Ebiten example - audio

// +build example

package main

import (
        "fmt"
        "image/color"
        "io/ioutil"
        "log"
        "time"

        "github.com/hajimehoshi/ebiten"
        "github.com/hajimehoshi/ebiten/audio"
        "github.com/hajimehoshi/ebiten/audio/vorbis"
        "github.com/hajimehoshi/ebiten/audio/wav"
        "github.com/hajimehoshi/ebiten/ebitenutil"
)

const (
        screenWidth  = 320
        screenHeight = 240
)

var (
        playerBarImage     *ebiten.Image
        playerCurrentImage *ebiten.Image
)

func init() {
        var err error
        playerBarImage, err = ebiten.NewImage(300, 4, ebiten.FilterNearest)
        if err != nil {
                log.Fatal(err)
        }
        if err := playerBarImage.Fill(&color.RGBA{0x80, 0x80, 0x80, 0xff}); err != nil {
                log.Fatal(err)
        }

        playerCurrentImage, err = ebiten.NewImage(4, 10, ebiten.FilterNearest)
        if err != nil {
                log.Fatal(err)
        }
        if err := playerCurrentImage.Fill(&color.RGBA{0xff, 0xff, 0xff, 0xff}); err != nil {
                log.Fatal(err)
        }
}

type Player struct {
        audioPlayer *audio.Player
        total       time.Duration
}

var (
        audioContext     *audio.Context
        musicPlayer      *Player
        seBytes          []byte
        musicCh          = make(chan *Player)
        seCh             = make(chan []byte)
        mouseButtonState = map[ebiten.MouseButton]int{}
        keyState         = map[ebiten.Key]int{}
        volume128        = 128
)

func playerBarRect() (x, y, w, h int) {
        w, h = playerBarImage.Size()
        x = (screenWidth - w) / 2
        y = screenHeight - h - 16
        return
}

func (p *Player) updateSE() error {
        if seBytes == nil {
                return nil
        }
        if !ebiten.IsKeyPressed(ebiten.KeyP) {
                keyState[ebiten.KeyP] = 0
                return nil
        }
        keyState[ebiten.KeyP]++
        if keyState[ebiten.KeyP] != 1 {
                return nil
        }
        sePlayer, err := audio.NewPlayerFromBytes(audioContext, seBytes)
        if err != nil {
                return err
        }
        return sePlayer.Play()
}

func (p *Player) updateVolume() error {
        if p.audioPlayer == nil {
                return nil
        }
        if ebiten.IsKeyPressed(ebiten.KeyZ) {
                volume128--
        }
        if ebiten.IsKeyPressed(ebiten.KeyX) {
                volume128++
        }
        if volume128 < 0 {
                volume128 = 0
        }
        if 128 < volume128 {
                volume128 = 128
        }
        p.audioPlayer.SetVolume(float64(volume128) / 128)
        return nil
}

func (p *Player) updatePlayPause() error {
        if p.audioPlayer == nil {
                return nil
        }
        if !ebiten.IsKeyPressed(ebiten.KeyS) {
                keyState[ebiten.KeyS] = 0
                return nil
        }
        keyState[ebiten.KeyS]++
        if keyState[ebiten.KeyS] != 1 {
                return nil
        }
        if p.audioPlayer.IsPlaying() {
                return p.audioPlayer.Pause()
        }
        return p.audioPlayer.Play()
}

func (p *Player) updateBar() error {
        if p.audioPlayer == nil {
                return nil
        }
        if !ebiten.IsMouseButtonPressed(ebiten.MouseButtonLeft) {
                mouseButtonState[ebiten.MouseButtonLeft] = 0
                return nil
        }
        mouseButtonState[ebiten.MouseButtonLeft]++
        if mouseButtonState[ebiten.MouseButtonLeft] != 1 {
                return nil
        }
        x, y := ebiten.CursorPosition()
        bx, by, bw, bh := playerBarRect()
        const padding = 4
        if y < by-padding || by+bh+padding <= y {
                return nil
        }
        if x < bx || bx+bw <= x {
                return nil
        }
        pos := time.Duration(x-bx) * p.total / time.Duration(bw)
        return p.audioPlayer.Seek(pos)
}

func (p *Player) close() error {
        return p.audioPlayer.Close()
}

func update(screen *ebiten.Image) error {
        if musicPlayer == nil {
                select {
                case musicPlayer = <-musicCh:
                default:
                }
        }
        if seBytes == nil {
                select {
                case seBytes = <-seCh:
                default:
                }
        }
        if musicPlayer != nil {
                if err := musicPlayer.updateBar(); err != nil {
                        return err
                }
                if err := musicPlayer.updatePlayPause(); err != nil {
                        return err
                }
                if err := musicPlayer.updateSE(); err != nil {
                        return err
                }
                if err := musicPlayer.updateVolume(); err != nil {
                        return err
                }
        }

        op := &ebiten.DrawImageOptions{}
        x, y, w, h := playerBarRect()
        op.GeoM.Translate(float64(x), float64(y))
        if err := screen.DrawImage(playerBarImage, op); err != nil {
                return err
        }
        currentTimeStr := "00:00"
        if musicPlayer != nil {
                c := musicPlayer.audioPlayer.Current()

                // Current Time
                m := (c / time.Minute) % 100
                s := (c / time.Second) % 60
                currentTimeStr = fmt.Sprintf("%02d:%02d", m, s)

                // Bar
                cw, ch := playerCurrentImage.Size()
                cx := int(time.Duration(w)*c/musicPlayer.total) + x - cw/2
                cy := y - (ch-h)/2
                op := &ebiten.DrawImageOptions{}
                op.GeoM.Translate(float64(cx), float64(cy))
                if err := screen.DrawImage(playerCurrentImage, op); err != nil {
                        return err
                }
        }

        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
%s`, ebiten.CurrentFPS(), currentTimeStr)
        if musicPlayer == nil {
                msg += "\nNow Loading..."
        }
        if err := ebitenutil.DebugPrint(screen, msg); err != nil {
                return err
        }
        if err := audioContext.Update(); err != nil {
                return err
        }
        return nil
}

func main() {
        wavF, err := ebitenutil.OpenFile("_resources/audio/jab.wav")
        if err != nil {
                log.Fatal(err)
        }
        oggF, err := ebitenutil.OpenFile("_resources/audio/ragtime.ogg")
        if err != nil {
                log.Fatal(err)
        }
        const sampleRate = 22050
        const bytesPerSample = 4 // TODO: This should be defined in audio package
        audioContext, err = audio.NewContext(sampleRate)
        if err != nil {
                log.Fatal(err)
        }
        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
                }
                seCh <- b
                close(seCh)
        }()
        go func() {
                s, err := vorbis.Decode(audioContext, oggF)
                if err != nil {
                        log.Fatal(err)
                        return
                }
                p, err := audio.NewPlayer(audioContext, s)
                if err != nil {
                        log.Fatal(err)
                        return
                }
                musicCh <- &Player{
                        audioPlayer: p,
                        total:       time.Second * time.Duration(s.Size()) / bytesPerSample / sampleRate,
                }
                close(musicCh)
                // TODO: Is this goroutine-safe?
                if err := p.Play(); err != nil {
                        log.Fatal(err)
                        return
                }
        }()
        if err := ebiten.Run(update, screenWidth, screenHeight, 2, "Audio (Ebiten Demo)"); err != nil {
                log.Fatal(err)
        }
        if musicPlayer != nil {
                if err := musicPlayer.close(); err != nil {
                        log.Fatal(err)
                }
        }
}