ebiten/audio/internal/readerdriver/driver_js.go

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// Copyright 2021 The Ebiten Authors
//
// Licensed under the Apache License, Version 2.0 (the "License");
// you may not use this file except in compliance with the License.
// You may obtain a copy of the License at
//
// http://www.apache.org/licenses/LICENSE-2.0
//
// Unless required by applicable law or agreed to in writing, software
// distributed under the License is distributed on an "AS IS" BASIS,
// WITHOUT WARRANTIES OR CONDITIONS OF ANY KIND, either express or implied.
// See the License for the specific language governing permissions and
// limitations under the License.
package readerdriver
import (
"errors"
"io"
"reflect"
"runtime"
"syscall/js"
"unsafe"
2021-01-09 10:21:32 +01:00
"github.com/hajimehoshi/ebiten/v2/audio/internal/go2cpp"
"github.com/hajimehoshi/ebiten/v2/internal/jsutil"
)
func IsAvailable() bool {
return true
}
type contextImpl struct {
audioContext js.Value
ready bool
callbacks map[string]js.Func
sampleRate int
channelNum int
bitDepthInBytes int
}
func NewContext(sampleRate int, channelNum int, bitDepthInBytes int) (Context, error) {
if js.Global().Get("go2cpp").Truthy() {
return &go2cppDriverWrapper{go2cpp.NewContext(sampleRate, channelNum, bitDepthInBytes)}, nil
}
class := js.Global().Get("AudioContext")
if !class.Truthy() {
class = js.Global().Get("webkitAudioContext")
}
if !class.Truthy() {
return nil, errors.New("readerdriver: AudioContext or webkitAudioContext was not found")
}
options := js.Global().Get("Object").New()
options.Set("sampleRate", sampleRate)
d := &contextImpl{
audioContext: class.New(options),
sampleRate: sampleRate,
channelNum: channelNum,
bitDepthInBytes: bitDepthInBytes,
}
setCallback := func(event string) js.Func {
var f js.Func
f = js.FuncOf(func(this js.Value, arguments []js.Value) interface{} {
if !d.ready {
d.audioContext.Call("resume")
d.ready = true
}
js.Global().Get("document").Call("removeEventListener", event, f)
return nil
})
js.Global().Get("document").Call("addEventListener", event, f)
d.callbacks[event] = f
return f
}
// Browsers require user interaction to start the audio.
// https://developers.google.com/web/updates/2017/09/autoplay-policy-changes#webaudio
d.callbacks = map[string]js.Func{}
setCallback("touchend")
setCallback("keyup")
setCallback("mouseup")
return d, nil
}
type playerImpl struct {
context *contextImpl
src io.Reader
eof bool
state playerState
gain js.Value
err error
nextPos float64
bufferSourceNodes []js.Value
appendBufferFunc js.Func
}
func (c *contextImpl) NewPlayer(src io.Reader) Player {
p := &playerImpl{
context: c,
src: src,
gain: c.audioContext.Call("createGain"),
}
p.appendBufferFunc = js.FuncOf(p.appendBuffer)
p.gain.Call("connect", c.audioContext.Get("destination"))
runtime.SetFinalizer(p, (*playerImpl).Close)
return p
}
func (c *contextImpl) Close() error {
// TODO: Implement this
return nil
}
// TODO: The term 'buffer' is confusing. Name each buffer with good terms.
// oneBufferSize returns the size of one buffer in the player implementation.
func (c *contextImpl) oneBufferSize() int {
return c.sampleRate * c.channelNum * c.bitDepthInBytes / 4
}
// maxBufferSize returns the maximum size of the buffer for the audio source.
// This buffer is used when unreading on pausing the player.
func (c *contextImpl) MaxBufferSize() int {
// The number of underlying buffers should be 2.
return c.oneBufferSize() * 2
}
func (p *playerImpl) Pause() {
if p.state != playerPlay {
return
}
// Change the state first. appendBuffer is called as an 'ended' callback.
for _, n := range p.bufferSourceNodes {
n.Set("onended", nil)
n.Call("stop")
n.Call("disconnect")
}
p.state = playerPaused
p.bufferSourceNodes = p.bufferSourceNodes[:0]
p.nextPos = 0
}
func (p *playerImpl) appendBuffer(this js.Value, args []js.Value) interface{} {
// appendBuffer is called as the 'ended' callback of a buffer.
