Merge pull request #139 from dweymouth/feature/alltracksview

Add searchable "All Tracks" page

CHANGELOG.md

@@ -10,6 +10,7 @@
 - [#115](https://github.com/dweymouth/supersonic/issues/115) Add search bar to artist, genres, and playlists pages
 - [#104](https://github.com/dweymouth/supersonic/issues/104) Add alternate (e.g. external) hostname to server connection config
 - [#136](https://github.com/dweymouth/supersonic/issues/136) Add "..." button to album page with menu to add album to queue or playlist
+- [#70](https://github.com/dweymouth/supersonic/issues/70) Add searchable "All Tracks" page, with button to play random tracks
 
 ### Fixes
 - **todo-commithash** Don't show update available prompt if the found version is the same as the running app version

backend/albumiterator.go

@@ -142,12 +142,9 @@ func (r *baseIter) Next() *subsonic.AlbumID3 {
 }
 
 type searchIter struct {
-	query         string
-	artistOffset  int
-	albumOffset   int
-	songOffset    int
+	searchIterBase
+
 	l             *LibraryManager
-	s             *subsonic.Client
 	filter        func(*subsonic.AlbumID3) bool
 	prefetched    []*subsonic.AlbumID3
 	prefetchedPos int
@@ -157,9 +154,11 @@ type searchIter struct {
 
 func (l *LibraryManager) newSearchIter(query string, filter func(*subsonic.AlbumID3) bool) *searchIter {
 	return &searchIter{
-		query:      query,
+		searchIterBase: searchIterBase{
+			query: query,
+			s:     l.s.Server,
+		},
 		l:          l,
-		s:          l.s.Server,
 		filter:     filter,
 		albumIDset: make(map[string]bool),
 	}
@@ -172,17 +171,8 @@ func (s *searchIter) Next() *subsonic.AlbumID3 {
 
 	// prefetch more search results from server
 	if s.prefetched == nil {
-		searchOpts := map[string]string{
-			"artistOffset": strconv.Itoa(s.artistOffset),
-			"albumOffset":  strconv.Itoa(s.albumOffset),
-			"songOffset":   strconv.Itoa(s.songOffset),
-		}
-		results, err := s.s.Search3(s.query, searchOpts)
-		if err != nil {
-			log.Println(err)
-			results = nil
-		}
-		if results == nil || len(results.Album)+len(results.Artist)+len(results.Song) == 0 {
+		results := s.searchIterBase.fetchResults()
+		if results == nil {
 			s.done = true
 			s.albumIDset = nil
 			return nil

backend/config.go

@@ -55,6 +55,10 @@ type PlaylistPageConfig struct {
 	TracklistColumns []string
 }
 
+type TracksPageConfig struct {
+	TracklistColumns []string
+}
+
 type LocalPlaybackConfig struct {
 	AudioDeviceName     string
 	AudioExclusive      bool
@@ -83,6 +87,7 @@ type Config struct {
 	FavoritesPage  FavoritesPageConfig
 	NowPlayingPage NowPlayingPageConfig
 	PlaylistPage   PlaylistPageConfig
+	TracksPage     TracksPageConfig
 	LocalPlayback  LocalPlaybackConfig
 	Scrobbling     ScrobbleConfig
 	ReplayGain     ReplayGainConfig
@@ -117,6 +122,9 @@ func DefaultConfig(appVersionTag string) *Config {
 		PlaylistPage: PlaylistPageConfig{
 			TracklistColumns: []string{"Artist", "Album", "Time", "Plays"},
 		},
+		TracksPage: TracksPageConfig{
+			TracklistColumns: []string{"Artist", "Album", "Time", "Plays"},
+		},
 		LocalPlayback: LocalPlaybackConfig{
 			// "auto" is the name to pass to MPV for autoselecting the output device
 			AudioDeviceName:     "auto",

backend/librarymanager.go

@@ -8,6 +8,10 @@ type AlbumIterator interface {
 	Next() *subsonic.AlbumID3
 }
 
+type TrackIterator interface {
+	Next() *subsonic.Child
+}
+
 type LibraryManager struct {
 	PreCacheCoverFn func(coverID string)
 

