Add some animation

sample/src/main/java/com/example/flow/MainActivity.java

@@ -23,11 +23,11 @@
 import android.view.Menu;
 import android.view.MenuItem;
 import android.view.View;
-import android.widget.FrameLayout;
 import butterknife.InjectView;
 import butterknife.Views;
 import com.example.flow.model.Conversation;
 import com.example.flow.model.User;
+import com.example.flow.view.ContainerView;
 import com.squareup.flow.Backstack;
 import com.squareup.flow.Flow;
 import com.squareup.flow.Screen;
@@ -42,7 +42,7 @@
 public class MainActivity extends Activity implements Flow.Listener {
   private static final String BUNDLE_BACKSTACK = "backstack";
 
-  @InjectView(R.id.container) FrameLayout containerView;
+  @InjectView(R.id.container) ContainerView containerView;
 
   private MenuItem friendsMenu;
 
@@ -99,7 +99,7 @@ protected void onCreate(Bundle savedInstanceState) {
 
   @Override public void go(Backstack backstack, Flow.Direction direction) {
     Screen screen = backstack.current().getScreen();
-    displayView(getView(screen));
+    containerView.displayView(getView(screen), direction);
 
     setTitle(screen.getClass().getSimpleName());
 
@@ -116,7 +116,7 @@ private Backstack getInitialBackstack(Bundle savedInstanceState) {
     if (savedInstanceState != null) {
       return savedInstanceState.getParcelable(BUNDLE_BACKSTACK);
     } else {
-      return Backstack.single(new App.FriendList());
+      return Backstack.single(new App.ConversationList());
     }
   }
 
@@ -126,11 +126,6 @@ private View getView(Screen screen) {
     return Screens.createView(scopedContext, screen);
   }
 
-  private void displayView(View view) {
-    containerView.removeAllViews();
-    containerView.addView(view);
-  }
-
   @Module(library = true) class ActivityModule {
     @Provides @App Flow provideAppFlow() {
       return flow;

sample/src/main/java/com/example/flow/ScopedContext.java

@@ -22,7 +22,7 @@
 import dagger.ObjectGraph;
 
 public class ScopedContext extends ContextWrapper implements Injector {
-  public final ObjectGraph graph;
+  private final ObjectGraph graph;
 
   private LayoutInflater inflater;
 

sample/src/main/java/com/example/flow/Utils.java

@@ -18,8 +18,34 @@
 
 import android.content.Context;
 import android.view.View;
+import android.view.ViewTreeObserver;
 
 public class Utils {
+  public interface OnMeasuredCallback {
+    void onMeasured(View view, int width, int height);
+  }
+
+  public static void waitForMeasure(final View view, final OnMeasuredCallback callback) {
+    int width = view.getWidth();
+    int height = view.getHeight();
+
+    if (width > 0 && height > 0) {
+      callback.onMeasured(view, width, height);
+      return;
+    }
+
+    final ViewTreeObserver observer = view.getViewTreeObserver();
+    observer.addOnPreDrawListener(new ViewTreeObserver.OnPreDrawListener() {
+      @Override public boolean onPreDraw() {
+        if (observer.isAlive()) observer.removeOnPreDrawListener(this);
+
+        callback.onMeasured(view, view.getWidth(), view.getHeight());
+
+        return true;
+      }
+    });
+  }
+
   public static void inject(Context context, View view) {
     ((Injector) context).inject(view);
   }

sample/src/main/java/com/example/flow/view/ContainerView.java

@@ -0,0 +1,85 @@
+/*
+ * Copyright 2013 Square Inc.
+ *
+ * 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.flow.view;
+
+import android.animation.Animator;
+import android.animation.AnimatorListenerAdapter;
+import android.animation.AnimatorSet;
+import android.animation.ObjectAnimator;
+import android.content.Context;
+import android.util.AttributeSet;
+import android.view.MotionEvent;
+import android.view.View;
+import android.widget.FrameLayout;
+import com.example.flow.Utils;
+import com.squareup.flow.Flow;
+
+public class ContainerView extends FrameLayout {
+  private boolean disabled;
+
+  private View activeView;
+
+  public ContainerView(Context context, AttributeSet attrs) {
+    super(context, attrs);
+  }
+
+  @Override public boolean dispatchTouchEvent(MotionEvent ev) {
+    return !disabled && super.dispatchTouchEvent(ev);
+  }
+
+  public void displayView(View view, final Flow.Direction direction) {
+    addView(view);
+
+    if (activeView != null) {
+      final View from = activeView;
+      final View to = view;
+      Utils.waitForMeasure(to, new Utils.OnMeasuredCallback() {
+        @Override public void onMeasured(View view, int width, int height) {
+          runAnimation(from, to, direction);
+        }
+      });
+    }
+
+    activeView = view;
+  }
+
+  private void runAnimation(final View from, final View to, Flow.Direction direction) {
+    disabled = true;
+
+    Animator animator = createSegue(from, to, direction);
+    animator.addListener(new AnimatorListenerAdapter() {
+      @Override public void onAnimationEnd(Animator animation) {
+        removeView(from);
+        disabled = false;
+      }
+    });
+    animator.start();
+  }
+
+  private Animator createSegue(View from, View to, Flow.Direction direction) {
+    boolean backward = direction == Flow.Direction.BACKWARD;
+    int fromTranslation = backward ? from.getWidth() : -from.getWidth();
+    int toTranslation = backward ? -to.getWidth() : to.getWidth();
+
+    AnimatorSet set = new AnimatorSet();
+
+    set.play(ObjectAnimator.ofFloat(from, View.TRANSLATION_X, fromTranslation));
+    set.play(ObjectAnimator.ofFloat(to, View.TRANSLATION_X, toTranslation, 0));
+
+    return set;
+  }
+}

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

@@ -14,7 +14,7 @@
   ~ limitations under the License.
   -->
 
-<FrameLayout xmlns:android="http://schemas.android.com/apk/res/android"
+<com.example.flow.view.ContainerView xmlns:android="http://schemas.android.com/apk/res/android"
     xmlns:tools="http://schemas.android.com/tools"
     android:id="@+id/container"
     android:layout_width="match_parent"