audio: Use a null context on go2cpp

audio/context_js.go

@@ -0,0 +1,58 @@
+// Copyright 2020 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"
+	"syscall/js"
+	"time"
+)
+
+type nullContext struct {
+	sampleRate int
+}
+
+type nullPlayer struct {
+	sampleRate int
+}
+
+func (c *nullContext) NewPlayer() io.WriteCloser {
+	return &nullPlayer{
+		sampleRate: c.sampleRate,
+	}
+}
+
+func (c *nullContext) Close() error {
+	return nil
+}
+
+func (p *nullPlayer) Write(data []byte) (int, error) {
+	time.Sleep(time.Second * time.Duration(len(data)) / time.Duration(p.sampleRate*4))
+	return len(data), nil
+}
+
+func (p *nullPlayer) Close() error {
+	return nil
+}
+
+func newContextImpl(sampleRate int, initCh chan struct{}) context {
+	if js.Global().Get("go2cpp").Truthy() {
+		return &nullContext{
+			sampleRate: sampleRate,
+		}
+	}
+
+	return newOtoContext(sampleRate, initCh)
+}

audio/context_notjs.go

@@ -0,0 +1,21 @@
+// Copyright 2020 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.
+
+// +build !js
+
+package audio
+
+func newContextImpl(sampleRate int, initCh chan struct{}) context {
+	return newOtoContext(sampleRate, initCh)
+}

otocontext.go

@@ -21,7 +21,7 @@ import (
 	"github.com/hajimehoshi/oto"
 )
 
-func newContextImpl(sampleRate int, initCh chan struct{}) context {
+func newOtoContext(sampleRate int, initCh chan struct{}) *otoContext {
 	return &otoContext{
 		sampleRate: sampleRate,
 		initCh:     initCh,