
-Just use `3.1.3-SNAPSHOT` as your version number in any of the dependencies above and add the url to the snapshot repository:
+Just use `3.1.4-SNAPSHOT` as your version number in any of the dependencies above and add the url to the snapshot repository:
 
 ```gradle
 allprojects {
@@ -76,7 +76,8 @@ public class MainActivity extends Activity {
 
         ViewGroup container = (ViewGroup) findViewById(R.id.controller_container);
 
-        router = Conductor.attachRouter(this, container, savedInstanceState);
+        router = Conductor.attachRouter(this, container, savedInstanceState)
+            .setPopRootControllerMode(PopRootControllerMode.NEVER);
         if (!router.hasRootController()) {
             router.setRoot(RouterTransaction.with(new HomeController()));
         }

conductor/src/main/java/com/bluelinelabs/conductor/ControllerHostedRouter.java

@@ -34,10 +34,6 @@ class ControllerHostedRouter extends Router {
 
     ControllerHostedRouter() { }
 
-    ControllerHostedRouter(int hostId, @Nullable String tag) {
-        this(hostId, tag, false);
-    }
-
     ControllerHostedRouter(int hostId, @Nullable String tag, boolean boundToContainer) {
         if (!boundToContainer && tag == null) {
             throw new IllegalStateException("ControllerHostedRouter can't be created without a tag if not bounded to its container");

conductor/src/main/java/com/bluelinelabs/conductor/Router.java

@@ -35,14 +35,14 @@ import java.util.List;
 public abstract class Router {
 
     private static final String KEY_BACKSTACK = "Router.backstack";
-    private static final String KEY_POPS_LAST_VIEW = "Router.popsLastView";
+    private static final String KEY_POP_ROOT_CONTROLLER_MODE = "Router.popRootControllerMode";
 
     final Backstack backstack = new Backstack();
     private final List<ControllerChangeListener> changeListeners = new ArrayList<>();
     private final List<ChangeTransaction> pendingControllerChanges = new ArrayList<>();
     final List<Controller> destroyingControllers = new ArrayList<>();
 
-    private boolean popsLastView = false;
+    private PopRootControllerMode popRootControllerMode = PopRootControllerMode.POP_ROOT_CONTROLLER_BUT_NOT_VIEW;
     boolean containerFullyAttached = false;
     boolean isActivityStopped = false;
 
@@ -95,7 +95,7 @@ public abstract class Router {
             //noinspection ConstantConditions
             if (backstack.peek().controller().handleBack()) {
                 return true;
-            } else if (popCurrentController()) {
+            } else if ((backstack.getSize() > 1 || popRootControllerMode != PopRootControllerMode.NEVER) && popCurrentController()) {
                 return true;
             }
         }
@@ -162,7 +162,7 @@ public abstract class Router {
             }
         }
 
-        if (popsLastView) {
+        if (popRootControllerMode == PopRootControllerMode.POP_ROOT_CONTROLLER_AND_VIEW) {
             return topTransaction != null;
         } else {
             return !backstack.isEmpty();
@@ -221,7 +221,7 @@ public abstract class Router {
     }
 
     void destroy(boolean popViews) {
-        popsLastView = true;
+        popRootControllerMode = PopRootControllerMode.POP_ROOT_CONTROLLER_AND_VIEW;
         final List<RouterTransaction> poppedControllers = backstack.popAll();
         trackDestroyingControllers(poppedControllers);
 
@@ -251,10 +251,24 @@ public abstract class Router {
      * If set to true, this router will handle back presses by performing a change handler on the last controller and view
      * in the stack. This defaults to false so that the developer can either finish its containing Activity or otherwise
      * hide its parent view without any strange artifacting.
+     *
+     * Note: This method has been deprecated and should be replaced with setPopRootControllerMode.
