audio: add an additional error information when creating a context

Updates hajimehoshi/oto#93

audio/context.go

@@ -22,6 +22,7 @@ import (
 
 func newContext(sampleRate, channelCount, bitDepthInBytes int) (context, chan struct{}, error) {
 	ctx, ready, err := oto.NewContext(sampleRate, channelCount, bitDepthInBytes)
+	err = addErrorInfoForContextCreation(err)
 	return &contextProxy{ctx}, ready, err
 }
 

audio/error_ios.go

@@ -0,0 +1,53 @@
+// Copyright 2022 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.
+
+//go:build ios
+// +build ios
+
+package audio
+
+// #cgo CFLAGS: -x objective-c
+// #cgo LDFLAGS: -framework UIKit
+//
+// #import <UIKit/UIKit.h>
+//
+// static UIApplicationState applicationState() {
+//   return [[UIApplication sharedApplication] applicationState];
+// }
+import "C"
+
+import (
+	"fmt"
+)
+
+// addErrorInfoForContextCreation adds an additional infomation to the error when creating an audio context.
+// See also hajimehoshi/oto#93.
+func addErrorInfoForContextCreation(err error) error {
+	if err == nil {
+		return nil
+	}
+
+	var state string
+	switch s := C.applicationState(); s {
+	case C.UIApplicationStateActive:
+		state = "active"
+	case C.UIApplicationStateInactive:
+		state = "inactive"
+	case C.UIApplicationStateBackground:
+		state = "background"
+	default:
+		state = fmt.Sprintf("UIApplicationState(%d)", s)
+	}
+	return fmt.Errorf("%w, application state: %s", err, state)
+}

audio/error_notios.go

@@ -0,0 +1,22 @@
+// Copyright 2022 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.
+
+//go:build !ios
+// +build !ios
+
+package audio
+
+func addErrorInfoForContextCreation(err error) error {
+	return err
+}