Ebitengine tool kit for creating graphical user interfaces
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package etk
import (
"fmt"
"image"
"math"
"github.com/hajimehoshi/ebiten/v2/inpututil"
"github.com/hajimehoshi/ebiten/v2"
)
var root Widget
var (
lastWidth, lastHeight int
lastX, lastY = -math.MaxInt, -math.MaxInt
)
func SetRoot(w Widget) {
root = w
}
func Layout(outsideWidth, outsideHeight int) {
if root == nil {
panic("no root widget specified")
}
if outsideWidth != lastWidth || outsideHeight != lastHeight {
root.SetRect(image.Rect(0, 0, outsideWidth, outsideHeight))
lastWidth, lastHeight = outsideWidth, outsideHeight
}
}
func Update() error {
if root == nil {
panic("no root widget specified")
}
x, y := ebiten.CursorPosition()
cursor := image.Point{x, y}
if lastX == -math.MaxInt && lastY == -math.MaxInt {
lastX, lastY = x, y
}
// TODO handle touch input
var pressed bool
for _, binding := range Bindings.ConfirmMouse {
pressed = ebiten.IsMouseButtonPressed(binding)
if pressed {
break
}
}
var clicked bool
for _, binding := range Bindings.ConfirmMouse {
clicked = inpututil.IsMouseButtonJustReleased(binding)
if clicked {
break
}
}
_, _, err := update(root, cursor, pressed, clicked, false, false)
return err
}
func update(w Widget, cursor image.Point, pressed bool, clicked bool, mouseHandled bool, keyboardHandled bool) (bool, bool, error) {
var err error
children := w.Children()
for _, child := range children {
mouseHandled, keyboardHandled, err = update(child, cursor, pressed, clicked, mouseHandled, keyboardHandled)
if err != nil {
return false, false, err
} else if mouseHandled && keyboardHandled {
return true, true, nil
}
}
if !mouseHandled && cursor.In(w.Rect()) {
_, err = w.HandleMouse(cursor, pressed, clicked)
if err != nil {
return false, false, fmt.Errorf("failed to handle widget mouse input: %s", err)
}
}
if !keyboardHandled {
_, err = w.HandleKeyboard()
if err != nil {
return false, false, fmt.Errorf("failed to handle widget keyboard input: %s", err)
}
}
return mouseHandled, keyboardHandled, nil
}
func Draw(screen *ebiten.Image) error {
if root == nil {
panic("no root widget specified")
}
return draw(root, screen)
}
func draw(w Widget, screen *ebiten.Image) error {
err := w.Draw(screen)
if err != nil {
return fmt.Errorf("failed to draw widget: %s", err)
}
children := w.Children()
for _, child := range children {
err = draw(child, screen)
if err != nil {
return fmt.Errorf("failed to draw widget: %s", err)
}
}
return nil
}