backend/searchiterbase.go

@@ -0,0 +1,33 @@
+package backend
+
+import (
+	"log"
+	"strconv"
+
+	"github.com/dweymouth/go-subsonic/subsonic"
+)
+
+type searchIterBase struct {
+	query        string
+	artistOffset int
+	albumOffset  int
+	songOffset   int
+	s            *subsonic.Client
+}
+
+func (s *searchIterBase) fetchResults() *subsonic.SearchResult3 {
+	searchOpts := map[string]string{
+		"artistOffset": strconv.Itoa(s.artistOffset),
+		"albumOffset":  strconv.Itoa(s.albumOffset),
+		"songOffset":   strconv.Itoa(s.songOffset),
+	}
+	results, err := s.s.Search3(s.query, searchOpts)
+	if err != nil {
+		log.Println(err)
+		results = nil
+	}
+	if results == nil || len(results.Album)+len(results.Artist)+len(results.Song) == 0 {
+		return nil
+	}
+	return results
+}

backend/trackiterator.go

@@ -0,0 +1,140 @@
+package backend
+
+import (
+	"log"
+
+	"github.com/dweymouth/go-subsonic/subsonic"
+)
+
+func (l *LibraryManager) AllTracksIterator() TrackIterator {
+	return &allTracksIterator{
+		l:         l,
+		albumIter: l.AlbumsIter(AlbumSortArtistAZ),
+	}
+}
+
+func (l *LibraryManager) SearchTracksIterator(query string) TrackIterator {
+	return &searchTracksIterator{
+		searchIterBase: searchIterBase{
+			s:     l.s.Server,
+			query: query,
+		},
+		trackIDset: make(map[string]bool),
+	}
+}
+
+type allTracksIterator struct {
+	l           *LibraryManager
+	albumIter   AlbumIterator
+	curAlbum    *subsonic.AlbumID3
+	curTrackIdx int
+	done        bool
+}
+
+func (a *allTracksIterator) Next() *subsonic.Child {
+	if a.done {
+		return nil
+	}
+
+	// fetch next album
+	if a.curAlbum == nil || a.curTrackIdx >= len(a.curAlbum.Song) {
+		al := a.albumIter.Next()
+		if al == nil {
+			a.done = true
+			return nil
+		}
+		al, err := a.l.s.Server.GetAlbum(al.ID)
+		if err != nil {
+			log.Printf("error fetching album: %s", err.Error())
+		}
+		if len(al.Song) == 0 {
+			// in the unlikely case of an album with zero tracks,
+			// just call recursively to move to next album
+			return a.Next()
+		}
+		a.curAlbum = al
+		a.curTrackIdx = 0
+	}
+
+	tr := a.curAlbum.Song[a.curTrackIdx]
+	a.curTrackIdx += 1
+	return tr
+}
+
+type searchTracksIterator struct {
+	searchIterBase
+
+	prefetched    []*subsonic.Child
+	prefetchedPos int
+	trackIDset    map[string]bool
+	done          bool
+}
+
+func (s *searchTracksIterator) Next() *subsonic.Child {
+	if s.done {
+		return nil
+	}
+
+	// prefetch more search results from server
+	if len(s.prefetched) == 0 {
+		results := s.searchIterBase.fetchResults()
+
+		if results != nil {
+			// add results from songs search
+			s.addNewTracks(results.Song)
+			s.songOffset += len(results.Song)
+
+			// add results from artists search
+			for _, artist := range results.Artist {
+				artist, err := s.s.GetArtist(artist.ID)
+				if err != nil {
+					log.Printf("error fetching artist: %s", err.Error())
+				} else {
+					s.addNewTracksFromAlbums(artist.Album)
+				}
+			}
+			s.artistOffset += len(results.Artist)
+
+			// add results from albums search
+			s.addNewTracksFromAlbums(results.Album)
+			s.albumOffset += len(results.Album)
+		}
+	}
+
+	// return from prefetched results
+	if len(s.prefetched) > 0 {
+		tr := s.prefetched[s.prefetchedPos]
+		s.prefetchedPos++
+		if s.prefetchedPos == len(s.prefetched) {
+			s.prefetched = s.prefetched[:0]
+			s.prefetchedPos = 0
+		}
+		return tr
+	}
+
+	// no more results
+	s.done = true
+	s.prefetched = nil
+	s.trackIDset = nil
+	return nil
+}
+
+func (s *searchTracksIterator) addNewTracks(tracks []*subsonic.Child) {
+	for _, tr := range tracks {
+		if _, have := s.trackIDset[tr.ID]; have {
+			continue
+		}
+		s.prefetched = append(s.prefetched, tr)
+		s.trackIDset[tr.ID] = true
+	}
+}
+
+func (s *searchTracksIterator) addNewTracksFromAlbums(albums []*subsonic.AlbumID3) {
+	for _, al := range albums {
+		if album, err := s.s.GetAlbum(al.ID); err != nil {
+			log.Printf("error fetching album: %s", err.Error())
+		} else {
+			s.addNewTracks(album.Song)
+		}
+	}
+}

