Add a Scroll demo to RotaryPlayground

Bug: 154971276
Test: make and install
Change-Id: Iaa884c4920b910115440ed8181b7fbd6c5ddafba

3 files changed, 199 insertions, 8 deletions

diff --git a/RotaryPlayground/src/com/android/car/rotaryplayground/RotaryActivity.java b/RotaryPlayground/src/com/android/car/rotaryplayground/RotaryActivity.java
index 1b44ac6..32ab6a5 100644
--- a/RotaryPlayground/src/com/android/car/rotaryplayground/RotaryActivity.java
+++ b/RotaryPlayground/src/com/android/car/rotaryplayground/RotaryActivity.java
@@ -24,6 +24,8 @@ import android.util.Log;
 import android.view.View;
 import android.widget.Toast;
 
+import java.util.Random;
+
 /**
  * The main activity for Rotary Playground
  *
@@ -33,7 +35,8 @@ import android.widget.Toast;
 public class RotaryActivity extends FragmentActivity {
 
     private static final String TAG = "RotaryActivity";
-    private static final String MESSAGE = "Hello there!";
+
+    private final Random mRandom = new Random();
 
     private Fragment mMenuFragment = null;
 
@@ -44,9 +47,10 @@ public class RotaryActivity extends FragmentActivity {
         showMenuFragment();
     }
 
-    /** Event handler for buttons in res/layout/rotary_cards.xml */
-    public void onRotaryCardsButtonClick(View v) {
-        showToast(MESSAGE);
+    /** Event handler for button clicks. */
+    public void onRotaryButtonClick(View v) {
+        final String[] greetings = getResources().getStringArray(R.array.greetings);
+        showToast(greetings[mRandom.nextInt(greetings.length)]);
     }
 
     private void showMenuFragment() {
diff --git a/RotaryPlayground/src/com/android/car/rotaryplayground/RotaryMenu.java b/RotaryPlayground/src/com/android/car/rotaryplayground/RotaryMenu.java
index d54a721..d28d007 100644
--- a/RotaryPlayground/src/com/android/car/rotaryplayground/RotaryMenu.java
+++ b/RotaryPlayground/src/com/android/car/rotaryplayground/RotaryMenu.java
@@ -33,10 +33,12 @@ public class RotaryMenu extends Fragment {
     private Fragment mRotaryCards = null;
     private Fragment mRotaryGrid = null;
     private Fragment mDirectManipulation = null;
+    private Fragment mScrollFragment = null;
 
     private Button mCardButton;
     private Button mGridButton;
     private Button mDirectManipulationButton;
+    private Button mScrollButton;
 
     @Override
     public View onCreateView(LayoutInflater inflater, @Nullable ViewGroup container,
@@ -56,6 +58,11 @@ public class RotaryMenu extends Fragment {
                 (v, hasFocus) -> showDirectManipulationExamples(hasFocus));
         mDirectManipulationButton.setOnClickListener(
                 (v -> showDirectManipulationExamples(/* hasFocus= */ true)));
+
+        mScrollButton = view.findViewById(R.id.scroll);
+        mScrollButton.setOnFocusChangeListener((v, hasFocus) -> showScrollFragment(hasFocus));
+        mScrollButton.setOnClickListener(v -> showScrollFragment(/* hasFocus= */ true));
+
         return view;
     }
 
@@ -66,7 +73,7 @@ public class RotaryMenu extends Fragment {
         if (mRotaryCards == null) {
             mRotaryCards = new RotaryCards();
         }
-        showContent(mRotaryCards);
+        showFragment(mRotaryCards);
     }
 
     private void showGridExample(boolean hasFocus) {
@@ -76,7 +83,7 @@ public class RotaryMenu extends Fragment {
         if (mRotaryGrid == null) {
             mRotaryGrid = new RotaryGrid();
         }
-        showContent(mRotaryGrid);
+        showFragment(mRotaryGrid);
     }
 
     // TODO(agathaman): refactor this and the showRotaryCards above into a
@@ -88,10 +95,20 @@ public class RotaryMenu extends Fragment {
         if (mDirectManipulation == null) {
             mDirectManipulation = new RotaryDirectManipulationWidgets();
         }
-        showContent(mDirectManipulation);
+        showFragment(mDirectManipulation);
+    }
+
+    private void showScrollFragment(boolean hasFocus) {
+        if (!hasFocus) {
+            return; // Do nothing if no focus.
+        }
+        if (mScrollFragment == null) {
+            mScrollFragment = new ScrollFragment();
+        }
+        showFragment(mScrollFragment);
     }
 
