Break out rotation animation into animation utils

app/src/main/java/acr/browser/lightning/animation/AnimationUtils.java

@@ -0,0 +1,52 @@
+package acr.browser.lightning.animation;
+
+import android.support.annotation.DrawableRes;
+import android.support.annotation.NonNull;
+import android.view.animation.AccelerateDecelerateInterpolator;
+import android.view.animation.Animation;
+import android.view.animation.Transformation;
+import android.widget.ImageView;
+
+/**
+ * Animation specific helper code.
+ */
+public class AnimationUtils {
+
+    /**
+     * Creates an animation that rotates an {@link ImageView}
+     * around the Y axis by 180 degrees and changes the image
+     * resource shown when the view is rotated 90 degrees to the user.
+     *
+     * @param imageView   the view to rotate.
+     * @param drawableRes the drawable to set when the view
+     *                    is rotated by 90 degrees.
+     * @return an animation that will change the image shown by the view.
+     */
+    @NonNull
+    public static Animation createRotationTransitionAnimation(@NonNull final ImageView imageView,
+                                                              @DrawableRes final int drawableRes) {
+        Animation animation = new Animation() {
+
+            private boolean mSetFinalDrawable;
+
+            @Override
+            protected void applyTransformation(float interpolatedTime, Transformation t) {
+                if (interpolatedTime < 0.5f) {
+                    imageView.setRotationY(90 * interpolatedTime * 2f);
+                } else {
+                    if (!mSetFinalDrawable) {
+                        mSetFinalDrawable = true;
+                        imageView.setImageResource(drawableRes);
+                    }
+                    imageView.setRotationY((-90) + (90 * (interpolatedTime - 0.5f) * 2f));
+                }
+            }
+        };
+
+        animation.setDuration(300);
+        animation.setInterpolator(new AccelerateDecelerateInterpolator());
+
+        return animation;
+    }
+
+}

app/src/main/java/acr/browser/lightning/fragment/BookmarksFragment.java

@@ -16,10 +16,7 @@ import android.support.v7.widget.RecyclerView;
 import android.view.LayoutInflater;
 import android.view.View;
 import android.view.ViewGroup;
-import android.view.animation.AccelerateInterpolator;
 import android.view.animation.Animation;
-import android.view.animation.DecelerateInterpolator;
-import android.view.animation.Transformation;
 import android.widget.FrameLayout;
 import android.widget.ImageView;
 import android.widget.TextView;
@@ -40,6 +37,7 @@ import javax.inject.Inject;
 import acr.browser.lightning.R;
 import acr.browser.lightning.activity.ReadingActivity;
 import acr.browser.lightning.activity.TabsManager;
+import acr.browser.lightning.animation.AnimationUtils;
 import acr.browser.lightning.app.BrowserApp;
 import acr.browser.lightning.browser.BookmarksView;
 import acr.browser.lightning.constant.Constants;
@@ -240,16 +238,6 @@ public class BookmarksFragment extends Fragment implements View.OnClickListener,
         }
     }
 
-    @Override
-    public void onStart() {
-        super.onStart();
-    }
-
-    @Override
-    public void onStop() {
-        super.onStop();
-    }
-
     public void reinitializePreferences() {
         Activity activity = getActivity();
         if (activity == null) {
@@ -293,40 +281,9 @@ public class BookmarksFragment extends Fragment implements View.OnClickListener,
             resource = R.drawable.ic_action_back;
         }
 
-        final Animation startRotation = new Animation() {
-            @Override
-            protected void applyTransformation(float interpolatedTime, Transformation t) {
-                mBookmarkTitleImage.setRotationY(90 * interpolatedTime);
-            }
-        };
-        final Animation finishRotation = new Animation() {
-            @Override
-            protected void applyTransformation(float interpolatedTime, Transformation t) {
-                mBookmarkTitleImage.setRotationY((-90) + (90 * interpolatedTime));
-            }
-        };
-        startRotation.setAnimationListener(new Animation.AnimationListener() {
-            @Override
-            public void onAnimationStart(Animation animation) {
-            }
-
-            @Override
-            public void onAnimationEnd(Animation animation) {
-                mBookmarkTitleImage.setImageResource(resource);
-                mBookmarkTitleImage.startAnimation(finishRotation);
-            }
-
-            @Override
-            public void onAnimationRepeat(Animation animation) {
-            }
-        });
-        startRotation.setInterpolator(new AccelerateInterpolator());
-        finishRotation.setInterpolator(new DecelerateInterpolator());
-        startRotation.setDuration(250);
-        finishRotation.setDuration(250);
-
         if (animate) {
-            mBookmarkTitleImage.startAnimation(startRotation);
+            Animation transition = AnimationUtils.createRotationTransitionAnimation(mBookmarkTitleImage, resource);
+            mBookmarkTitleImage.startAnimation(transition);
         } else {
             mBookmarkTitleImage.setImageResource(resource);
         }