ui/browsing/router.go

@@ -46,6 +46,8 @@ func (r Router) CreatePage(rte controller.Route) Page {
 		return NewPlaylistPage(rte.Arg, &r.App.Config.PlaylistPage, r.Controller, r.App.ServerManager, r.App.PlaybackManager, r.App.ImageManager)
 	case controller.Playlists:
 		return NewPlaylistsPage(r.Controller, r.App.ServerManager)
+	case controller.Tracks:
+		return NewTracksPage(r.Controller, &r.App.Config.TracksPage, r.App.LibraryManager)
 	}
 	return nil
 }

ui/browsing/trackspage.go

@@ -0,0 +1,141 @@
+package browsing
+
+import (
+	"supersonic/backend"
+	"supersonic/res"
+	"supersonic/sharedutil"
+	"supersonic/ui/controller"
+	"supersonic/ui/layouts"
+	"supersonic/ui/widgets"
+
+	"fyne.io/fyne/v2"
+	"fyne.io/fyne/v2/container"
+	"fyne.io/fyne/v2/layout"
+	"fyne.io/fyne/v2/widget"
+	"github.com/dweymouth/go-subsonic/subsonic"
+)
+
+type TracksPage struct {
+	widget.BaseWidget
+
+	tracksPageState
+
+	nowPlayingID string
+
+	title           *widget.RichText
+	searcher        *widgets.Searcher
+	tracklist       *widgets.Tracklist
+	loader          widgets.TracklistLoader
+	searchTracklist *widgets.Tracklist
+	searchLoader    widgets.TracklistLoader
+	playRandom      *widget.Button
+	container       *fyne.Container
+}
+
+type tracksPageState struct {
+	searchText string
+	contr      *controller.Controller
+	conf       *backend.TracksPageConfig
+	lm         *backend.LibraryManager
+}
+
+func NewTracksPage(contr *controller.Controller, conf *backend.TracksPageConfig, lm *backend.LibraryManager) *TracksPage {
+	t := &TracksPage{tracksPageState: tracksPageState{contr: contr, conf: conf, lm: lm}}
+	t.ExtendBaseWidget(t)
+	t.tracklist = widgets.NewTracklist(nil)
+	t.tracklist.AutoNumber = true
+	t.tracklist.SetVisibleColumns(conf.TracklistColumns)
+	contr.ConnectTracklistActions(t.tracklist)
+	t.title = widget.NewRichTextWithText("All Tracks")
+	t.title.Segments[0].(*widget.TextSegment).Style.SizeName = widget.RichTextStyleHeading.SizeName
+	t.playRandom = widget.NewButtonWithIcon("Play random", res.ResShuffleInvertSvg, t.playRandomSongs)
+	t.searcher = widgets.NewSearcher()
+	t.searcher.OnSearched = t.OnSearched
+	t.createContainer()
+	t.Reload()
+	return t
+}
+
+func (t *TracksPage) createContainer() {
+	playRandomVbox := container.NewVBox(layout.NewSpacer(), t.playRandom, layout.NewSpacer())
+	searchVbox := container.NewVBox(layout.NewSpacer(), t.searcher.Entry, layout.NewSpacer())
+	topRow := container.NewHBox(t.title, playRandomVbox, layout.NewSpacer(), searchVbox)
