messeji/inputfield.go

package messeji

import (
	"github.com/hajimehoshi/ebiten/v2"
	"github.com/hajimehoshi/ebiten/v2/inpututil"
	"golang.org/x/image/font"
)

// InputField is a text input field. Call Update and Draw when your Game's
// Update and Draw methods are called.
//
// Note: A position and size must be set via SetRect before the field will appear.
// Keyboard events are not handled by default, and may be enabled via SetHandleKeyboard.
type InputField struct {
	*TextField

	// changedFunc is a function which is called when the text buffer is changed.
	// The function may return false to skip adding the rune to the text buffer.
	changedFunc func(r rune) (accept bool)

	// selectedFunc is a function which is called when the enter key is pressed. The
	// function may return true to skip adding a newline to text.
	selectedFunc func() (accept bool)

	// readBuffer is where incoming runes are stored before being added to the input buffer.
	readBuffer []rune
}

// NewInputField returns a new InputField. See type documentation for more info.
func NewInputField(face font.Face) *InputField {
	f := &InputField{
		TextField: NewTextField(face),
	}
	f.TextField.suffix = "_"
	return f
}

// SetHandleKeyboard sets a flag controlling whether keyboard input should be handled
// by the field. This can be used to facilitate focus changes between multiple inputs.
func (f *InputField) SetHandleKeyboard(handle bool) {
	f.Lock()
	defer f.Unlock()

	f.handleKeyboard = handle

	// Show or hide cursor.
	if f.handleKeyboard {
		f.TextField.suffix = "_"
	} else {
		f.TextField.suffix = ""
	}
}

// SetChangedFunc sets a handler which is called when the text buffer is changed.
// The handler may return true to add the rune to the text buffer.
func (f *InputField) SetChangedFunc(changedFunc func(r rune) (accept bool)) {
	f.changedFunc = changedFunc
}

// SetSelectedFunc sets a handler which is called when the enter key is pressed.
// Providing a nil function value will remove the existing handler (if set).
// The handler may return true to skip adding a newline to the text.
func (f *InputField) SetSelectedFunc(selectedFunc func() (accept bool)) {
	f.selectedFunc = selectedFunc
}

// Update updates the input field. This function should be called when
// Game.Update is called.
func (f *InputField) Update() error {
	f.Lock()

	if !f.visible || rectIsZero(f.r) {
		return nil
	}

	if !f.handleKeyboard {
		f.Unlock()
		return f.TextField.Update()
	}

	var redraw bool

	f.readBuffer = ebiten.AppendInputChars(f.readBuffer[:0])
	for _, r := range f.readBuffer {
		if f.changedFunc != nil {
			f.Unlock()
			accept := f.changedFunc(r)
			f.Lock()

			if !accept {
				continue
			}
		}

		f.buffer += string(r)
		redraw = true
	}

	if inpututil.IsKeyJustPressed(ebiten.KeyBackspace) && len(f.buffer) > 0 {
		f.buffer = f.buffer[:len(f.buffer)-1]
		redraw = true
	}

	if inpututil.IsKeyJustPressed(ebiten.KeyEnter) {
		var skipNewline bool
		if f.selectedFunc != nil {
			f.Unlock()
			skipNewline = f.selectedFunc()
			f.Lock()
		}
		if !skipNewline {
			f.buffer += "\n"
			redraw = true
		}
	}

	if redraw {
		f.bufferModified()
	}

	f.Unlock()
	return f.TextField.Update()
}