Fix calendar prev/forward month buttons

Not a very good implementation

README.md

@@ -1,4 +1,6 @@
 # objects
 
+[![Go Reference](https://pkg.go.dev/badge/git.tebibyte.media/tomo/objects.svg)](https://pkg.go.dev/git.tebibyte.media/tomo/objects)
+
 Objects contains a standard collection of re-usable objects. All objects in this
 module visually conform to whatever the theme is set to.

button.go

@@ -1,13 +1,22 @@
 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"
+
+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.TextBox
+	tomo.ContainerBox
+
+	label *Label
+	icon  *Icon
+	labelActive bool
+	
 	on struct {
 		click event.FuncBroadcaster
 	}
@@ -15,21 +24,71 @@ type Button struct {
 
 // NewButton creates a new button with the specified text.
 func NewButton (text string) *Button {
-	box := &Button { TextBox: tomo.NewTextBox() }
-	theme.Apply(box, theme.R("objects", "Button", ""))
+	box := &Button {
+		ContainerBox: tomo.NewContainerBox(),
+		label:        NewLabel(text),
+	}
+	box.SetRole(tomo.R("objects", "Button", ""))
+	box.label.SetAlign(tomo.AlignMiddle, tomo.AlignMiddle)
+	box.SetLayout(buttonLayout)
 	box.SetText(text)
-	box.SetAlign(tomo.AlignMiddle, tomo.AlignMiddle)
+	
+	box.CaptureDND(true)
+	box.CaptureMouse(true)
+	box.CaptureScroll(true)
+	box.CaptureKeyboard(true)
+	
 	box.OnMouseUp(box.handleMouseUp)
 	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.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()

calendar.go

@@ -0,0 +1,167 @@
+package objects
+
+import "fmt"
+import "time"
+import "git.tebibyte.media/tomo/tomo"
+import "git.tebibyte.media/tomo/tomo/event"
+import "git.tebibyte.media/tomo/objects/layouts"
+
+// Calendar is an object that can display a date and allow the user to change
+// it. It can display one month at a time.
+type Calendar struct {
+	tomo.ContainerBox
+	
+	grid tomo.ContainerBox
+	time time.Time
+	monthLabel *Label
+	
+	on struct {
+		edit event.FuncBroadcaster
+	}
+}
+
+// NewCalendar creates a new calendar with the specified date.
+func NewCalendar (tm time.Time) *Calendar {
+	calendar := &Calendar {
+		ContainerBox: tomo.NewContainerBox(),
+		time:         tm,
+	}
+	calendar.SetRole(tomo.R("objects", "Calendar", ""))
+	calendar.SetLayout(layouts.ContractVertical)
+	
+	prevButton := NewButton("")
+	prevButton.SetIcon(tomo.IconGoPrevious)
+	prevButton.OnClick(func () {
+		calendar.prevMonth()
+		calendar.on.edit.Broadcast()
+	})
+	nextButton := NewButton("")
+	nextButton.SetIcon(tomo.IconGoNext)
+	nextButton.OnClick(func () {
+		calendar.nextMonth()
+		calendar.on.edit.Broadcast()
+	})
+	calendar.monthLabel = NewLabel("")
+	calendar.monthLabel.SetAlign(tomo.AlignMiddle, tomo.AlignMiddle)
+	
+	calendar.grid = tomo.NewContainerBox()
+	calendar.grid.SetRole(tomo.R("objects", "CalendarGrid", ""))
+	calendar.grid.SetLayout(layouts.NewGrid (
+		[]bool { true, true, true, true, true, true, true },
+		[]bool { }))
+	calendar.Add(NewInnerContainer (
+		layouts.Row { false, true, false },
+		prevButton, calendar.monthLabel, nextButton))
+	calendar.Add(calendar.grid)
+	
+	calendar.OnScroll(calendar.handleScroll)
+	calendar.CaptureScroll(true)
+	
+	calendar.refresh()
+	return calendar
+}
+
+// SetTime sets the date the calendar will display.
+func (this *Calendar) SetTime (tm time.Time) {
+	if this.time == tm { return }
+	this.time = tm
+	this.refresh()
+}
+
+// OnEdit sets a function to be called when the user changes the date on the
+// calendar.
+func (this *Calendar) OnEdit (callback func ()) {
+	this.on.edit.Connect(callback)
+}
+
+func (this *Calendar) prevMonth () {
+	this.time = firstOfMonth(this.time.Add(24 * time.Hour * -20))
+	this.refresh()
+}
+
+func (this *Calendar) nextMonth () {
+	this.time = firstOfMonth(this.time.Add(24 * time.Hour * 40))
+	this.refresh()
+}
+
+var weekdayAbbreviations = []string {
+	"Sun", "Mon", "Tue", "Wed", "Thu", "Fri", "Sat",
+}
+
+func (this *Calendar) refresh () {
+	this.monthLabel.SetText(this.time.Format("2006 January"))
+
+	this.grid.Clear()
+	for _, day := range weekdayAbbreviations {
+		dayLabel := tomo.NewTextBox()
+		dayLabel.SetRole(tomo.R("objects", "CalendarWeekdayHeader", ""))
+		dayLabel.SetText(day)
+		dayLabel.SetAlign(tomo.AlignMiddle, tomo.AlignMiddle)
+		this.grid.Add(dayLabel)
+	}
+	
+	dayIter := 0 - int(firstOfMonth(this.time).Weekday())
+	if dayIter <= -6 {
+		dayIter = 1
+	}
+	weekday := 0
+	totalDays := daysInMonth(this.time)
+	for ; dayIter <= totalDays; dayIter ++ {
+		weekday = (weekday + 1) % 7
+		if dayIter > 0 {
+			day := tomo.NewTextBox()
+			day.SetText(fmt.Sprint(dayIter))
+			if weekday == 1 || weekday == 0 {
+				day.SetRole(tomo.R("objects", "CalendarDay", "weekend"))
+			} else {
+				day.SetRole(tomo.R("objects", "CalendarDay", "weekday"))
+			}
+			this.grid.Add(day)
+		} else {
+			this.grid.Add(tomo.NewBox())
+		}
+	}
+}
+
+func (this *Calendar) handleScroll (x, y float64) {
+	if y < 0 {
+		this.prevMonth()
+	} else {
+		this.nextMonth()
+	}
+}
+
+func firstOfMonth (tm time.Time) time.Time {
+	return time.Date(tm.Year(), tm.Month(), 0, 0, 0, 0, 0, time.Local)
+}
+
+func daysInMonth (tm time.Time) (days int) {
+	year  := tm.Year()
+	month := tm.Month()
+	switch month {
+	case 1:  days = 31
+	case 2:
+		// betcha didn't know this about leap years
+		if year % 4 == 0 && (year % 100 != 0 || year % 400 == 0) {
+			days = 29
+		} else {
+			days = 28
+		}
+	case 3:  days = 31
+	case 4:  days = 30
+	case 5:  days = 31
+	case 6:  days = 30
+	case 7:  days = 31
+	case 8:  days = 31
+	case 9:  days = 30
+	case 10: days = 31
+	case 11: days = 30
+	case 12: days = 31
+	}
+
+	return
+}
+
+func canonMonth (tm time.Time) int {
+	return int(tm.Month() - 1) + tm.Year() * 12
+}

checkbox.go

@@ -0,0 +1,66 @@
+package objects
+
+import "git.tebibyte.media/tomo/tomo"
+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(),
+	}
+	box.SetRole(tomo.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 {
+		this.SetTextureCenter(tomo.IconCheckboxChecked.Texture(tomo.IconSizeSmall))
+	} else {
+		this.SetTextureCenter(tomo.IconCheckboxUnchecked.Texture(tomo.IconSizeSmall))
+	}
+}
+
+// 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()
+	}
+}

container.go

@@ -1,7 +1,6 @@
 package objects
 
 import "git.tebibyte.media/tomo/tomo"
-import "git.tebibyte.media/tomo/tomo/theme"
 
 // Container is an object that can contain other objects. It can be used as a
 // primitive for building more complex layouts. It has two variants: an outer
@@ -23,17 +22,27 @@ func newContainer (layout tomo.Layout, children ...tomo.Object) *Container {
 	return this
 }
 
-// NewOuterContainer creates a new container that has padding around it.
+// NewOuterContainer creates a new container that has padding around it, as well
+// as a solid background color. It is meant to be used as a root container for a
+// window, tab pane, etc.
 func NewOuterContainer (layout tomo.Layout, children ...tomo.Object) *Container {
 	this := newContainer(layout, children...)
-	theme.Apply(this, theme.R("objects", "Container", "outer"))
+	this.SetRole(tomo.R("objects", "Container", "outer"))
+	return this
+}
+
+// NewSunkenContainer creates a new container with a sunken style and padding
+// around it. It is meant to be used as a root container for a ScrollContainer.
+func NewSunkenContainer (layout tomo.Layout, children ...tomo.Object) *Container {
+	this := newContainer(layout, children...)
+	this.SetRole(tomo.R("objects", "Container", "sunken"))
 	return this
 }
 
