cleaned up the fragment animation bug fix and provided some loging for potential bug fixes

Author: marksalpeter

fragment/src/main/java/com/marksalpeter/fragment/ContractFragment.java

@@ -1,24 +1,23 @@
 package com.marksalpeter.fragment;
 
 import android.app.Activity;
-import android.app.Fragment;
 
 import java.lang.reflect.ParameterizedType;
 
 /**
- * ContractFragment is a fragment whos parent fragment or parent activity must implement an interface
- * Created by Mark Salpeter. Original concepts taken from Jake Thwarton
+ * ContractFragment is a fragment whos parent fragment or parent activity must implement the interface T
+ * Created by Mark Salpeter. Original concepts taken from Jake Wharton
  * see https://gist.github.com/JakeWharton/2621173
  */
-public abstract class ContractFragment<T> extends ChildFragment {
+public abstract class ContractFragment<T> extends Fragment {
 
-    public final static String TAG = ChildFragment.class.getSimpleName();
+    public final static String TAG = Fragment.class.getSimpleName();
 
     private T mContract;
 
     @Override
     public void onAttach(Activity activity) {
-        Fragment parentFragment = getParentFragment();
+        android.app.Fragment parentFragment = getParentFragment();
         if (parentFragment != null && isContractImplemented(parentFragment.getClass())) {
             mContract = (T) getParentFragment();
         } else if (isContractImplemented(activity.getClass())) {
@@ -44,6 +43,10 @@ public void onDetach() {
         mContract = null;
     }
 
+    /**
+     * getContract returns the interface of type T that must be
+     * implemented on either the parent fragment or the parent activity
+     */
     public final T getContract() {
         return mContract;
     }

fragment/src/main/java/com/marksalpeter/fragment/ChildFragment.java renamed to fragment/src/main/java/com/marksalpeter/fragment/Fragment.java

@@ -3,55 +3,50 @@
 import android.animation.Animator;
 import android.animation.AnimatorInflater;
 import android.animation.ValueAnimator;
-import android.app.Fragment;
 import android.content.res.Resources;
+import android.util.Log;
 
 import java.lang.reflect.Field;
 
 /**
- * ChildFragment fixes a critical view bug where child fragments are sometimes removed from the screen
+ * Fragment fixes an animation bug where child fragments are sometimes removed from the screen
  * before their parents are removed from the screen.
  * More Info: http://stackoverflow.com/questions/14900738/nested-fragments-disappear-during-transition-animation
  * Created by Mark Salpeter on 9/20/16.
  */
-public class ChildFragment extends Fragment {
+public class Fragment extends android.app.Fragment {
 
-    public static String TAG = ChildFragment.class.getSimpleName();
+    public static String TAG = Fragment.class.getSimpleName();
 
     /**
      * sDefaultChildAnimationDuration is an arbitrary, but reasonable transition duration we can use if
      * reflection fails to obtain the parent Fragment next animation id
      */
     private static final int sDefaultChildAnimationDuration = 1000;
 
-    @Override public Animator onCreateAnimator(int transit, boolean enter, int nextAnim) {
 
-        // if a child fragment is being removed because its parent is being removed
-        // return a fake animator that lasts the duration of the parent's animator
-        Fragment removingParentFragment = getRemovingParent(getParentFragment());
-        if (!enter && removingParentFragment != null) {
-            // This is a workaround for the bug where child fragments disappear when
-            // the parent is removed (as all children are first removed from the parent)
-            // See https://code.google.com/p/android/issues/detail?id=55228
-            long duration = getNextAnimatiorDuration(removingParentFragment);
-            return ValueAnimator.ofFloat(0, 1).setDuration(duration);
+    /**
+     * onCreateAnimator is overridden to fix the following animation bug:
+     * http://stackoverflow.com/questions/14900738/nested-fragments-disappear-during-transition-animation
+     */
+    @Override public Animator onCreateAnimator(int transit, boolean enter, int nextAnim) {
+        if(!enter) {
+            android.app.Fragment removingParentFragment = getRemovingParentFragment();
+            if (removingParentFragment != null) {
+                return ValueAnimator.ofFloat(0f, 1f).setDuration(getNextAnimatorDuration(removingParentFragment));
+            }
         }
-
-        // inflate the animator
-        Animator animator = null;
-        try {
-            animator = AnimatorInflater.loadAnimator(getActivity(), nextAnim);
-        } catch (Exception e) {}
-
-        return animator;
+        return super.onCreateAnimator(transit, enter, nextAnim);
     }
 
     /**
-     * getRemovingParent returns the first fragment or parent fragment that is removing r null if it can't find one
+     * getRemovingParentFragment returns the first fragment or parent fragment that is removing r null if it can't find one
      */
-    private static Fragment getRemovingParent(Fragment fragment) {
+    private android.app.Fragment getRemovingParentFragment() {
+            android.app.Fragment fragment = getParentFragment();
             while (fragment != null) {
                 if (fragment.isRemoving()) {
+                    Log.v(TAG, fragment.toString() + " is removing");
                     return fragment;
                 }
                 fragment = fragment.getParentFragment();
@@ -63,21 +58,29 @@ private static Fragment getRemovingParent(Fragment fragment) {
      * getNextAnimationDuration returns the "mNextAnim" animators duration
      * TODO: this needs a bug fix, but its not mission critical unless people are adding fragment transition
      */
-    private static long getNextAnimatiorDuration(Fragment fragment) {
+    private static long getNextAnimatorDuration(android.app.Fragment fragment) {
         try {
 
             // attempt to get the resource ID of the next animation that will be applied to the given fragment.
-            Field nextAnimField = Fragment.class.getDeclaredField("mNextAnim");
+            Field nextAnimField = android.app.Fragment.class.getDeclaredField("mNextAnim");
             nextAnimField.setAccessible(true);
-            int nextAnimResource = nextAnimField.getInt(fragment);
+            int nextAnimResourceID = nextAnimField.getInt(fragment);
+
+            Log.v(TAG, "nextAnimResourceID: " + nextAnimResourceID);
+            if (nextAnimResourceID < 1) {
+                return sDefaultChildAnimationDuration;
+            }
 
             // load the animator
-            Animator nextAnim = AnimatorInflater.loadAnimator(fragment.getActivity(), nextAnimResource);
+            Animator nextAnim = AnimatorInflater.loadAnimator(fragment.getActivity(), nextAnimResourceID);
+
+            Log.v(TAG, "nextAnim.getDuration(): " + nextAnim.getDuration());
 
             // return its duration
             return(nextAnim == null || nextAnim.getDuration() < 0) ? sDefaultChildAnimationDuration : nextAnim.getDuration();
 
         } catch (NoSuchFieldException|IllegalAccessException|Resources.NotFoundException ex) {
+            Log.e(TAG, ex.getMessage(), ex);
             return sDefaultChildAnimationDuration;
         }
     }