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ebiten/docs/examples/audio.html
Hajime Hoshi f325a70da2 docs: Update
2018-01-24 12:06:12 +09:00

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<!DOCTYPE html>
<meta charset="utf-8">
<meta property="og:image" itemprop="image primaryImageOfPage" content="https://hajimehoshi.github.io/ebiten/images/examples/audio.png">
<meta name="description" content="Ebiten example - audio">
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<title>Ebiten example - audio</title>
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<h2>Ebiten example - audio</h2>
<iframe src="audio.content.html" width="640" height="480"></iframe>
<div class="card"><pre class="card-body"><code class="language-go">// &#43;build example
// This is an example to implement an audio player.
// See examples/wav for a simpler example to play a sound file.
package main
import (
&#34;fmt&#34;
&#34;image/color&#34;
&#34;io/ioutil&#34;
&#34;log&#34;
&#34;time&#34;
&#34;github.com/hajimehoshi/ebiten&#34;
&#34;github.com/hajimehoshi/ebiten/audio&#34;
&#34;github.com/hajimehoshi/ebiten/audio/mp3&#34;
&#34;github.com/hajimehoshi/ebiten/audio/wav&#34;
&#34;github.com/hajimehoshi/ebiten/ebitenutil&#34;
)
const (
screenWidth = 320
screenHeight = 240
// This sample rate doesn&#39;t match with wav/mp3&#39;s sample rate,
// but decoders adjust them.
sampleRate = 48000
)
var (
playerBarColor = color.RGBA{0x80, 0x80, 0x80, 0xff}
playerCurrentColor = color.RGBA{0xff, 0xff, 0xff, 0xff}
)
// Input manages the current input state to detect keys &#39;just pressed&#39;.
//
// Note: &#39;just pressed&#39; is a very common idiom.
// There is a plan to create a new package for input utility.
// See https://github.com/hajimehoshi/ebiten/issues/415.
type Input struct {
mouseButtonStates map[ebiten.MouseButton]int
keyStates map[ebiten.Key]int
}
func (i *Input) update() {
for _, key := range []ebiten.Key{ebiten.KeyP, ebiten.KeyS, ebiten.KeyX, ebiten.KeyZ, ebiten.KeyB} {
if !ebiten.IsKeyPressed(key) {
i.keyStates[key] = 0
} else {
i.keyStates[key]&#43;&#43;
}
}
if !ebiten.IsMouseButtonPressed(ebiten.MouseButtonLeft) {
i.mouseButtonStates[ebiten.MouseButtonLeft] = 0
} else {
i.mouseButtonStates[ebiten.MouseButtonLeft]&#43;&#43;
}
}
func (i *Input) isKeyJustPressed(key ebiten.Key) bool {
return i.keyStates[key] == 1
}
func (i *Input) isKeyPressed(key ebiten.Key) bool {
return i.keyStates[key] &gt; 0
}
func (i *Input) isMouseButtonJustPressed(mouseButton ebiten.MouseButton) bool {
return i.mouseButtonStates[mouseButton] == 1
}
// Player represents the current audio state.
type Player struct {
input *Input
audioContext *audio.Context
audioPlayer *audio.Player
current time.Duration
total time.Duration
seBytes []byte
seCh chan []byte
volume128 int
}
func playerBarRect() (x, y, w, h int) {
w, h = 300, 4
x = (screenWidth - w) / 2
y = screenHeight - h - 16
return
}
func NewPlayer(audioContext *audio.Context) (*Player, error) {
const bytesPerSample = 4 // TODO: This should be defined in audio package
wavF, err := ebitenutil.OpenFile(ebitenutil.JoinStringsIntoFilePath(&#34;_resources&#34;, &#34;audio&#34;, &#34;jab.wav&#34;))
if err != nil {
return nil, err
}
mp3F, err := ebitenutil.OpenFile(ebitenutil.JoinStringsIntoFilePath(&#34;_resources&#34;, &#34;audio&#34;, &#34;classic.mp3&#34;))
if err != nil {
return nil, err
}
s, err := mp3.Decode(audioContext, mp3F)
if err != nil {
return nil, err
}
p, err := audio.NewPlayer(audioContext, s)
if err != nil {
return nil, err
}
player := &amp;Player{
input: &amp;Input{
mouseButtonStates: map[ebiten.MouseButton]int{},
keyStates: map[ebiten.Key]int{},
},
audioContext: audioContext,
audioPlayer: p,
total: time.Second * time.Duration(s.Length()) / bytesPerSample / sampleRate,
volume128: 128,
seCh: make(chan []byte),
}
if player.total == 0 {
player.total = 1
}
player.audioPlayer.Play()
go func() {
s, err := wav.Decode(audioContext, wavF)
if err != nil {
log.Fatal(err)
return
}
b, err := ioutil.ReadAll(s)
if err != nil {
log.Fatal(err)
return
}
player.seCh &lt;- b
}()
return player, nil
}
func (p *Player) update() error {
p.input.update()
select {
case p.seBytes = &lt;-p.seCh:
close(p.seCh)
p.seCh = nil
default:
}
if p.audioPlayer.IsPlaying() {
p.current = p.audioPlayer.Current()
}
p.seekBarIfNeeded()
p.switchPlayStateIfNeeded()
p.playSEIfNeeded()
p.updateVolumeIfNeeded()
if p.input.isKeyJustPressed(ebiten.KeyB) {
b := ebiten.IsRunnableInBackground()
ebiten.SetRunnableInBackground(!b)
}
return nil
}
func (p *Player) playSEIfNeeded() {
if p.seBytes == nil {
// Bytes for the SE is not loaded yet.