 // NewInnerContainer creates a new container that has no padding around it.
 func NewInnerContainer (layout tomo.Layout, children ...tomo.Object) *Container {
 	this := newContainer(layout, children...)
-	theme.Apply(this, theme.R("objects", "Container", "inner"))
+	this.SetRole(tomo.R("objects", "Container", "inner"))
 	return this
 }
 

dialog.go

@@ -0,0 +1,100 @@
+package objects
+
+import "image"
+import "git.tebibyte.media/tomo/tomo"
+import "git.tebibyte.media/tomo/tomo/event"
+import "git.tebibyte.media/tomo/objects/layouts"
+
+// DialogKind defines the semantic role of a dialog window.
+type DialogKind int; const (
+	DialogInformation DialogKind = iota
+	DialogQuestion
+	DialogWarning
+	DialogError
+)
+
+// Dialog is a modal dialog window.
+type Dialog struct {
+	tomo.Window
+	controlRow tomo.ContainerBox
+}
+
+type clickable interface {
+	OnClick (func ()) event.Cookie
+}
+
+// NewDialog creates a new dialog window given a dialog kind.
+func NewDialog (kind DialogKind, parent tomo.Window, title, message string, options ...tomo.Object) (*Dialog, error) {
+	if title == "" {
+		switch kind {
+		case DialogInformation: title = "Information"
+		case DialogQuestion:    title = "Question"
+		case DialogWarning:     title = "Warning"
+		case DialogError:       title = "Error"
+		}
+	}
+
+	dialog := &Dialog { }
+	if parent == nil {
+		window, err := tomo.NewWindow(image.Rectangle { })
+		if err != nil { return nil, err }
+		dialog.Window = window
+	} else {
+		window, err := parent.NewModal(image.Rectangle { })
+		if err != nil { return nil, err }
+		dialog.Window = window
+	}
+
+	var iconId tomo.Icon
+	switch kind {
+	case DialogInformation: iconId = tomo.IconDialogInformation
+	case DialogQuestion:    iconId = tomo.IconDialogQuestion
+	case DialogWarning:     iconId = tomo.IconDialogWarning
+	case DialogError:       iconId = tomo.IconDialogError
+	}
+	dialog.SetTitle(title)
+	icon := NewIcon(iconId, tomo.IconSizeLarge)
+	messageText := NewLabel(message)
+	messageText.SetAlign(tomo.AlignStart, tomo.AlignMiddle)
+
+	for _, option := range options {
+		if option, ok := option.(clickable); ok {
+			option.OnClick(dialog.Close)
+		}
+	}
+	dialog.controlRow = NewInnerContainer(layouts.ContractHorizontal, options...)
+	dialog.controlRow.SetAlign(tomo.AlignEnd, tomo.AlignEnd)
+
+	dialog.SetRoot(NewOuterContainer (
+		layouts.NewGrid([]bool { true }, []bool { true, false }),
+		NewInnerContainer(layouts.ContractHorizontal, icon, messageText),
+		dialog.controlRow))
+	return dialog, nil
+}
+
+// NewDialogOk creates a new dialog window with an OK option.
+func NewDialogOk (kind DialogKind, parent tomo.Window, title, message string, onOk func ()) (*Dialog, error) {
+	okButton := NewButton("OK")
+	okButton.SetIcon(tomo.IconDialogOkay)
+	okButton.OnClick(func () {
+		if onOk != nil { onOk() }
+	})
+	okButton.SetFocused(true)
+	
+	return NewDialog(kind, parent, title, message, okButton)
+}
+
+// NewDialogOkCancel creates a new dialog window with OK and Cancel options.
+func NewDialogOkCancel (kind DialogKind, parent tomo.Window, title, message string, onOk func ()) (*Dialog, error) {
+	cancelButton := NewButton("Cancel")
+	cancelButton.SetIcon(tomo.IconDialogCancel)
+	
+	okButton := NewButton("OK")
+	okButton.SetIcon(tomo.IconDialogOkay)
+	okButton.OnClick(func () {
+		if onOk != nil { onOk() }
+	})
+	okButton.SetFocused(true)
+
+	return NewDialog(kind, parent, title, message, cancelButton, okButton)
+}

go.mod

@@ -2,6 +2,6 @@ module git.tebibyte.media/tomo/objects
 
 go 1.20
 
-require git.tebibyte.media/tomo/tomo v0.23.0
+require git.tebibyte.media/tomo/tomo v0.38.0
 
 require golang.org/x/image v0.11.0 // indirect

go.sum

@@ -1,5 +1,5 @@
-git.tebibyte.media/tomo/tomo v0.23.0 h1:OZwI4oLKMP7JqFc98VxBoRxwjL+W9NyTQZLB/m1BvaA=
-git.tebibyte.media/tomo/tomo v0.23.0/go.mod h1:C9EzepS9wjkTJjnZaPBh22YvVPyA4hbBAJVU20Rdmps=
+git.tebibyte.media/tomo/tomo v0.38.0 h1:K5TP67RxnszudeNfmGZiU5cFTRjFueXiI3NCsgw+05U=
+git.tebibyte.media/tomo/tomo v0.38.0/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=

heading.go

@@ -2,7 +2,6 @@ package objects
 
 import "fmt"
 import "git.tebibyte.media/tomo/tomo"
-import "git.tebibyte.media/tomo/tomo/theme"
 
 // Heading is a label that denotes the start of some section of content. It can
 // have a level from 0 to 2, with 0 being the most prominent and 2 being the
@@ -12,11 +11,11 @@ type Heading struct {
 }
 
 // NewHeading creates a new section heading. The level can be from 0 to 2.
-func NewHeading (level int, text string) *Label {
+func NewHeading (level int, text string) *Heading {
 	if level < 0 { level = 0 }
 	if level > 2 { level = 2 }
-	this := &Label { TextBox: tomo.NewTextBox() }
-	theme.Apply(this, theme.R("objects", "Heading", fmt.Sprint(level)))
+	this := &Heading { TextBox: tomo.NewTextBox() }
+	this.SetRole(tomo.R("objects", "Heading", fmt.Sprint(level)))
 	this.SetText(text)
 	return this
 }

icon.go

@@ -0,0 +1,41 @@
+package objects
+
+import "image"
+import "git.tebibyte.media/tomo/tomo"
+import "git.tebibyte.media/tomo/tomo/data"
+import "git.tebibyte.media/tomo/tomo/canvas"
+
+// Icon displays a single icon.
+type Icon struct {
+	tomo.Box
+}
+
+// NewIcon creates a new icon from an icon ID.
+func NewIcon (id tomo.Icon, size tomo.IconSize) *Icon {
+	this := &Icon {
+		Box: tomo.NewBox(),
+	}
+	this.SetRole(tomo.R("objects", "Icon", size.String()))
+	this.SetTexture(id.Texture(size))
+	return this
+}
+
+// NewMimeIcon creates a new icon from a MIME type.
+func NewMimeIcon (mime data.Mime, size tomo.IconSize) *Icon {
+	this := &Icon {
+		Box: tomo.NewBox(),
+	}
+	this.SetRole(tomo.R("objects", "Icon", size.String()))
+	this.SetTexture(tomo.MimeIcon(mime, size))
+	return this
+}
+
+func (this *Icon) SetTexture (texture canvas.Texture) {
+	this.Box.SetTextureCenter(texture)
+	if texture == nil {
+		this.SetMinimumSize(image.Pt(0, 0))
+	} else {
+		bounds := texture.Bounds()
+		this.SetMinimumSize(bounds.Max.Sub(bounds.Min))
+	}
+}

label.go

@@ -1,7 +1,6 @@
 package objects
 
 import "git.tebibyte.media/tomo/tomo"
-import "git.tebibyte.media/tomo/tomo/theme"
 
 // Label is a simple text label.
 type Label struct {
@@ -11,8 +10,7 @@ type Label struct {
 // NewLabel creates a new text label.
 func NewLabel (text string) *Label {
 	this := &Label { TextBox: tomo.NewTextBox() }
-	theme.Apply(this, theme.R("objects", "Label", ""))
+	this.SetRole(tomo.R("objects", "Label", ""))
 	this.SetText(text)
 	return this
 }
-

labelcheckbox.go

@@ -0,0 +1,61 @@
+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"
+
+// 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),
+	}
+	box.SetRole(tomo.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 { false }))
+
+	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()
+	}
+}

layouts/contract.go

@@ -0,0 +1,40 @@
+package layouts
+
+import "image"
+import "git.tebibyte.media/tomo/tomo"
+
+var _ tomo.Layout = ContractVertical
+
+// Contract is a layout that arranges boxes in a simple row or column according
+// to their minimum sizes.
+type Contract bool
+
+// ContractVertical is a vertical contracted layout.
+const ContractVertical Contract = true
+
+// ContractHorizontal is a horizontal contracted layout.
+const ContractHorizontal Contract = false
+
+func (contract Contract) MinimumSize (hints tomo.LayoutHints, boxes []tomo.Box) image.Point {
+	return contract.fallback().MinimumSize(hints, boxes)
+}
+
+func (contract Contract) Arrange (hints tomo.LayoutHints, boxes []tomo.Box) {
+	contract.fallback().Arrange(hints, boxes)
+}
+
+func (contract Contract) RecommendedHeight (hints tomo.LayoutHints, boxes []tomo.Box, width int) int {
+	return contract.fallback().RecommendedHeight(hints, boxes, width)
+}
+
+func (contract Contract) RecommendedWidth (hints tomo.LayoutHints, boxes []tomo.Box, height int) int {
+	return contract.fallback().RecommendedWidth(hints, boxes, height)
+}
+
+func (contract Contract) fallback () tomo.Layout {
+	if contract == ContractVertical {
+		return Column { }
+	} else {
+		return Row { }
+	}
+}

