more views

draw_buffer.go

@@ -5,8 +5,31 @@ import (
 )
 
 func drawBuffer(scr tcell.Screen, buf *ViewBuffer) {
-	buf.ForEach(func(x, y int, rn Rune) {
+	// buf.ForEach(func(x, y int, rn Rune) {
-		scr.SetContent(x, y, rn.Rn, nil, rn.Style)
+	// 	scr.SetContent(x, y, rn.Rn, nil, rn.Style)
+	// })
+
+	buf.ForEachLine(func(y int, content []Rune) {
+		for x := 0; x < buf.Width(); x++ {
+			rn := content[x]
+			if rn.Rn >= '─' && rn.Rn <= '╿' {
+				scr.SetContent(x, y, rn.Rn, []rune{content[x+1].Rn}, rn.Style)
+				x++
+			} else {
+				scr.SetContent(x, y, rn.Rn, nil, rn.Style)
+			}
+		}
 	})
+
 	scr.Show()
 }
+
+func truncateBuffer(buf *ViewBuffer, w, h int) *ViewBuffer {
+	if w < 0 {
+		w = buf.Width()
+	}
+	if h < 0 {
+		h = buf.Height()
+	}
+	return buf.Sub(0, 0, w, h)
+}

events.go

@@ -1,5 +1,8 @@
 package tui
 
 type Events interface {
+
+	// KeyPressed is called every time a key or key-combination is pressed.
+	// If KeyPressed returns true, the event will not be passed onto child views
 	OnKeyPressed(event *KeyEvent) (consumed bool)
 }

go.mod

@@ -3,8 +3,9 @@ module git.tordarus.net/Tordarus/tui
 go 1.18
 
 require (
-	git.tordarus.net/Tordarus/buf2d v1.1.0
+	git.tordarus.net/Tordarus/buf2d v1.1.1
 	github.com/gdamore/tcell v1.4.0
+	golang.org/x/text v0.3.7
 )
 
 require (
@@ -12,5 +13,4 @@ require (
 	github.com/lucasb-eyer/go-colorful v1.0.3 // indirect
 	github.com/mattn/go-runewidth v0.0.7 // indirect
 	golang.org/x/sys v0.0.0-20190626150813-e07cf5db2756 // indirect
-	golang.org/x/text v0.3.0 // indirect
 )

go.sum

@@ -1,5 +1,5 @@
-git.tordarus.net/Tordarus/buf2d v1.1.0 h1:rIZjD7yeX5XK2D1h75ET5Og0u/NQF3eVonnC5aaqVkQ=
+git.tordarus.net/Tordarus/buf2d v1.1.1 h1:rYvQ2YveqogCoKy5andQxuORPusWbUhpnqJhzVkTlRs=
-git.tordarus.net/Tordarus/buf2d v1.1.0/go.mod h1:XXPpS8nQK0gUI0ki7ftV/qlprsGCRWFVSD4ybvDuUL8=
+git.tordarus.net/Tordarus/buf2d v1.1.1/go.mod h1:XXPpS8nQK0gUI0ki7ftV/qlprsGCRWFVSD4ybvDuUL8=
 github.com/gdamore/encoding v1.0.0 h1:+7OoQ1Bc6eTm5niUzBa0Ctsh6JbMW6Ra+YNuAtDBdko=
 github.com/gdamore/encoding v1.0.0/go.mod h1:alR0ol34c49FCSBLjhosxzcPHQbf2trDkoo5dl+VrEg=
 github.com/gdamore/tcell v1.4.0 h1:vUnHwJRvcPQa3tzi+0QI4U9JINXYJlOz9yiaiPQ2wMU=
@@ -10,5 +10,6 @@ github.com/mattn/go-runewidth v0.0.7 h1:Ei8KR0497xHyKJPAv59M1dkC+rOZCMBJ+t3fZ+tw
 github.com/mattn/go-runewidth v0.0.7/go.mod h1:H031xJmbD/WCDINGzjvQ9THkh0rPKHF+m2gUSrubnMI=
 golang.org/x/sys v0.0.0-20190626150813-e07cf5db2756 h1:9nuHUbU8dRnRRfj9KjWUVrJeoexdbeMjttk6Oh1rD10=
 golang.org/x/sys v0.0.0-20190626150813-e07cf5db2756/go.mod h1:h1NjWce9XRLGQEsW7wpKNCjG9DtNlClVuFLEZdDNbEs=
-golang.org/x/text v0.3.0 h1:g61tztE5qeGQ89tm6NTjjM9VPIm088od1l6aSorWRWg=
 golang.org/x/text v0.3.0/go.mod h1:NqM8EUOU14njkJ3fqMW+pc6Ldnwhi/IjpwHt7yyuwOQ=
+golang.org/x/text v0.3.7 h1:olpwvP2KacW1ZWvsR7uQhoyTYvKAupfQrRGBFM352Gk=
+golang.org/x/text v0.3.7/go.mod h1:u+2+/6zg+i71rQMx5EYifcz6MCKuco9NR6JIITiCfzQ=

