Have each Fragment register its own back pressed callback
By splitting the OnBackPressedCallback apart at
a FragmentManager level, we can ensure that the
appropriate Lifecycle is used for each callback,
allowing developers to interleave the Fragment
back stack management with their own custom
callbacks.
Test: updated PrimaryNavFragmentTest tests
BUG: 111598096
Change-Id: I22cc38794c1ee20da370f1843d667b34a9529c22
diff --git a/activity/api/1.0.0-alpha07.txt b/activity/api/1.0.0-alpha07.txt
index 7b3c69f..ba5e733 100644
--- a/activity/api/1.0.0-alpha07.txt
+++ b/activity/api/1.0.0-alpha07.txt
@@ -1,7 +1,7 @@
// Signature format: 3.0
package androidx.activity {
- public class ComponentActivity extends androidx.core.app.ComponentActivity implements androidx.lifecycle.LifecycleOwner androidx.savedstate.SavedStateRegistryOwner androidx.lifecycle.ViewModelStoreOwner {
+ public class ComponentActivity extends androidx.core.app.ComponentActivity implements androidx.lifecycle.LifecycleOwner androidx.activity.OnBackPressedDispatcherOwner androidx.savedstate.SavedStateRegistryOwner androidx.lifecycle.ViewModelStoreOwner {
ctor public ComponentActivity();
ctor @ContentView public ComponentActivity(@LayoutRes int);
method @Deprecated public void addOnBackPressedCallback(androidx.activity.OnBackPressedCallback);
@@ -31,5 +31,9 @@
method @MainThread public void onBackPressed();
}
+ public interface OnBackPressedDispatcherOwner extends androidx.lifecycle.LifecycleOwner {
+ method public androidx.activity.OnBackPressedDispatcher getOnBackPressedDispatcher();
+ }
+
}
diff --git a/activity/api/current.txt b/activity/api/current.txt
index 7b3c69f..ba5e733 100644
--- a/activity/api/current.txt
+++ b/activity/api/current.txt
@@ -1,7 +1,7 @@
// Signature format: 3.0
package androidx.activity {
- public class ComponentActivity extends androidx.core.app.ComponentActivity implements androidx.lifecycle.LifecycleOwner androidx.savedstate.SavedStateRegistryOwner androidx.lifecycle.ViewModelStoreOwner {
+ public class ComponentActivity extends androidx.core.app.ComponentActivity implements androidx.lifecycle.LifecycleOwner androidx.activity.OnBackPressedDispatcherOwner androidx.savedstate.SavedStateRegistryOwner androidx.lifecycle.ViewModelStoreOwner {
ctor public ComponentActivity();
ctor @ContentView public ComponentActivity(@LayoutRes int);
method @Deprecated public void addOnBackPressedCallback(androidx.activity.OnBackPressedCallback);
@@ -31,5 +31,9 @@
method @MainThread public void onBackPressed();
}
+ public interface OnBackPressedDispatcherOwner extends androidx.lifecycle.LifecycleOwner {
+ method public androidx.activity.OnBackPressedDispatcher getOnBackPressedDispatcher();
+ }
+
}
diff --git a/activity/src/main/java/androidx/activity/ComponentActivity.java b/activity/src/main/java/androidx/activity/ComponentActivity.java
index 46ae98f..fde474e 100644
--- a/activity/src/main/java/androidx/activity/ComponentActivity.java
+++ b/activity/src/main/java/androidx/activity/ComponentActivity.java
@@ -49,7 +49,8 @@
public class ComponentActivity extends androidx.core.app.ComponentActivity implements
LifecycleOwner,
ViewModelStoreOwner,
- SavedStateRegistryOwner {
+ SavedStateRegistryOwner,
+ OnBackPressedDispatcherOwner {
static final class NonConfigurationInstances {
Object custom;
@@ -287,6 +288,7 @@
* @return The {@link OnBackPressedDispatcher} associated with this ComponentActivity.