+	t.container = container.New(&layouts.MaxPadLayout{PadLeft: 15, PadRight: 15, PadTop: 5, PadBottom: 15},
+		container.NewBorder(topRow, nil, nil, nil, t.tracklist))
+}
+
+func (t *TracksPage) Route() controller.Route {
+	return controller.TracksRoute()
+}
+
+func (t *TracksPage) Reload() {
+	t.tracklist.Clear()
+	iter := t.lm.AllTracksIterator()
+	// loads asynchronously
+	t.loader = widgets.NewTracklistLoader(t.tracklist, iter)
+}
+
+func (t *TracksPage) OnSongChange(track *subsonic.Child, lastScrobbledIfAny *subsonic.Child) {
+	t.nowPlayingID = sharedutil.TrackIDOrEmptyStr(track)
+	t.tracklist.SetNowPlaying(t.nowPlayingID)
+	if t.searchTracklist != nil {
+		t.searchTracklist.SetNowPlaying(t.nowPlayingID)
+	}
+	playedID := sharedutil.TrackIDOrEmptyStr(lastScrobbledIfAny)
+	t.tracklist.IncrementPlayCount(playedID)
+	if t.searchTracklist != nil {
+		t.searchTracklist.IncrementPlayCount(playedID)
+	}
+}
+
+func (t *TracksPage) OnSearched(query string) {
+	t.searchText = query
+	if query == "" {
+		t.container.Objects[0].(*fyne.Container).Objects[0] = t.tracklist
+		if t.searchTracklist != nil {
+			t.searchTracklist.Clear()
+		}
+		t.Refresh()
+		return
+	}
+	t.doSearch(query)
+}
+
+func (t *TracksPage) doSearch(query string) {
+	if t.searchTracklist == nil {
+		t.searchTracklist = widgets.NewTracklist(nil)
+		t.searchTracklist.AutoNumber = true
+		t.searchTracklist.SetVisibleColumns(t.conf.TracklistColumns)
+		t.searchTracklist.SetNowPlaying(t.nowPlayingID)
+		t.contr.ConnectTracklistActions(t.searchTracklist)
+	} else {
+		t.searchTracklist.Clear()
+	}
+	iter := t.lm.SearchTracksIterator(query)
+	t.searchLoader = widgets.NewTracklistLoader(t.searchTracklist, iter)
+	t.container.Objects[0].(*fyne.Container).Objects[0] = t.searchTracklist
+	t.Refresh()
+}
+
+func (t *TracksPage) CreateRenderer() fyne.WidgetRenderer {
+	return widget.NewSimpleRenderer(t.container)
+}
+
+func (t *TracksPage) Save() SavedPage {
+	state := t.tracksPageState
+	return &state
+}
+
+func (s *tracksPageState) Restore() Page {
+	t := NewTracksPage(s.contr, s.conf, s.lm)
+	t.searchText = s.searchText
+	if t.searchText != "" {
+		t.searcher.Entry.Text = t.searchText
+		t.doSearch(t.searchText)
+	}
+	return t
+}
+
+func (t *TracksPage) playRandomSongs() {
+	t.contr.App.PlaybackManager.PlayRandomSongs("")
+}

ui/controller/routes.go

@@ -14,6 +14,7 @@ const (
 	NowPlaying
 	Playlist
 	Playlists
+	Tracks
 )
 
 type Route struct {
@@ -52,6 +53,10 @@ func PlaylistsRoute() Route {
 	return Route{Page: Playlists}
 }
 
