Added shared element transitions to Sunshine.

app/src/main/java/com/example/android/sunshine/app/DetailActivity.java

@@ -16,6 +16,7 @@
 package com.example.android.sunshine.app;
 
 import android.content.Intent;
+import android.os.Build;
 import android.os.Bundle;
 import android.support.v7.app.ActionBarActivity;
 import android.support.v7.app.AppCompatActivity;
@@ -37,6 +38,7 @@ public class DetailActivity extends AppCompatActivity {
 
             Bundle arguments = new Bundle();
             arguments.putParcelable(DetailFragment.DETAIL_URI, getIntent().getData());
+            arguments.putBoolean(DetailFragment.DETAIL_TRANSITION_ANIMATION, true);
 
             DetailFragment fragment = new DetailFragment();
             fragment.setArguments(arguments);
@@ -44,6 +46,9 @@ public class DetailActivity extends AppCompatActivity {
             getSupportFragmentManager().beginTransaction()
                     .add(R.id.weather_detail_container, fragment)
                     .commit();
+
+            // Being here means we are in animation mode
+            supportPostponeEnterTransition();
         }
     }
 }

app/src/main/java/com/example/android/sunshine/app/DetailFragment.java

@@ -48,11 +48,13 @@ public class DetailFragment extends Fragment implements LoaderManager.LoaderCall
 
     private static final String LOG_TAG = DetailFragment.class.getSimpleName();
     static final String DETAIL_URI = "URI";
+    static final String DETAIL_TRANSITION_ANIMATION = "DTA";
 
     private static final String FORECAST_SHARE_HASHTAG = " #SunshineApp";
 
     private String mForecast;
     private Uri mUri;
+    private boolean mTransitionAnimation;
 
     private static final int DETAIL_LOADER = 0;
 
@@ -108,6 +110,7 @@ public class DetailFragment extends Fragment implements LoaderManager.LoaderCall
         Bundle arguments = getArguments();
         if (arguments != null) {
             mUri = arguments.getParcelable(DetailFragment.DETAIL_URI);
+            mTransitionAnimation = arguments.getBoolean(DetailFragment.DETAIL_TRANSITION_ANIMATION, false);
         }
 
         View rootView = inflater.inflate(R.layout.fragment_detail_start, container, false);
@@ -265,7 +268,7 @@ public class DetailFragment extends Fragment implements LoaderManager.LoaderCall
         Toolbar toolbarView = (Toolbar) getView().findViewById(R.id.toolbar);
 
         // We need to start the enter transition after the data has loaded
-        if (activity instanceof DetailActivity) {
+        if ( mTransitionAnimation ) {
             activity.supportStartPostponedEnterTransition();
 
             if ( null != toolbarView ) {

app/src/main/java/com/example/android/sunshine/app/ForecastAdapter.java

@@ -21,6 +21,7 @@ import android.os.Build;
 import android.os.Bundle;
 import android.support.v4.view.ViewCompat;
 import android.support.v7.widget.RecyclerView;
+import android.util.Log;
 import android.view.LayoutInflater;
 import android.view.View;
 import android.view.ViewGroup;
@@ -145,6 +146,10 @@ public class ForecastAdapter extends RecyclerView.Adapter<ForecastAdapter.Foreca
                     .into(forecastAdapterViewHolder.mIconView);
         }
 
+        // this enables better animations. even if we lose state due to a device rotation,
+        // the animator can use this to re-find the original view
+        ViewCompat.setTransitionName(forecastAdapterViewHolder.mIconView, "iconView" + position);
+
         // Read date from cursor
         long dateInMillis = mCursor.getLong(ForecastFragment.COL_WEATHER_DATE);
 

app/src/main/java/com/example/android/sunshine/app/ForecastFragment.java

@@ -57,6 +57,7 @@ public class ForecastFragment extends Fragment implements LoaderManager.LoaderCa
     private int mPosition = RecyclerView.NO_POSITION;
     private boolean mUseTodayLayout, mAutoSelectView;
     private int mChoiceMode;
+    private boolean mHoldForTransition;
 
     private static final String SELECTED_KEY = "selected_position";
 
