Button now removes its label if it is empty

button.go

@@ -7,13 +7,17 @@ import "git.tebibyte.media/tomo/tomo/event"
 import "git.tebibyte.media/tomo/objects/layouts"
 
 var buttonLayout     = layouts.NewGrid([]bool { true        }, []bool { true })
-var iconButtonLayout = layouts.NewGrid([]bool { false, true }, []bool { true })
+var iconButtonLayout = layouts.NewGrid([]bool { false       }, []bool { true })
+var bothButtonLayout = layouts.NewGrid([]bool { false, true }, []bool { true })
 
 // Button is a clickable button.
 type Button struct {
 	tomo.ContainerBox
+
 	label *Label
 	icon  *Icon
+	labelActive bool
+	
 	on struct {
 		click event.FuncBroadcaster
 	}
@@ -27,8 +31,8 @@ func NewButton (text string) *Button {
 	}
 	theme.Apply(box, theme.R("objects", "Button", ""))
 	box.label.SetAlign(tomo.AlignMiddle, tomo.AlignMiddle)
-	box.Add(box.label)
 	box.SetLayout(buttonLayout)
+	box.SetText(text)
 	
 	box.CaptureDND(true)
 	box.CaptureMouse(true)
@@ -44,20 +48,31 @@ func NewButton (text string) *Button {
 // SetText sets the text of the button's label.
 func (this *Button) SetText (text string) {
 	this.label.SetText(text)
+	if this.labelActive && text == "" {
+		this.Delete(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.
-// TODO: use tomo.Icon instead, use small size icons
-func (this *Button) SetIcon (icon *Icon) {
+// SetIcon sets an icon for this button. Setting the icon to IconUnknown will
+// remove it.
+func (this *Button) SetIcon (id theme.Icon) {
 	if this.icon != nil { this.Delete(this.icon) }
+
+	var icon *Icon; if id != theme.IconUnknown {
+		icon = NewIcon(id, theme.IconSizeSmall)
+	}
 	this.icon = icon
 
-	if this.icon == nil {
-		this.SetLayout(buttonLayout)
-	} else {
-		this.SetLayout(iconButtonLayout)
+	if this.icon != nil {
 		this.Insert(this.icon, this.label)
 	}
+	this.applyLayout()
 }
 
 // OnClick specifies a function to be called when the button is clicked.
@@ -65,6 +80,16 @@ 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.SetLayout(buttonLayout)
+	} else if !this.labelActive && this.icon != nil {
+		this.SetLayout(iconButtonLayout)
+	} else {
+		this.SetLayout(bothButtonLayout)
+	}
+}
+
 func (this *Button) handleKeyUp (key input.Key, numberPad bool) {
 	if key != input.KeyEnter && key != input.Key(' ') { return }
 	this.on.click.Broadcast()

checkbox.go

@@ -0,0 +1,69 @@
+package objects
+
+import "git.tebibyte.media/tomo/tomo"
+import "git.tebibyte.media/tomo/tomo/theme"
+import "git.tebibyte.media/tomo/tomo/input"
+import "git.tebibyte.media/tomo/tomo/event"
+
+// Checkbox is a control that can be toggled.
+type Checkbox struct {
+	tomo.Box
+	value bool
+	on struct {
+		valueChange event.FuncBroadcaster
+	}
+}
+
+// NewCheckbox creates a new checkbox with the specified value.
+func NewCheckbox (value bool) *Checkbox {
+	box := &Checkbox {
+		Box: tomo.NewBox(),
+	}
+	theme.Apply(box, theme.R("objects", "Checkbox", ""))
+	box.SetValue(false)
+	
+	box.OnMouseUp(box.handleMouseUp)
+	box.OnKeyUp(box.handleKeyUp)
+	box.SetFocusable(true)
+	return box
+}
+
+// SetValue sets the value of the checkbox.
+func (this *Checkbox) SetValue (value bool) {
+	this.value = value
+	if this.value {
+		// TODO perhaps have IconStatusOkay/Cancel in actions, and have
+		// a status icon for checked checkboxes.
+		this.SetTexture(theme.IconStatusOkay.Texture(theme.IconSizeSmall))
+	} else {
+		this.SetTexture(nil)
+	}
+}
+
+// Toggle toggles the value of the checkbox between true and false.
+func (this *Checkbox) Toggle () {
+	this.SetValue(!this.Value())
+}
+
+// Value returns the value of the checkbox.
+func (this *Checkbox) Value () bool {
+	return this.value
+}
+
+// OnValueChange specifies a function to be called when the checkbox's value
+// changes.
+func (this *Checkbox) OnValueChange (callback func ()) event.Cookie {
+	return this.on.valueChange.Connect(callback)
+}
+
+func (this *Checkbox) handleKeyUp (key input.Key, numberPad bool) {
+	if key != input.KeyEnter && key != input.Key(' ') { return }
+	this.Toggle()
+}
+
+func (this *Checkbox) handleMouseUp (button input.Button) {
+	if button != input.ButtonLeft { return }
+	if this.MousePosition().In(this.Bounds()) {
+		this.Toggle()
+	}
+}