+func TracksRoute() Route {
+	return Route{Page: Tracks}
+}
+
 func ArtistsRoute() Route {
 	return Route{Page: Artists}
 }

ui/mainwindow.go

@@ -26,9 +26,10 @@ var (
 	ShortcutNavFour  = desktop.CustomShortcut{KeyName: fyne.Key4, Modifier: os.ControlModifier}
 	ShortcutNavFive  = desktop.CustomShortcut{KeyName: fyne.Key5, Modifier: os.ControlModifier}
 	ShortcutNavSix   = desktop.CustomShortcut{KeyName: fyne.Key6, Modifier: os.ControlModifier}
+	ShortcutNavSeven = desktop.CustomShortcut{KeyName: fyne.Key7, Modifier: os.ControlModifier}
 
 	NavShortcuts = []desktop.CustomShortcut{ShortcutNavOne, ShortcutNavTwo, ShortcutNavThree,
-		ShortcutNavFour, ShortcutNavFive, ShortcutNavSix}
+		ShortcutNavFour, ShortcutNavFive, ShortcutNavSix, ShortcutNavSeven}
 )
 
 type MainWindow struct {
@@ -187,6 +188,9 @@ func (m *MainWindow) addNavigationButtons() {
 	m.BrowsingPane.AddNavigationButton(res.ResPlaylistInvertPng, func() {
 		m.Router.NavigateTo(controller.PlaylistsRoute())
 	})
+	m.BrowsingPane.AddNavigationButton(res.ResMusicnotesInvertPng, func() {
+		m.Router.NavigateTo(controller.TracksRoute())
+	})
 }
 
 func (m *MainWindow) addShortcuts() {

ui/widgets/tracklist.go

@@ -9,6 +9,7 @@ import (
 	"supersonic/ui/layouts"
 	"supersonic/ui/os"
 	"supersonic/ui/util"
+	"sync"
 	"time"
 
 	"fyne.io/fyne/v2"
@@ -35,6 +36,8 @@ type Tracklist struct {
 	widget.BaseWidget
 
 	// Tracks is the set of tracks displayed by the widget.
+	// Direct access to this is not thread-safe but OK for
+	// views that only load tracks into the widget once at page load.
 	Tracks []*subsonic.Child
 
 	// AutoNumber sets whether to auto-number the tracks 1..N in display order,
@@ -64,23 +67,25 @@ type Tracklist struct {
 	OnShowAlbumPage  func(albumID string)
 
 	OnColumnVisibilityMenuShown func(*widget.PopUp)
+	OnTrackShown                func(tracknum int)
 
 	visibleColumns []bool
 
-	selectionMgr  util.ListSelectionManager
-	nowPlayingIdx int
-	colLayout     *layouts.ColumnsLayout
-	hdr           *ListHeader
-	list          *widget.List
-	ctxMenu       *fyne.Menu
-	container     *fyne.Container
+	tracksMutex  sync.RWMutex
+	selectionMgr util.ListSelectionManager
+	nowPlayingID string
+	colLayout    *layouts.ColumnsLayout
+	hdr          *ListHeader
+	list         *widget.List
+	ctxMenu      *fyne.Menu
+	container    *fyne.Container
 }
 
 func NewTracklist(tracks []*subsonic.Child) *Tracklist {
-	t := &Tracklist{Tracks: tracks, nowPlayingIdx: -1, visibleColumns: make([]bool, 11)}
+	t := &Tracklist{Tracks: tracks, visibleColumns: make([]bool, 11)}
 