screen.go

@@ -10,8 +10,12 @@ import (
 
 type Screen struct {
 	scr    tcell.Screen
+	buf    *ViewBuffer
 	stopCh chan error
 	Root   View
+
+	// KeyPressed is called every time a key or key-combination is pressed.
+	KeyPressed func(event *KeyEvent) (consumed bool)
 }
 
 func NewScreen(root View) (*Screen, error) {
@@ -37,10 +41,7 @@ func (s *Screen) eventloop() {
 		case *tcell.EventResize:
 			go s.Redraw()
 		case *tcell.EventKey:
-			go func() {
+			go s.onKeyPressed(event)
-				s.Root.OnKeyPressed(event)
-				s.Redraw()
-			}()
 		default:
 			s.StopWithError(errors.New(fmt.Sprintf("%#v", event)))
 		}
@@ -67,9 +68,21 @@ func (s *Screen) StopWithError(err error) {
 	s.stopCh <- err
 }
 
+func (s *Screen) onKeyPressed(event *KeyEvent) {
+	if s.KeyPressed == nil || !s.KeyPressed(event) {
+		s.Root.OnKeyPressed(event)
+	}
+	s.Redraw()
+}
+
 func (s *Screen) Redraw() {
 	w, h := s.scr.Size()
-	buf := buf2d.NewBuffer(w, h, DefaultRune)
+
-	s.Root.Draw(buf)
+	if s.buf == nil || s.buf.Width() != w || s.buf.Height() != h {
-	drawBuffer(s.scr, buf)
+		s.buf = buf2d.NewBuffer(w, h, DefaultRune)
+	}
+
+	rw, rh := s.Root.Layout()
+	s.Root.Draw(truncateBuffer(s.buf, rw, rh))
+	drawBuffer(s.scr, s.buf)
 }

tests/screen_test.go

@@ -10,21 +10,90 @@ import (
 	"github.com/gdamore/tcell"
 )
 
-func TestScreen(t *testing.T) {
+func TestFlowGroup(t *testing.T) {
-	textView := views.NewTextView("hello world")
+	textView := views.NewTextView("hello world!")
-	eventView := views.NewEventView(textView)
+	textView.SetStyle(tui.StyleDefault.Background(tcell.ColorRed).Foreground(tcell.ColorBlack))
-	screen, err := tui.NewScreen(eventView)
+
+	marginView := views.NewMarginView(textView)
+	marginView.SetMargin(3, 1, 1, 0)
+
+	//borderView := views.NewBorderView(textView)
+
+	textView2 := views.NewTextView("Hi!")
+	textView2.SetStyle(tui.StyleDefault.Background(tcell.ColorBlue).Foreground(tcell.ColorYellow))
+
+	growView := views.NewGrowView()
+	growView.SetStyle(tui.StyleDefault.Background(tcell.ColorGreen))
+
+	growView2 := views.NewGrowView()
+	growView2.SetStyle(tui.StyleDefault.Background(tcell.ColorYellow))
+
+	flowGroup := views.NewFlowGroup(tui.Vertical)
+	flowGroup.AppendViews(marginView, growView, textView2)
+
+	constrainView := views.NewConstrainView(flowGroup)
+	constrainView.SetStyle(tui.StyleDefault.Background(tcell.ColorPurple))
+	constrainView.Constrain(-1, -1)
+
+	screen, err := tui.NewScreen(constrainView)
 	if err != nil {
 		t.Error(err)
 		return
 	}
 
