keyboard-layer-display/main.go

package main

import (
	"errors"
	"log"
	"os"
	"strconv"
	"sync"

	"fyne.io/fyne/v2"
	"fyne.io/fyne/v2/app"
	"fyne.io/fyne/v2/canvas"
	"fyne.io/fyne/v2/container"
	"fyne.io/fyne/v2/driver/desktop"
	"golang.design/x/hotkey"
)

type Layer struct {
	Hotkey hotkey.Key
	Image  *canvas.Image
}

var keymap = map[string]hotkey.Key{
	"KeyF13": hotkey.KeyF13,
	"KeyF14": hotkey.KeyF14,
	"KeyF15": hotkey.KeyF15,
	"KeyF16": hotkey.KeyF16,
	"KeyF17": hotkey.KeyF17,
}

func main() {
	userConfigDir, _ := os.UserConfigDir()
	appConfigDir := userConfigDir + "/keyboard-layer-display"
	imageDir := appConfigDir + "/layers"
	log.Println(imageDir)
	os.MkdirAll(imageDir, 0755)

	a := app.New()
	w := a.NewWindow("SysTray")

	icon, _ := fyne.LoadResourceFromPath("./keyboard.svg")

	if desk, ok := a.(desktop.App); ok {
		m := fyne.NewMenu("MyApp",
			fyne.NewMenuItem("Show", func() {
				w.Show()
			}))
		desk.SetSystemTrayMenu(m)
		desk.SetSystemTrayIcon(icon)
	}
	w.Resize(fyne.Size{
		Width:  1656 / 2,
		Height: 546 / 2,
	})

	defaultImage := canvas.NewImageFromFile(imageDir + "/default.png")
	w.SetContent(container.NewPadded(defaultImage))

	w.SetCloseIntercept(func() {
		w.Hide()
	})

	layers := []Layer{}
	for i := range 5 {
		imagePath := imageDir + "/layer_" + strconv.Itoa(i+1) + ".png"
		if _, err := os.Stat(imagePath); errors.Is(err, os.ErrNotExist) {
			continue
		}

		newLayer := Layer{
			Image:  canvas.NewImageFromFile(imagePath),
			Hotkey: keymap["KeyF"+strconv.Itoa(13+i)],
		}

		layers = append(layers, newLayer)
	}

	go func() {
		wg := sync.WaitGroup{}
		wg.Add(len(layers))

		for _, v := range layers {
			go func() {
				defer wg.Done()

				log.Printf("Registering %+v", v)

				err := listenHotkey(
					func() { w.SetContent(container.NewPadded(v.Image)) },
					func() { w.SetContent(container.NewPadded(defaultImage)) },
					v.Hotkey,
				)
				if err != nil {
					log.Println(err)
					return
				}
			}()
		}
		wg.Wait()
	}()

	w.ShowAndRun()
}

func listenHotkey(downfn func(), upfn func(), key hotkey.Key, mods ...hotkey.Modifier) (err error) {
	ms := []hotkey.Modifier{}
	ms = append(ms, mods...)
	hk := hotkey.New(ms, key)

	err = hk.Register()
	if err != nil {
		return
	}

	for {
		select {
		case <-hk.Keyup():
			go upfn()
		case <-hk.Keydown():
			go downfn()
		}
	}
}