go.mod

@@ -2,6 +2,6 @@ module git.tebibyte.media/tomo/objects
 
 go 1.20
 
-require git.tebibyte.media/tomo/tomo v0.29.0
+require git.tebibyte.media/tomo/tomo v0.31.0
 
 require golang.org/x/image v0.11.0 // indirect

go.sum

@@ -1,5 +1,5 @@
-git.tebibyte.media/tomo/tomo v0.29.0 h1:uvdPaEQYcWH965y85SjIKwhLklnTbs+x6MRwLfdRvfo=
-git.tebibyte.media/tomo/tomo v0.29.0/go.mod h1:C9EzepS9wjkTJjnZaPBh22YvVPyA4hbBAJVU20Rdmps=
+git.tebibyte.media/tomo/tomo v0.31.0 h1:LHPpj3AWycochnC8F441aaRNS6Tq6w6WnBrp/LGjyhM=
+git.tebibyte.media/tomo/tomo v0.31.0/go.mod h1:C9EzepS9wjkTJjnZaPBh22YvVPyA4hbBAJVU20Rdmps=
 github.com/yuin/goldmark v1.4.13/go.mod h1:6yULJ656Px+3vBD8DxQVa3kxgyrAnzto9xy5taEt/CY=
 golang.org/x/crypto v0.0.0-20190308221718-c2843e01d9a2/go.mod h1:djNgcEr1/C05ACkg1iLfiJU5Ep61QUkGW8qpdssI0+w=
 golang.org/x/crypto v0.0.0-20210921155107-089bfa567519/go.mod h1:GvvjBRRGRdwPK5ydBHafDWAxML/pGHZbMvKqRZ5+Abc=

icon.go

@@ -31,16 +31,6 @@ func NewMimeIcon (mime data.Mime, size theme.IconSize) *Icon {
 	return this
 }
 
-// NewApplicationIcon creates a new icon from an application description.
-func NewApplicationIcon (id theme.ApplicationIcon, size theme.IconSize) *Icon {
-	this := &Icon {
-		Box: tomo.NewBox(),
-	}
-	theme.Apply(this, theme.R("objects", "Icon", size.String()))
-	this.SetTexture(id.Texture(size))
-	return this
-}
-
 func (this *Icon) SetTexture (texture canvas.Texture) {
 	this.Box.SetTexture(texture)
 	if texture == nil {

input.go

@@ -13,6 +13,7 @@ type TextInput struct {
 	text []rune
 	on struct {
 		enter event.FuncBroadcaster
+		edit  event.FuncBroadcaster
 	}
 }
 
@@ -20,6 +21,7 @@ type TextInput struct {
 func NewTextInput (text string) *TextInput {
 	this := &TextInput { TextBox: tomo.NewTextBox() }
 	theme.Apply(this, theme.R("objects", "TextInput", ""))
+	this.SetAlign(tomo.AlignStart, tomo.AlignMiddle)
 	this.SetText(text)
 	this.SetFocusable(true)
 	this.SetSelectable(true)
@@ -46,6 +48,11 @@ func (this *TextInput) OnEnter (callback func ()) event.Cookie {
 	return this.on.enter.Connect(callback)
 }
 
+// OnEdit specifies a function to be called when the user edits the input text.
+func (this *TextInput) OnEdit (callback func ()) event.Cookie {
+	return this.on.edit.Connect(callback)
+}
+
 func (this *TextInput) handleKeyDown (key input.Key, numpad bool) {
 	dot       := this.Dot()
 	modifiers := this.Modifiers()
@@ -53,6 +60,9 @@ func (this *TextInput) handleKeyDown (key input.Key, numpad bool) {
 	sel       := modifiers.Shift
 	changed   := false
 
