render/event/event.go

package event

import (
	"strings"
)

// State holds the current state of key/mouse events.
type State struct {
	// Mouse buttons.
	Button1 bool // Left
	Button2 bool // Middle
	Button3 bool // Right

	// Special keys
	Escape bool
	Space  bool
	Enter  bool
	Shift  bool
	Ctrl   bool
	Alt    bool
	Up     bool
	Left   bool
	Right  bool
	Down   bool

	// Pressed keys.
	keydown map[string]interface{}

	// Cursor position
	CursorX int
	CursorY int

	// Window resized
	WindowResized bool

	// Touch state
	Touching        bool // A touch event this tick
	TouchNumFingers int
	TouchCenterX    int
	TouchCenterY    int
	GestureRotated  float64
	GesturePinched  float64

	// Will be true if at least one finger is currently still held down on
	// a touch screen. Meaning a FingerDown event happened in the past, but
	// not yet a FingerUp event. If IsFingerDown, you can extrapolate that
	// mouse movement events were actually touch swipes and not a mouse.
	IsFingerDown bool

	// Game controller events.
	// NOTE: for SDL2 you will need to call GameControllerEventState(1)
	// from veandco/go-sdl2/sdl for events to be read by SDL2.
	Controllers map[int]GameController
}

// NewState creates a new event.State.
func NewState() *State {
	return &State{
		keydown:     map[string]interface{}{},
		Controllers: map[int]GameController{},
	}
}

// SetKeyDown sets that a named key is pressed down.
func (s *State) SetKeyDown(name string, down bool) {
	if down {
		s.keydown[name] = nil
	} else {
		delete(s.keydown, name)
	}
}

// KeyDown returns whether a named key is currently pressed.
func (s *State) KeyDown(name string) bool {
	_, ok := s.keydown[name]
	return ok
}

// KeysDown returns a list of all key names currently pressed down.
// Set shifted to True to return the key symbols correctly shifted
// (uppercase, or symbols on number keys, etc.)
func (s *State) KeysDown(shifted bool) []string {
	var (
		result = make([]string, len(s.keydown))
		i      = 0
	)

	for key := range s.keydown {
		if shifted && s.Shift {
			if symbol, ok := shiftMap[key]; ok {
				result[i] = symbol
			} else {
				result[i] = strings.ToUpper(key)
			}
		} else {
			result[i] = key
		}

		i++
	}
	return result
}

// ResetKeyDown clears all key-down states.
func (s *State) ResetKeyDown() {
	s.keydown = map[string]interface{}{}
}

// shiftMap maps keys to their Shift versions.
var shiftMap = map[string]string{
	"`": "~",
	"1": "!",
	"2": "@",
	"3": "#",
	"4": "$",
	"5": "%",
	"6": "^",
	"7": "&",
	"8": "*",
	"9": "(",
	"0": ")",
	"-": "_",
	"=": "+",
	"[": "{",
	"]": "}",
	`\`: "|",
	";": ":",
	`'`: `"`,
	",": "<",
	".": ">",
	"/": "?",
}

// AddController adds a new controller to the event state. This is typically called
// automatically by the render engine, e.g. on an SDL ControllerDeviceEvent.
func (s *State) AddController(index int, v GameController) bool {
	if _, ok := s.Controllers[index]; ok {
		return false
	}
	s.Controllers[index] = v
	return true
}

// RemoveController removes the available controller.
func (s *State) RemoveController(index int) bool {
	if _, ok := s.Controllers[index]; ok {
		delete(s.Controllers, index)
		return true
	}
	return false
}

// GetController gets a registered controller by index.
func (s *State) GetController(index int) (GameController, bool) {
	if c, ok := s.Controllers[index]; ok {
		return c, true
	}
	return nil, false
}