-	eventView.KeyPressed = func(event *tui.KeyEvent) (consumed bool) {
+	screen.KeyPressed = func(event *tui.KeyEvent) (consumed bool) {
+		textView.Text = event.When().String()
+
 		if event.Key() == tcell.KeyCtrlC {
 			screen.StopWithError(errors.New(fmt.Sprintf("key: %#v | rune: %s", event.Key(), string(event.Rune()))))
 		}
 
-		//textView.Text = event.When().String()
+		return true
+	}
+
+	err = screen.Start()
+	fmt.Println(err)
+}
+
+func TestBorderGroup(t *testing.T) {
+	topView := views.NewConstrainView(nil)
+	topView.SetStyle(tui.StyleDefault.Background(tcell.ColorBlue))
+	topView.Constrain(10, 10)
+
+	bottomView := views.NewConstrainView(nil)
+	bottomView.SetStyle(tui.StyleDefault.Background(tcell.ColorRed))
+	bottomView.Constrain(10, 10)
+
+	leftView := views.NewConstrainView(nil)
+	leftView.SetStyle(tui.StyleDefault.Background(tcell.ColorYellow))
+	leftView.Constrain(10, 10)
+
+	rightView := views.NewConstrainView(nil)
+	rightView.SetStyle(tui.StyleDefault.Background(tcell.ColorGreen))
+	rightView.Constrain(10, 10)
+
+	centerView := views.NewConstrainView(nil)
+	centerView.SetStyle(tui.StyleDefault.Background(tcell.ColorPurple))
+	centerView.Constrain(10, 10)
+
+	borderGroup := views.NewBorderGroup()
+	borderGroup.SetStyle(tui.StyleDefault.Background(tcell.ColorPurple))
+	borderGroup.SetView(topView, views.Top)
+	borderGroup.SetView(bottomView, views.Bottom)
+	borderGroup.SetView(leftView, views.Left)
+	borderGroup.SetView(rightView, views.Right)
+	borderGroup.SetView(centerView, views.Center)
+
+	screen, err := tui.NewScreen(borderGroup)
+	if err != nil {
+		t.Error(err)
+		return
+	}
+
+	screen.KeyPressed = func(event *tui.KeyEvent) (consumed bool) {
+		if event.Key() == tcell.KeyCtrlC {
+			screen.StopWithError(errors.New(fmt.Sprintf("key: %#v | rune: %s", event.Key(), string(event.Rune()))))
+		}
 		return true
 	}
 

types.go

@@ -11,3 +11,32 @@ type Style = tcell.Style
 type Color = tcell.Color
 
 var StyleDefault Style = tcell.StyleDefault
+
+type Point struct {
+	X, Y int
+}
+
+type Size struct {
+	Width, Height int
+}
+
+type Dimension struct {
+	Point
+	Size
+}
+
+type Orientation uint8
+
+const (
+	Horizontal Orientation = iota
+	Vertical
+)
+
+type Side uint8
+
+const (
+	Top Side = iota
+	Bottom
+	Left
+	Right
+)

utils.go

@@ -2,30 +2,88 @@ package tui
 
 import (
 	"strings"
+
+	"golang.org/x/text/width"
 )
 
 // WriteString writes a whole string to the buffer at position (x,y)
 // no word wrap is applied at all. If the string does not fit, it will be truncated
-func WriteString(b *ViewBuffer, str string, style Style, x, y int) {
+func WriteString(b *ViewBuffer, str string, style Style, x, y int) (width int) {
 	dx := x
 	for _, r := range str {
 		if dx >= b.Width() {
 			return
 		}
+
 		b.Set(dx, y, Rune{r, style})
-		dx++
+		dx += runeWidth(r)
 	}
+	return dx - x
 }
 