*/
@NonNull
+ @Override
public final OnBackPressedDispatcher getOnBackPressedDispatcher() {
return mOnBackPressedDispatcher;
}
diff --git a/activity/src/main/java/androidx/activity/OnBackPressedDispatcherOwner.java b/activity/src/main/java/androidx/activity/OnBackPressedDispatcherOwner.java
new file mode 100644
index 0000000..e07b3f9
--- /dev/null
+++ b/activity/src/main/java/androidx/activity/OnBackPressedDispatcherOwner.java
@@ -0,0 +1,40 @@
+/*
+ * Copyright 2019 The Android Open Source Project
+ *
+ * Licensed under the Apache License, Version 2.0 (the "License");
+ * you may not use this file except in compliance with the License.
+ * You may obtain a copy of the License at
+ *
+ * http://www.apache.org/licenses/LICENSE-2.0
+ *
+ * Unless required by applicable law or agreed to in writing, software
+ * distributed under the License is distributed on an "AS IS" BASIS,
+ * WITHOUT WARRANTIES OR CONDITIONS OF ANY KIND, either express or implied.
+ * See the License for the specific language governing permissions and
+ * limitations under the License.
+ */
+
+package androidx.activity;
+
+import androidx.annotation.NonNull;
+import androidx.lifecycle.LifecycleOwner;
+
+/**
+ * A class that has an {@link OnBackPressedDispatcher} that allows you to register a
+ * {@link OnBackPressedCallback} for handling the system back button.
+ * <p>
+ * It is expected that classes that implement this interface route the system back button
+ * to the dispatcher
+ *
+ * @see OnBackPressedDispatcher
+ */
+public interface OnBackPressedDispatcherOwner extends LifecycleOwner {
+
+ /**
+ * Retrieve the {@link OnBackPressedDispatcher} that should handle the system back button.
+ *
+ * @return The {@link OnBackPressedDispatcher}.
+ */
+ @NonNull
+ OnBackPressedDispatcher getOnBackPressedDispatcher();
+}
diff --git a/fragment/src/androidTest/java/androidx/fragment/app/PrimaryNavFragmentTest.kt b/fragment/src/androidTest/java/androidx/fragment/app/PrimaryNavFragmentTest.kt
index 2b06bf5..b1ed36a 100644
--- a/fragment/src/androidTest/java/androidx/fragment/app/PrimaryNavFragmentTest.kt
+++ b/fragment/src/androidTest/java/androidx/fragment/app/PrimaryNavFragmentTest.kt
@@ -16,6 +16,7 @@
package androidx.fragment.app
+import android.app.Activity
import androidx.fragment.app.test.EmptyFragmentTestActivity
import androidx.test.ext.junit.runners.AndroidJUnit4
import androidx.test.filters.SmallTest
@@ -58,10 +59,7 @@
.that(cfm.backStackEntryCount)
.isEqualTo(1)
- // Should execute the pop for the child fragmentmanager
- assertWithMessage("popBackStackImmediate returned no action performed")
- .that(popBackStackImmediate(fm))
- .isTrue()
+ activityRule.onBackPressed()
assertWithMessage("child transaction still on back stack")
.that(cfm.backStackEntryCount)
@@ -93,7 +91,7 @@
.that(fm.primaryNavigationFragment)
.isNull()
- popBackStackImmediate(fm)
+ activityRule.onBackPressed()
assertWithMessage("primary nav fragment was not restored on pop")
.that(fm.primaryNavigationFragment)
@@ -112,7 +110,7 @@
.that(fm.primaryNavigationFragment)
.isSameAs(strictFragment2)
- popBackStackImmediate(fm)
+ activityRule.onBackPressed()
assertWithMessage("primary nav fragment not restored on pop")
.that(fm.primaryNavigationFragment)
@@ -127,7 +125,7 @@
assertWithMessage("primary nav fragment not retained when set again in new transaction")
.that(fm.primaryNavigationFragment)
.isSameAs(strictFragment1)
- popBackStackImmediate(fm)
+ activityRule.onBackPressed()
assertWithMessage(
"same primary nav fragment not retained when set primary nav transaction popped")
@@ -162,7 +160,7 @@
.that(fm.primaryNavigationFragment)