// 'this' is an AudioBufferSourceNode that already finishes its playing.
for i, n := range p.bufferSourceNodes {
if jsutil.Equal(n, this) {
p.bufferSourceNodes = append(p.bufferSourceNodes[:i], p.bufferSourceNodes[i+1:]...)
break
}
}
if p.state != playerPlay {
return nil
}
if p.eof {
if len(p.bufferSourceNodes) == 0 {
p.Pause()
}
return nil
}
c := p.context.audioContext.Get("currentTime").Float()
if p.nextPos < c {
// The exact current time might be too early. Add some delay on purpose to avoid buffer overlapping.
p.nextPos = c + 1.0/60.0
}
bs := make([]byte, p.context.oneBufferSize())
n, err := io.ReadFull(p.src, bs)
if err != nil {
if err != io.EOF && err != io.ErrUnexpectedEOF {
p.err = err
p.Pause()
return nil
}
p.eof = true
}
if n == 0 {
return nil
}
bs = bs[:n]
l, r := toLR(bs)
tl, tr := float32SliceToTypedArray(l), float32SliceToTypedArray(r)
buf := p.context.audioContext.Call("createBuffer", p.context.channelNum, len(bs)/p.context.channelNum/p.context.bitDepthInBytes, p.context.sampleRate)
if buf.Get("copyToChannel").Truthy() {
buf.Call("copyToChannel", tl, 0, 0)
buf.Call("copyToChannel", tr, 1, 0)
} else {
// copyToChannel is not defined on Safari 11.
buf.Call("getChannelData", 0).Call("set", tl)
buf.Call("getChannelData", 1).Call("set", tr)
}
s := p.context.audioContext.Call("createBufferSource")
s.Set("buffer", buf)
s.Set("onended", p.appendBufferFunc)
s.Call("connect", p.gain)
s.Call("start", p.nextPos)
p.nextPos += buf.Get("duration").Float()
p.bufferSourceNodes = append(p.bufferSourceNodes, s)
return nil
}
func (p *playerImpl) Play() {
if p.state != playerPaused {
return
}
p.state = playerPlay
p.appendBuffer(js.Undefined(), nil)
p.appendBuffer(js.Undefined(), nil)
}
func (p *playerImpl) IsPlaying() bool {
return p.state == playerPlay
}
func (p *playerImpl) Reset() {
if p.state == playerClosed {
return
}
p.Pause()
p.eof = false
}
func (p *playerImpl) Volume() float64 {
return p.gain.Get("gain").Get("value").Float()
}
func (p *playerImpl) SetVolume(volume float64) {
p.gain.Get("gain").Set("value", volume)
}
func (p *playerImpl) UnplayedBufferSize() int64 {
// This is not an accurate buffer size as part of the buffers might already be consumed.
var sec float64
for _, n := range p.bufferSourceNodes {
sec += n.Get("buffer").Get("duration").Float()
}
return int64(sec * float64(p.context.sampleRate*p.context.channelNum*p.context.bitDepthInBytes))
}
func (p *playerImpl) Err() error {
return p.err
}
func (p *playerImpl) Close() error {
runtime.SetFinalizer(p, nil)
p.Reset()
p.state = playerClosed
p.appendBufferFunc.Release()
return nil
}
type go2cppDriverWrapper struct {
c *go2cpp.Context
}
func (w *go2cppDriverWrapper) NewPlayer(r io.Reader) Player {
return w.c.NewPlayer(r)
}
func (w *go2cppDriverWrapper) MaxBufferSize() int {
return w.c.MaxBufferSize()
}
func (w *go2cppDriverWrapper) Close() error {
return w.c.Close()
}
func toLR(data []byte) ([]float32, []float32) {
const max = 1 << 15
l := make([]float32, len(data)/4)
r := make([]float32, len(data)/4)
for i := 0; i < len(data)/4; i++ {
l[i] = float32(int16(data[4*i])|int16(data[4*i+1])<<8) / max
r[i] = float32(int16(data[4*i+2])|int16(data[4*i+3])<<8) / max
}
return l, r
}
func float32SliceToTypedArray(s []float32) js.Value {
h := (*reflect.SliceHeader)(unsafe.Pointer(&s))
h.Len *= 4
h.Cap *= 4
bs := *(*[]byte)(unsafe.Pointer(h))
a := js.Global().Get("Uint8Array").New(len(bs))
js.CopyBytesToJS(a, bs)
runtime.KeepAlive(s)
buf := a.Get("buffer")
return js.Global().Get("Float32Array").New(buf, a.Get("byteOffset"), a.Get("byteLength").Int()/4)
}