objects/button.go

package objects

import "git.tebibyte.media/tomo/tomo"
import "git.tebibyte.media/tomo/tomo/input"
import "git.tebibyte.media/tomo/tomo/event"
import "git.tebibyte.media/tomo/objects/layouts"

var buttonLayout     = layouts.Row { true        }
var iconButtonLayout = layouts.Row { true        }
var bothButtonLayout = layouts.Row { false, true }

// Button is a clickable button.
type Button struct {
	tomo.ContainerBox

	label *Label
	icon  *Icon
	labelActive bool
	
	on struct {
		click event.FuncBroadcaster
	}
}

// NewButton creates a new button with the specified text.
func NewButton (text string) *Button {
	box := &Button {
		ContainerBox: tomo.NewContainerBox(),
		label:        NewLabel(text),
	}
	box.SetRole(tomo.R("objects", "Button"))
	box.label.SetAttr(tomo.AAlign(tomo.AlignMiddle, tomo.AlignMiddle))
	box.SetAttr(tomo.ALayout(buttonLayout))
	box.SetText(text)
	
	box.SetInputMask(true)
	box.OnButtonDown(box.handleButtonDown)
	box.OnButtonUp(box.handleButtonUp)
	box.OnKeyDown(box.handleKeyDown)
	box.OnKeyUp(box.handleKeyUp)
	box.SetFocusable(true)
	return box
}

// SetText sets the text of the button's label.
func (this *Button) SetText (text string) {
	this.label.SetText(text)
	if this.labelActive && text == "" {
		this.Remove(this.label)
		this.labelActive = false
	}
	if !this.labelActive && text != "" {
		this.Add(this.label)
		this.labelActive = true
	}
	this.applyLayout()
}

// SetIcon sets an icon for this button. Setting the icon to IconUnknown will
// remove it.
func (this *Button) SetIcon (id tomo.Icon) {
	if this.icon != nil { this.Remove(this.icon) }

	var icon *Icon; if id != tomo.IconUnknown {
		icon = NewIcon(id, tomo.IconSizeSmall)
	}
	this.icon = icon

	if this.icon != nil {
		this.Insert(this.icon, this.label)
	}
	this.applyLayout()
}

// OnClick specifies a function to be called when the button is clicked.
func (this *Button) OnClick (callback func ()) event.Cookie {
	return this.on.click.Connect(callback)
}

func (this *Button) applyLayout () {
	if this.labelActive && this.icon == nil {
		this.SetAttr(tomo.ALayout(buttonLayout))
	} else if !this.labelActive && this.icon != nil {
		this.SetAttr(tomo.ALayout(iconButtonLayout))
	} else {
		this.SetAttr(tomo.ALayout(bothButtonLayout))
	}
}

func (this *Button) handleKeyDown (key input.Key, numberPad bool) bool {
	if key != input.KeyEnter && key != input.Key(' ') { return false }
	return true
}

func (this *Button) handleKeyUp (key input.Key, numberPad bool) bool {
	if key != input.KeyEnter && key != input.Key(' ') { return false }
	this.on.click.Broadcast()
	return true
}

func (this *Button) handleButtonDown (button input.Button) bool {
	if button != input.ButtonLeft { return false }
	return true
}

func (this *Button) handleButtonUp (button input.Button) bool {
	if button != input.ButtonLeft { return false }
	if this.Window().MousePosition().In(this.Bounds()) {
		this.on.click.Broadcast()
	}
	return true
}