layouts/cut.go

@@ -1,212 +0,0 @@
-package layouts
-
-import "image"
-import "git.tebibyte.media/tomo/tomo"
-
-// Cut is a layout that can be divided into smaller and smaller sections.
-type Cut struct {
-	branches [2]*Cut
-	expand   [2]bool
-	vertical bool
-}
-
-// Vertical divides the layout in equal halves vertically.
-func (this *Cut) Vertical () (top, bottom *Cut) {
-	this.fill()
-	this.even()
-	this.vertical = true
-	return this.Branches()
-}
-
-// Top divides the layout vertically, expanding the top half and contracting the
-// bottom half.
-func (this *Cut) Top () (top, bottom *Cut) {
-	this.fill()
-	this.first()
-	this.vertical = true
-	return this.Branches()
-}
-
-// Bottom divides the layout vertically, expanding the bottom half and
-// contracting the top half.
-func (this *Cut) Bottom () (top, bottom *Cut) {
-	this.fill()
-	this.second()
-	this.vertical = true
-	return this.Branches()
-}
-
-// Horizontal divides the layout in equal halves horizontally.
-func (this *Cut) Horizontal () (top, bottom *Cut) {
-	this.fill()
-	this.even()
-	return this.Branches()
-}
-
-// Left divides the layout horizontally, expanding the left half and contracting
-// the right half.
-func (this *Cut) Left () (top, bottom *Cut) {
-	this.fill()
-	this.first()
-	return this.Branches()
-}
-
-// Right divides the layout horizontally, expanding the right half and
-// contracting the left half.
-func (this *Cut) Right () (top, bottom *Cut) {
-	this.fill()
-	this.second()
-	return this.Branches()
-}
-
-// Branches returns the two halves of this layout.
-func (this *Cut) Branches () (first, second *Cut) {
-	return this.branches[0], this.branches[1]
-}
-
-func (this *Cut) real () bool {
-	return this != nil && this.branches[0] != nil && this.branches[1] != nil
-}
-
-func (this *Cut) fill () {
-	this.branches[0] = &Cut { }
-	this.branches[1] = &Cut { }
-}
-
-func (this *Cut) first () {
-	this.expand[0] = true
-	this.expand[1] = false
-}
-
-func (this *Cut) second () {
-	this.expand[0] = false
-	this.expand[1] = true
-}
-
-func (this *Cut) even () {
-	this.expand[0] = true
-	this.expand[1] = true
-}
-
-func (this *Cut) MinimumSize (hints tomo.LayoutHints, boxes []tomo.Box) image.Point {
-	size, _ := this.minimumSize(hints, boxes)
-	return size
-}
-
-func (this *Cut) Arrange (hints tomo.LayoutHints, boxes []tomo.Box) {
-	this.arrange(hints, boxes)
-}
-
-func (this *Cut) minimumSize (hints tomo.LayoutHints, boxes []tomo.Box) (image.Point, []tomo.Box) {
-	size := image.Point { }
-
-	for index, branch := range this.branches {
-		if len(boxes) == 0 { break }
-
-		var point image.Point
-		if branch.real() {
-			point, boxes = branch.minimumSize(hints, boxes)
-		} else {
-			point = boxes[0].MinimumSize()
-			boxes = boxes[1:]
-		}
-
-		if this.vertical {
-			if point.X > size.X { size.X  = point.X     }
-			if index   > 0      { size.Y += hints.Gap.Y }
-			size.Y += point.Y
-		} else {
-			if point.Y > size.Y { size.Y  = point.Y     }
-			if index   > 0      { size.X += hints.Gap.X }
-			size.X += point.X
-		}
-	}
-
-	return size, boxes
-}
-
-func (this *Cut) arrange (hints tomo.LayoutHints, boxes []tomo.Box) []tomo.Box {
-	// collect minimum sizes and physical endpoints
-	var minimums [2]image.Point
-	var leaves   [2]tomo.Box
-	var nBranches int
-	remaining := boxes
-	for index, branch := range this.branches {
-		if branch.real() {
-			minimums[index], remaining = branch.minimumSize(hints, remaining)
-		} else {
-			if len(remaining) == 0 { break }
-			leaves[index]   = remaining[0]
-			minimums[index] = remaining[0].MinimumSize()
-			remaining       = remaining[1:]
-		}
-		nBranches ++
-	}
-
-	// determine the amount of space to divide among expanding branches
-	gaps := nBranches - 1
-	var freeSpace float64; if this.vertical {
-		freeSpace = float64(hints.Bounds.Dy() - hints.Gap.Y * gaps)
-	} else {
-		freeSpace = float64(hints.Bounds.Dx() - hints.Gap.X * gaps)
-	}
-	var nExpanding float64
-	for index, minimum := range minimums {
-		if this.expand[index] {
-			nExpanding ++
-		} else if this.vertical {
-			freeSpace -= float64(minimum.Y)
-		} else {
-			freeSpace -= float64(minimum.X)
-		}
-	}
-	expandingSize := freeSpace / nExpanding
-
-	// calculate the size and position of branches
-	var bounds [2]image.Rectangle
-	x := float64(hints.Bounds.Min.X)
-	y := float64(hints.Bounds.Min.Y)
-	for index, minimum := range minimums {
-		// get size along significant axis
-		var size float64; if this.expand[index] {
-			size = expandingSize
-		} else if this.vertical {
-			size = float64(minimum.Y)
-		} else {
-			size = float64(minimum.X)
-		}
-
-		// figure out bounds from size
-		if this.vertical {
-			bounds[index].Max = image.Pt (
-				int(hints.Bounds.Dx()),
-				int(size))
-		} else {
-			bounds[index].Max = image.Pt (
-				int(size),
-				int(hints.Bounds.Dy()))
-		}
-		bounds[index] = bounds[index].Add(image.Pt(int(x), int(y)))
-
-		// move along
-		if this.vertical {
-			y += float64(hints.Gap.Y) + size
-		} else {
-			x += float64(hints.Gap.X) + size
-		}
-	}
-
-	// apply the size and position
-	for index, bound := range bounds {
-		if leaves[index] != nil {
-			leaves[index].SetBounds(bound)
-			boxes = boxes[1:]
-		} else if this.branches[index] != nil {
-			newHints := hints
-			newHints.Bounds = bound
-			boxes = this.branches[index].arrange(newHints, boxes)
-		}
-	}
-	
-	return boxes
-}

layouts/flow.go

@@ -0,0 +1,136 @@
+package layouts
+
+import "image"
+import "git.tebibyte.media/tomo/tomo"
+
+var _ tomo.Layout = FlowVertical
+
+// Flow is a grid layout where the number of rows and columns changes depending
+// on the size of the container. It is designed to be used with an overflowing
+// container. If the container does not overflow in the correct direction, the
+// layout will behave like Contract.
+type Flow bool
+
+// FlowVertical is a vertical flow layout.
+const FlowVertical Flow = true
+
+// FlowHorizontal is a horizontal flow layout.
+const FlowHorizontal Flow = false
+
+func (flow Flow) MinimumSize (hints tomo.LayoutHints, boxes []tomo.Box) image.Point {
+	// TODO: write down somewhere that layout minimums aren't taken into
+	// account when the respective direction is overflowed
+	return flow.fallback().MinimumSize(hints, boxes)
+}
+
+func (flow Flow) Arrange (hints tomo.LayoutHints, boxes []tomo.Box) {
+	if flow.v() && !hints.OverflowY || flow.h() && !hints.OverflowX {
+		flow.fallback().Arrange(hints, boxes)
+	}
+
+	// find a minor size value that will fit all boxes
+	minorSize := 0
+	for _, box := range boxes {
+		boxSize := flow.minor(box.MinimumSize())
+		if boxSize > minorSize { minorSize = boxSize }
+	}
+	if minorSize == 0 { return }
+	minorSteps :=
+		(flow.deltaMinor(hints.Bounds) + flow.minor(hints.Gap)) /
+		(minorSize + flow.minor(hints.Gap))
+	if minorSteps < 1 { minorSteps = 1 }
+
+	// arrange
+	point := hints.Bounds.Min
+	index := 0
+	for index < len(boxes) {
+		// get a slice of boxes for this major step
+		stepIndexEnd := index + minorSteps
+		if stepIndexEnd > len(boxes) { stepIndexEnd = len(boxes) }
+		step := boxes[index:stepIndexEnd]
+		index += minorSteps
+		
+		// find a major size that will fit all boxes on this major step
+		majorSize := 0
+		for _, box := range step {
+			boxSize := flow.major(box.MinimumSize())
+			if boxSize > majorSize { majorSize = boxSize }
+		}
+		if majorSize == 0 { continue }
+
+		// arrange all boxes on this major step
+		var size image.Point
+		size = flow.incrMajor(size, majorSize)
+		size = flow.incrMinor(size, minorSize)
+		for _, box := range step {
+			bounds := image.Rectangle { Min: point, Max: point.Add(size) }
+			box.SetBounds(bounds)
+
+			point = flow.incrMinor(point, minorSize + flow.minor(hints.Gap))
+		}
+
+		if flow.v() {
+			point.Y += majorSize + hints.Gap.Y
+			point.X = hints.Bounds.Min.X
+		} else {
+			point.X += majorSize + hints.Gap.X
+			point.Y = hints.Bounds.Min.Y
+		}
+	}
+}
+
+func (flow Flow) v () bool { return flow == FlowVertical   }
+func (flow Flow) h () bool { return flow == FlowHorizontal }
+
+func (flow Flow) minor (point image.Point) int {
+	if flow.v() {
+		return point.X
+	} else {
+		return point.Y
+	}
+}
+func (flow Flow) major (point image.Point) int {
+	if flow.v() {
+		return point.Y
+	} else {
+		return point.X
+	}
+}
+func (flow Flow) incrMinor (point image.Point, delta int) image.Point {
+	if flow.v() {
+		point.X += delta
+		return point
+	} else {
+		point.Y += delta
+		return point
+	}
+}
+func (flow Flow) incrMajor (point image.Point, delta int) image.Point {
+	if flow.v() {
+		point.Y += delta
+		return point
+	} else {
+		point.X += delta
+		return point
+	}
+}
+func (flow Flow) deltaMinor (rectangle image.Rectangle) int {
+	if flow.v() {
+		return rectangle.Dx()
+	} else {
+		return rectangle.Dy()
+	}
+}
+func (flow Flow) fallback () tomo.Layout {
+	return Contract(flow)
+}
+
+func (flow Flow) RecommendedHeight (hints tomo.LayoutHints, boxes []tomo.Box, width int) int {
+	// TODO
+	return 0
+}
+
+func (flow Flow) RecommendedWidth (hints tomo.LayoutHints, boxes []tomo.Box, height int) int {
+	// TODO
+	return 0
+}

