groovy/examples/splashmenu/scenes/menu.go

package splashmenu

import (
	"cosmos/diego/groovy"
	"image/color"
	"log"
	"math"
	"strconv"

	"github.com/hajimehoshi/ebiten/v2"
	"github.com/hajimehoshi/ebiten/v2/examples/resources/fonts"
	"github.com/hajimehoshi/ebiten/v2/inpututil"
	"github.com/hajimehoshi/ebiten/v2/text"
	"golang.org/x/image/font"
	"golang.org/x/image/font/opentype"
)

var (
	titleFont           font.Face
	menuFont            font.Face
	backgroundBaseColor color.RGBA
)

func init() {

	backgroundBaseColor = color.RGBA{0x33, 0x33, 0x99, 0xFF}

	tt, err := opentype.Parse(fonts.PressStart2P_ttf)
	if err != nil {
		log.Fatal(err)
	}

	const dpi = 72
	titleFont, err = opentype.NewFace(tt, &opentype.FaceOptions{
		Size:    16,
		DPI:     dpi,
		Hinting: font.HintingVertical,
	})
	if err != nil {
		log.Fatal(err)
	}

	menuFont, err = opentype.NewFace(tt, &opentype.FaceOptions{
		Size:    10,
		DPI:     dpi,
		Hinting: font.HintingVertical,
	})
	if err != nil {
		log.Fatal(err)
	}
}

type Menu struct {
	bgcolor   color.RGBA
	increment int
	options   map[int]MenuOption
	events    map[groovy.SceneEvent]func()
}

func NewMenu() Menu {
	return Menu{
		bgcolor: backgroundBaseColor,
		events:  make(map[groovy.SceneEvent]func()),
	}
}

func (m *Menu) Draw(screen *ebiten.Image) {
	screen.Fill(m.bgcolor)
	text.Draw(screen, "menu", titleFont, 40, 40, color.White)

	bgcolor := " 0x" + strconv.FormatUint(uint64(m.bgcolor.R), 16) + " 0x" + strconv.FormatUint(uint64(m.bgcolor.G), 16) + " 0x" + strconv.FormatUint(uint64(m.bgcolor.B), 16)

	text.Draw(screen, bgcolor, menuFont, 40, 700, color.White)
	m.RenderOptions(screen)
}

func (m Menu) SetEventHandler(event groovy.SceneEvent, f func()) {
	m.events[event] = f
}

func (m *Menu) SetOptions(options map[int]MenuOption) {
	m.options = make(map[int]MenuOption)

	for k, v := range options {
		m.options[k] = v
	}
}

func (m *Menu) RenderOptions(screen *ebiten.Image) {

	var offset int = 20

	for k, v := range m.options {
		m.options[k] = v
		text.Draw(screen, strconv.Itoa(k)+": "+v.Description, menuFont, 40, 60+offset*k, color.White)
	}

}

func (m *Menu) Update() error {
	m.increment++

	var keysPressed []ebiten.Key
	keysPressed = inpututil.AppendPressedKeys(keysPressed[:0])

	for _, o := range m.options {
		if m.events[o.SelectionEvent] != nil {
			for _, k := range keysPressed {
				if k == o.Mapping {
					m.events[o.SelectionEvent]()
				}
			}
		}
	}

	colorOffset := uint8(int(math.Sin(float64(m.increment)/300) * 6))

	m.bgcolor.R = (colorOffset + backgroundBaseColor.R) % 0xFF
	m.bgcolor.G = (colorOffset + backgroundBaseColor.G) % 0xFF
	m.bgcolor.B = (colorOffset + backgroundBaseColor.B) % 0xFF

	return nil
}