ebiten/audio/vorbis/internal/stb/decode.go

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// Copyright 2018 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 stb
import (
"fmt"
"github.com/gopherjs/gopherwasm/js"
)
var flatten = js.Global().Get("window").Call("eval", `(function(arr) {
var ch = arr.length;
var len = arr[0].length;
var result = new Float32Array(ch * len);
for (var j = 0; j < len; j++) {
for (var i = 0; i < ch; i++) {
result[j*ch+i] = arr[i][j];
}
}
return result;
})`)
func init() {
// Eval wasm.js first to set the Wasm binary to Module.
js.Global().Get("window").Call("eval", string(stbvorbis_js))
}
func DecodeVorbis(buf []byte) ([]float32, int, int, error) {
var r js.Value
ch := make(chan struct{})
arr := js.TypedArrayOf(buf)
var f js.Callback
f = js.NewCallback(func(args []js.Value) {
r = args[0]
close(ch)
f.Release()
})
js.Global().Get("stbvorbis").Call("decode", arr).Call("then", f)
arr.Release()
<-ch
if r == js.Null() {
return nil, 0, 0, fmt.Errorf("audio/vorbis/internal/stb: decode failed")
}
channels := r.Get("data").Length()
flattened := flatten.Invoke(r.Get("data"))
data := make([]float32, flattened.Length())
arr = js.TypedArrayOf(data)
arr.Call("set", flattened)
arr.Release()
return data, channels, r.Get("sampleRate").Int(), nil
}