ebiten/exp/audio/inner/audio_js.go

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// 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
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package internal
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import (
"github.com/gopherjs/gopherjs/js"
)
func withChannels(f func()) {
f()
}
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// Keep this so as not to be destroyed by GC.
var (
nodes = []*js.Object{}
dummies = []*js.Object{} // Dummy source nodes for iOS.
context *js.Object
)
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const bufferSize = 1024
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type audioProcessor struct {
channel int
}
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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) Process(e *js.Object) {
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// Can't use 'go' here. Probably it may cause race conditions.
b := e.Get("outputBuffer")
l := b.Call("getChannelData", 0)
r := b.Call("getChannelData", 1)
inputL, inputR := toLR(loadChannelBuffer(a.channel, bufferSize*4))
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const max = 1 << 15
for i := 0; i < len(inputL); i++ {
// TODO: Use copyToChannel?
l.SetIndex(i, float64(inputL[i])/max)
r.SetIndex(i, float64(inputR[i])/max)
}
}
func initialize() {
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// Do nothing in node.js.
if js.Global.Get("require") != js.Undefined {
return
}
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class := js.Global.Get("AudioContext")
if class == js.Undefined {
class = js.Global.Get("webkitAudioContext")
}
if class == js.Undefined {
return
}
context = class.New()
// TODO: ScriptProcessorNode will be replaced with Audio WebWorker.
// https://developer.mozilla.org/ja/docs/Web/API/ScriptProcessorNode
for i := 0; i < MaxChannel; i++ {
node := context.Call("createScriptProcessor", bufferSize, 0, 2)
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processor := &audioProcessor{i}
node.Call("addEventListener", "audioprocess", processor.Process)
nodes = append(nodes, node)
dummy := context.Call("createBufferSource")
dummies = append(dummies, dummy)
}
audioEnabled = true
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}
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func start() {
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// Do nothing in node.js.
if js.Global.Get("require") != js.Undefined {
return
}
destination := context.Get("destination")
for i, node := range nodes {
dummy := dummies[i]
dummy.Call("connect", node)
node.Call("connect", destination)
}
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}