Add internal/hooks to replace internal/audiobinding

audio/audio.go

@@ -44,8 +44,8 @@ import (
 
 	"github.com/hajimehoshi/oto"
 
-	"github.com/hajimehoshi/ebiten/internal/audiobinding"
 	"github.com/hajimehoshi/ebiten/internal/clock"
+	"github.com/hajimehoshi/ebiten/internal/hooks"
 	"github.com/hajimehoshi/ebiten/internal/sync"
 	"github.com/hajimehoshi/ebiten/internal/web"
 )
@@ -155,6 +155,8 @@ type Context struct {
 	initedCh   chan struct{}
 	pingCount  int
 	sampleRate int
+	err        error
+
 	m sync.Mutex
 }
 
@@ -163,6 +165,15 @@ var (
 	theContextLock sync.Mutex
 )
 
+func init() {
+	hooks.AppendHookOnUpdate(func() error {
+		theContext.m.Lock()
+		err := theContext.err
+		theContext.m.Unlock()
+		return err
+	})
+}
+
 // NewContext creates a new audio context with the given sample rate.
 //
 // The sample rate is also used for decoding MP3 with audio/mp3 package
@@ -234,7 +245,7 @@ func (c *Context) loop() {
 	// but there are some known environment that is too short (e.g. Windows on Parallels, iOS).
 	p, err := oto.NewPlayer(c.sampleRate, channelNum, bytesPerSample, 8192)
 	if err != nil {
-		audiobinding.SetError(err)
+		c.err = err
 		return
 	}
 	defer p.Close()
@@ -256,7 +267,7 @@ func (c *Context) loop() {
 
 		const n = 4096
 		if _, err := io.CopyN(p, c.players, n); err != nil {
-			audiobinding.SetError(err)
+			c.err = err
 			return
 		}
 

graphicscontext.go

@@ -17,8 +17,8 @@ package ebiten
 import (
 	"math"
 
-	"github.com/hajimehoshi/ebiten/internal/audiobinding"
 	"github.com/hajimehoshi/ebiten/internal/clock"
+	"github.com/hajimehoshi/ebiten/internal/hooks"
 	"github.com/hajimehoshi/ebiten/internal/restorable"
 	"github.com/hajimehoshi/ebiten/internal/ui"
 	"github.com/hajimehoshi/ebiten/internal/web"
@@ -98,11 +98,6 @@ func drawWithFittingScale(dst *Image, src *Image) {
 }
 
 func (c *graphicsContext) Update(afterFrameUpdate func()) error {
-	select {
-	case err := <-audiobinding.Error():
-		return err
-	default:
-	}
 	updateCount := clock.Update()
 
 	if err := c.initializeIfNeeded(); err != nil {
@@ -111,6 +106,9 @@ func (c *graphicsContext) Update(afterFrameUpdate func()) error {
 	for i := 0; i < updateCount; i++ {
 		restorable.ClearVolatileImages()
 		setRunningSlowly(i < updateCount-1)
+		if err := hooks.Run(); err != nil {
+			return err
+		}
 		if err := c.f(c.offscreen); err != nil {
 			return err
 		}

internal/hooks/hooks.go

@@ -1,4 +1,4 @@
-// Copyright 2017 The Ebiten Authors
+// 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.
@@ -12,14 +12,21 @@
 // See the License for the specific language governing permissions and
 // limitations under the License.
 
-package audiobinding
+package hooks
 
-var ch = make(chan error, 1)
+var onUpdateHooks = []func() error{}
 
-func Error() <-chan error {
-	return ch
+// AppendHookOnUpdate appends a hook function that is run before the main update function
+// every frame.
+func AppendHookOnUpdate(f func() error) {
+	onUpdateHooks = append(onUpdateHooks, f)
 }
 
-func SetError(err error) {
-	ch <- err
+func Run() error {
+	for _, f := range onUpdateHooks {
+		if err := f(); err != nil {
+			return err
+		}
+	}
+	return nil
 }