inpututil: Add AppendJustConnectedTouchIDs

Closes #1705

examples/audio/main.go

@@ -112,6 +112,7 @@ func (t musicType) String() string {
 
 // Player represents the current audio state.
 type Player struct {
+	game         *Game
 	audioContext *audio.Context
 	audioPlayer  *audio.Player
 	current      time.Duration
@@ -129,7 +130,7 @@ func playerBarRect() (x, y, w, h int) {
 	return
 }
 
-func NewPlayer(audioContext *audio.Context, musicType musicType) (*Player, error) {
+func NewPlayer(game *Game, audioContext *audio.Context, musicType musicType) (*Player, error) {
 	type audioStream interface {
 		io.ReadSeeker
 		Length() int64
@@ -160,6 +161,7 @@ func NewPlayer(audioContext *audio.Context, musicType musicType) (*Player, error
 		return nil, err
 	}
 	player := &Player{
+		game:         game,
 		audioContext: audioContext,
 		audioPlayer:  p,
 		total:        time.Second * time.Duration(s.Length()) / bytesPerSample / sampleRate,
@@ -232,7 +234,7 @@ func (p *Player) shouldPlaySE() bool {
 			return true
 		}
 	}
-	for _, id := range inpututil.JustPressedTouchIDs() {
+	for _, id := range p.game.justPressedTouchIDs {
 		if image.Pt(ebiten.TouchPosition(id)).In(r) {
 			return true
 		}
@@ -277,7 +279,7 @@ func (p *Player) shouldSwitchPlayStateIfNeeded() bool {
 			return true
 		}
 	}
-	for _, id := range inpututil.JustPressedTouchIDs() {
+	for _, id := range p.game.justPressedTouchIDs {
 		if image.Pt(ebiten.TouchPosition(id)).In(r) {
 			return true
 		}
@@ -296,14 +298,14 @@ func (p *Player) switchPlayStateIfNeeded() {
 	p.audioPlayer.Play()
 }
 
-func justPressedPosition() (int, int, bool) {
+func (p *Player) justPressedPosition() (int, int, bool) {
 	if inpututil.IsMouseButtonJustPressed(ebiten.MouseButtonLeft) {
 		x, y := ebiten.CursorPosition()
 		return x, y, true
 	}
 
-	if ts := inpututil.JustPressedTouchIDs(); len(ts) > 0 {
-		x, y := ebiten.TouchPosition(ts[0])
+	if len(p.game.justPressedTouchIDs) > 0 {
+		x, y := ebiten.TouchPosition(p.game.justPressedTouchIDs[0])
 		return x, y, true
 	}
 
@@ -312,7 +314,7 @@ func justPressedPosition() (int, int, bool) {
 
 func (p *Player) seekBarIfNeeded() {
 	// Calculate the next seeking position from the current cursor position.
-	x, y, ok := justPressedPosition()
+	x, y, ok := p.justPressedPosition()
 	if !ok {
 		return
 	}
@@ -376,21 +378,25 @@ type Game struct {
 	musicPlayer   *Player
 	musicPlayerCh chan *Player
 	errCh         chan error
+
+	justPressedTouchIDs []ebiten.TouchID
 }
 
 func NewGame() (*Game, error) {
 	audioContext := audio.NewContext(sampleRate)
 
-	m, err := NewPlayer(audioContext, typeOgg)
+	g := &Game{
+		musicPlayerCh: make(chan *Player),
+		errCh:         make(chan error),
+	}
+
+	m, err := NewPlayer(g, audioContext, typeOgg)
 	if err != nil {
 		return nil, err
 	}
 
-	return &Game{
-		musicPlayer:   m,
-		musicPlayerCh: make(chan *Player),
-		errCh:         make(chan error),
-	}, nil
+	g.musicPlayer = m
+	return g, nil
 }
 
 func (g *Game) Update() error {
@@ -402,6 +408,8 @@ func (g *Game) Update() error {
 	default:
 	}
 