      */
     @NonNull
+    @Deprecated
     public Router setPopsLastView(boolean popsLastView) {
-        this.popsLastView = popsLastView;
+        this.popRootControllerMode = popsLastView ? PopRootControllerMode.POP_ROOT_CONTROLLER_AND_VIEW : PopRootControllerMode.POP_ROOT_CONTROLLER_BUT_NOT_VIEW;
+        return this;
+    }
+
+    /**
+     * Sets the method this router will use to handle back presses when there is only one controller left in the backstack.
+     * Defaults to POP_ROOT_CONTROLLER_LEAVING_VIEW so that the developer can either finish its containing Activity or
+     * otherwise hide its parent view without any strange artifacting.
+     */
+    @NonNull
+    public Router setPopRootControllerMode(@NonNull PopRootControllerMode popRootControllerMode) {
+        this.popRootControllerMode = popRootControllerMode;
         return this;
     }
 
@@ -650,14 +664,14 @@ public abstract class Router {
         backstack.saveInstanceState(backstackState);
 
         outState.putParcelable(KEY_BACKSTACK, backstackState);
-        outState.putBoolean(KEY_POPS_LAST_VIEW, popsLastView);
+        outState.putInt(KEY_POP_ROOT_CONTROLLER_MODE, popRootControllerMode.ordinal());
     }
 
     public void restoreInstanceState(@NonNull Bundle savedInstanceState) {
         Bundle backstackBundle = savedInstanceState.getParcelable(KEY_BACKSTACK);
         //noinspection ConstantConditions
         backstack.restoreInstanceState(backstackBundle);
-        popsLastView = savedInstanceState.getBoolean(KEY_POPS_LAST_VIEW);
+        popRootControllerMode = PopRootControllerMode.values()[savedInstanceState.getInt(KEY_POP_ROOT_CONTROLLER_MODE)];
 
         Iterator<RouterTransaction> backstackIterator = backstack.reverseIterator();
         while (backstackIterator.hasNext()) {
@@ -803,7 +817,7 @@ public abstract class Router {
         if (to != null) {
             to.ensureValidIndex(getTransactionIndexer());
             setRouterOnController(toController);
-        } else if (backstack.getSize() == 0 && !popsLastView) {
+        } else if (backstack.getSize() == 0 && popRootControllerMode == PopRootControllerMode.POP_ROOT_CONTROLLER_BUT_NOT_VIEW) {
             // We're emptying out the backstack. Views get weird if you transition them out, so just no-op it. The host
             // Activity or controller should be handling this by finishing or at least hiding this view.
             changeHandler = new NoOpControllerChangeHandler();
@@ -1011,4 +1025,25 @@ public abstract class Router {
     @NonNull abstract Router getRootRouter();
     @NonNull abstract TransactionIndexer getTransactionIndexer();
 
+    /**
+     * Defines the way a Router will handle back button or pop events when there is only one controller
+     * left in the backstack.
+     */
+    public enum PopRootControllerMode {
+        /**
+         * The Router will not pop the final controller left on the backstack when the back button is pressed
+         * or when pop events are called. This mode should generally be used for Activity-hosted routers.
+         */
+        NEVER,
+        /**
+         * The Router will pop the final controller, but will leave its view in the hierarchy. This is useful
+         * when the developer wishes to allow its containing Activity to finish or otherwise hide its parent
+         * view without any strange artifacting.
+         */
+        POP_ROOT_CONTROLLER_BUT_NOT_VIEW,
+        /**
+         * The Router will pop both the final controller as well as its view.
