Put the launch form behind a FAB

This greatly reduces the amount of scrolling needed to switch between
the overview-view and the launch-view. When launching the next activity
the launch view is dismissed and the user return to the overview-view
if they press back.

Test: Manual
Change-Id: I051ba98b29d666cf56753feebfaa87d2e181a3ab

samples/IntentPlayground/Android.mk

@@ -9,8 +9,11 @@ LOCAL_SRC_FILES := $(call all-java-files-under, src)
 LOCAL_RESOURCE_DIR := $(LOCAL_PATH)/res
 
 LOCAL_STATIC_ANDROID_LIBRARIES := \
+    androidx.design_design \
     androidx.appcompat_appcompat \
-    androidx.recyclerview_recyclerview
+    androidx.recyclerview_recyclerview \
+    androidx.lifecycle_lifecycle-livedata \
+    androidx.lifecycle_lifecycle-viewmodel
 
 LOCAL_USE_AAPT2 := true
 

samples/IntentPlayground/res/layout/activity_main.xml

@@ -49,4 +49,12 @@
             </LinearLayout>
           </ScrollView>
         </LinearLayout>
+    <android.support.design.widget.FloatingActionButton
+        android:id="@+id/launch_fab"
+        android:layout_width="wrap_content"
+        android:layout_height="wrap_content"
+        android:layout_gravity="end|bottom"
+        android:layout_marginEnd="@dimen/smallMargin"
+        android:layout_marginBottom="@dimen/smallMargin"
+        android:src="@drawable/icon_launch" />
 </FrameLayout>

samples/IntentPlayground/src/com/example/android/intentplayground/BaseActivity.java

@@ -22,8 +22,8 @@ import android.content.ComponentName;
 import android.content.Intent;
 import android.os.Build;
 import android.os.Bundle;
+import android.support.design.widget.FloatingActionButton;
 import android.util.Log;
-import android.view.View;
 import android.view.Menu;
 import android.view.MenuItem;
 import android.view.ViewGroup;
@@ -34,6 +34,7 @@ import androidx.appcompat.app.AppCompatActivity;
 import androidx.appcompat.widget.Toolbar;
 import androidx.fragment.app.FragmentManager;
 import androidx.fragment.app.FragmentTransaction;
+import androidx.lifecycle.ViewModelProvider;
 
 import java.util.ArrayList;
 
@@ -63,6 +64,31 @@ public abstract class BaseActivity extends AppCompatActivity implements
         appBar.setTitle(this.getClass().getSimpleName());
         setSupportActionBar(appBar);
 
+        FloatingActionButton launchButton = findViewById(R.id.launch_fab);
+        launchButton.setOnClickListener(l -> {
+            LaunchFragment fragment = new LaunchFragment();
+
+            getSupportFragmentManager().beginTransaction()
+                    .addToBackStack(null)
+                    .replace(R.id.fragment_container, fragment)
+                    .commit();
+        });
+
+        BaseActivityViewModel viewModel = (new ViewModelProvider(this,
+                new ViewModelProvider.NewInstanceFactory())).get(BaseActivityViewModel.class);
+
+        viewModel.getFabActions().observe(this, action -> {
+            switch (action) {
+                case Show:
+                    launchButton.show();
+                    break;
+                case Hide:
+                    launchButton.hide();
+                    break;
+            }
+        });
+
+
         loadMode(Mode.LAUNCH);
     }
 