 	t.ExtendBaseWidget(t)
-	t.selectionMgr = util.NewListSelectionManager(func() int { return len(t.Tracks) })
+	t.selectionMgr = util.NewListSelectionManager(t.lenTracks)
 	// #, Title, Artist, Album, Time, Year, Favorite, Plays, Bitrate, Size, Path
 	t.colLayout = layouts.NewColumnsLayout([]float32{40, -1, -1, -1, 60, 60, 47, 65, 75, 70, -1})
 	t.buildHeader()
@@ -92,7 +97,7 @@ func NewTracklist(tracks []*subsonic.Child) *Tracklist {
 	}
 	playingIcon := container.NewCenter(container.NewHBox(util.NewHSpace(2), widget.NewIcon(theme.MediaPlayIcon())))
 	t.list = widget.NewList(
-		func() int { return len(t.Tracks) },
+		t.lenTracks,
 		func() fyne.CanvasObject {
 			tr := NewTrackRow(t, playingIcon)
 			tr.OnTapped = func() { t.onSelectTrack(tr.trackIdx) }
@@ -108,7 +113,10 @@ func NewTracklist(tracks []*subsonic.Child) *Tracklist {
 			if t.AutoNumber {
 				i = itemID + 1
 			}
-			tr.Update(t.Tracks[itemID], itemID == t.nowPlayingIdx, i)
+			tr.Update(t.TrackAt(itemID), i)
+			if t.OnTrackShown != nil {
+				t.OnTrackShown(itemID)
+			}
 		})
 	t.container = container.NewBorder(t.hdr, nil, nil, nil, t.list)
 	return t
@@ -130,6 +138,16 @@ func (t *Tracklist) buildHeader() {
 		t.colLayout)
 }
 
+// Gets the track at the given index. Thread-safe.
+func (t *Tracklist) TrackAt(idx int) *subsonic.Child {
+	t.tracksMutex.RLock()
+	defer t.tracksMutex.RUnlock()
+	if idx >= len(t.Tracks) {
+		return nil
+	}
+	return t.Tracks[idx]
+}
+
 func (t *Tracklist) SetVisibleColumns(cols []string) {
 	t.visibleColumns[0] = true
 	t.visibleColumns[1] = true
@@ -167,23 +185,34 @@ func (t *Tracklist) setColumnVisible(colNum int, vis bool) {
 }
 
 func (t *Tracklist) SetNowPlaying(trackID string) {
-	t.nowPlayingIdx = -1
-	for i, tr := range t.Tracks {
-		if tr.ID == trackID {
-			t.nowPlayingIdx = i
-			break
-		}
-	}
+	t.nowPlayingID = trackID
 	t.list.Refresh()
 }
 
 func (t *Tracklist) IncrementPlayCount(trackID string) {
-	if tr := sharedutil.FindTrackByID(trackID, t.Tracks); tr != nil {
+	t.tracksMutex.RLock()
+	tr := sharedutil.FindTrackByID(trackID, t.Tracks)
+	t.tracksMutex.RUnlock()
+	if tr != nil {
 		tr.PlayCount += 1
 		t.list.Refresh()
 	}
 }
 
+// Remove all tracks from the tracklist. Thread-safe.
+func (t *Tracklist) Clear() {
+	t.tracksMutex.Lock()
+	defer t.tracksMutex.Unlock()
+	t.Tracks = nil
+}
+
+// Append more tracks to the tracklist. Thread-safe.
+func (t *Tracklist) AppendTracks(trs []*subsonic.Child) {
+	t.tracksMutex.Lock()
+	defer t.tracksMutex.Unlock()
+	t.Tracks = append(t.Tracks, trs...)
+}
+
 func (t *Tracklist) SelectAll() {
 	t.selectionMgr.SelectAll()
 	t.list.Refresh()
@@ -255,7 +284,9 @@ func (t *Tracklist) onShowContextMenu(e *fyne.PointEvent, trackIdx int) {
 
 func (t *Tracklist) onSetFavorite(trackID string, fav bool) {
 	// update our own track model
+	t.tracksMutex.RLock()
 	tr := sharedutil.FindTrackByID(trackID, t.Tracks)
+	t.tracksMutex.RUnlock()
 	if fav {
 		tr.Starred = time.Now()
 	} else {
@@ -282,6 +313,8 @@ func (t *Tracklist) onAlbumTapped(albumID string) {
 func (t *Tracklist) selectedTracks() []*subsonic.Child {
 	sel := t.selectionMgr.GetSelection()
 	tracks := make([]*subsonic.Child, 0, len(sel))
+	t.tracksMutex.RLock()
+	defer t.tracksMutex.RUnlock()
 	for _, idx := range sel {
 		tracks = append(tracks, t.Tracks[idx])
 	}
@@ -291,6 +324,8 @@ func (t *Tracklist) selectedTracks() []*subsonic.Child {
 func (t *Tracklist) selectedTrackIDs() []string {
 	sel := t.selectionMgr.GetSelection()
 	tracks := make([]string, 0, len(sel))
+	t.tracksMutex.RLock()
+	defer t.tracksMutex.RUnlock()
 	for _, idx := range sel {
 		tracks = append(tracks, t.Tracks[idx].ID)
 	}
@@ -301,6 +336,12 @@ func (t *Tracklist) SelectedTrackIndexes() []int {
 	return t.selectionMgr.GetSelection()
 }
 
