/
context.go
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/
context.go
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// Copyright 2019 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 audio
import (
"io"
"sync"
"github.com/hajimehoshi/oto"
"github.com/hajimehoshi/ebiten/internal/hooks"
)
type context interface {
NewPlayer() io.WriteCloser
io.Closer
}
var contextForTesting context
type otoContext struct {
sampleRate int
initCh <-chan struct{}
c *oto.Context
once sync.Once
}
func (c *otoContext) NewPlayer() io.WriteCloser {
return &otoPlayer{c: c}
}
func (c *otoContext) Close() error {
if c.c == nil {
return nil
}
return c.c.Close()
}
func (c *otoContext) ensureContext() error {
var err error
c.once.Do(func() {
<-c.initCh
c.c, err = oto.NewContext(c.sampleRate, channelNum, bytesPerSample/channelNum, bufferSize())
})
return err
}
type otoPlayer struct {
c *otoContext
p *oto.Player
once sync.Once
}
func (p *otoPlayer) Write(buf []byte) (int, error) {
// Initialize oto.Player lazily to enable calling NewContext in an 'init' function.
// Accessing oto.Player functions requires the environment to be already initialized,
// but if Ebiten is used for a shared library, the timing when init functions are called
// is unexpectable.
// e.g. a variable for JVM on Android might not be set.
if err := p.ensurePlayer(); err != nil {
return 0, err
}
return p.p.Write(buf)
}
func (p *otoPlayer) Close() error {
if p.p == nil {
return nil
}
return p.p.Close()
}
func (p *otoPlayer) ensurePlayer() error {
if err := p.c.ensureContext(); err != nil {
return err
}
p.once.Do(func() {
p.p = p.c.c.NewPlayer()
})
return nil
}
func newContext(sampleRate int) context {
if contextForTesting != nil {
return contextForTesting
}
ch := make(chan struct{})
var once sync.Once
hooks.AppendHookOnBeforeUpdate(func() error {
once.Do(func() {
close(ch)
})
return nil
})
return &otoContext{
sampleRate: sampleRate,
initCh: ch,
}
}
type hook interface {
OnSuspendAudio(f func())
OnResumeAudio(f func())
AppendHookOnBeforeUpdate(f func() error)
}
var hookForTesting hook
func getHook() hook {
if hookForTesting != nil {
return hookForTesting
}
return &hookImpl{}
}
type hookImpl struct{}
func (h *hookImpl) OnSuspendAudio(f func()) {
hooks.OnSuspendAudio(f)
}
func (h *hookImpl) OnResumeAudio(f func()) {
hooks.OnResumeAudio(f)
}
func (h *hookImpl) AppendHookOnBeforeUpdate(f func() error) {
hooks.AppendHookOnBeforeUpdate(f)
}