@@ -81,40 +107,34 @@ public abstract class BaseActivity extends AppCompatActivity implements
      * @param mode The mode to display.
      */
     protected void loadMode(Mode mode) {
-        Intent intent = getIntent();
-        ViewGroup container = findViewById(R.id.fragment_container);
         FragmentManager fragmentManager = getSupportFragmentManager();
+
+        if (fragmentManager.findFragmentById(R.id.fragment_container) == null) {
             FragmentTransaction transaction = fragmentManager.beginTransaction()
                     .setCustomAnimations(android.R.animator.fade_in, android.R.animator.fade_out);
             if (mode == Mode.LAUNCH) {
-            if (Build.VERSION.SDK_INT >= Build.VERSION_CODES.O) {
                 TreeFragment currentTaskFragment = new TreeFragment();
                 Bundle args = new Bundle();
                 args.putString(TreeFragment.FRAGMENT_TITLE,
                         getString(R.string.current_task_hierarchy_title));
                 currentTaskFragment.setArguments(args);
                 transaction.add(R.id.fragment_container, currentTaskFragment, TREE_FRAGMENT);
-            }
                 transaction.add(R.id.fragment_container, new IntentFragment());
                 transaction.commit();
-            // Ensure IntentBuilderView is last by adding it to the container after commit()
+
-            transaction.runOnCommit(() -> {
-                IntentBuilderView builderView = new IntentBuilderView(this, mode);
-                builderView.setOnLaunchCallback(this::launchActivity);
-                View bottomAnchorView = new View(this);
-                bottomAnchorView.setId(R.id.fragment_container_bottom);
-                container.addView(builderView);
-                container.addView(bottomAnchorView);
-            });
                 mStatus = Mode.LAUNCH;
             }
         }
+    }
 
     /**
      * Launches activity with the selected options.
      */
     public void launchActivity(Intent intent) {
+        // If people press back we want them to see the overview rather than the launch fragment.
+        // To achieve this we pop the launchFragment from the stack when we go to the next activity.
         startActivity(intent);
+        getSupportFragmentManager().popBackStack();
     }
 
     @Override

samples/IntentPlayground/src/com/example/android/intentplayground/BaseActivityViewModel.java

@@ -0,0 +1,36 @@
+/*
+ * Copyright (C) 2018 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 com.example.android.intentplayground;
+
+import androidx.lifecycle.LiveData;
+import androidx.lifecycle.MutableLiveData;
+import androidx.lifecycle.ViewModel;
+
+public class BaseActivityViewModel extends ViewModel {
+    enum FabAction {Show, Hide }
+
+    private MutableLiveData<FabAction> mFabActions = new MutableLiveData<>();
+
+    public void actOnFab(FabAction action) {
+        mFabActions.setValue(action);
+    }
+
+    public LiveData<FabAction> getFabActions() {
+        return mFabActions;
+    }
+}
+

samples/IntentPlayground/src/com/example/android/intentplayground/LaunchFragment.java

@@ -0,0 +1,49 @@
+package com.example.android.intentplayground;
+
+import android.os.Bundle;
+import android.view.LayoutInflater;
+import android.view.View;
+import android.view.ViewGroup;
+
+import androidx.annotation.NonNull;
+import androidx.annotation.Nullable;
+import androidx.fragment.app.Fragment;
+import androidx.fragment.app.FragmentActivity;
+import androidx.lifecycle.ViewModelProvider;
+
+import com.example.android.intentplayground.BaseActivity.Mode;
+import com.example.android.intentplayground.IntentBuilderView.OnLaunchCallback;
+
+public class LaunchFragment extends Fragment {
+    private IntentBuilderView mIntentBuilderView;
+    private BaseActivityViewModel mViewModel;
+
+    @Nullable
+    @Override
+    public View onCreateView(@NonNull LayoutInflater inflater, @Nullable ViewGroup container,
+            @Nullable Bundle savedInstanceState) {
+        mIntentBuilderView = new IntentBuilderView(getContext(), Mode.LAUNCH);
+        setOnLaunchCallBack();
+        return mIntentBuilderView;
+    }
+
+
+    @Override
+    public void onViewCreated(@NonNull View view, @Nullable Bundle savedInstanceState) {
+        mViewModel = (new ViewModelProvider(getActivity(),
+                new ViewModelProvider.NewInstanceFactory())).get(BaseActivityViewModel.class);
+    }
+
+    @Override
+    public void onResume() {
+        super.onResume();
+        mViewModel.actOnFab(BaseActivityViewModel.FabAction.Hide);
+    }
+
+    private void setOnLaunchCallBack() {
+        FragmentActivity activity = this.getActivity();
+        if (activity instanceof OnLaunchCallback) {
+            mIntentBuilderView.setOnLaunchCallback((OnLaunchCallback) activity);
+        }
+    }
+}

samples/IntentPlayground/src/com/example/android/intentplayground/LauncherActivity.java