layouts/grid.go

@@ -0,0 +1,120 @@
+package layouts
+
+import "math"
+import "image"
+import "git.tebibyte.media/tomo/tomo"
+
+var _ tomo.Layout = new(Grid)
+
+// Grid is a layout that arranges boxes in a grid formation with distinct rows
+// and columns. It is great for creating forms.
+type Grid struct {
+	xExpand []bool
+	yExpand []bool
+}
+
+// NewGrid creates a new grid layout. Rows and columns are specified as slices
+// of booleans, where true means a row or column will expand and false means it
+// will contract. Boxes are laid out left to right, then top to bottom. Boxes
+// that go beyond the lengh of rows will be laid out according to columns, but
+// they will not expand vertically.
+func NewGrid (columns, rows []bool) *Grid {
+	this := &Grid {
+		xExpand: columns,
+		yExpand: rows,
+	}
+	return this
+}
+
+func (this *Grid) MinimumSize (hints tomo.LayoutHints, boxes []tomo.Box) image.Point {
+	cols, rows := this.minimums(boxes)
+	size := image.Pt (
+		(len(cols) - 1) * hints.Gap.X,
+		(len(rows) - 1) * hints.Gap.Y)
+	for _, width  := range cols { size.X += width  }
+	for _, height := range rows { size.Y += height }
+	return size
+}
+
+func (this *Grid) Arrange (hints tomo.LayoutHints, boxes []tomo.Box) {
+	xExpand := func (index int) bool {
+		return this.xExpand[index]
+	}
+	yExpand := func (index int) bool {
+		if index < len(this.yExpand) { return this.yExpand[index] }
+		return false
+	}
+
+	cols, rows := this.minimums(boxes)
+	expand(hints, cols, hints.Bounds.Dx(), xExpand)
+	expand(hints, rows, hints.Bounds.Dy(), yExpand)
+
+	position := hints.Bounds.Min
+	for index, box := range boxes {
+		col, row := index % len(cols), index / len(cols)
+		box.SetBounds(image.Rectangle {
+			Min: position,
+			Max: position.Add(image.Pt(cols[col], rows[row])),
+		})
+		if col == len(cols) - 1 {
+			position.X = hints.Bounds.Min.X
+			position.Y += rows[row] + hints.Gap.Y
+		} else {
+			position.X += cols[col] + hints.Gap.X
+		}
+	}
+}
+
+func (this *Grid) minimums (boxes []tomo.Box) ([]int, []int) {
+	nCols, nRows := this.dimensions(boxes)
+	cols,  rows  := make([]int, nCols), make([]int, nRows)
+
+	for index, box := range boxes {
+		col, row := index % len(cols), index / len(cols)
+		minimum := box.MinimumSize()
+		if cols[col] < minimum.X {
+			cols[col] = minimum.X
+		}
+		if rows[row] < minimum.Y {
+			rows[row] = minimum.Y
+		}
+	}
+	
+	return cols, rows
+}
+
+func (this *Grid) dimensions (boxes []tomo.Box) (int, int) {
+	return len(this.xExpand), ceilDiv(len(boxes), len(this.xExpand)) 
+}
+
+func expand (hints tomo.LayoutHints, sizes []int, space int, expands func (int) bool) {
+	gaps       := len(sizes) - 1
+	freeSpace  := float64(space - hints.Gap.Y * gaps)
+	nExpanding := 0; for index, minimum := range sizes {
+		if expands(index) {
+			nExpanding ++
+		} else {
+			freeSpace -= float64(minimum)
+		}
+	}
+	expandingSize := freeSpace / float64(nExpanding)
+	for index := range sizes {
+		if expands(index) {
+			sizes[index] = int(expandingSize)
+		}
+	}
+}
+
+func ceilDiv (x, y int) int {
+	return int(math.Ceil(float64(x) / float64(y)))
+}
+
+func (this *Grid) RecommendedHeight (hints tomo.LayoutHints, boxes []tomo.Box, width int) int {
+	// TODO
+	return 0
+}
+
+func (this *Grid) RecommendedWidth (hints tomo.LayoutHints, boxes []tomo.Box, height int) int {
+	// TODO
+	return 0
+}

layouts/layouts.go

@@ -1,88 +0,0 @@
-package layouts
-
-import "image"
-import "git.tebibyte.media/tomo/tomo"
-
-type Row struct { }
-
-func (Row) MinimumSize (hints tomo.LayoutHints, boxes []tomo.Box) image.Point {
-	dot := image.Point { }
-	for _, box := range boxes {
-		minimum := box.MinimumSize()
-		dot.X += minimum.X
-		if dot.Y < minimum.Y {
-			dot.Y = minimum.Y
-		}
-	}
-	dot.X += hints.Gap.X * (len(boxes) - 1)
-	return dot
-}
-
-func (Row) Arrange (hints tomo.LayoutHints, boxes []tomo.Box) {
-	// TODO respect alignment value
-	dot := hints.Bounds.Min
-	for index, box := range boxes {
-		if index > 0 { dot.X += hints.Gap.X }
-		minimum := box.MinimumSize()
-		box.SetBounds(image.Rectangle {
-			Min: dot,
-			Max: dot.Add(image.Pt(minimum.X, hints.Bounds.Dy())),
-		})
-		dot.X += minimum.X
-	}
-
-	width  := dot.X - hints.Bounds.Min.X
-	offset := 0
-	
-	switch hints.AlignX {
-	case tomo.AlignMiddle:
-		offset = (hints.Bounds.Dx() - width) / 2
-	case tomo.AlignEnd:
-		offset = hints.Bounds.Dx() - width
-	}
-	for _, box := range boxes {
-		box.SetBounds(box.Bounds().Add(image.Pt(offset, 0)))
-	}
-}
-
-type Column struct { }
-
-func (Column) MinimumSize (hints tomo.LayoutHints, boxes []tomo.Box) image.Point {
-	dot := image.Point { }
-	for _, box := range boxes {
-		minimum := box.MinimumSize()
-		dot.Y += minimum.Y
-		if dot.X < minimum.X {
-			dot.X = minimum.X
-		}
-	}
-	dot.Y += hints.Gap.Y * (len(boxes) - 1)
-	return dot
-}
-
-func (Column) Arrange (hints tomo.LayoutHints, boxes []tomo.Box) {
-	// TODO respect alignment value
-	dot := hints.Bounds.Min
-	for index, box := range boxes {
-		if index > 0 { dot.Y += hints.Gap.Y }
-		minimum := box.MinimumSize()
-		box.SetBounds(image.Rectangle {
-			Min: dot,
-			Max: dot.Add(image.Pt(hints.Bounds.Dx(), minimum.Y)),
-		})
-		dot.Y += minimum.Y
-	}
-	
-	height := dot.Y - hints.Bounds.Min.Y
-	offset := 0
-	
-	switch hints.AlignY {
-	case tomo.AlignMiddle:
-		offset = (hints.Bounds.Dy() - height) / 2
-	case tomo.AlignEnd:
-		offset = hints.Bounds.Dy() - height
-	}
-	for _, box := range boxes {
-		box.SetBounds(box.Bounds().Add(image.Pt(0, offset)))
-	}
-}