+	// TODO all this (except editing stuff) really should be moved into the
+	// backend
+
 	switch {
 	case key == input.KeyEnter:
 		this.on.enter.Broadcast()
@@ -89,7 +99,10 @@ func (this *TextInput) handleKeyDown (key input.Key, numpad bool) {
 	}
 
 	this.Select(dot)
-	if changed { this.SetText(string(this.text)) }
+	if changed {
+		this.SetText(string(this.text))
+		this.on.edit.Broadcast()
+	}
 }
 
 func (this *TextInput) handleScroll (x, y float64) {

label.go

@@ -15,4 +15,3 @@ func NewLabel (text string) *Label {
 	this.SetText(text)
 	return this
 }
-

labelcheckbox.go

@@ -0,0 +1,62 @@
+package objects
+
+import "git.tebibyte.media/tomo/tomo"
+import "git.tebibyte.media/tomo/tomo/theme"
+import "git.tebibyte.media/tomo/tomo/input"
+import "git.tebibyte.media/tomo/tomo/event"
+import "git.tebibyte.media/tomo/objects/layouts"
+
+// LabelCheckbox is a checkbox with a label.
+type LabelCheckbox struct {
+	tomo.ContainerBox
+	checkbox *Checkbox
+	label    *Label
+}
+
+// NewLabelCheckbox creates a new labeled checkbox with the specified value and
+// label text.
+func NewLabelCheckbox (value bool, text string) *LabelCheckbox {
+	box := &LabelCheckbox {
+		ContainerBox: tomo.NewContainerBox(),
+		checkbox:     NewCheckbox(value),
+		label:        NewLabel(text),
+	}
+	theme.Apply(box, theme.R("objects", "LabelCheckbox", ""))
+	box.label.SetAlign(tomo.AlignStart, tomo.AlignMiddle)
+	box.Add(box.checkbox)
+	box.Add(box.label)
+	box.SetLayout(layouts.NewGrid([]bool { false, true }, []bool { true }))
+
+	box.OnMouseUp(box.handleMouseUp)
+	box.label.OnMouseUp(box.handleMouseUp)
+	return box
+}
+
+// SetValue sets the value of the checkbox.
+func (this *LabelCheckbox) SetValue (value bool) {
+	this.checkbox.SetValue(value)
+}
+
+// Toggle toggles the value of the checkbox between true and false.
+func (this *LabelCheckbox) Toggle () {
+	this.checkbox.Toggle()
+}
+
+// Value returns the value of the checkbox.
+func (this *LabelCheckbox) Value () bool {
+	return this.checkbox.Value()
+}
+
+// OnValueChange specifies a function to be called when the checkbox's value
+// changes.
+func (this *LabelCheckbox) OnValueChange (callback func ()) event.Cookie {
+	return this.checkbox.OnValueChange(callback)
+}
+
+func (this *LabelCheckbox) handleMouseUp (button input.Button) {
+	if button != input.ButtonLeft { return }
+	if this.MousePosition().In(this.Bounds()) {
+		this.checkbox.SetFocused(true)
+		this.checkbox.Toggle()
+	}
+}

