yay/term.go

package yay

import (
	"log"
	"time"

	"github.com/nsf/termbox-go"
)

func init() {
	log.SetFlags(log.Ldate | log.Ltime | log.Lshortfile)
}

type Animation interface {
	Next() []rune
}

type ViewPort struct {
	viewX, viewY int
	vcenter      int
	hcenter      int

	timeout time.Duration

	animation Animation
}

func NewViewPort(a Animation, to time.Duration) *ViewPort {
	vp := &ViewPort{
		animation: a,
		timeout:   to,
	}
	return vp
}

func (tb *ViewPort) Run() {
	err := termbox.Init()
	if err != nil {
		log.Fatal(err)
	}

	defer termbox.Close()

	tb.viewX, tb.viewY = termbox.Size()
	tb.vcenter = tb.viewY / 2.0
	tb.hcenter = tb.viewX / 2.0

	events := make(chan termbox.Event)
	go func() {
		for {
			events <- termbox.PollEvent()
		}
	}()

	termbox.HideCursor()

	func() {

		tick := time.Tick(tb.timeout)
		for {
			termbox.Clear(termbox.ColorBlack, termbox.ColorBlack)
			tb.draw()
			err := termbox.Flush()
			if err != nil {
				log.Fatal(err)
			}

			select {
			case <-tick:
			case event := <-events:
				switch event.Type {
				case termbox.EventKey:
					switch event.Key {
					case termbox.KeyCtrlZ, termbox.KeyCtrlC:
						log.Printf("exiting ...")
						return
					}

					switch event.Ch {
					case 'q':
						return
					}

				case termbox.EventResize:
					tb.viewX, tb.viewY = event.Width, event.Height
					tb.vcenter = tb.viewY / 2.0
					tb.hcenter = tb.viewX / 2.0
				case termbox.EventError:
					log.Fatalf("Quitting because of termbox error: \n%s\n", event.Err)
				}
			}
		}
	}()
}

func (tb *ViewPort) draw() {
	curFrame := tb.animation.Next()
	width := len(curFrame) / 2
	for i, r := range curFrame {
		termbox.SetCell(
			tb.hcenter-width+i,
			tb.vcenter,
			r,
			termbox.ColorWhite|termbox.AttrBold, termbox.ColorBlack,
		)
	}
}