ebiten/internal/audio/audio_js.go
2016-02-09 22:55:18 +09:00

109 lines
2.7 KiB
Go

// Copyright 2015 Hajime Hoshi
//
// 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.
// +build js
package audio
import (
"github.com/gopherjs/gopherjs/js"
)
// Keep this as global so as not to be destroyed by GC.
var (
nodes = []*js.Object{}
dummies = []*js.Object{} // Dummy source nodes for iOS.
context *js.Object
)
type audioProcessor struct {
channel int
sampleRate int
position float64
}
var audioProcessors [MaxChannel]*audioProcessor
func toLR(data []byte) ([]int16, []int16) {
l := make([]int16, len(data)/4)
r := make([]int16, len(data)/4)
for i := 0; i < len(data)/4; i++ {
l[i] = int16(data[4*i]) | int16(data[4*i+1])<<8
r[i] = int16(data[4*i+2]) | int16(data[4*i+3])<<8
}
return l, r
}
func (a *audioProcessor) playChunk(buf []byte) {
if len(buf) == 0 {
return
}
const channelNum = 2
const bytesPerSample = channelNum * 16 / 8
b := context.Call("createBuffer", channelNum, len(buf)/bytesPerSample, a.sampleRate)
l := b.Call("getChannelData", 0)
r := b.Call("getChannelData", 1)
il, ir := toLR(buf)
const max = 1 << 15
for i := 0; i < len(il); i++ {
l.SetIndex(i, float64(il[i])/max)
r.SetIndex(i, float64(ir[i])/max)
}
s := context.Call("createBufferSource")
s.Set("buffer", b)
s.Call("connect", context.Get("destination"))
c := context.Get("currentTime").Float()
if a.position < c {
a.position = c
}
s.Call("start", a.position)
a.position += float64(len(il)) / float64(a.sampleRate)
}
func isPlaying(channel int) bool {
c := context.Get("currentTime").Float()
return c < audioProcessors[channel].position
}
func tick() {
const bufferSize = 1024
for _, a := range audioProcessors {
a.playChunk(loadChannelBuffer(a.channel, bufferSize*4))
}
}
func initialize() {
// Do nothing in node.js.
if js.Global.Get("require") != js.Undefined {
return
}
class := js.Global.Get("AudioContext")
if class == js.Undefined {
class = js.Global.Get("webkitAudioContext")
}
if class == js.Undefined {
return
}
context = class.New()
audioEnabled = true
for i := 0; i < len(audioProcessors); i++ {
audioProcessors[i] = &audioProcessor{
channel: i,
sampleRate: 44100, // TODO: Change this for each chunks
position: 0,
}
}
}