Limit scene transition animations to API 23 and above

to work-around android bug #224270.
This is only necessary if the transitioning view might not be available
anymore when the exit transition is made.

briar-android/src/org/briarproject/android/blogs/BlogPostViewHolder.java

@@ -3,6 +3,7 @@ package org.briarproject.android.blogs;
 import android.app.Activity;
 import android.content.Context;
 import android.content.Intent;
+import android.os.Build;
 import android.support.annotation.Nullable;
 import android.support.annotation.UiThread;
 import android.support.v4.app.ActivityCompat;
@@ -134,11 +135,17 @@ class BlogPostViewHolder extends RecyclerView.ViewHolder {
 				i.putExtra(GROUP_ID, item.getGroupId().getBytes());
 				i.putExtra(POST_ID, item.getId().getBytes());
 
-				ActivityOptionsCompat options =
-						makeSceneTransitionAnimation((Activity) ctx, layout,
-								getTransitionName(item.getId()));
-				ActivityCompat
-						.startActivity((Activity) ctx, i, options.toBundle());
+				// work-around for android bug #224270
+				if (Build.VERSION.SDK_INT >= 23) {
+					ActivityOptionsCompat options =
+							makeSceneTransitionAnimation((Activity) ctx, layout,
+									getTransitionName(item.getId()));
+					ActivityCompat
+							.startActivity((Activity) ctx, i,
+									options.toBundle());
+				} else {
+					ctx.startActivity(i);
+				}
 			}
 		});
 

briar-android/src/org/briarproject/android/contact/ContactListFragment.java

 package org.briarproject.android.contact;
 
 import android.content.Intent;
+import android.os.Build;
 import android.os.Bundle;
 import android.support.annotation.Nullable;
 import android.support.v4.app.ActivityCompat;
@@ -121,22 +122,28 @@ public class ContactListFragment extends BaseFragment implements EventListener {
 								ConversationActivity.class);
 						i.putExtra(GROUP_ID, groupId.getBytes());
 
-						ContactListAdapter.ContactHolder holder =
-								(ContactListAdapter.ContactHolder) list
-										.getRecyclerView()
-										.findViewHolderForAdapterPosition(
-												adapter.findItemPosition(item));
-						Pair<View, String> avatar =
-								Pair.create((View) holder.avatar, ViewCompat
-										.getTransitionName(holder.avatar));
-						Pair<View, String> bulb =
-								Pair.create((View) holder.bulb, ViewCompat
-										.getTransitionName(holder.bulb));
-						ActivityOptionsCompat options =
-								makeSceneTransitionAnimation(getActivity(),
-										avatar, bulb);
-						ActivityCompat.startActivity(getActivity(), i,
-								options.toBundle());
+						// work-around for android bug #224270
+						if (Build.VERSION.SDK_INT >= 23) {
+							ContactListAdapter.ContactHolder holder =
+									(ContactListAdapter.ContactHolder) list
+											.getRecyclerView()
+											.findViewHolderForAdapterPosition(
+													adapter.findItemPosition(
+															item));
+							Pair<View, String> avatar =
+									Pair.create((View) holder.avatar, ViewCompat
+											.getTransitionName(holder.avatar));
+							Pair<View, String> bulb =
+									Pair.create((View) holder.bulb, ViewCompat.
+											getTransitionName(holder.bulb));
+							ActivityOptionsCompat options =
+									makeSceneTransitionAnimation(getActivity(),
+											avatar, bulb);
+							ActivityCompat.startActivity(getActivity(), i,
+									options.toBundle());
+						} else {
+							getActivity().startActivity(i);
+						}
 					}
 				};