regHotkey.go

// HOTKEYS to listen to
var HOTKEYS = map[int16]*Hotkey{
	1: &Hotkey{4, ModAlt + ModCtrl, 'D'},
}

const (
	ModAlt = 1 << iota
	ModCtrl
	ModShift
	ModWin
)

//Hotkey ..
type Hotkey struct {
	ID        int // Unique id
	Modifiers int // Mask of modifiers
	KeyCode   int // Key code, e.g. 'A'
}

// In order for fmt.Println to give us a human friendly display of the hotkey, 
// we provide a custom String() function to the Hotkey struc
// such as "Hotkey[Id: 1, Alt+Ctrl+O]"
func (h *Hotkey) String() string {
	mod := &bytes.Buffer{}
	if h.Modifiers&ModAlt != 0 {
		mod.WriteString("Alt+")
	}
	if h.Modifiers&ModCtrl != 0 {
		mod.WriteString("Ctrl+")
	}
	if h.Modifiers&ModShift != 0 {
		mod.WriteString("Shift+")
	}
	if h.Modifiers&ModWin != 0 {
		mod.WriteString("Win+")
	}
	return fmt.Sprintf("Hotkey[Id: %d, %s%c]", h.ID, mod, h.KeyCode)
}

func registerHotkeys(user32 *syscall.DLL) {

	reghotkey := user32.MustFindProc("RegisterHotKey") // https://docs.microsoft.com/en-us/windows/win32/api/winuser/nf-winuser-registerhotkey

	// Register hotkeys:
	for _, v := range HOTKEYS {
		r1, _, err := reghotkey.Call(
			0, uintptr(v.ID), uintptr(v.Modifiers), uintptr(v.KeyCode))
		if r1 == 1 {
			fmt.Println("Registered", v)
		} else {
			fmt.Println("Failed to register", v, ", error:", err)
		}
	}
}