etk/game.go

package etk

import (
	"fmt"
	"image"
	"math"

	"github.com/hajimehoshi/ebiten/v2/inpututil"

	"github.com/hajimehoshi/ebiten/v2"
)

var root Widget

var (
	lastWidth, lastHeight int

	lastX, lastY = -math.MaxInt, -math.MaxInt
)

func SetRoot(w Widget) {
	root = w
}

func Layout(outsideWidth, outsideHeight int) {
	if root == nil {
		panic("no root widget specified")
	}

	if outsideWidth != lastWidth || outsideHeight != lastHeight {
		root.SetRect(image.Rect(0, 0, outsideWidth, outsideHeight))
		lastWidth, lastHeight = outsideWidth, outsideHeight
	}
}

func Update() error {
	if root == nil {
		panic("no root widget specified")
	}

	x, y := ebiten.CursorPosition()
	cursor := image.Point{x, y}

	if lastX == -math.MaxInt && lastY == -math.MaxInt {
		lastX, lastY = x, y
	}

	// TODO handle touch input

	var pressed bool
	for _, binding := range Bindings.ConfirmMouse {
		pressed = ebiten.IsMouseButtonPressed(binding)
		if pressed {
			break
		}
	}

	var clicked bool
	for _, binding := range Bindings.ConfirmMouse {
		clicked = inpututil.IsMouseButtonJustReleased(binding)
		if clicked {
			break
		}
	}

	_, _, err := update(root, cursor, pressed, clicked, false, false)
	return err
}

func update(w Widget, cursor image.Point, pressed bool, clicked bool, mouseHandled bool, keyboardHandled bool) (bool, bool, error) {
	var err error
	children := w.Children()
	for _, child := range children {
		mouseHandled, keyboardHandled, err = update(child, cursor, pressed, clicked, mouseHandled, keyboardHandled)
		if err != nil {
			return false, false, err
		} else if mouseHandled && keyboardHandled {
			return true, true, nil
		}
	}
	if !mouseHandled && cursor.In(w.Rect()) {
		_, err = w.HandleMouse(cursor, pressed, clicked)
		if err != nil {
			return false, false, fmt.Errorf("failed to handle widget mouse input: %s", err)
		}
	}
	if !keyboardHandled {
		_, err = w.HandleKeyboard()
		if err != nil {
			return false, false, fmt.Errorf("failed to handle widget keyboard input: %s", err)
		}
	}
	return mouseHandled, keyboardHandled, nil
}

func Draw(screen *ebiten.Image) error {
	if root == nil {
		panic("no root widget specified")
	}

	return draw(root, screen)
}

func draw(w Widget, screen *ebiten.Image) error {
	err := w.Draw(screen)
	if err != nil {
		return fmt.Errorf("failed to draw widget: %s", err)
	}

	children := w.Children()
	for _, child := range children {
		err = draw(child, screen)
		if err != nil {
			return fmt.Errorf("failed to draw widget: %s", err)
		}
	}

	return nil
}