Spotify Streamer - stage 2

(1) ArtistFragment inflate(R.layout.fragment_artist, container, false) , and it will pick fragment_artist_grid.xml for tablet, and fragment_artist_list.xml for phone.

(2) I did two fragments : ArtistFragment and MediaPlayerDialogFragment. I didn't make the third, TrackFragment, yet. Previouly I tried to do generic 2-pane UI, left half screen for artist search and right half screen for popular tracks. Yet I realized left half for artist search on phone is too narrow and not convenient for users. Following guide from coaches in office hour, I use 1 screen for artist search (SpotifyActivity + ArtistFragment), 1 screen for popular tracks of an artist (TracksActivity), and a DialogFragment for media player ( MediaPlayerDialogFragment ). To support tablet better, we may create a track fragment and do extended work to make 2-pane UI for tablet.

(3) For MediaPlayerDialogFragment , song playing and progress bar play or pause at the same pace. We can mixed play, pause, and a few phone roatations. Song playing and progress bar are synced. We use thread and synchronized to suppot progress bar.

(4) To avoid playing a song from beginning after rotations and reduce repeated slower operations (e.g., mediaPlayer.prepare() ), we save and restore previous state from ArtistTracksC, for TracksActivity and MediaPlayerDialogFragment.

(5) I added album name to DialogFragment in rev 2.