@@ -37,6 +37,7 @@ import static android.view.ViewGroup.LayoutParams.MATCH_PARENT;
 import static android.view.ViewGroup.LayoutParams.WRAP_CONTENT;
 import static android.view.WindowManager.LayoutParams.FLAG_NOT_TOUCH_MODAL;
 import static android.view.WindowManager.LayoutParams.TYPE_APPLICATION_OVERLAY;
+
 import static com.example.android.intentplayground.Node.newTaskNode;
 
 /**
@@ -64,6 +65,9 @@ public class LauncherActivity extends BaseActivity {
     @Override
     public void launchActivity(Intent intent) {
         startActivityForResult(intent, LAUNCH_REQUEST_CODE);
+        // If people press back we want them to see the overview rather than the launch fragment.
+        // To achieve this we pop the launchFragment from the stack when we go to the next activity.
+        getSupportFragmentManager().popBackStack();
     }
 
     @Override

samples/IntentPlayground/src/com/example/android/intentplayground/TreeFragment.java

@@ -25,7 +25,10 @@ import android.view.ViewGroup;
 import android.widget.LinearLayout;
 import android.widget.TextView;
 
+import androidx.annotation.NonNull;
+import androidx.annotation.Nullable;
 import androidx.fragment.app.Fragment;
+import androidx.lifecycle.ViewModelProvider;
 import androidx.recyclerview.widget.LinearLayoutManager;
 import androidx.recyclerview.widget.RecyclerView;
 
@@ -33,25 +36,31 @@ import androidx.recyclerview.widget.RecyclerView;
  * This fragment displays a hierarchy of tasks and activities in an expandable list.
  */
 public class TreeFragment extends Fragment {
-
     public static final String TREE_NODE = "com.example.android.NODE_TREE";
     public static final String FRAGMENT_TITLE = "com.example.android.TREE_FRAGMENT_TITLE";
     private Activity mActivity;
-    private Node mTree;
     private String mTitle;
     private ViewGroup mContainer;
+    private BaseActivityViewModel mViewModel;
+
 
     @Override
     public View onCreateView(LayoutInflater inflater, ViewGroup container,
             Bundle savedInstanceState) {
         Bundle args = getArguments();
         if (args != null) {
-            mTree = args.getParcelable(TREE_NODE);
             mTitle = args.getString(FRAGMENT_TITLE);
         }
         return inflater.inflate(R.layout.fragment_tree, container, false /* attachToRoot */);
     }
 
+    @Override
+    public void onViewCreated(@NonNull View view, @Nullable Bundle savedInstanceState) {
+        super.onViewCreated(view, savedInstanceState);
+        mViewModel = (new ViewModelProvider(getActivity(),
+                new ViewModelProvider.NewInstanceFactory())).get(BaseActivityViewModel.class);
+    }
+
     @Override
     public void onResume() {
         super.onResume();
@@ -62,11 +71,9 @@ public class TreeFragment extends Fragment {
         if (mTitle != null) {
             titleView.setText(mTitle);
         }
-        if (mTree != null) {
+
-            displayRecycler(mTree, recyclerView);
-        } else {
         displayRecycler(TestBase.describeTaskHierarchy(mActivity), recyclerView);
-        }
+        mViewModel.actOnFab(BaseActivityViewModel.FabAction.Show);
     }
 
     private void displayRecycler(Node root, RecyclerView recyclerView) {