krampus19/alui/menu.go

package alui

import (
	"opslag.de/schobers/allg5"
)

type Menu struct {
	Column

	OnEscape func()

	active  int
	buttons []*Button
}

func NewMenu() *Menu {
	m := &Menu{}
	m.Init()
	return m
}

func (m *Menu) Activate(i int) {
	if len(m.buttons) == 0 || i < 0 {
		return
	}
	m.active = i % len(m.buttons)
}

func (m *Menu) Add(text string, onClick func()) {
	idx := len(m.buttons)
	button := &Button{Text: text, TextAlign: allg5.AlignCenter}
	button.OnClick = onClick
	button.OnEnter = func() {
		m.updateActiveButton(idx)
	}
	if idx == 0 {
		button.Over = true
	}
	m.buttons = append(m.buttons, button)
	m.AddChild(button)
}

func (m *Menu) Handle(e allg5.Event) {
	m.Column.Handle(e)

	if len(m.buttons) == 0 {
		return
	}

	switch e := e.(type) {
	case *allg5.KeyDownEvent:
		switch e.KeyCode {
		case allg5.KeyEscape:
			if onEscape := m.OnEscape; onEscape != nil {
				onEscape()
			}
		}
	case *allg5.KeyCharEvent:
		switch e.KeyCode {
		case allg5.KeyDown:
			m.updateActiveButton((m.active + 1) % len(m.buttons))
		case allg5.KeyUp:
			m.updateActiveButton((m.active + len(m.buttons) - 1) % len(m.buttons))
		case allg5.KeyEnter:
			if onClick := m.buttons[m.active].OnClick; onClick != nil {
				onClick()
			}
		}
	case *allg5.MouseMoveEvent:
		for i, btn := range m.buttons {
			if btn.Over {
				m.updateActiveButton(i)
				break
			}
		}
		m.updateActiveButton(m.active)
	}
}

func (m *Menu) updateActiveButton(active int) {
	m.active = active
	for i, btn := range m.buttons {
		btn.Over = i == m.active
	}
}