check.go

package widget

import (
	"image/color"

	"fyne.io/fyne"
	"fyne.io/fyne/canvas"
	"fyne.io/fyne/theme"
)

type checkRenderer struct {
	icon  *canvas.Image
	label *canvas.Text

	objects []fyne.CanvasObject
	check   *Check
}

// MinSize calculates the minimum size of a check.
// This is based on the contained text, the check icon and a standard amount of padding added.
func (c *checkRenderer) MinSize() fyne.Size {
	min := c.label.MinSize().Add(fyne.NewSize(theme.Padding()*4, theme.Padding()*2))
	min = min.Add(fyne.NewSize(theme.IconInlineSize()+theme.Padding(), 0))

	return min
}

// Layout the components of the check widget
func (c *checkRenderer) Layout(size fyne.Size) {
	offset := fyne.NewSize(theme.IconInlineSize()+theme.Padding(), 0)
	labelSize := size.Subtract(offset)
	c.label.Resize(labelSize)
	c.label.Move(fyne.NewPos(theme.IconInlineSize()+theme.Padding(), 0))

	c.icon.Resize(fyne.NewSize(theme.IconInlineSize(), theme.IconInlineSize()))
	c.icon.Move(fyne.NewPos(0,
		(size.Height-theme.IconInlineSize())/2))
}

// ApplyTheme is called when the Check may need to update it's look
func (c *checkRenderer) ApplyTheme() {
	c.label.Color = theme.TextColor()

	c.Refresh()
}

func (c *checkRenderer) BackgroundColor() color.Color {
	return theme.BackgroundColor()
}

func (c *checkRenderer) Refresh() {
	c.label.Text = c.check.Text

	if c.check.Checked {
		c.icon.Resource = theme.CheckButtonCheckedIcon()
	} else {
		c.icon.Resource = theme.CheckButtonIcon()
	}

	canvas.Refresh(c.check)
}

func (c *checkRenderer) Objects() []fyne.CanvasObject {
	return c.objects
}

func (c *checkRenderer) Destroy() {
}

// Check widget has a text label and a checked (or unchecked) icon and triggers an event func when toggled
type Check struct {
	baseWidget
	Text    string
	Checked bool

	OnChanged func(bool) `json:"-"`
}

// SetChecked sets the the checked state and refreshes widget
func (c *Check) SetChecked(checked bool) {
	if checked == c.Checked {
		return
	}

	c.Checked = checked

	if c.OnChanged != nil {
		c.OnChanged(c.Checked)
	}

	Refresh(c)
}

// Resize sets a new size for a widget.
// Note this should not be used if the widget is being managed by a Layout within a Container.
func (c *Check) Resize(size fyne.Size) {
	c.resize(size, c)
}

// Move the widget to a new position, relative to it's parent.
// Note this should not be used if the widget is being managed by a Layout within a Container.
func (c *Check) Move(pos fyne.Position) {
	c.move(pos, c)
}

// MinSize returns the smallest size this widget can shrink to
func (c *Check) MinSize() fyne.Size {
	return c.minSize(c)
}

// Show this widget, if it was previously hidden
func (c *Check) Show() {
	c.show(c)
}

// Hide this widget, if it was previously visible
func (c *Check) Hide() {
	c.hide(c)
}

// Tapped is called when a pointer tapped event is captured and triggers any change handler
func (c *Check) Tapped(*fyne.PointEvent) {
	c.SetChecked(!c.Checked)
}

// TappedSecondary is called when a secondary pointer tapped event is captured
func (c *Check) TappedSecondary(*fyne.PointEvent) {
}

// CreateRenderer is a private method to Fyne which links this widget to it's renderer
func (c *Check) CreateRenderer() fyne.WidgetRenderer {
	icon := canvas.NewImageFromResource(theme.CheckButtonIcon())

	text := canvas.NewText(c.Text, theme.TextColor())
	text.Alignment = fyne.TextAlignLeading

	return &checkRenderer{icon, text, []fyne.CanvasObject{icon, text}, c}
}

// NewCheck creates a new check widget with the set label and change handler
func NewCheck(label string, changed func(bool)) *Check {
	c := &Check{
		baseWidget{},
		label,
		false,
		changed,
	}

	Renderer(c).Layout(c.MinSize())
	return c
}