.isNull()
- popBackStackImmediate(fm)
+ activityRule.onBackPressed()
assertWithMessage("primary nav fragment not restored after popping replace")
.that(fm.primaryNavigationFragment)
@@ -188,7 +186,7 @@
.that(fm.primaryNavigationFragment)
.isSameAs(strictFragment2)
- popBackStackImmediate(fm)
+ activityRule.onBackPressed()
assertWithMessage("primary nav fragment not null after popping replace")
.that(fm.primaryNavigationFragment)
@@ -199,9 +197,7 @@
activityRule.runOnUiThread { fm.executePendingTransactions() }
}
- private fun popBackStackImmediate(fm: FragmentManager): Boolean {
- var popped = false
- activityRule.runOnUiThread { popped = fm.popBackStackImmediate() }
- return popped
+ private fun ActivityTestRule<out Activity>.onBackPressed() = runOnUiThread {
+ activity.onBackPressed()
}
}
diff --git a/fragment/src/main/java/androidx/fragment/app/FragmentActivity.java b/fragment/src/main/java/androidx/fragment/app/FragmentActivity.java
index d70aaca..1718a2a 100644
--- a/fragment/src/main/java/androidx/fragment/app/FragmentActivity.java
+++ b/fragment/src/main/java/androidx/fragment/app/FragmentActivity.java
@@ -35,7 +35,8 @@
import android.view.Window;
import androidx.activity.ComponentActivity;
-import androidx.activity.OnBackPressedCallback;
+import androidx.activity.OnBackPressedDispatcher;
+import androidx.activity.OnBackPressedDispatcherOwner;
import androidx.annotation.CallSuper;
import androidx.annotation.ContentView;
import androidx.annotation.LayoutRes;
@@ -116,7 +117,6 @@
*/
public FragmentActivity() {
super();
- init();
}
/**
@@ -132,47 +132,6 @@
@ContentView
public FragmentActivity(@LayoutRes int contentLayoutId) {
super(contentLayoutId);
- init();
- }
-
- private void init() {
- // Route onBackPressed() callbacks to the FragmentManager
- getOnBackPressedDispatcher().addCallback(this, new OnBackPressedCallback(true) {
- @Override
- public boolean isEnabled() {
- FragmentManager fragmentManager = mFragments.getSupportFragmentManager();
- // Either this FragmentManager needs to have a back stack
- // or its primary navigation Fragment needs to have one
- return fragmentManager.getBackStackEntryCount() > 0
- || hasPrimaryNavigationBackStack(fragmentManager);
- }
-
- /**
- * Recursively check down the FragmentManager hierarchy of primary
- * navigation Fragments for a FragmentManager that has a back stack
- * that can be popped.
- */
- private boolean hasPrimaryNavigationBackStack(
- @NonNull FragmentManager fragmentManager) {
- Fragment primaryNavFragment = fragmentManager.getPrimaryNavigationFragment();
- if (primaryNavFragment == null) {
- return false;
- }
- FragmentManager primaryNavFragmentManager =
- primaryNavFragment.peekChildFragmentManager();
- if (primaryNavFragmentManager == null) {
- return false;
- }
- return primaryNavFragmentManager.getBackStackEntryCount() > 0
- || hasPrimaryNavigationBackStack(primaryNavFragmentManager);
- }
-
- @Override
- public void handleOnBackPressed() {
- FragmentManager fragmentManager = mFragments.getSupportFragmentManager();
- fragmentManager.popBackStackImmediate();
- }
- });
}
// ------------------------------------------------------------------------
@@ -891,18 +850,31 @@
}
}
- class HostCallbacks extends FragmentHostCallback<FragmentActivity>
- implements ViewModelStoreOwner {
+ class HostCallbacks extends FragmentHostCallback<FragmentActivity> implements
+ ViewModelStoreOwner,
+ OnBackPressedDispatcherOwner {
public HostCallbacks() {
super(FragmentActivity.this /*fragmentActivity*/);
}
@NonNull
@Override
+ public Lifecycle getLifecycle() {
+ return FragmentActivity.this.getLifecycle();
+ }
+