layouts/rowcol.go

@@ -0,0 +1,238 @@
+package layouts
+
+import "image"
+import "git.tebibyte.media/tomo/tomo"
+
+var _ tomo.Layout = ContractVertical
+
+// Row arranges boxes in a row. Boxes that share an index with a true value will
+// expand, and others will contract.
+type Row []bool
+
+// Column arranges boxes in a column. Boxes that share an index with a true
+// value will expand, and others will contract.
+type Column []bool
+
+func (column Column) MinimumSize (hints tomo.LayoutHints, boxes []tomo.Box) image.Point {
+	dot := image.Point { }
+	for _, box := range boxes {
+		minimum := box.MinimumSize()
+		dot.Y += minimum.Y
+		if dot.X < minimum.X {
+			dot.X = minimum.X
+		}
+	}
+	dot.Y += hints.Gap.Y * (len(boxes) - 1)
+	return dot
+}
+
+func (row Row) MinimumSize (hints tomo.LayoutHints, boxes []tomo.Box) image.Point {
+	dot := image.Point { }
+	for _, box := range boxes {
+		minimum := box.MinimumSize()
+		dot.X += minimum.X
+		if dot.Y < minimum.Y {
+			dot.Y = minimum.Y
+		}
+	}
+	dot.X += hints.Gap.X * (len(boxes) - 1)
+	return dot
+}
+
+func (column Column) Arrange (hints tomo.LayoutHints, boxes []tomo.Box) {
+	expands := func (index int) bool {
+		if index >= len(column) { return false }
+		return column[index]
+	}
+
+	// determine expanding box size
+	expandingSize := 0.0
+	if !hints.OverflowY {
+		gaps       := len(boxes) - 1
+		freeSpace  := float64(hints.Bounds.Dy() - hints.Gap.Y * gaps)
+		nExpanding := 0; for index, box := range boxes {
+			if expands(index) {
+				nExpanding ++
+			} else {
+				freeSpace -= float64(box.MinimumSize().Y)
+			}
+		}
+		expandingSize = freeSpace / float64(nExpanding)
+	}
+
+	// determine width
+	width := 0
+	if hints.OverflowX {
+		for _, box := range boxes {
+			minimum := box.MinimumSize()
+			if width < minimum.X { width = minimum.X }
+		}
+	} else {
+		width = hints.Bounds.Dx()
+	}
+
+	// arrange
+	dot := hints.Bounds.Min
+	for index, box := range boxes {
+		if index > 0 { dot.Y += hints.Gap.Y }
+
+		// determine height
+		height := box.MinimumSize().Y
+		if hints.OverflowY {
+			if box, ok := box.(tomo.ContentBox); ok {
+				height = box.RecommendedHeight(width)
+			}
+		} else {
+			if expands(index) {
+				height = int(expandingSize)
+			}
+		}
+
+		// set bounds
+		box.SetBounds(image.Rectangle {
+			Min: dot,
+			Max: dot.Add(image.Pt(width, height)),
+		})
+		dot.Y += height
+	}
+	
+	height := dot.Y - hints.Bounds.Min.Y
+	offset := 0
+	
+	switch hints.AlignY {
+	case tomo.AlignMiddle:
+		offset = (hints.Bounds.Dy() - height) / 2
+	case tomo.AlignEnd:
+		offset = hints.Bounds.Dy() - height
+	}
+	for _, box := range boxes {
+		box.SetBounds(box.Bounds().Add(image.Pt(0, offset)))
+	}
+}
+
+func (row Row) Arrange (hints tomo.LayoutHints, boxes []tomo.Box) {
+	expands := func (index int) bool {
+		if index >= len(row) { return false }
+		return row[index]
+	}
+
+	// determine expanding box size
+	expandingSize := 0.0
+	if !hints.OverflowY {
+		gaps       := len(boxes) - 1
+		freeSpace  := float64(hints.Bounds.Dx() - hints.Gap.X * gaps)
+		nExpanding := 0; for index, box := range boxes {
+			if expands(index) {
+				nExpanding ++
+			} else {
+				freeSpace -= float64(box.MinimumSize().X)
+			}
+		}
+		expandingSize = freeSpace / float64(nExpanding)
+	}
+
+	// determine height
+	height := 0
+	if hints.OverflowY {
+		for _, box := range boxes {
+			minimum := box.MinimumSize()
+			if height < minimum.Y { height = minimum.Y }
+		}
+	} else {
+		height = hints.Bounds.Dy()
+	}
+
+	// arrange
+	dot := hints.Bounds.Min
+	for index, box := range boxes {
+		if index > 0 { dot.X += hints.Gap.X }
+
+		// determine width
+		width := box.MinimumSize().X
+		if hints.OverflowY {
+			if box, ok := box.(tomo.ContentBox); ok {
+				width = box.RecommendedHeight(height)
+			}
+		} else {
+			if expands(index) {
+				width = int(expandingSize)
+			}
+		}
+
+		// set bounds
+		box.SetBounds(image.Rectangle {
+			Min: dot,
+			Max: dot.Add(image.Pt(width, height)),
+		})
+		dot.X += width
+	}
+
+	width  := dot.X - hints.Bounds.Min.X
+	offset := 0
+	
+	switch hints.AlignX {
+	case tomo.AlignMiddle:
+		offset = (hints.Bounds.Dx() - width) / 2
+	case tomo.AlignEnd:
+		offset = hints.Bounds.Dx() - width
+	}
+	for _, box := range boxes {
+		box.SetBounds(box.Bounds().Add(image.Pt(offset, 0)))
+	}
+}
+
+func (column Column) RecommendedHeight (hints tomo.LayoutHints, boxes []tomo.Box, width int) int {
+	height := 0
+	for _, box := range boxes {
+		if box, ok := box.(tomo.ContentBox); ok {
+			height += box.RecommendedHeight(width) 
+		} else {
+			height += box.MinimumSize().Y
+		}
+	}
+	height += hints.Gap.Y * (len(boxes) - 1)
+	return height
+}
+
+func (row Row) RecommendedHeight (hints tomo.LayoutHints, boxes []tomo.Box, width int) int {
+	height := 0
+	for _, box := range boxes {
+		minimum   := box.MinimumSize()
+		boxHeight := 0
+		if box, ok := box.(tomo.ContentBox); ok {
+			boxHeight = box.RecommendedHeight(minimum.X)
+		} else {
+			boxHeight = minimum.Y
+		}
+		if boxHeight > height { height = boxHeight }
+	}
+	return height
+}
+
+func (column Column) RecommendedWidth (hints tomo.LayoutHints, boxes []tomo.Box, height int) int {
+	width := 0
+	for _, box := range boxes {
+		minimum   := box.MinimumSize()
+		boxWidth := 0
+		if box, ok := box.(tomo.ContentBox); ok {
+			boxWidth = box.RecommendedHeight(minimum.Y)
+		} else {
+			boxWidth = minimum.X
+		}
+		if boxWidth > width { width = boxWidth }
+	}
+	return width
+}
+
+func (row Row) RecommendedWidth (hints tomo.LayoutHints, boxes []tomo.Box, height int) int {
+	width := 0
+	for _, box := range boxes {
+		if box, ok := box.(tomo.ContentBox); ok {
+			width += box.RecommendedWidth(height)
+		} else {
+			width += box.MinimumSize().X
+		}
+	}
+	width += hints.Gap.X * (len(boxes) - 1)
+	return width
+}

menu.go

@@ -0,0 +1,99 @@
+package objects
+
+import "image"
+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"
+
+// Menu is a menu window.
+type Menu struct {
+	tomo.Window
+
+	parent        tomo.Window
+	bounds        image.Rectangle
+	rootContainer tomo.ContainerBox
+	tearLine      tomo.Box
+	torn          bool
+}
+
+// NewMenu creates a new menu with the specified items. The menu will appear
+// directly under the anchor Object. If the anchor is nil, it will appear
+// directly under the mouse pointer instead.
+func NewMenu (anchor tomo.Object, items ...tomo.Object) (*Menu, error) {
+	menu := &Menu { }
+	if anchor == nil {
+		// TODO: *actually* put it under the mouse
+		window, err := tomo.NewWindow(menu.bounds)
+		if err != nil { return nil, err }
+		menu.Window = window
+	} else {
+		menu.bounds = menuBoundsFromAnchor(anchor)
+		menu.parent = anchor.GetBox().Window()
+		window, err := menu.parent.NewMenu(menu.bounds)
+		if err != nil { return nil, err }
+		menu.Window = window
+	}
+
+	menu.rootContainer = tomo.NewContainerBox()
+	menu.rootContainer.SetLayout(layouts.ContractVertical)
+
+	if !menu.torn {
+		menu.tearLine = tomo.NewBox()
+		menu.tearLine.SetRole(tomo.R("objects", "TearLine", ""))
+		menu.tearLine.SetFocusable(true)
+		menu.tearLine.OnKeyUp(func (key input.Key, numberPad bool) {
+			if key != input.KeyEnter && key != input.Key(' ') { return }
+			menu.TearOff()
+		})
+		menu.tearLine.OnMouseUp(func (button input.Button) {
+			if button != input.ButtonLeft { return }
+			if menu.tearLine.MousePosition().In(menu.tearLine.Bounds()) {
+				menu.TearOff()
+			}
+		})
+		menu.rootContainer.Add(menu.tearLine)
+	}
+	
+	for _, item := range items {
+		menu.rootContainer.Add(item)
+		if item, ok := item.(*MenuItem); ok {
+			item.OnClick(func () {
+				if !menu.torn {
+					menu.Close()
+				}
+			})
+		}
+	}
+	menu.rootContainer.SetRole(tomo.R("objects", "Container", "menu"))
+
+	menu.Window.SetRoot(menu.rootContainer)
+	return menu, nil
+}
+
+// TearOff converts this menu into a tear-off menu.
+func (this *Menu) TearOff () {
+	if this.torn          { return }
+	if this.parent == nil { return }
+	this.torn = true
+
+	window, err := this.parent.NewChild(this.bounds)
+	if err != nil { return }
+
+	visible := this.Window.Visible()
+	this.Window.SetRoot(nil)
+	this.Window.Close()
+
+	this.rootContainer.Remove(this.tearLine)
+	
+	this.Window = window
+	this.Window.SetRoot(this.rootContainer)
+	this.Window.SetVisible(visible)
+}
+
+func menuBoundsFromAnchor (anchor tomo.Object) image.Rectangle {
+	bounds := anchor.GetBox().Bounds()
+	return image.Rect (
+		bounds.Min.X, bounds.Max.Y,
+		bounds.Max.X, bounds.Max.Y)//.Add(windowBounds.Min)
+}