@@ -102,7 +103,7 @@ public class ForecastFragment extends Fragment implements LoaderManager.LoaderCa
         /**
          * DetailFragmentCallback for when an item has been selected.
          */
-        public void onItemSelected(Uri dateUri);
+        public void onItemSelected(Uri dateUri, ForecastAdapter.ForecastAdapterViewHolder vh);
     }
 
     public ForecastFragment() {
@@ -159,6 +160,7 @@ public class ForecastFragment extends Fragment implements LoaderManager.LoaderCa
                 0, 0);
         mChoiceMode = a.getInt(R.styleable.ForecastFragment_android_choiceMode, AbsListView.CHOICE_MODE_NONE);
         mAutoSelectView = a.getBoolean(R.styleable.ForecastFragment_autoSelectView, false);
+        mHoldForTransition = a.getBoolean(R.styleable.ForecastFragment_sharedElementTransitions, false);
         a.recycle();
     }
 
@@ -188,7 +190,8 @@ public class ForecastFragment extends Fragment implements LoaderManager.LoaderCa
                 String locationSetting = Utility.getPreferredLocation(getActivity());
                 ((Callback) getActivity())
                         .onItemSelected(WeatherContract.WeatherEntry.buildWeatherLocationWithDate(
-                                        locationSetting, date)
+                                        locationSetting, date),
+                                vh
                         );
                 mPosition = vh.getAdapterPosition();
             }
@@ -237,6 +240,12 @@ public class ForecastFragment extends Fragment implements LoaderManager.LoaderCa
 
     @Override
     public void onActivityCreated(Bundle savedInstanceState) {
+        // We hold for transition here just in-case the activity
+        // needs to be re-created. In a standard return transition,
+        // this doesn't actually make a difference.
+        if ( mHoldForTransition ) {
+            getActivity().supportPostponeEnterTransition();
+        }
         getLoaderManager().initLoader(FORECAST_LOADER, null, this);
         super.onActivityCreated(savedInstanceState);
     }
@@ -316,7 +325,9 @@ public class ForecastFragment extends Fragment implements LoaderManager.LoaderCa
             mRecyclerView.smoothScrollToPosition(mPosition);
         }
         updateEmptyView();
-        if ( data.getCount() > 0 ) {
+        if ( data.getCount() == 0 ) {
+            getActivity().supportStartPostponedEnterTransition();
+        } else {
             mRecyclerView.getViewTreeObserver().addOnPreDrawListener(new ViewTreeObserver.OnPreDrawListener() {
                 @Override
                 public boolean onPreDraw() {
@@ -330,6 +341,9 @@ public class ForecastFragment extends Fragment implements LoaderManager.LoaderCa
                         if ( null != vh && mAutoSelectView ) {
                             mForecastAdapter.selectView( vh );
                         }
+                        if ( mHoldForTransition ) {
+                            getActivity().supportStartPostponedEnterTransition();
+                        }
                         return true;
                     }
                     return false;
@@ -339,6 +353,8 @@ public class ForecastFragment extends Fragment implements LoaderManager.LoaderCa
 
     }
 
+
+
     @Override
     public void onDestroy() {
         super.onDestroy();

app/src/main/java/com/example/android/sunshine/app/MainActivity.java

@@ -26,11 +26,13 @@ import android.os.AsyncTask;
 import android.os.Bundle;
 import android.support.v4.app.ActivityCompat;
 import android.support.v4.app.ActivityOptionsCompat;
+import android.support.v4.util.Pair;
 import android.support.v7.app.AppCompatActivity;
 import android.support.v7.widget.Toolbar;
 import android.util.Log;
 import android.view.Menu;
 import android.view.MenuItem;
+import android.view.View;
 
 import com.example.android.sunshine.app.sync.SunshineSyncAdapter;
 import com.google.android.gms.common.ConnectionResult;
@@ -161,7 +163,7 @@ public class MainActivity extends AppCompatActivity implements ForecastFragment.
     }
 
