ui: event handlers

internal/ui/window.go

@@ -4,6 +4,7 @@ import (
 	"flag"
 
 	"github.com/hajimehoshi/ebiten"
+	"github.com/hajimehoshi/ebiten/inpututil"
 )
 
 var (
@@ -12,8 +13,9 @@ var (
 )
 
 type Window struct {
-	Title            string
-	KeyEventHandlers map[ebiten.Key][]func()
+	Title             string
+	KeyUpHandlers     map[ebiten.Key]func()
+	MouseWheelHandler func(float64, float64)
 
 	// User-provided update actions
 	updateFn func() error
@@ -25,13 +27,18 @@ type Window struct {
 // ebiten assumes a single window, so only call this once...
 func NewWindow(title string) (*Window, error) {
 	return &Window{
-		Title:            title,
-		KeyEventHandlers: make(map[ebiten.Key][]func()),
+		Title:         title,
+		KeyUpHandlers: make(map[ebiten.Key]func()),
 	}, nil
 }
 
+// TODO: multiple handlers for the same key?
 func (w *Window) OnKeyUp(key ebiten.Key, f func()) {
+	w.KeyUpHandlers[key] = f
+}
 
+func (w *Window) OnMouseWheel(f func(x, y float64)) {
+	w.MouseWheelHandler = f
 }
 
 func (w *Window) run(screen *ebiten.Image) error {
@@ -40,6 +47,20 @@ func (w *Window) run(screen *ebiten.Image) error {
 	}
 
 	// Process keys
+	// TODO: efficient set operations
+
+	for key, cb := range w.KeyUpHandlers {
+		if inpututil.IsKeyJustReleased(key) {
+			cb()
+		}
+	}
+
+	if w.MouseWheelHandler != nil {
+		x, y := ebiten.Wheel()
+		if x != 0 || y != 0 {
+			w.MouseWheelHandler(x, y)
+		}
+	}
 
 	if !ebiten.IsDrawingSkipped() {
 		if err := w.drawFn(screen); err != nil {