Brought in screen manager, minor refactor.

screenmanager/manager.go

@@ -0,0 +1,136 @@
+package screenmanager
+
+import (
+	"mover/gamedata"
+	"mover/screens"
+
+	"github.com/hajimehoshi/ebiten/v2"
+)
+
+const (
+	defaultWidth  = 1024
+	defaultHeight = 768
+)
+
+type Manager struct {
+	Info           gamedata.GameInfo
+	currentScene   screens.Screen
+	currentSceneId uint
+	nextSceneId    uint
+	screens        []screens.Screen
+	internalerr    error
+}
+
+// can be used to create default manager instance
+func NewManager() Manager {
+	return Manager{
+		Info: gamedata.GameInfo{
+			Name:    "survive",
+			Version: "0.12",
+			Dimensions: gamedata.Area{
+				Width:  defaultWidth,
+				Height: defaultHeight,
+			},
+		},
+		currentSceneId: 0,
+		nextSceneId:    1,
+		internalerr:    nil,
+	}
+}
+
+// ebitengine update proxy on behalf of current scene
+func (m *Manager) Update() error {
+	if m.currentScene == nil {
+		return nil
+	}
+
+	err := m.currentScene.Update()
+	if err != nil {
+		return err
+	}
+
+	return m.internalerr
+}
+
+// shutdown application
+func (m *Manager) Quit() {
+	m.internalerr = ebiten.Termination
+}
+
+// calls current scene's draw method if the currentscene is valid
+func (m *Manager) Draw(screen *ebiten.Image) {
+	if m.currentScene != nil {
+		m.currentScene.Draw(screen)
+	}
+}
+
+// ebitengine proxy for layout
+func (m *Manager) Layout(outsideWidth, outsideHeight int) (screenWidth, screenHeight int) {
+	return m.Info.Dimensions.Width, m.Info.Dimensions.Height
+}
+
+// appends scene to the managed screens
+func (m *Manager) AddScene(s screens.Screen) {
+	setDefaultHandlers(m, s)
+	s.SetDimensions(m.Info.Dimensions)
+	m.screens = append(m.screens, s)
+}
+
+// sets the default callback handlers for a given scene within manager
+// Default Handling behaviours:
+//
+//	reset: sets (scene, nextscene) to {0, 1}
+//	scene completion: sets (scene, nextscene) to {nextscene, nextscene+1}
+//	end game: shutdown groovy
+//
+//	note: NOOP and RELOAD are purposefully not mapped; they are scene
+//	specific and should be mapped to by user of groovy
+func setDefaultHandlers(m *Manager, s screens.Screen) {
+	s.SetEventHandler(screens.EventReset, func() { m.ResetScenes() })
+	s.SetEventHandler(screens.EventCompleted, func() { m.TransitionScene() })
+	s.SetEventHandler(screens.EventEndgame, func() { m.Quit() })
+}
+
+// we're going to reset the scene to the first one
+func (m *Manager) ResetScenes() {
+	m.currentSceneId = 0
+	m.nextSceneId = 1
+	m.SetCurrentScene(0)
+}
+
+// sets the current scene, based on sceneindex n
+// n > scenelist, quit
+// otherwise, scene = n
+func (m *Manager) SetCurrentScene(sceneId uint) {
+	if sceneId >= uint(len(m.screens)) {
+		m.Quit()
+	} else {
+		m.currentSceneId = sceneId
+		m.currentScene = m.screens[sceneId]
+		m.nextSceneId = m.currentSceneId + 1
+	}
+}
+
+// handle scene transition
+func (m *Manager) TransitionScene() {
+	m.SetCurrentScene(m.nextSceneId)
+}
+
+// set new sceneId as the successor
+func (m *Manager) SetNextScene(sceneId uint) {
+	m.nextSceneId = sceneId
+}
+
+// sets sene dimensions
+func (m *Manager) SetDimensions(a gamedata.Area) {
+	m.Info.Dimensions = a
+}
+
+// report number of total screens
+func (m *Manager) SceneCount() uint {
+	return uint(len(m.screens))
+}
+
+func (m *Manager) GetScene(sceneId uint) screens.Screen {
+	return m.screens[sceneId]
+}