menuitem.go

@@ -0,0 +1,73 @@
+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"
+
+// MenuItem is a clickable button.
+type MenuItem struct {
+	tomo.ContainerBox
+
+	label *Label
+	icon  *Icon
+	labelActive bool
+	
+	on struct {
+		click event.FuncBroadcaster
+	}
+}
+
+// NewMenuItem creates a new menu item with the specified text.
+func NewMenuItem (text string) *MenuItem {
+	box := &MenuItem {
+		ContainerBox: tomo.NewContainerBox(),
+		label:        NewLabel(text),
+		icon:         NewIcon("", tomo.IconSizeSmall),
+	}
+	box.SetRole(tomo.R("objects", "MenuItem", ""))
+	box.label.SetAlign(tomo.AlignStart, tomo.AlignMiddle)
+	box.SetLayout(layouts.NewGrid([]bool { false, true }, []bool { true }))
+	
+	box.Add(box.icon)
+	box.Add(box.label)
+	
+	box.CaptureDND(true)
+	box.CaptureMouse(true)
+	box.CaptureScroll(true)
+	box.CaptureKeyboard(true)
+	
+	box.OnMouseUp(box.handleMouseUp)
+	box.OnKeyUp(box.handleKeyUp)
+	box.SetFocusable(true)
+	return box
+}
+
+// SetText sets the text of the items's label.
+func (this *MenuItem) SetText (text string) {
+	this.label.SetText(text)
+}
+
+// SetIcon sets an icon for this item. Setting the icon to IconUnknown will
+// remove it.
+func (this *MenuItem) SetIcon (id tomo.Icon) {
+	if this.icon != nil { this.Remove(this.icon) }
+	this.Insert(NewIcon(id, tomo.IconSizeSmall), this.label)
+}
+
+// OnClick specifies a function to be called when the menu item is clicked.
+func (this *MenuItem) OnClick (callback func ()) event.Cookie {
+	return this.on.click.Connect(callback)
+}
+
+func (this *MenuItem) handleKeyUp (key input.Key, numberPad bool) {
+	if key != input.KeyEnter && key != input.Key(' ') { return }
+	this.on.click.Broadcast()
+}
+
+func (this *MenuItem) handleMouseUp (button input.Button) {
+	if button != input.ButtonLeft { return }
+	if this.MousePosition().In(this.Bounds()) {
+		this.on.click.Broadcast()
+	}
+}

numberinput.go

@@ -0,0 +1,99 @@
+package objects
+
+import "math"
+import "strconv"
+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"
+
+// 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(""),
+	}
+	box.SetRole(tomo.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(tomo.IconValueIncrement)
+	box.decrement.SetIcon(tomo.IconValueDecrement)
+	
+	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

