make input events consumable

Having a input queue of consumable input events allow widgets to prevent
the further handling of the same event by different collections by
consuming the event.

1 files changed, 74 insertions, 0 deletions

diff --git a/go/ui/update.go b/go/ui/update.go
new file mode 100644
index 00000000..fdb0f19e
--- /dev/null
+++ b/go/ui/update.go
@@ -0,0 +1,74 @@
+package ui
+
+import (
+	"log"
+
+	"github.com/hajimehoshi/ebiten/v2"
+	"github.com/hajimehoshi/ebiten/v2/inpututil"
+)
+
+type InputType int
+
+const (
+	Click InputType = iota + 1
+	Scroll
+	Text
+)
+
+type InputEvent struct {
+	kind InputType
+	x, y int
+	ctx  any
+}
+
+type ClickCtx struct {
+	btn ebiten.MouseButton
+}
+
+type ScrollCtx struct {
+	scrollX, scrollY int
+}
+
+type TextCtx struct {
+	in []rune
+}
+
+// Input queue
+var Input []InputEvent
+
+func consumeInput(i int) {
+	log.Println("consume input", i)
+	if len(Input) == 1 {
+		Input = []InputEvent{}
+	} else {
+		Input[i] = Input[len(Input)-1]
+	}
+}
+
+// Update all ui singletons and collect all occurred input
+func Update() error {
+	Input = []InputEvent{}
+	if err := TouchManager.Update(); err != nil {
+		return err
+	}
+
+	// TODO: make hover detector a singleton
+
+	x, y := ebiten.CursorPosition()
+	scrollX, scrollY := ebiten.Wheel()
+	if scrollX != 0 || scrollY != 0 {
+		Input = append(Input, InputEvent{Scroll, x, y, ScrollCtx{int(scrollX), int(scrollY)}})
+	}
+
+	var in []rune
+	in = ebiten.AppendInputChars(in)
+	if len(in) > 0 {
+		Input = append(Input, InputEvent{Text, x, y, TextCtx{in}})
+	}
+
+	if inpututil.IsMouseButtonJustPressed(ebiten.MouseButtonLeft) {
+		Input = append(Input, InputEvent{Click, x, y, ClickCtx{ebiten.MouseButtonLeft}})
+	}
+
+	return nil
+}