clui/button.go

package clui

import (
	xs "github.com/huandu/xstrings"
	term "github.com/nsf/termbox-go"
	"time"
)

/*
Button is a simpe push button control. Every time a user clicks a Button, it
emits OnClick event. Event has only one valid field Sender.
Button can be clicked with mouse or using space on keyboard while the Button is active.
*/
type Button struct {
	ControlBase
	pressed     bool
	shadowColor term.Attribute

	onClick func(Event)
}

func NewButton(view View, parent Control, width, height int, title string, scale int) *Button {
	b := new(Button)

	b.view = view
	b.parent = parent
	b.align = AlignCenter

	if height == AutoSize {
		height = 4
	}
	if width == AutoSize {
		width = xs.Len(title) + 2 + 1
	}

	if height < 4 {
		height = 4
	}
	if width < 6 {
		width = 6
	}

	b.SetTitle(title)
	b.SetSize(width, height)
	b.SetConstraints(width, height)

	if parent != nil {
		parent.AddChild(b, scale)
	}

	return b
}

func (b *Button) Repaint() {
	x, y := b.Pos()
	w, h := b.Size()
	canvas := b.view.Canvas()
	tm := b.view.Screen().Theme()

	fg, bg := b.fg, b.bg
	shadow := RealColor(tm, b.shadowColor, ColorControlShadow)
	if !b.Enabled() {
		fg, bg = RealColor(tm, fg, ColorControlDisabledText), RealColor(tm, bg, ColorControlDisabledBack)
	} else if b.Active() {
		fg, bg = RealColor(tm, b.fgActive, ColorControlActiveText), RealColor(tm, b.bgActive, ColorControlActiveBack)
	} else {
		fg, bg = RealColor(tm, fg, ColorControlText), RealColor(tm, bg, ColorControlBack)
	}

	dy := int((h - 1) / 2)
	shift, text := AlignText(b.title, w-1, b.align)
	if !b.pressed {
		canvas.FillRect(x+1, y+1, w-1, h-1, term.Cell{Ch: ' ', Bg: shadow})
		canvas.FillRect(x, y, w-1, h-1, term.Cell{Ch: ' ', Bg: bg})
		canvas.PutText(x+shift, y+dy, text, fg, bg)
	} else {
		canvas.FillRect(x+1, y+1, w-1, h-1, term.Cell{Ch: ' ', Bg: bg})
		canvas.PutText(x+1+shift, y+1+dy, b.title, fg, bg)
	}
}

func (b *Button) ProcessEvent(event Event) bool {
	if (!b.active && event.Type == EventKey) || !b.Enabled() || b.pressed {
		return false
	}

	if (event.Type == EventKey && event.Key == term.KeySpace) || event.Type == EventMouse {
		b.pressed = true
		timer := time.NewTimer(time.Millisecond * 150)
		go func() {
			<-timer.C
			b.pressed = false
			// generate ButtonClickEvent
			if b.parent != nil {
				if b.onClick != nil {
					ev := Event{Sender: b}
					b.onClick(ev)
				}

				ev := Event{Type: EventRedraw, Sender: b}
				b.view.Screen().PutEvent(ev)
			}
		}()
		return true
	}

	return false
}

func (b *Button) OnClick(fn func(Event)) {
	b.onClick = fn
}