Scroll to the source event in TrackScheduleListFragment when navigating

up from EventDetailsActivity. Also select the source event by default in
dual-pane mode.

src/be/digitalia/fosdem/activities/EventDetailsActivity.java

@@ -69,6 +69,7 @@ public class EventDetailsActivity extends ActionBarActivity implements LoaderCal
 			Intent upIntent = new Intent(this, TrackScheduleActivity.class);
 			upIntent.putExtra(TrackScheduleActivity.EXTRA_DAY, event.getDay());
 			upIntent.putExtra(TrackScheduleActivity.EXTRA_TRACK, event.getTrack());
+			upIntent.putExtra(TrackScheduleActivity.EXTRA_FROM_EVENT_ID, event.getId());
 			upIntent.setFlags(Intent.FLAG_ACTIVITY_CLEAR_TOP);
 
 			finish();

src/be/digitalia/fosdem/activities/TrackScheduleActivity.java

@@ -27,6 +27,8 @@ public class TrackScheduleActivity extends ActionBarActivity implements TrackSch
 
 	public static final String EXTRA_DAY = "day";
 	public static final String EXTRA_TRACK = "track";
+	// Optional extra used as a hint for up navigation from an event
+	public static final String EXTRA_FROM_EVENT_ID = "from_event_id";
 
 	private Day day;
 	private Track track;
@@ -51,7 +53,12 @@ public class TrackScheduleActivity extends ActionBarActivity implements TrackSch
 		TrackScheduleListFragment trackScheduleListFragment;
 		FragmentManager fm = getSupportFragmentManager();
 		if (savedInstanceState == null) {
-			trackScheduleListFragment = TrackScheduleListFragment.newInstance(day, track);
+			long fromEventId = extras.getLong(EXTRA_FROM_EVENT_ID, -1L);
+			if (fromEventId != -1L) {
+				trackScheduleListFragment = TrackScheduleListFragment.newInstance(day, track, fromEventId);
+			} else {
+				trackScheduleListFragment = TrackScheduleListFragment.newInstance(day, track);
+			}
 			fm.beginTransaction().add(R.id.schedule, trackScheduleListFragment).commit();
 		} else {
 			trackScheduleListFragment = (TrackScheduleListFragment) fm.findFragmentById(R.id.schedule);

src/be/digitalia/fosdem/fragments/TrackScheduleListFragment.java

@@ -39,12 +39,15 @@ public class TrackScheduleListFragment extends ListFragment implements LoaderCal
 	}
 
 	private static final int EVENTS_LOADER_ID = 1;
+
 	private static final String ARG_DAY = "day";
 	private static final String ARG_TRACK = "track";
+	private static final String ARG_FROM_EVENT_ID = "from_event_id";
 
 	private TrackScheduleAdapter adapter;
 	private Callbacks listener;
 	private boolean selectionEnabled = false;
+	private boolean isListAlreadyShown = false;
 
 	public static TrackScheduleListFragment newInstance(Day day, Track track) {
 		TrackScheduleListFragment f = new TrackScheduleListFragment();
@@ -55,12 +58,32 @@ public class TrackScheduleListFragment extends ListFragment implements LoaderCal
 		return f;
 	}
 
+	public static TrackScheduleListFragment newInstance(Day day, Track track, long fromEventId) {
+		TrackScheduleListFragment f = new TrackScheduleListFragment();
+		Bundle args = new Bundle();
+		args.putParcelable(ARG_DAY, day);
+		args.putParcelable(ARG_TRACK, track);
+		args.putLong(ARG_FROM_EVENT_ID, fromEventId);
+		f.setArguments(args);
+		return f;
+	}
+
 	@Override
 	public void onCreate(Bundle savedInstanceState) {
 		super.onCreate(savedInstanceState);
 
 		adapter = new TrackScheduleAdapter(getActivity());
 		setListAdapter(adapter);
+
+		if (savedInstanceState != null) {
+			isListAlreadyShown = savedInstanceState.getBoolean("isListAlreadyShown");
+		}
+	}
+
+	@Override
+	public void onSaveInstanceState(Bundle outState) {
+		super.onSaveInstanceState(outState);
+		outState.putBoolean("isListAlreadyShown", isListAlreadyShown);
 	}
 
 	@Override
@@ -79,7 +102,7 @@ public class TrackScheduleListFragment extends ListFragment implements LoaderCal
 
 	private void notifyEventSelected(int position) {
 		if (listener != null) {
-			listener.onEventSelected(position, (position == -1) ? null : adapter.getItem(position));
+			listener.onEventSelected(position, (position == ListView.INVALID_POSITION) ? null : adapter.getItem(position));
 		}
 	}
 
@@ -114,23 +137,27 @@ public class TrackScheduleListFragment extends ListFragment implements LoaderCal
 				final int count = adapter.getCount();
 				int checkedPosition = getListView().getCheckedItemPosition();
 				if ((checkedPosition == ListView.INVALID_POSITION) || (checkedPosition >= count)) {
-					if (count > 0) {
+					// There is no current valid selection, use the default one
-						// Select the first item if any
+					checkedPosition = getDefaultPosition();
-						getListView().setItemChecked(0, true);
+					if (checkedPosition != ListView.INVALID_POSITION) {
-						checkedPosition = 0;
+						getListView().setItemChecked(checkedPosition, true);
-					} else {
-						// No result, nothing selected
-						checkedPosition = -1;
 					}
 				}
 
 				// Ensure the current selection is visible
-				if (checkedPosition != -1) {
+				if (checkedPosition != ListView.INVALID_POSITION) {
 					setSelection(checkedPosition);
 				}
 				// Notify the parent of the current selection to synchronize its state
 				notifyEventSelected(checkedPosition);
+
+			} else if (!isListAlreadyShown) {
+				int position = getDefaultPosition();
+				if (position != ListView.INVALID_POSITION) {
+					setSelection(position);
+				}
 			}
+			isListAlreadyShown = true;
 		}
 
 		// The list should now be shown.
@@ -141,6 +168,26 @@ public class TrackScheduleListFragment extends ListFragment implements LoaderCal
 		}
 	}
 
+	/**
+	 * @return The default position in the list, or -1 if the list is empty
+	 */
+	private int getDefaultPosition() {
+		final int count = adapter.getCount();
+		if (count == 0) {
+			return ListView.INVALID_POSITION;
+		}
+		long fromEventId = getArguments().getLong(ARG_FROM_EVENT_ID, -1L);
+		if (fromEventId != -1L) {
+			// Look for the source event in the list and return its position
+			for (int i = 0; i < count; ++i) {
+				if (adapter.getItemId(i) == fromEventId) {
+					return i;
+				}
+			}
+		}
+		return 0;
+	}
+
 	@Override
 	public void onLoaderReset(Loader<Cursor> loader) {
 		adapter.swapCursor(null);