+ @NonNull
+ @Override
public ViewModelStore getViewModelStore() {
return FragmentActivity.this.getViewModelStore();
}
+ @NonNull
+ @Override
+ public OnBackPressedDispatcher getOnBackPressedDispatcher() {
+ return FragmentActivity.this.getOnBackPressedDispatcher();
+ }
+
@Override
public void onDump(@NonNull String prefix, @Nullable FileDescriptor fd,
@NonNull PrintWriter writer, @Nullable String[] args) {
diff --git a/fragment/src/main/java/androidx/fragment/app/FragmentManagerImpl.java b/fragment/src/main/java/androidx/fragment/app/FragmentManagerImpl.java
index 6213072..fed4bd3 100644
--- a/fragment/src/main/java/androidx/fragment/app/FragmentManagerImpl.java
+++ b/fragment/src/main/java/androidx/fragment/app/FragmentManagerImpl.java
@@ -45,6 +45,9 @@
import android.view.animation.ScaleAnimation;
import android.view.animation.Transformation;
+import androidx.activity.OnBackPressedCallback;
+import androidx.activity.OnBackPressedDispatcher;
+import androidx.activity.OnBackPressedDispatcherOwner;
import androidx.annotation.NonNull;
import androidx.annotation.Nullable;
import androidx.collection.ArraySet;
@@ -52,6 +55,7 @@
import androidx.core.util.LogWriter;
import androidx.core.view.OneShotPreDrawListener;
import androidx.lifecycle.Lifecycle;
+import androidx.lifecycle.LifecycleOwner;
import androidx.lifecycle.ViewModelStore;
import androidx.lifecycle.ViewModelStoreOwner;
@@ -2463,11 +2467,54 @@
}
public void attachController(@NonNull FragmentHostCallback host,
- @NonNull FragmentContainer container, @Nullable Fragment parent) {
+ @NonNull FragmentContainer container, @Nullable final Fragment parent) {
if (mHost != null) throw new IllegalStateException("Already attached");
mHost = host;
mContainer = container;
mParent = parent;
+ // Set up the OnBackPressedCallback
+ if (host instanceof OnBackPressedDispatcherOwner) {
+ OnBackPressedDispatcherOwner dispatcherOwner = ((OnBackPressedDispatcherOwner) host);
+ OnBackPressedDispatcher dispatcher = dispatcherOwner.getOnBackPressedDispatcher();
+ LifecycleOwner owner = parent != null ? parent : dispatcherOwner;
+ dispatcher.addCallback(owner, new OnBackPressedCallback(true) {
+ @Override
+ public boolean isEnabled() {
+ // This FragmentManager needs to have a back stack for this to be enabled
+ // and the parent fragment, if it exists, needs to be the primary navigation
+ // fragment.
+ return getBackStackEntryCount() > 0 && isPrimaryNavigation(parent);
+ }
+
+ /**
+ * Recursively check up the FragmentManager hierarchy of primary
+ * navigation Fragments to ensure that all of the parent Fragments are the
+ * primary navigation Fragment for their associated FragmentManager
+ */
+ private boolean isPrimaryNavigation(@Nullable Fragment parent) {
+ // If the parent is null, then we're at the root host
+ // and we're always the primary navigation
+ if (parent == null) {
+ return true;
+ }
+ FragmentManagerImpl parentFragmentManager = parent.mFragmentManager;
+ Fragment primaryNavigationFragment = parentFragmentManager
+ .getPrimaryNavigationFragment();
+ // The parent Fragment needs to be the primary navigation Fragment
+ // and, if it has a parent itself, that parent also needs to be
+ // the primary navigation fragment, recursively up the stack
+ return parent == primaryNavigationFragment
+ && isPrimaryNavigation(parentFragmentManager.mParent);
+ }
+
+ @Override
+ public void handleOnBackPressed() {
+ popBackStackImmediate();
+ }
+ });
+ }
+
+ // Get the FragmentManagerViewModel
if (parent != null) {
mNonConfig = parent.mFragmentManager.getChildNonConfig(parent);
} else if (host instanceof ViewModelStoreOwner) {