-    private void showContent(Fragment fragment) {
+    private void showFragment(Fragment fragment) {
         getFragmentManager().beginTransaction()
                 .replace(R.id.rotary_content, fragment)
                 .commit();
diff --git a/RotaryPlayground/src/com/android/car/rotaryplayground/ScrollFragment.java b/RotaryPlayground/src/com/android/car/rotaryplayground/ScrollFragment.java
new file mode 100644
index 0000000..49e341d
--- /dev/null
+++ b/RotaryPlayground/src/com/android/car/rotaryplayground/ScrollFragment.java
@@ -0,0 +1,170 @@
+/*
+ * Copyright (C) 2020 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.android.car.rotaryplayground;
+
+import android.content.Context;
+import android.os.Bundle;
+import android.view.LayoutInflater;
+import android.view.View;
+import android.view.ViewGroup;
+import android.widget.TextView;
+
+import androidx.annotation.NonNull;
+import androidx.annotation.Nullable;
+import androidx.fragment.app.Fragment;
+import androidx.recyclerview.widget.LinearLayoutManager;
+import androidx.recyclerview.widget.RecyclerView;
+
+import java.util.ArrayList;
+import java.util.Arrays;
+import java.util.List;
+
+/** Fragment to demo scrolling with CarRecyclerView. */
+public class ScrollFragment extends Fragment {
+
+    // Item types
+    private static final int TYPE_BUTTONS = 1;
+    private static final int TYPE_TEXT = 2;
+
+    private View mScrollView;
+
+    @Override
+    public View onCreateView(LayoutInflater inflater, @Nullable ViewGroup container,
+            @Nullable Bundle savedInstanceState) {
+        mScrollView = inflater.inflate(R.layout.rotary_scroll, container, false);
+        initView();
+        return mScrollView;
+    }
+
+    private void initView() {
+        List<ScrollListItem> items = new ArrayList<>();
+
+        // List of height for items to be added to the demo.
+        // 0 indicates focusable buttons inflated by R.layout.rotary_scroll.button.
+        // Values > 0 indiciates non-focusable texts inflated by R.layout.rotary_scroll_text.
+        final int[] itemHeights = getResources().getIntArray(R.array.scroll_item_heights);
+
+        for (int height : itemHeights) {
+            if (height < 0) {
+                continue;
+            }
+            ScrollListItem item = (height == 0)
+                    ? ScrollListItem.createButtonsItem()
+                    : ScrollListItem.createTextItemWithHeight(height);
+            items.add(item);
+        }
+
+        // Set adapter
+        Context context = getContext();
+        ScrollListItemAdapter adapter = new ScrollListItemAdapter(context, items);
+        RecyclerView view = (RecyclerView) mScrollView.findViewById(R.id.rotary_scroll_view);
+        view.setAdapter(adapter);
+    }
+
+    /** The adapter used by RotaryScroll to render ScrollListItems. */
+    private static class ScrollListItemAdapter extends
+            RecyclerView.Adapter<RecyclerView.ViewHolder> {
+
+        final Context mContext;
+        final List<ScrollListItem> mItems;
+
+        ScrollListItemAdapter(Context context, List<ScrollListItem> items) {
+            this.mContext = context;
+            this.mItems = items;
+        }
+
+        @NonNull
+        @Override
+        public RecyclerView.ViewHolder onCreateViewHolder(
+                @NonNull ViewGroup viewGroup, int viewType) {
+            View view;
+            switch (viewType) {
+                case TYPE_BUTTONS:
+                    view = LayoutInflater.from(mContext).inflate(
+                            R.layout.rotary_scroll_button, viewGroup, false);
+                    return new RecyclerView.ViewHolder(view) {};
+
+                case TYPE_TEXT:
+                    view = LayoutInflater.from(mContext).inflate(
+                            R.layout.rotary_scroll_text, viewGroup, false);
+                    return new ScrollTextHolder(view);
+
+                default:
+                    throw new IllegalArgumentException("Unexpected viewType: " + viewType);
+            }
+        }
+
+        @Override
+        public int getItemViewType(int position) {
+            return mItems.get(position).getType();
+        }
+
+        @Override
+        public void onBindViewHolder(@NonNull RecyclerView.ViewHolder viewHolder, int position) {
+            if (getItemViewType(position) == TYPE_TEXT) {
+                ((ScrollTextHolder) viewHolder).setHeight(mItems.get(position).getHeight());
+            }
+        }
+
+        @Override
+        public int getItemCount() {
+            return mItems.size();
+        }
+    }
+
+    /** A ViewHolder for non-focusable ScrollListItems */
+    private static class ScrollTextHolder extends RecyclerView.ViewHolder {
+
+        @NonNull
+        final TextView mScrollTextView;
+
+        ScrollTextHolder(@NonNull View itemView) {
+            super(itemView);
+            mScrollTextView = itemView.findViewById(R.id.scroll_text_view);
+        }
+
+        void setHeight(int height) {
+            mScrollTextView.setHeight(height);
+        }
+    }
+
+    private static class ScrollListItem {
+
+        final int mHeight;
+        final int mType;
+
+        static ScrollListItem createTextItemWithHeight(int height) {
+          return new ScrollListItem(TYPE_TEXT, height);
+        }
+        static ScrollListItem createButtonsItem() {
+          return new ScrollListItem(TYPE_BUTTONS, 0);
+        }
+
+        ScrollListItem(int type, int height) {
+            this.mType = type;
+            this.mHeight = height;
+        }
+
+        int getHeight() {
+            return mHeight;
+        }
+
+        int getType() {
+            return mType;
+        }
+    }
+}