numberinput.go

@@ -0,0 +1,100 @@
+package objects
+
+import "math"
+import "strconv"
+import "git.tebibyte.media/tomo/tomo"
+import "git.tebibyte.media/tomo/tomo/theme"
+import "git.tebibyte.media/tomo/tomo/input"
+import "git.tebibyte.media/tomo/tomo/event"
+import "git.tebibyte.media/tomo/objects/layouts"
+
+// NumberInput is an editable text box which accepts only numbers, and has
+// controls to increment and decrement its value.
+type NumberInput struct {
+	tomo.ContainerBox
+	input     *TextInput
+	increment *Button
+	decrement *Button
+	on struct {
+		enter event.FuncBroadcaster
+		edit  event.FuncBroadcaster
+	}
+}
+
+// NewNumberInput creates a new number input with the specified value.
+func NewNumberInput (value float64) *NumberInput {
+	box := &NumberInput {
+		ContainerBox: tomo.NewContainerBox(),
+		input:        NewTextInput(""),
+		increment:    NewButton(""),
+		decrement:    NewButton(""),
+	}
+	theme.Apply(box, theme.R("objects", "NumberInput", ""))
+	box.Add(box.input)
+	box.Add(box.decrement)
+	box.Add(box.increment)
+	box.SetLayout(layouts.NewGrid([]bool { true, false, false }, []bool { true }))
+	box.increment.SetIcon(theme.IconActionIncrement)
+	box.decrement.SetIcon(theme.IconActionDecrement)
+	
+	box.SetValue(value)
+	
+	box.CaptureScroll(true)
+	box.CaptureKeyboard(true)
+	
+	box.OnScroll(box.handleScroll)
+	box.OnKeyDown(box.handleKeyDown)
+	box.input.OnEnter(box.handleEnter)
+	box.input.OnEdit(box.on.edit.Broadcast)
+	box.increment.OnClick(func () { box.shift(1)  })
+	box.decrement.OnClick(func () { box.shift(-1) })
+	return box
+}
+
+// SetValue sets the value of the input.
+func (this *NumberInput) SetValue (value float64) {
+	this.input.SetText(strconv.FormatFloat(value, 'g', -1, 64))
+}
+
+// Value returns the value of the input.
+func (this *NumberInput) Value () float64 {
+	value, _ := strconv.ParseFloat(this.input.Text(), 64)
+	return value
+}
+
+// OnEnter specifies a function to be called when the user presses enter within
+// the text input.
+func (this *NumberInput) OnEnter (callback func ()) event.Cookie {
+	return this.on.enter.Connect(callback)
+}
+
+// OnEdit specifies a function to be called when the user edits the input value.
+func (this *NumberInput) OnEdit (callback func ()) event.Cookie {
+	return this.on.edit.Connect(callback)
+}
+
+func (this *NumberInput) shift (by int) {
+	this.SetValue(this.Value() + float64(by))
+	this.on.edit.Broadcast()
+}
+
+func (this *NumberInput) handleKeyDown (key input.Key, numpad bool) {
+	switch key {
+	case input.KeyUp:   this.shift(1)
+	case input.KeyDown: this.shift(-1)
+	default:            this.input.handleKeyDown(key, numpad)
+	}
+}
+
+func (this *NumberInput) handleScroll (x, y float64) {
+	if x == 0 {
+		this.shift(-int(math.Round(y)))
+	} else {
+		this.input.handleScroll(x, y)
+	}
+}
+
+func (this *NumberInput) handleEnter () {
+	this.SetValue(this.Value())
+	this.on.enter.Broadcast()
+}

scrollbar.go

@@ -173,15 +173,15 @@ func (this *Scrollbar) handleMouseDown (button input.Button) {
 		}
 	case input.ButtonMiddle:
 		if above {
-			this.SetValue(0)
+			this.scrollBy(-this.pageSize())
 		} else {
-			this.SetValue(1)
+			this.scrollBy(this.pageSize())
 		}
 	case input.ButtonRight:
 		if above {
-			this.SetValue(this.Value() - 0.05)
+			this.scrollBy(-this.stepSize())
 		} else {
-			this.SetValue(this.Value() + 0.05)
+			this.scrollBy(this.stepSize())
 		}
 	}
 }
@@ -229,6 +229,34 @@ func (this *Scrollbar) fallbackDragOffset () image.Point {
 	}
 }
 
+func (this *Scrollbar) pageSize () int {
+	if this.layout.linked == nil { return 0 }
+	viewport := this.layout.linked.InnerBounds()
+	if this.layout.vertical {
+		return viewport.Dy()
+	} else {
+		return viewport.Dx()
+	}
+}
+
+func (this *Scrollbar) stepSize () int {
+	// FIXME: this should not be hardcoded, need to get base font metrics
+	// from theme somehow. should be (emspace, lineheight)
+	return 16
+}
+
+func (this *Scrollbar) scrollBy (distance int) {
+	if this.layout.linked == nil { return }
+	var vector image.Point; if this.layout.vertical {
+		vector.Y = distance
+	} else {
+		vector.X = distance
+	}
+	this.layout.linked.ScrollTo (
+		this.layout.linked.ContentBounds().Min.
+		Add(vector))
+}
+
 type scrollbarCookie struct {
 	owner *Scrollbar
 	subCookies []event.Cookie
@@ -278,7 +306,13 @@ func (this scrollbarLayout) Arrange (hints tomo.LayoutHints, boxes []tomo.Box) {
 	// calculate handle length
 	handleLength := gutterLength * this.viewportContentRatio()
 	if handleLength < handleMin { handleLength = handleMin }
-	if handleLength > gutterLength { handleLength = gutterLength }
+	if handleLength >= gutterLength {
+		// just hide the handle if it isn't needed.
+		// TODO: we need a way to hide and show boxes, this is janky as
+		// fuck
+		boxes[0].SetBounds(image.Rect(-16, -16, 0, 0))
+		return
+	}
 	if this.vertical {
 		handle.Max.Y = int(handleLength)
 	} else {