@@ -0,0 +1,373 @@
+package objects
+
+import "image"
+import "git.tebibyte.media/tomo/tomo"
+import "git.tebibyte.media/tomo/tomo/input"
+import "git.tebibyte.media/tomo/tomo/event"
+
+// Scrollbar is a special type of slider that can control the scroll of any
+// overflowing ContainerBox.
+type Scrollbar struct {
+	tomo.ContainerBox
+	handle     *SliderHandle
+	layout     scrollbarLayout
+	dragging   bool
+	dragOffset image.Point
+
+	linkCookie event.Cookie
+
+	on struct {
+		valueChange event.FuncBroadcaster
+	}
+}
+
+func newScrollbar (orient string) *Scrollbar {
+	this := &Scrollbar {
+		ContainerBox: tomo.NewContainerBox(),
+		handle: &SliderHandle {
+			Box: tomo.NewBox(),
+		},
+		layout: scrollbarLayout {
+			vertical: orient == "vertical",
+		},
+	}
+
+	this.Add(this.handle)
+	this.SetFocusable(true)
+
+	this.CaptureDND(true)
+	this.CaptureMouse(true)
+	this.CaptureScroll(true)
+	this.CaptureKeyboard(true)
+
+	this.OnKeyDown(this.handleKeyDown)
+	this.OnMouseDown(this.handleMouseDown)
+	this.OnMouseUp(this.handleMouseUp)
+	this.OnMouseMove(this.handleMouseMove)
+	this.OnScroll(this.handleScroll)
+	
+	this.handle.SetRole(tomo.R("objects", "SliderHandle", orient))
+	this.SetRole(tomo.R("objects", "Slider", orient))
+	return this
+}
+
+// NewVerticalScrollbar creates a new vertical scrollbar.
+func NewVerticalScrollbar () *Scrollbar {
+	return newScrollbar("vertical")
+}
+
+// NewHorizontalScrollbar creates a new horizontal scrollbar.
+func NewHorizontalScrollbar () *Scrollbar {
+	return newScrollbar("horizontal")
+}
+
+// Link assigns this scrollbar to a ContentObject. Closing the returned cookie
+// will unlink it.
+func (this *Scrollbar) Link (box tomo.ContentObject) event.Cookie {
+	this.layout.linked = box
+	this.linkCookie = this.newLinkCookie (
+		box.OnContentBoundsChange(this.handleLinkedContentBoundsChange))
+	this.SetLayout(this.layout)
+	return this.linkCookie
+}
+
+func (this *Scrollbar) handleLinkedContentBoundsChange () {
+	if this.layout.linked == nil { return }
+	previousValue := this.layout.value
+	trackLength := this.layout.contentLength() - this.layout.viewportLength()
+	if trackLength == 0 {
+		this.layout.value = 0
+	} else {
+		this.layout.value = this.layout.contentPos() / trackLength
+	}
+	this.SetLayout(this.layout)
+	if this.layout.value != previousValue {
+		this.on.valueChange.Broadcast()
+	}
+}
+
+// SetValue sets the value of the scrollbar between 0 and 1, where 0 is scrolled
+// all the way to the left/top, and 1 is scrolled all the way to the
+// right/bottom.
+func (this *Scrollbar) SetValue (value float64) {
+	if this.layout.linked == nil { return }
+	if value > 1 { value = 1 }
+	if value < 0 { value = 0 }
+	
+	trackLength := this.layout.contentLength() - this.layout.viewportLength()
+	position    := trackLength * value
+	point       := this.layout.linked.ContentBounds().Min
+	if this.layout.vertical {
+		point.Y = -int(position)
+	} else {
+		point.X = -int(position)
+	}
+	this.layout.linked.ScrollTo(point)
+	
+}
+
+// Value returns the value of the scrollbar between 0 and 1 where 0 is scrolled
+// all the way to the left/top, and 1 is scrolled all the way to the
+// right/bottom.
+func (this *Scrollbar) Value () float64 {
+	if this.layout.linked == nil { return 0 }
+	return this.layout.value
+}
+
+// OnValueChange specifies a function to be called when the position of the
+// scrollbar changes.
+func (this *Scrollbar) OnValueChange (callback func ()) event.Cookie {
+	return this.on.valueChange.Connect(callback)
+}
+
+func (this *Scrollbar) handleKeyDown (key input.Key, numpad bool) {
+	var increment float64; if this.layout.vertical {
+		increment = -0.05
+	} else {
+		increment = 0.05
+	}
+
+	switch key {
+	case input.KeyUp, input.KeyLeft:
+		if this.Modifiers().Alt {
+			this.SetValue(0)
+		} else {
+			this.SetValue(this.Value() - increment)
+		}
+	case input.KeyDown, input.KeyRight:
+		if this.Modifiers().Alt {
+			this.SetValue(1)
+		} else {
+			this.SetValue(this.Value() + increment)
+		}
+	case input.KeyHome:
+		this.SetValue(0)
+	case input.KeyEnd:
+		this.SetValue(1)
+	}
+}
+
+func (this *Scrollbar) handleMouseDown (button input.Button) {
+	pointer := this.MousePosition()
+	handle  := this.handle.Bounds()
+
+	within := pointer.In(handle)
+	var above bool; if this.layout.vertical {
+		above = pointer.Y < handle.Min.Y + handle.Dy() / 2
+	} else {
+		above = pointer.X < handle.Min.X + handle.Dx() / 2
+	}
+
+	switch button {
+	case input.ButtonLeft:
+		if within {
+			this.dragging   = true
+			this.dragOffset =
+				pointer.Sub(this.handle.Bounds().Min).
+				Add(this.InnerBounds().Min)
+			this.drag()
+		} else {
+			this.dragOffset = this.fallbackDragOffset()
+			this.dragging   = true
+			this.drag()
+		}
+	case input.ButtonMiddle:
+		if above {
+			this.scrollBy(this.pageSize())
+		} else {
+			this.scrollBy(-this.pageSize())
+		}
+	case input.ButtonRight:
+		if above {
+			this.scrollBy(this.stepSize())
+		} else {
+			this.scrollBy(-this.stepSize())
+		}
+	}
+}
+
+func (this *Scrollbar) handleMouseUp (button input.Button) {
+	if button != input.ButtonLeft || !this.dragging { return }
+	this.dragging = false
+}
+
+func (this *Scrollbar) handleMouseMove () {
+	if !this.dragging { return }
+	this.drag()
+}
+
+func (this *Scrollbar) handleScroll (x, y float64) {
+	if this.layout.linked == nil { return }
+	this.layout.linked.ScrollTo (
+		this.layout.linked.ContentBounds().Min.
+		Sub(image.Pt(int(x), int(y))))
+}
+
+func (this *Scrollbar) drag () {
+	pointer := this.MousePosition().Sub(this.dragOffset)
+	gutter  := this.InnerBounds()
+	handle  := this.handle.Bounds()
+
+	if this.layout.vertical {
+		this.SetValue (
+			float64(pointer.Y) /
+			float64(gutter.Dy() - handle.Dy()))
+	} else {
+		this.SetValue (
+			float64(pointer.X) /
+			float64(gutter.Dx() - handle.Dx()))
+	}
+}
+
+func (this *Scrollbar) fallbackDragOffset () image.Point {
+	if this.layout.vertical {
+		return this.InnerBounds().Min.
+			Add(image.Pt(0, this.handle.Bounds().Dy() / 2))
+	} else {
+		return this.InnerBounds().Min.
+			Add(image.Pt(this.handle.Bounds().Dx() / 2, 0))
+	}
+}
+
+func (this *Scrollbar) pageSize () int {
+	if this.layout.linked == nil { return 0 }
+	viewport := this.layout.linked.GetBox().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 tomo.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
+}
+
+func (this *Scrollbar) newLinkCookie (subCookies ...event.Cookie) *scrollbarCookie {
+	return &scrollbarCookie {
+		owner:      this,
+		subCookies: subCookies,
+	}
+}
+
+func (this *scrollbarCookie) Close () {
+	for _, cookie := range this.subCookies {
+		cookie.Close()
+	}
+	this.owner.layout.linked = nil
+	this.owner.SetLayout(this.owner.layout)
+}
+
+type scrollbarLayout struct {
+	vertical bool
+	value    float64
+	linked   tomo.ContentObject
+}
+
+func (scrollbarLayout) MinimumSize (hints tomo.LayoutHints, boxes []tomo.Box) image.Point {
+	if len(boxes) != 1 { return image.Pt(0, 0) }
+	return boxes[0].MinimumSize()
+}
+
+func (this scrollbarLayout) Arrange (hints tomo.LayoutHints, boxes []tomo.Box) {
+	if len(boxes) != 1 { return }
+	handle := image.Rectangle { Max: boxes[0].MinimumSize() }
+	gutter := hints.Bounds
+
+	var gutterLength float64;
+	var handleMin    float64;
+	if this.vertical {
+		gutterLength = float64(gutter.Dy())
+		handleMin    = float64(handle.Dy())
+	} else {
+		gutterLength = float64(gutter.Dx())
+		handleMin    = float64(handle.Dx())
+	}
+
+	// calculate handle length
+	handleLength := gutterLength * this.viewportContentRatio()
+	if handleLength < handleMin { handleLength = handleMin }
+	if handleLength >= gutterLength {
+		// just hide the handle if it isn't needed. we are the layout
+		// and we shouldn't be adding and removing boxes, so this is
+		// really the only good way to hide things.
+		// TODO perhaps have a "Hidden" rectangle in the Tomo API?
+		boxes[0].SetBounds(image.Rect(-16, -16, 0, 0))
+		return
+	}
+	if this.vertical {
+		handle.Max.Y = int(handleLength)
+	} else {
+		handle.Max.X = int(handleLength)
+	}
+
+	// calculate handle position
+	handlePosition := (gutterLength - handleLength) * this.value
+	var handleOffset image.Point
+	if this.vertical {
+		handleOffset = image.Pt(0, int(handlePosition))
+	} else {
+		handleOffset = image.Pt(int(handlePosition), 0)
+	}
+	handle = handle.Sub(handleOffset).Add(gutter.Min)
+	
+	// place handle
+	boxes[0].SetBounds(handle)
+	
+}
+
+func (this scrollbarLayout) RecommendedHeight (hints tomo.LayoutHints, boxes []tomo.Box, width int) int {
+	return this.MinimumSize(hints, boxes).X
+}
+
+func (this scrollbarLayout) RecommendedWidth (hints tomo.LayoutHints, boxes []tomo.Box, height int) int {
+	return this.MinimumSize(hints, boxes).Y
+}
+
+func (this scrollbarLayout) viewportContentRatio () float64 {
+	if this.linked == nil { return 0 }
+	return this.viewportLength() / this.contentLength()
+}
+
+func (this scrollbarLayout) viewportLength () float64 {
+	if this.vertical {
+		return float64(this.linked.GetBox().InnerBounds().Dy())
+	} else {
+		return float64(this.linked.GetBox().InnerBounds().Dx())
+	}
+}
+
+func (this scrollbarLayout) contentLength () float64 {
+	if this.vertical {
+		return float64(this.linked.ContentBounds().Dy())
+	} else {
+		return float64(this.linked.ContentBounds().Dx())
+	}
+}
+
+func (this scrollbarLayout) contentPos () float64 {
+	if this.vertical {
+		return float64(this.linked.ContentBounds().Min.Y)
+	} else {
+		return float64(this.linked.ContentBounds().Min.X)
+	}
+}

scrollcontainer.go

@@ -0,0 +1,198 @@
+package objects
+
+import "image"
+import "git.tebibyte.media/tomo/tomo"
+import "git.tebibyte.media/tomo/tomo/event"
+
+// 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)
+	this.SetRole(tomo.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.ContentObject) {
+	if this.layout.root != nil {
+		// remove root and close cookies
+		this.Remove(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)
+		}
+	}
+}
+
+// SetValue sets the horizontal and vertical scrollbar values where 0 is all the
+// way to the left/top, and 1 is all the way to the right/bottom.
+func (this *ScrollContainer) SetValue (x, y float64) {
+	if this.layout.horizontal != nil {
+		this.layout.horizontal.SetValue(x)
+	}
+	if this.layout.vertical != nil {
+		this.layout.vertical.SetValue(y)
+	}
+}
+
+// Value returns the horizontal and vertical scrollbar values where 0 is all the
+// way to the left/top, and 1 is all the way to the right/bottom.
+func (this *ScrollContainer) Value () (x, y float64) {
+	if this.layout.horizontal != nil {
+		x = this.layout.horizontal.Value()
+	}
+	if this.layout.vertical != nil {
+		y = this.layout.vertical.Value()
+	}
+	return x, y
+}
+
+func (this *ScrollContainer) handleScroll (x, y float64) {
+	if this.layout.root == nil { return }
+	this.layout.root.ScrollTo (
+		this.layout.root.ContentBounds().Min.
+		Sub(image.Pt(int(x), int(y))))
+}
+
+// TODO: remove this and replace it with something from the layouts package
+type scrollContainerLayout struct {
+	root       tomo.ContentObject
+	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.GetBox().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.GetBox().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 (this *scrollContainerLayout) RecommendedHeight (hints tomo.LayoutHints, boxes []tomo.Box, width int) int {
+	return this.MinimumSize(hints, boxes).X
+}
+
+func (this *scrollContainerLayout) RecommendedWidth (hints tomo.LayoutHints, boxes []tomo.Box, height int) int {
+	return this.MinimumSize(hints, boxes).Y
+}
+
+func max (x, y int) int {
+	if x > y { return x }
+	return y
+}

separator.go

@@ -1,7 +1,6 @@
 package objects
 
 import "git.tebibyte.media/tomo/tomo"
-import "git.tebibyte.media/tomo/tomo/theme"
 
 // Separator is a line for visually separating elements.
 type Separator struct {
@@ -13,7 +12,6 @@ func NewSeparator () *Separator {
 	this := &Separator {
 		Box: tomo.NewBox(),
 	}
-	theme.Apply(this, theme.R("objects", "Separator", ""))
+	this.SetRole(tomo.R("objects", "Separator", ""))
 	return this
 }
-

slider.go

@@ -2,24 +2,25 @@ package objects
 
 import "image"
 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"
 