+         */
+        POP_ROOT_CONTROLLER_AND_VIEW
+    }
 }

conductor/src/test/java/com/bluelinelabs/conductor/ControllerLifecycleActivityReferenceTests.kt

@@ -112,7 +112,7 @@ class ControllerLifecycleActivityReferenceTests {
     child.addLifecycleListener(listener)
 
     val childRouter = parent.getChildRouter(parent.view!!.findViewById(TestController.VIEW_ID))
-    childRouter.setPopsLastView(true)
+    childRouter.setPopRootControllerMode(Router.PopRootControllerMode.POP_ROOT_CONTROLLER_AND_VIEW)
     childRouter.pushController(
       child.asTransaction(
         pushChangeHandler = MockChangeHandler.defaultHandler(),
@@ -146,7 +146,7 @@ class ControllerLifecycleActivityReferenceTests {
     child.addLifecycleListener(listener)
 
     val childRouter = parent.getChildRouter(parent.view!!.findViewById(TestController.VIEW_ID))
-    childRouter.setPopsLastView(true)
+    childRouter.setPopRootControllerMode(Router.PopRootControllerMode.POP_ROOT_CONTROLLER_AND_VIEW)
     childRouter.pushController(
       child.asTransaction(
         pushChangeHandler = MockChangeHandler.defaultHandler(),
@@ -199,7 +199,7 @@ class ControllerLifecycleActivityReferenceTests {
     val listener = ActivityReferencingLifecycleListener()
     child.addLifecycleListener(listener)
     val childRouter = parent.getChildRouter(parent.view!!.findViewById(TestController.VIEW_ID))
-    childRouter.setPopsLastView(true)
+    childRouter.setPopRootControllerMode(Router.PopRootControllerMode.POP_ROOT_CONTROLLER_AND_VIEW)
     childRouter.pushController(
       child.asTransaction(
         pushChangeHandler = MockChangeHandler.defaultHandler(),

conductor/src/test/java/com/bluelinelabs/conductor/ControllerTests.kt

@@ -276,7 +276,7 @@ class ControllerTests {
     Assert.assertNull(child2.parentController)
 
     var childRouter = parent.getChildRouter(parent.view!!.findViewById(TestController.VIEW_ID))
-    childRouter.setPopsLastView(true)
+    childRouter.setPopRootControllerMode(Router.PopRootControllerMode.POP_ROOT_CONTROLLER_AND_VIEW)
     childRouter.setRoot(child1.asTransaction())
     Assert.assertEquals(1, parent.childRouters.size)
     Assert.assertEquals(childRouter, parent.childRouters[0])
@@ -362,7 +362,7 @@ class ControllerTests {
     val childTransaction1 = TestController().asTransaction()
     val childTransaction2 = TestController().asTransaction()
     var childRouter = parent.getChildRouter(parent.view!!.findViewById(TestController.CHILD_VIEW_ID_1))
-    childRouter.setPopsLastView(true)
+    childRouter.setPopRootControllerMode(Router.PopRootControllerMode.POP_ROOT_CONTROLLER_AND_VIEW)
     childRouter.setRoot(childTransaction1)
     childRouter.pushController(childTransaction2)
     val savedState = Bundle()

conductor/src/test/java/com/bluelinelabs/conductor/ReattachCaseTests.kt

@@ -124,7 +124,7 @@ class ReattachCaseTests {
     val childRouter = controllerB.getChildRouter(
       controllerB.view!!.findViewById(TestController.VIEW_ID)
     )
-    childRouter.setPopsLastView(true)
+    childRouter.setPopRootControllerMode(Router.PopRootControllerMode.POP_ROOT_CONTROLLER_AND_VIEW)
     childRouter.pushController(
       childController.asTransaction(
         pushChangeHandler = MockChangeHandler.defaultHandler(),
@@ -179,7 +179,7 @@ class ReattachCaseTests {
     val childRouter = controllerB.getChildRouter(
       controllerB.view!!.findViewById(TestController.VIEW_ID)
     )
-    childRouter.setPopsLastView(true)
+    childRouter.setPopRootControllerMode(Router.PopRootControllerMode.POP_ROOT_CONTROLLER_AND_VIEW)
     childRouter.pushController(
