Example 1 with RoomTag
use of org.matrix.androidsdk.data.RoomTag in project matrix-android-sdk by matrix-org.
the class MXSession method tagOrderToBeAtIndex.
/**
* Compute the tag order to use for a room tag so that the room will appear in the expected position
* in the list of rooms stamped with this tag.
*
* @param index the targeted index of the room in the list of rooms with the tag `tag`.
* @param originIndex the origin index. Integer.MAX_VALUE if there is none.
* @param tag the tag
* @return the tag order to apply to get the expected position.
*/
public Double tagOrderToBeAtIndex(int index, int originIndex, String tag) {
// Algo (and the [0.0, 1.0] assumption) inspired from matrix-react-sdk:
// We sort rooms by the lexicographic ordering of the 'order' metadata on their tags.
// For convenience, we calculate this for now a floating point number between 0.0 and 1.0.
// by default we're next to the beginning of the list
Double orderA = 0.0;
// by default we're next to the end of the list too
Double orderB = 1.0;
List<Room> roomsWithTag = roomsWithTag(tag);
if (roomsWithTag.size() > 0) {
// because the object will be removed from the list to be inserted after its destination
if ((originIndex != Integer.MAX_VALUE) && (originIndex < index)) {
index++;
}
if (index > 0) {
// Bound max index to the array size
int prevIndex = (index < roomsWithTag.size()) ? index : roomsWithTag.size();
RoomTag prevTag = roomsWithTag.get(prevIndex - 1).getAccountData().roomTag(tag);
if (null == prevTag.mOrder) {
Log.e(LOG_TAG, "computeTagOrderForRoom: Previous room in sublist has no ordering metadata. This should never happen.");
} else {
orderA = prevTag.mOrder;
}
}
if (index <= roomsWithTag.size() - 1) {
RoomTag nextTag = roomsWithTag.get(index).getAccountData().roomTag(tag);
if (null == nextTag.mOrder) {
Log.e(LOG_TAG, "computeTagOrderForRoom: Next room in sublist has no ordering metadata. This should never happen.");
} else {
orderB = nextTag.mOrder;
}
}
}
return (orderA + orderB) / 2.0;
}