Fix the event handling model

example/main.go

@@ -62,8 +62,8 @@ func main() {
 
 	drawing := make(chan *graphics.LazyCanvas)
 	go func() {
-		inputStateUpdated := u.ObserveInputStateUpdated()
+		inputStateUpdated := u.InputStateUpdated()
-		screenSizeUpdated := u.ObserveScreenSizeUpdated()
+		screenSizeUpdated := u.ScreenSizeUpdated()
 
 		frameTime := time.Duration(int64(time.Second) / int64(fps))
 		tick := time.Tick(frameTime)
@@ -78,8 +78,9 @@ func main() {
 					if game2, ok := game.(Handler); ok {
 						game2.OnInputStateUpdated(e)
 					}
+				} else {
+					inputStateUpdated = nil
 				}
-				inputStateUpdated = u.ObserveInputStateUpdated()
 			case e, ok := <-screenSizeUpdated:
 				if ok {
 					type Handler interface {
@@ -88,8 +89,9 @@ func main() {
 					if game2, ok := game.(Handler); ok {
 						game2.OnScreenSizeUpdated(e)
 					}
+				} else {
+					screenSizeUpdated = nil
 				}
-				screenSizeUpdated = u.ObserveScreenSizeUpdated()
 			case <-tick:
 				game.Update()
 			case canvas := <-drawing:

graphics/texture_factory.go

@@ -4,6 +4,7 @@ import (
 	"image"
 )
 
+// TODO: Remove this?
 type TextureFactory interface {
 	CreateRenderTarget(width, height int) (RenderTargetId, error)
 	CreateTextureFromImage(img image.Image) (TextureId, error)

ui/cocoa/cocoa.go

@@ -34,10 +34,8 @@ type UI struct {
 	graphicsDevice    *opengl.Device
 	window            unsafe.Pointer
 	initialEventSent  bool
-	inputStateUpdatedChs      chan chan ui.InputStateUpdatedEvent
+	screenSizeUpdated chan ui.ScreenSizeUpdatedEvent // initialized lazily
-	inputStateUpdatedNotified chan ui.InputStateUpdatedEvent
+	inputStateUpdated chan ui.InputStateUpdatedEvent // initialized lazily
-	screenSizeUpdatedChs      chan chan ui.ScreenSizeUpdatedEvent
-	screenSizeUpdatedNotified chan ui.ScreenSizeUpdatedEvent
 }
 
 var currentUI *UI
@@ -51,10 +49,6 @@ func New(screenWidth, screenHeight, screenScale int, title string) *UI {
 		screenHeight:     screenHeight,
 		screenScale:      screenScale,
 		initialEventSent: false,
-		inputStateUpdatedChs:      make(chan chan ui.InputStateUpdatedEvent),
-		inputStateUpdatedNotified: make(chan ui.InputStateUpdatedEvent),
-		screenSizeUpdatedChs:      make(chan chan ui.ScreenSizeUpdatedEvent),
-		screenSizeUpdatedNotified: make(chan ui.ScreenSizeUpdatedEvent),
 	}
 
 	cTitle := C.CString(title)
@@ -75,45 +69,9 @@ func New(screenWidth, screenHeight, screenScale int, title string) *UI {
 		context)
 	currentUI = u
 