+func (t *Tracklist) lenTracks() int {
+	t.tracksMutex.RLock()
+	defer t.tracksMutex.RUnlock()
+	return len(t.Tracks)
+}
+
 func ColNumber(colName string) int {
 	// built-in columns # and Title are always visible
 	switch colName {
@@ -417,7 +458,7 @@ func NewTrackRow(tracklist *Tracklist, playingIcon fyne.CanvasObject) *TrackRow
 	return t
 }
 
-func (t *TrackRow) Update(tr *subsonic.Child, isPlaying bool, rowNum int) {
+func (t *TrackRow) Update(tr *subsonic.Child, rowNum int) {
 	// Update info that can change if this row is bound to
 	// a new track (*subsonic.Child)
 	if tr.ID != t.trackID {
@@ -467,7 +508,7 @@ func (t *TrackRow) Update(tr *subsonic.Child, isPlaying bool, rowNum int) {
 	}
 
 	// Render whether track is playing or not
-	if isPlaying != t.isPlaying {
+	if isPlaying := t.tracklist.nowPlayingID == tr.ID; isPlaying != t.isPlaying {
 		t.isPlaying = isPlaying
 		t.name.Segments[0].(*widget.TextSegment).Style.TextStyle.Bold = isPlaying
 		t.dur.Segments[0].(*widget.TextSegment).Style.TextStyle.Bold = isPlaying

ui/widgets/tracklistloader.go

@@ -0,0 +1,66 @@
+package widgets
+
+import (
+	"supersonic/backend"
+
+	"github.com/dweymouth/go-subsonic/subsonic"
+)
+
+// Component that manages lazily loading more tracks into a Tracklist
+// as the user scrolls near the bottom.
+type TracklistLoader struct {
+	tracklist *Tracklist
+	iter      backend.TrackIterator
+
+	trackBuffer  []*subsonic.Child
+	fetching     bool
+	done         bool
+	len          int
+	highestShown int
+}
+
+func NewTracklistLoader(tracklist *Tracklist, iter backend.TrackIterator) TracklistLoader {
+	t := TracklistLoader{
+		tracklist: tracklist,
+		iter:      iter,
+	}
+	t.tracklist.OnTrackShown = t.onTrackShown
+	t.fetching = true
+	go t.loadMoreTracks(25)
+	return t
+}
+
+func (t *TracklistLoader) onTrackShown(tracknum int) {
+	if tracknum > t.highestShown {
+		t.highestShown = tracknum
+	}
+	if t.highestShown >= t.len-25 && !t.fetching && !t.done {
+		t.fetching = true
+		go t.loadMoreTracks(25)
+	}
+}
+
+func (t *TracklistLoader) loadMoreTracks(num int) {
+	// repeat fetch task as long as user has scrolled near bottom
+	for !t.done && t.highestShown >= t.len-25 {
+		if t.trackBuffer == nil {
+			t.trackBuffer = make([]*subsonic.Child, 0, num)
+		}
+		t.trackBuffer = t.trackBuffer[:0]
+		for i := 0; i < num; i++ {
+			tr := t.iter.Next()
+			if tr == nil {
+				t.done = true
+				break
+			}
+			t.trackBuffer = append(t.trackBuffer, tr)
+		}
+		t.tracklist.AppendTracks(t.trackBuffer)
+		t.tracklist.Refresh()
+		t.len += len(t.trackBuffer)
+	}
+	if t.done {
+		t.trackBuffer = nil
+	}
+	t.fetching = false
+}