+	g.justPressedTouchIDs = inpututil.AppendJustPressedTouchIDs(g.justPressedTouchIDs[:0])
+
 	if g.musicPlayer != nil && inpututil.IsKeyJustPressed(ebiten.KeyA) {
 		var t musicType
 		switch g.musicPlayer.musicType {
@@ -417,7 +425,7 @@ func (g *Game) Update() error {
 		g.musicPlayer = nil
 
 		go func() {
-			p, err := NewPlayer(audio.CurrentContext(), t)
+			p, err := NewPlayer(g, audio.CurrentContext(), t)
 			if err != nil {
 				g.errCh <- err
 				return

examples/drag/main.go

@@ -184,8 +184,9 @@ func (s *Stroke) SetDraggingObject(object interface{}) {
 }
 
 type Game struct {
-	strokes map[*Stroke]struct{}
-	sprites []*Sprite
+	touchIDs []ebiten.TouchID
+	strokes  map[*Stroke]struct{}
+	sprites  []*Sprite
 }
 
 var ebitenImage *ebiten.Image
@@ -273,7 +274,8 @@ func (g *Game) Update() error {
 		s.SetDraggingObject(g.spriteAt(s.Position()))
 		g.strokes[s] = struct{}{}
 	}
-	for _, id := range inpututil.JustPressedTouchIDs() {
+	g.touchIDs = inpututil.AppendJustPressedTouchIDs(g.touchIDs[:0])
+	for _, id := range g.touchIDs {
 		s := NewStroke(&TouchStrokeSource{id})
 		s.SetDraggingObject(g.spriteAt(s.Position()))
 		g.strokes[s] = struct{}{}

examples/flappy/main.go

@@ -178,6 +178,7 @@ type Game struct {
 	gameoverCount int
 
 	keys       []ebiten.Key
+	touchIDs   []ebiten.TouchID
 	gamepadIDs []ebiten.GamepadID
 }
 
@@ -215,7 +216,8 @@ func (g *Game) jump() bool {
 	if inpututil.IsMouseButtonJustPressed(ebiten.MouseButtonLeft) {
 		return true
 	}
-	if len(inpututil.JustPressedTouchIDs()) > 0 {
+	g.touchIDs = inpututil.AppendJustPressedTouchIDs(g.touchIDs)
+	if len(g.touchIDs) > 0 {
 		return true
 	}
 	g.gamepadIDs = ebiten.AppendGamepadIDs(g.gamepadIDs[:0])

examples/touch/main.go

@@ -110,7 +110,8 @@ func (g *Game) Update() error {
 	}
 
 	// What touches are new in this frame?
-	for _, id := range inpututil.JustPressedTouchIDs() {
+	g.touchIDs = inpututil.AppendJustPressedTouchIDs(g.touchIDs[:0])
+	for _, id := range g.touchIDs {
 		x, y := ebiten.TouchPosition(id)
 		g.touches[id] = &touch{
 			originX: x, originY: y,

inpututil/inpututil.go

@@ -253,8 +253,6 @@ func MouseButtonPressDuration(button ebiten.MouseButton) int {
 // and returns the extended buffer.
 // Giving a slice that already has enough capacity works efficiently.
 //
-// AppendJustConnectedGamepadIDs might append nothing when there is no connected gamepad.
-//
 // AppendJustConnectedGamepadIDs is concurrent safe.
 func AppendJustConnectedGamepadIDs(gamepadIDs []ebiten.GamepadID) []ebiten.GamepadID {
 	origLen := len(gamepadIDs)
@@ -330,24 +328,32 @@ func GamepadButtonPressDuration(id ebiten.GamepadID, button ebiten.GamepadButton
 	return s
 }
 
-// JustPressedTouchIDs returns touch IDs that are created just in the current frame.
+// AppendJustPressedTouchIDs append touch IDs that are created just in the current frame to touchIDs,
+// and returns the extended buffer.
+// Giving a slice that already has enough capacity works efficiently.
 //
-// JustPressedTouchIDs might return nil when there is not touch.
-//
-// JustPressedTouchIDs is concurrent safe.
-func JustPressedTouchIDs() []ebiten.TouchID {
-	var ids []ebiten.TouchID
+// AppendJustPressedTouchIDs is concurrent safe.
+func AppendJustPressedTouchIDs(touchIDs []ebiten.TouchID) []ebiten.TouchID {
+	origLen := len(touchIDs)
 	theInputState.m.RLock()
 	for id, s := range theInputState.touchDurations {
 		if s == 1 {
-			ids = append(ids, id)
+			touchIDs = append(touchIDs, id)
 		}
 	}
 	theInputState.m.RUnlock()
-	sort.Slice(ids, func(a, b int) bool {
-		return ids[a] < ids[b]
+	s := touchIDs[origLen:]
+	sort.Slice(s, func(a, b int) bool {
+		return s[a] < s[b]
 	})
-	return ids
+	return touchIDs
+}
+
+// JustPressedTouchIDs returns touch IDs that are created just in the current frame.
+//
+// Deprecated: as of v2.2. Use AppendJustPressedTouchIDs instead.
+func JustPressedTouchIDs() []ebiten.TouchID {
+	return AppendJustPressedTouchIDs(nil)
 }
 
 // IsTouchJustReleased returns a boolean value indicating