     @Override
-    public void onItemSelected(Uri contentUri) {
+    public void onItemSelected(Uri contentUri, ForecastAdapter.ForecastAdapterViewHolder vh) {
         if (mTwoPane) {
             // In two-pane mode, show the detail view in this activity by
             // adding or replacing the detail fragment using a
@@ -180,7 +182,8 @@ public class MainActivity extends AppCompatActivity implements ForecastFragment.
                     .setData(contentUri);
 
             ActivityOptionsCompat activityOptions =
-                    ActivityOptionsCompat.makeSceneTransitionAnimation(this);
+                    ActivityOptionsCompat.makeSceneTransitionAnimation(this,
+                            new Pair<View, String>(vh.mIconView, getString(R.string.detail_icon_transition_name)));
             ActivityCompat.startActivity(this, intent, activityOptions.toBundle());
         }
     }

app/src/main/res/layout/activity_main.xml

@@ -15,9 +15,11 @@
  -->
 <fragment xmlns:android="http://schemas.android.com/apk/res/android"
     xmlns:tools="http://schemas.android.com/tools"
+    xmlns:app="http://schemas.android.com/apk/res-auto"
     android:id="@+id/fragment_forecast"
     android:name="com.example.android.sunshine.app.ForecastFragment"
     android:layout_width="match_parent"
     android:layout_height="match_parent"
     tools:layout="@android:layout/list_content"
+    app:sharedElementTransitions="true"
     />

app/src/main/res/layout/detail_today_grid.xml

@@ -49,7 +49,8 @@
         android:maxWidth="@dimen/today_icon"
         app:layout_columnWeight="1"
         app:layout_gravity="fill_horizontal"
-        tools:src="@drawable/art_clouds" />
+        tools:src="@drawable/art_clouds"
+        android:transitionName="@string/detail_icon_transition_name"/>
 
     <TextView
         android:id="@+id/detail_high_textview"

app/src/main/res/transition-land-v21/details_window_enter_transition.xml

@@ -16,7 +16,7 @@
  -->
 <transitionSet xmlns:android="http://schemas.android.com/apk/res/android"
     android:transitionOrdering="together"
-    android:duration="500">
+    android:duration="250">
     <fade xmlns:android="http://schemas.android.com/apk/res/android">
         <targets>
             <target android:excludeId="@android:id/statusBarBackground"/>

app/src/main/res/transition-land-v21/details_window_return_transition.xml

@@ -16,7 +16,7 @@
  -->
 <transitionSet xmlns:android="http://schemas.android.com/apk/res/android"
     android:transitionOrdering="together"
-    android:duration="500">
+    android:duration="250">
     <fade>
         <targets>
             <target android:excludeId="@android:id/statusBarBackground" />

app/src/main/res/transition-v21/details_window_enter_transition.xml

@@ -16,7 +16,7 @@
  -->
 <transitionSet xmlns:android="http://schemas.android.com/apk/res/android"
     android:transitionOrdering="together"
-    android:duration="500">
+    android:duration="250">
     <fade xmlns:android="http://schemas.android.com/apk/res/android">
         <targets>
             <target android:excludeId="@android:id/statusBarBackground"/>

app/src/main/res/transition-v21/details_window_return_transition.xml

@@ -16,7 +16,7 @@
  -->
 <transitionSet xmlns:android="http://schemas.android.com/apk/res/android"
     android:transitionOrdering="together"
-    android:duration="500">
+    android:duration="250">
     <fade>
         <targets>
             <target android:excludeId="@android:id/statusBarBackground" />

app/src/main/res/values/attrs.xml

@@ -21,5 +21,6 @@
     <declare-styleable name="ForecastFragment">
         <attr name="android:choiceMode" />
         <attr name="autoSelectView" format="boolean"/>
+        <attr name="sharedElementTransitions" format="boolean"/>
     </declare-styleable>
 </resources>

app/src/main/res/values/strings.xml

@@ -211,4 +211,8 @@
     <string name="condition_962">Hurricane</string>
 
     <string name="condition_unknown">Unknown (<xliff:g id="low">%1$s</xliff:g>)</string>
+
+    <!-- For Shared Element Transitions -->
+    <string name="detail_icon_transition_name" translatable="false">TN_DetailIcon</string>
+
 </resources>