scrollcontainer.go

@@ -0,0 +1,167 @@
+package objects
+
+import "image"
+import "git.tebibyte.media/tomo/tomo"
+import "git.tebibyte.media/tomo/tomo/event"
+import "git.tebibyte.media/tomo/tomo/theme"
+
+// ScrollSide determines which Scrollbars are active in a ScrollContainer.
+type ScrollSide int; const (
+	ScrollVertical ScrollSide = 1 << iota
+	ScrollHorizontal
+	ScrollBoth = ScrollVertical | ScrollHorizontal
+)
+
+// Horizontal returns true if the side includes a horizontal bar.
+func (sides ScrollSide) Horizontal () bool {
+	return sides & ScrollHorizontal > 0
+}
+
+// Vertical returns true if the side includes a vertical bar.
+func (sides ScrollSide) Vertical () bool {
+	return sides & ScrollVertical > 0
+}
+
+// String returns one of:
+//   - both
+//   - horizontal
+//   - vertical
+//   - none
+func (sides ScrollSide) String () string {
+	switch {
+	case sides.Horizontal() && sides.Vertical(): return "both"
+	case sides.Horizontal():                     return "horizontal"
+	case sides.Vertical():                       return "vertical"
+	default:                                     return "none"
+	}
+}
+
+// ScrollContainer couples a ContentBox with one or two Scrollbars.
+type ScrollContainer struct {
+	tomo.ContainerBox
+	layout *scrollContainerLayout
+
+	horizontalCookie event.Cookie
+	verticalCookie   event.Cookie
+}
+
+// NewScrollContainer creates a new scroll container.
+func NewScrollContainer (sides ScrollSide) *ScrollContainer {
+	this := &ScrollContainer {
+		ContainerBox: tomo.NewContainerBox(),
+		layout:       &scrollContainerLayout { },
+	}
+	if sides.Vertical() {
+		this.layout.vertical = NewVerticalScrollbar()
+		this.Add(this.layout.vertical)
+	}
+	if sides.Horizontal() {
+		this.layout.horizontal = NewHorizontalScrollbar()
+		this.Add(this.layout.horizontal)
+	}
+	this.CaptureScroll(true)
+	this.OnScroll(this.handleScroll)
+	theme.Apply(this, theme.R("objects", "ScrollContainer", sides.String()))
+	this.SetLayout(this.layout)
+	return this
+}
+
+// SetRoot sets the root child of the ScrollContainer. There can only be one at
+// a time, and setting it will remove and unlink the current child if there is
+// one.
+func (this *ScrollContainer) SetRoot (root tomo.ContentBox) {
+	if this.layout.root != nil {
+		// delete root and close cookies
+		this.Delete(this.layout.root)
+		if this.horizontalCookie != nil {
+			this.horizontalCookie.Close()
+			this.horizontalCookie = nil
+		}
+		if this.verticalCookie != nil {
+			this.verticalCookie.Close()
+			this.verticalCookie = nil
+		}
+	}
+	this.layout.root = root
+	if root != nil {
+		// insert root at the beginning (for keynav)
+		switch {
+		case this.layout.vertical != nil:
+			this.Insert(root, this.layout.vertical)
+		case this.layout.horizontal != nil:
+			this.Insert(root, this.layout.horizontal)
+		default:
+			this.Add(root)
+		}
+		
+		// link root and remember cookies
+		if this.layout.horizontal != nil {
+			this.horizontalCookie = this.layout.horizontal.Link(root)
+		}
+		if this.layout.vertical != nil {
+			this.verticalCookie =  this.layout.vertical.Link(root)
+		}
+	}
+}
+
+func (this *ScrollContainer) handleScroll (x, y float64) {
+	if this.layout.root == nil { return }
+	this.layout.root.ScrollTo (
+		this.layout.root.ContentBounds().Min.
+		Add(image.Pt(int(x), int(y))))
+}
+
+type scrollContainerLayout struct {
+	root       tomo.ContentBox
+	horizontal *Scrollbar
+	vertical   *Scrollbar
+}
+
+func (this *scrollContainerLayout) MinimumSize (hints tomo.LayoutHints, boxes []tomo.Box) image.Point {
+	var minimum image.Point; if this.root != nil {
+		minimum = this.root.MinimumSize()
+	}
+	if this.horizontal != nil {
+		minimum.Y += this.horizontal.MinimumSize().Y
+	}
+	if this.vertical != nil {
+		minimum.X += this.vertical.MinimumSize().X
+		minimum.Y = max(minimum.Y, this.vertical.MinimumSize().Y)
+	}
+	if this.horizontal != nil {
+		minimum.X = max(minimum.X, this.horizontal.MinimumSize().X)
+	}
+	return minimum
+}
+
+func (this *scrollContainerLayout) Arrange (hints tomo.LayoutHints, boxes []tomo.Box) {
+	rootBounds := hints.Bounds
+	if this.horizontal != nil {
+		rootBounds.Max.Y -= this.horizontal.MinimumSize().Y
+	}
+	if this.vertical != nil {
+		rootBounds.Max.X -= this.vertical.MinimumSize().X
+	}
+	if this.root != nil {
+		this.root.SetBounds(rootBounds)
+	}
+	if this.horizontal != nil {
+		this.horizontal.SetBounds(image.Rect (
+			hints.Bounds.Min.X,
+			rootBounds.Max.Y,
+			rootBounds.Max.X,
+			hints.Bounds.Max.Y))
+	}
+	if this.vertical != nil {
+		this.vertical.SetBounds(image.Rect (
+			rootBounds.Max.X,
+			hints.Bounds.Min.Y,
+			hints.Bounds.Max.X,
+			rootBounds.Max.Y))
+	}
+}
+
+func max (x, y int) int {
+	if x > y { return x }
+	return y
+}

