audio: Add NewPlayerFromBytes (#231)

audio/audio.go

@@ -26,6 +26,7 @@
 package audio
 
 import (
+	"bytes"
 	"errors"
 	"io"
 	"runtime"
@@ -295,6 +296,27 @@ func NewPlayer(context *Context, src ReadSeekCloser) (*Player, error) {
 	return p, nil
 }
 
+type bytesReadSeekCloser struct {
+	*bytes.Reader
+}
+
+func (b *bytesReadSeekCloser) Close() error {
+	return nil
+}
+
+// NewPlayerFromBytes creates a new player with the given bytes.
+//
+// As opposed to NewPlayer, you don't have to care if src is already used by another player or not.
+// src can be shared by multiple players.
+//
+// The format of src should be same as noted at NewPlayer.
+//
+// This function is concurrent-safe.
+func NewPlayerFromBytes(context *Context, src []byte) (*Player, error) {
+	b := &bytesReadSeekCloser{bytes.NewReader(src)}
+	return NewPlayer(context, b)
+}
+
 // Close closes the stream. Ths source stream passed by NewPlayer will also be closed.
 //
 // After closing, the stream owned by the player will be usable to a new player again.

examples/pcm/main.go

@@ -15,7 +15,6 @@
 package main
 
 import (
-	"bytes"
 	"fmt"
 	"log"
 	"math"
@@ -97,15 +96,6 @@ func toBytes(l, r []int16) []byte {
 	return b
 }
 
-type srcStream struct {
-	*bytes.Reader
-}
-
-func (s *srcStream) Close() error {
-	s.Reader = nil
-	return nil
-}
-
 func addNote() error {
 	size := sampleRate / ebiten.FPS
 	notes := []float64{freqC, freqD, freqE, freqF, freqG, freqA * 2, freqB * 2}
@@ -135,8 +125,7 @@ func addNote() error {
 	square(l, vol, freq, 0.25)
 	square(r, vol, freq, 0.25)
 	b := toBytes(l, r)
-	s := &srcStream{bytes.NewReader(b)}
-	p, err := audio.NewPlayer(audioContext, s)
+	p, err := audio.NewPlayerFromBytes(audioContext, b)
 	if err != nil {
 		return err
 	}

examples/piano/main.go

@@ -15,7 +15,6 @@
 package main
 
 import (
-	"bytes"
 	"fmt"
 	"image/color"
 	"log"
@@ -80,22 +79,13 @@ func toBytes(l, r []int16) []byte {
 	return b
 }
 
-type stream struct {
-	*bytes.Reader
-}
-
-func (s *stream) Close() error {
-	s.Reader = nil
-	return nil
-}
-
 func addNote(freq float64, vol float64) error {
 	// TODO: Call Close method of *audio.Player.
 	// However, this works without Close because Close is automatically called when GC
 	// collects a *audio.Player object.
 	f := int(freq)
 	if n, ok := noteCache[f]; ok {
-		p, err := audio.NewPlayer(audioContext, &stream{bytes.NewReader(n)})
+		p, err := audio.NewPlayerFromBytes(audioContext, n)
 		if err != nil {
 			return err
 		}
@@ -116,7 +106,7 @@ func addNote(freq float64, vol float64) error {
 	}
 	n := toBytes(l, r)
 	noteCache[f] = n
-	p, err := audio.NewPlayer(audioContext, &stream{bytes.NewReader(n)})
+	p, err := audio.NewPlayerFromBytes(audioContext, n)
 	if err != nil {
 		return err
 	}