       childController.asTransaction(
         pushChangeHandler = MockChangeHandler.defaultHandler(),

demo/src/main/java/com/bluelinelabs/conductor/demo/MainActivity.kt

@@ -5,6 +5,7 @@ import androidx.appcompat.app.AppCompatActivity
 import androidx.appcompat.widget.Toolbar
 import com.bluelinelabs.conductor.Conductor.attachRouter
 import com.bluelinelabs.conductor.Router
+import com.bluelinelabs.conductor.Router.PopRootControllerMode
 import com.bluelinelabs.conductor.RouterTransaction.Companion.with
 import com.bluelinelabs.conductor.demo.controllers.HomeController
 import com.bluelinelabs.conductor.demo.databinding.ActivityMainBinding
@@ -23,6 +24,8 @@ class MainActivity : AppCompatActivity(), ToolbarProvider {
     setContentView(binding.root)
 
     router = attachRouter(this, binding.controllerContainer, savedInstanceState)
+      .setPopRootControllerMode(PopRootControllerMode.NEVER)
+
     if (!router.hasRootController()) {
       router.setRoot(with(HomeController()))
     }

demo/src/main/java/com/bluelinelabs/conductor/demo/controllers/MultipleChildRouterController.kt

@@ -1,6 +1,7 @@
 package com.bluelinelabs.conductor.demo.controllers
 
 import android.view.View
+import com.bluelinelabs.conductor.Router.PopRootControllerMode
 import com.bluelinelabs.conductor.RouterTransaction
 import com.bluelinelabs.conductor.demo.R
 import com.bluelinelabs.conductor.demo.controllers.base.BaseController
@@ -18,7 +19,7 @@ class MultipleChildRouterController : BaseController(R.layout.controller_multipl
     val childContainers = listOf(binding.container0, binding.container1, binding.container2)
 
     childContainers.forEach { container ->
-      val childRouter = getChildRouter(container).setPopsLastView(false)
+      val childRouter = getChildRouter(container).setPopRootControllerMode(PopRootControllerMode.POP_ROOT_CONTROLLER_BUT_NOT_VIEW)
       if (!childRouter.hasRootController()) {
         childRouter.setRoot(RouterTransaction.with(NavigationDemoController(0, NavigationDemoController.DisplayUpMode.HIDE)))
       }

demo/src/main/java/com/bluelinelabs/conductor/demo/controllers/ParentController.kt

@@ -3,6 +3,7 @@ package com.bluelinelabs.conductor.demo.controllers
 import com.bluelinelabs.conductor.Controller
 import com.bluelinelabs.conductor.ControllerChangeHandler
 import com.bluelinelabs.conductor.ControllerChangeType
+import com.bluelinelabs.conductor.Router.PopRootControllerMode
 import com.bluelinelabs.conductor.RouterTransaction
 import com.bluelinelabs.conductor.changehandler.FadeChangeHandler
 import com.bluelinelabs.conductor.demo.R
@@ -11,7 +12,6 @@ import com.bluelinelabs.conductor.demo.databinding.ControllerParentBinding
 import com.bluelinelabs.conductor.demo.util.getMaterialColor
 import com.bluelinelabs.conductor.demo.util.viewBinding
 
-
 class ParentController : BaseController(R.layout.controller_parent) {
   private val binding: ControllerParentBinding by viewBinding(ControllerParentBinding::bind)
 
@@ -50,7 +50,7 @@ class ParentController : BaseController(R.layout.controller_parent) {
       else -> throw IllegalStateException("Invalid child index $index")
     }
 
-    val childRouter = getChildRouter(container).setPopsLastView(true)
+    val childRouter = getChildRouter(container).setPopRootControllerMode(PopRootControllerMode.POP_ROOT_CONTROLLER_AND_VIEW)
     if (!childRouter.hasRootController()) {
       val child = ChildController(
         title = "Child Controller #$index",

gradle.properties

@@ -1,5 +1,5 @@
 VERSION_CODE=3
-VERSION_NAME=3.1.3-SNAPSHOT
+VERSION_NAME=3.1.4-SNAPSHOT
 android.useAndroidX=true
 org.gradle.jvmargs=-Xmx1536m