return
}
if !p.input.isKeyJustPressed(ebiten.KeyP) {
return
}
sePlayer, _ := audio.NewPlayerFromBytes(p.audioContext, p.seBytes)
sePlayer.Play()
}
func (p *Player) updateVolumeIfNeeded() {
if p.input.isKeyPressed(ebiten.KeyZ) {
p.volume128--
}
if p.input.isKeyPressed(ebiten.KeyX) {
p.volume128&#43;&#43;
}
if p.volume128 &lt; 0 {
p.volume128 = 0
}
if 128 &lt; p.volume128 {
p.volume128 = 128
}
p.audioPlayer.SetVolume(float64(p.volume128) / 128)
}
func (p *Player) switchPlayStateIfNeeded() {
if !p.input.isKeyJustPressed(ebiten.KeyS) {
return
}
if p.audioPlayer.IsPlaying() {
p.audioPlayer.Pause()
return
}
p.audioPlayer.Play()
}
func (p *Player) seekBarIfNeeded() {
if !p.input.isMouseButtonJustPressed(ebiten.MouseButtonLeft) {
return
}
// Calculate the next seeking position from the current cursor position.
x, y := ebiten.CursorPosition()
bx, by, bw, bh := playerBarRect()
const padding = 4
if y &lt; by-padding || by&#43;bh&#43;padding &lt;= y {
return
}
if x &lt; bx || bx&#43;bw &lt;= x {
return
}
pos := time.Duration(x-bx) * p.total / time.Duration(bw)
p.current = pos
p.audioPlayer.Seek(pos)
}
func (p *Player) close() error {
return p.audioPlayer.Close()
}
func (p *Player) draw(screen *ebiten.Image) {
// Draw the bar.
x, y, w, h := playerBarRect()
ebitenutil.DrawRect(screen, float64(x), float64(y), float64(w), float64(h), playerBarColor)
// Draw the cursor on the bar.
c := p.current
cw, ch := 4, 10
cx := int(time.Duration(w)*c/p.total) &#43; x - cw/2
cy := y - (ch-h)/2
ebitenutil.DrawRect(screen, float64(cx), float64(cy), float64(cw), float64(ch), playerCurrentColor)
// Compose the curren time text.
m := (c / time.Minute) % 100
s := (c / time.Second) % 60
currentTimeStr := fmt.Sprintf(&#34;%02d:%02d&#34;, m, s)
// Draw the debug message.
msg := fmt.Sprintf(`FPS: %0.2f
Press S to toggle Play/Pause
Press P to play SE
Press Z or X to change volume of the music
Press B to switch the run-in-background state
Current Time: %s`, ebiten.CurrentFPS(), currentTimeStr)
ebitenutil.DebugPrint(screen, msg)
}
var (
musicPlayer *Player
)
func update(screen *ebiten.Image) error {
if err := musicPlayer.update(); err != nil {
return err
}
if ebiten.IsRunningSlowly() {
return nil
}
musicPlayer.draw(screen)
return nil
}
func main() {
audioContext, err := audio.NewContext(sampleRate)
if err != nil {
log.Fatal(err)
}
musicPlayer, err = NewPlayer(audioContext)
if err != nil {
log.Fatal(err)
}
if err := ebiten.Run(update, screenWidth, screenHeight, 2, &#34;Audio (Ebiten Demo)&#34;); err != nil {
log.Fatal(err)
}
if err := musicPlayer.close(); err != nil {
log.Fatal(err)
}
}
</code></pre></div>
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