-// UNDER CONSTRUCTION!
-
+// Slider is a control that selects a numeric value between 0 and 1.
 type Slider struct {
 	tomo.ContainerBox
 	handle     *SliderHandle
 	layout     sliderLayout
 	dragging   bool
 	dragOffset image.Point
-	
+	step       float64
+
 	on struct {
-		valueChange event.FuncBroadcaster
+		slide event.FuncBroadcaster
 	}
 }
 
+// SliderHandle is a simple object that serves as a handle for sliders and
+// scrollbars. It is completely inert.
 type SliderHandle struct {
 	tomo.Box
 }
@@ -33,80 +34,101 @@ func newSlider (orient string, value float64) *Slider {
 		layout: sliderLayout {
 			vertical: orient == "vertical",
 		},
+		step: 0.05,
 	}
-	
+
 	this.Add(this.handle)
 	this.SetFocusable(true)
-	this.SetPropagateEvents(false)
+
+	this.CaptureDND(true)
+	this.CaptureMouse(true)
+	this.CaptureScroll(true)
+	this.CaptureKeyboard(true)
+
 	this.SetValue(value)
 	this.OnKeyDown(this.handleKeyDown)
 	this.OnMouseDown(this.handleMouseDown)
 	this.OnMouseUp(this.handleMouseUp)
 	this.OnMouseMove(this.handleMouseMove)
-	theme.Apply(this.handle, theme.R("objects", "SliderHandle", orient))
-	theme.Apply(this,        theme.R("objects", "Slider", orient))
+	this.OnScroll(this.handleScroll)
+	
+	this.handle.SetRole(tomo.R("objects", "SliderHandle", orient))
+	this.SetRole(tomo.R("objects", "Slider", orient))
 	return this
 }
 
+// NewVerticalSlider creates a new vertical slider with the specified value.
 func NewVerticalSlider (value float64) *Slider {
 	return newSlider("vertical", value)
 }
 
+// NewHorizontalSlider creates a new horizontal slider with the specified value.
 func NewHorizontalSlider (value float64) *Slider {
 	return newSlider("horizontal", value)
 }
 
+// SetValue sets the value of the slider between 0 and 1.
 func (this *Slider) SetValue (value float64) {
 	if value < 0 { value = 0 }
 	if value > 1 { value = 1 }
 	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.
 func (this *Slider) Value () float64 {
 	return this.layout.value
 }
 
-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) {
+	var increment float64; if this.layout.vertical {
+		increment = -0.05
+	} else {
+		increment = 0.05
+	}
+
 	switch key {
 	case input.KeyUp, input.KeyLeft:
 		if this.Modifiers().Alt {
 			this.SetValue(0)
 		} else {
-			this.SetValue(this.Value() - 0.05)		
+			this.SetValue(this.Value() - increment)
 		}
+		this.on.slide.Broadcast()
 	case input.KeyDown, input.KeyRight:
 		if this.Modifiers().Alt {
 			this.SetValue(1)
 		} else {
-			this.SetValue(this.Value() + 0.05)		
+			this.SetValue(this.Value() + increment)
 		}
+		this.on.slide.Broadcast()
 	case input.KeyHome:
 		this.SetValue(0)
+		this.on.slide.Broadcast()
 	case input.KeyEnd:
 		this.SetValue(1)
+		this.on.slide.Broadcast()
 	}
 }
 
 func (this *Slider) handleMouseDown (button input.Button) {
 	pointer := this.MousePosition()
 	handle  := this.handle.Bounds()
-	var above, within bool
 	
-	if pointer.In(handle) {
-		within = true
-	} else if this.layout.vertical {
-		above = pointer.Y < handle.Min.Y
+	within := pointer.In(handle)
+	var above bool; if this.layout.vertical {
+		above = pointer.Y < handle.Min.Y + handle.Dy() / 2
 	} else {
-		above = pointer.X < handle.Min.X
+		above = pointer.X < handle.Min.X + handle.Dx() / 2
 	}
-	
+
 	switch button {
 	case input.ButtonLeft:
 		if within {
@@ -123,14 +145,18 @@ 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.SetValue(this.Value() - this.step)
+			this.on.slide.Broadcast()
 		} else {
-			this.SetValue(this.Value() + 0.05)
+			this.SetValue(this.Value() + this.step)
+			this.on.slide.Broadcast()
 		}
 	}
 }
@@ -145,6 +171,12 @@ func (this *Slider) handleMouseMove () {
 	this.drag()
 }
 
+func (this *Slider) handleScroll (x, y float64) {
+	delta := (x + y) * 0.005
+	this.SetValue(this.Value() + delta)
+	this.on.slide.Broadcast()
+}
+
 func (this *Slider) drag () {
 	pointer := this.MousePosition().Sub(this.dragOffset)
 	gutter  := this.InnerBounds()
@@ -152,6 +184,7 @@ func (this *Slider) drag () {
 
 	if this.layout.vertical {
 		this.SetValue (
+			1 -
 			float64(pointer.Y) /
 			float64(gutter.Dy() - handle.Dy()))
 	} else {
@@ -159,6 +192,7 @@ func (this *Slider) drag () {
 			float64(pointer.X) /
 			float64(gutter.Dx() - handle.Dx()))
 	}
+	this.on.slide.Broadcast()
 }
 
 func (this *Slider) fallbackDragOffset () image.Point {
@@ -185,11 +219,11 @@ func (this sliderLayout) Arrange (hints tomo.LayoutHints, boxes []tomo.Box) {
 	if len(boxes) != 1 { return }
 	handle := image.Rectangle { Max: boxes[0].MinimumSize() }
 	gutter := hints.Bounds
-	
+
 	if this.vertical {
 		height := gutter.Dy() - handle.Dy()
-		offset := int(float64(height) * this.value)
-		gutter.Max.X = handle.Max.X
+		offset := int(float64(height) * (1 - this.value))
+		handle.Max.X = gutter.Dx()
 		boxes[0].SetBounds (
 			handle.
 			Add(image.Pt(0, offset)).
@@ -197,10 +231,18 @@ func (this sliderLayout) Arrange (hints tomo.LayoutHints, boxes []tomo.Box) {
 	} else {
 		width  := gutter.Dx() - handle.Dx()
 		offset := int(float64(width) * this.value)
-		gutter.Max.Y = handle.Max.Y
+		handle.Max.Y = gutter.Dy()
 		boxes[0].SetBounds (
 			handle.
 			Add(image.Pt(offset, 0)).
 			Add(gutter.Min))
 	}
 }
+
+func (this sliderLayout) RecommendedHeight (tomo.LayoutHints, []tomo.Box, int) int {
+	return 0
+}
+
+func (this sliderLayout) RecommendedWidth (tomo.LayoutHints, []tomo.Box, int) int {
+	return 0
+}

textinput.go

@@ -1,8 +1,8 @@
 package objects
 
+import "image"
 import "git.tebibyte.media/tomo/tomo"
 import "git.tebibyte.media/tomo/tomo/text"
-import "git.tebibyte.media/tomo/tomo/theme"
 import "git.tebibyte.media/tomo/tomo/input"
 import "git.tebibyte.media/tomo/tomo/event"
 
@@ -12,17 +12,21 @@ type TextInput struct {
 	text []rune
 	on struct {
 		enter event.FuncBroadcaster
+		edit  event.FuncBroadcaster
 	}
 }
 
 // NewTextInput creates a new text input containing the specified text.
 func NewTextInput (text string) *TextInput {
 	this := &TextInput { TextBox: tomo.NewTextBox() }
-	theme.Apply(this, theme.R("objects", "TextInput", ""))
+	this.SetRole(tomo.R("objects", "TextInput", ""))
+	this.SetAlign(tomo.AlignStart, tomo.AlignMiddle)
 	this.SetText(text)
 	this.SetFocusable(true)
 	this.SetSelectable(true)
+	this.SetOverflow(true, false)
 	this.OnKeyDown(this.handleKeyDown)
+	this.OnScroll(this.handleScroll)
 	return this
 }
 
@@ -43,13 +47,21 @@ 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()
 	word      := modifiers.Control
 	sel       := modifiers.Shift
 	changed   := false
-	
+
+	// TODO all dot control (movement, selection, etc) should be done in the
+	// backend. (editing should be done here, though)
+
 	switch {
 	case key == input.KeyEnter:
 		this.on.enter.Broadcast()
@@ -84,7 +96,22 @@ func (this *TextInput) handleKeyDown (key input.Key, numpad bool) {
 		this.text, dot = text.Type(this.text, dot, rune(key))
 		changed = true
 	}
-	
+
 	this.Select(dot)
-	if changed { this.SetText(string(this.text)) }
+	if changed {
+		this.SetText(string(this.text))
+		this.on.edit.Broadcast()
+	}
+}
+
+// Type types a character at the current dot position.
+func (this *TextInput) Type (char rune) {
+	dot := this.Dot()
+	this.text, dot = text.Type(this.text, dot, rune(char))
+	this.Select(dot)
+	this.SetText(string(this.text))
+}
+
+func (this *TextInput) handleScroll (x, y float64) {
+	this.ScrollTo(this.ContentBounds().Min.Add(image.Pt(int(x), int(y))))
 }

textview.go

@@ -0,0 +1,26 @@
+package objects
+
+import "image"
+import "git.tebibyte.media/tomo/tomo"
+
+// 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() }
+	this.SetRole(tomo.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))))
+}