-	u.eventLoop()
-
 	return u
 }
 
-func (u *UI) eventLoop() {
-	go func() {
-		inputStateUpdated := []chan ui.InputStateUpdatedEvent{}
-		for {
-			select {
-			case ch := <-u.inputStateUpdatedChs:
-				inputStateUpdated = append(inputStateUpdated, ch)
-			case e := <-u.inputStateUpdatedNotified:
-				for _, ch := range inputStateUpdated {
-					ch <- e
-					close(ch)
-				}
-				inputStateUpdated = inputStateUpdated[0:0]
-			}
-		}
-	}()
-
-	go func() {
-		screenSizeUpdated := []chan ui.ScreenSizeUpdatedEvent{}
-		for {
-			select {
-			case ch := <-u.screenSizeUpdatedChs:
-				screenSizeUpdated = append(screenSizeUpdated, ch)
-			case e := <-u.screenSizeUpdatedNotified:
-				for _, ch := range screenSizeUpdated {
-					ch <- e
-					close(ch)
-				}
-				screenSizeUpdated = []chan ui.ScreenSizeUpdatedEvent{}
-			}
-		}
-	}()
-}
-
 func (u *UI) PollEvents() {
 	C.PollEvents()
 	if !u.initialEventSent {
@@ -123,6 +81,10 @@ func (u *UI) PollEvents() {
 	}
 }
 
+func (u *UI) LoadTextures(map[int]string) {
+	// TODO: Implement
+}
+
 func (u *UI) LoadResources(f func(graphics.TextureFactory)) {
 	C.BeginDrawing(u.window)
 	f(u.graphicsDevice.TextureFactory())
@@ -135,31 +97,37 @@ func (u *UI) Draw(f func(graphics.Canvas)) {
 	C.EndDrawing(u.window)
 }
 
-func (u *UI) ObserveInputStateUpdated() <-chan ui.InputStateUpdatedEvent {
+func (u *UI) ScreenSizeUpdated() <-chan ui.ScreenSizeUpdatedEvent {
-	ch := make(chan ui.InputStateUpdatedEvent)
+	if u.screenSizeUpdated != nil {
-	go func() {
+		return u.screenSizeUpdated
-		u.inputStateUpdatedChs <- ch
+	}
-	}()
+	u.screenSizeUpdated = make(chan ui.ScreenSizeUpdatedEvent)
-	return ch
+	return u.screenSizeUpdated
-}
-
-func (u *UI) notifyInputStateUpdated(e ui.InputStateUpdatedEvent) {
-	go func() {
-		u.inputStateUpdatedNotified <- e
-	}()
-}
-
-func (u *UI) ObserveScreenSizeUpdated() <-chan ui.ScreenSizeUpdatedEvent {
-	ch := make(chan ui.ScreenSizeUpdatedEvent)
-	go func() {
-		u.screenSizeUpdatedChs <- ch
-	}()
-	return ch
 }
 
 func (u *UI) notifyScreenSizeUpdated(e ui.ScreenSizeUpdatedEvent) {
+	if u.screenSizeUpdated == nil {
+		return
+	}
 	go func() {
-		u.screenSizeUpdatedNotified <- e
+		u.screenSizeUpdated <- e
+	}()
+}
+
+func (u *UI) InputStateUpdated() <-chan ui.InputStateUpdatedEvent {
+	if u.inputStateUpdated != nil {
+		return u.inputStateUpdated
+	}
+	u.inputStateUpdated = make(chan ui.InputStateUpdatedEvent)
+	return u.inputStateUpdated
+}
+
+func (u *UI) notifyInputStateUpdated(e ui.InputStateUpdatedEvent) {
+	if u.inputStateUpdated == nil {
+		return
+	}
+	go func() {
+		u.inputStateUpdated <- e
 	}()
 }
 

ui/ui.go

@@ -15,13 +15,14 @@ type InputStateUpdatedEvent struct {
 }
 
 type UIEvents interface {
-	ObserveScreenSizeUpdated() <-chan ScreenSizeUpdatedEvent
+	ScreenSizeUpdated() <-chan ScreenSizeUpdatedEvent
-	ObserveInputStateUpdated() <-chan InputStateUpdatedEvent
+	InputStateUpdated() <-chan InputStateUpdatedEvent
 }
 
 type UI interface {
 	PollEvents()
 	LoadResources(func(graphics.TextureFactory))
+	LoadTextures(map[int]string)
 	Draw(func(graphics.Canvas))
 	UIEvents
 }