slider.go

@@ -15,7 +15,7 @@ type Slider struct {
 	dragOffset image.Point
 
 	on struct {
-		valueChange event.FuncBroadcaster
+		slide event.FuncBroadcaster
 	}
 }
 
@@ -71,7 +71,6 @@ func (this *Slider) SetValue (value float64) {
 	if value == this.layout.value { return }
 	this.layout.value = value
 	this.SetLayout(this.layout)
-	this.on.valueChange.Broadcast()
 }
 
 // Value returns the value of the slider between 0 and 1.
@@ -79,10 +78,10 @@ func (this *Slider) Value () float64 {
 	return this.layout.value
 }
 
-// OnValueChange specifies a function to be called when the slider's value
-// changes.
-func (this *Slider) OnValueChange (callback func ()) event.Cookie {
-	return this.on.valueChange.Connect(callback)
+// OnValueChange specifies a function to be called when the user moves the
+// slider.
+func (this *Slider) OnSlide (callback func ()) event.Cookie {
+	return this.on.slide.Connect(callback)
 }
 
 func (this *Slider) handleKeyDown (key input.Key, numpad bool) {
@@ -139,14 +138,18 @@ func (this *Slider) handleMouseDown (button input.Button) {
 	case input.ButtonMiddle:
 		if above {
 			this.SetValue(0)
+			this.on.slide.Broadcast()
 		} else {
 			this.SetValue(1)
+			this.on.slide.Broadcast()
 		}
 	case input.ButtonRight:
 		if above {
 			this.SetValue(this.Value() - 0.05)
+			this.on.slide.Broadcast()
 		} else {
 			this.SetValue(this.Value() + 0.05)
+			this.on.slide.Broadcast()
 		}
 	}
 }
@@ -176,6 +179,7 @@ func (this *Slider) drag () {
 			float64(pointer.X) /
 			float64(gutter.Dx() - handle.Dx()))
 	}
+	this.on.slide.Broadcast()
 }
 
 func (this *Slider) fallbackDragOffset () image.Point {

textview.go

@@ -0,0 +1,27 @@
+package objects
+
+import "image"
+import "git.tebibyte.media/tomo/tomo"
+import "git.tebibyte.media/tomo/tomo/theme"
+
+// TextView is an area for displaying a large amount of multi-line text.
+type TextView struct {
+	tomo.TextBox
+}
+
+// NewTextView creates a new text view.
+func NewTextView (text string) *TextView {
+	this := &TextView { TextBox: tomo.NewTextBox() }
+	theme.Apply(this, theme.R("objects", "TextView", ""))
+	this.SetFocusable(true)
+	this.SetSelectable(true)
+	this.SetText(text)
+	this.SetOverflow(false, true)
+	this.SetWrap(true)
+	this.OnScroll(this.handleScroll)
+	return this
+}
+
+func (this *TextView) handleScroll (x, y float64) {
+	this.ScrollTo(this.ContentBounds().Min.Add(image.Pt(int(x), int(y))))
+}