 // WriteMultiLineString writes a multi-line string to the buffer at position (x,y)
 // no word wrap is applied at all. If a line does not fit horizontally, it will be truncated
 // All lines which do not fit vertically will be truncated as well
-func WriteMultiLineString(b *ViewBuffer, str string, style Style, x, y int) {
+func WriteMultiLineString(b *ViewBuffer, str string, style Style, x, y int) (maxLineWidth, lineCount int) {
 	lines := strings.Split(str, "\n")
 	for dy, line := range lines {
 		if dy >= b.Height() {
 			return
 		}
-		WriteString(b, line, style, x, y+dy)
+		lineWidth := WriteString(b, line, style, x, y+dy)
+		maxLineWidth = max(maxLineWidth, lineWidth)
+	}
+	return maxLineWidth, len(lines)
+}
+
+// MeasureString measures how much horizontal space str consumes when drawn to a buffer
+func MeasureString(str string) (width int) {
+	dx := 0
+	for _, r := range str {
+		dx += runeWidth(r)
+	}
+	return dx
+}
+
+// MeasureString measures how much horizontal and vertical space str consumes when drawn to a buffer
+func MeasureMultiLineString(str string) (maxLineWidth, lineCount int) {
+	lines := strings.Split(str, "\n")
+	for _, line := range lines {
+		lineWidth := MeasureString(line)
+		maxLineWidth = max(maxLineWidth, lineWidth)
+	}
+	return maxLineWidth, len(lines)
+}
+
+func runeWidth(r rune) int {
+	//fmt.Println(r, width.LookupRune(r).Kind())
+	switch width.LookupRune(r).Kind() {
+	case width.EastAsianFullwidth:
+		fallthrough
+	case width.EastAsianWide:
+		return 2
+	default:
+		return 1
 	}
 }
+
+func min(x, y int) int {
+	if x < y {
+		return x
+	}
+	return y
+}
+
+func max(x, y int) int {
+	if x > y {
+		return x
+	}
+	return y
+}
+
+func iff[T any](condition bool, trueValue, falseValue T) T {
+	if condition {
+		return trueValue
+	}
+	return falseValue
+}

view.go

@@ -1,34 +1,27 @@
 package tui
 
-// View defines the behavior of any element displayable on screen
+// View defines the behavior of any element displayable on screen.
 // To define custom Views, it is recommended to add ViewTmpl
 // as the promoted anonymous field for your custom View struct.
 // It implements the View interface with useful default behavior
 type View interface {
 	Events
 
-	SetForeground(color Color)
+	SetStyle(s Style)
-	Foreground() Color
-
-	SetBackground(color Color)
-	Background() Color
-
 	Style() Style
 
-	Draw(*ViewBuffer)
+	Layout() (prefWidth, prefHeight int)
+	Draw(buf *ViewBuffer)
 }
 
 // Group defines the behavior of a View which can hold multiple sub views
-// To define custom Groups, it is recommended to add GroupTmpl
-// as the promoted anonymous field for your custom Wrapper struct.
-// It implements the Group interface with useful default behavior
 type Group interface {
 	View
 
-	Children() []View
+	Views() []View
 }
 
-// Wrapper defines the behavior of a GroupView which can hold exactly one sub view
+// Wrapper defines the behavior of a GroupView which can hold exactly one sub view.
 // To define custom Wrappers, it is recommended to add WrapperTmpl
 // as the promoted anonymous field for your custom Wrapper struct.
 // It implements the Wrapper interface with useful default behavior

viewgroup.go

@@ -1,3 +0,0 @@
-package tui
-
-// TODO GroupTmpl

views/bordergroup.go

@@ -0,0 +1,149 @@
+package views
+
+import (
+	"git.tordarus.net/Tordarus/tui"
+)
+
+// BorderGroup ia a tui.Group which places its children in a linear layout
+type BorderGroup struct {
+	tui.ViewTmpl
+	views            map[Slot]tui.View
+	horizontalLayout *LayoutResult
+	verticalLayout   *LayoutResult
+}
+
+var _ tui.Group = &BorderGroup{}
+
+func NewBorderGroup() *BorderGroup {
+	return &BorderGroup{
+		views: map[Slot]tui.View{},
+	}
+}
+
+func (g *BorderGroup) Views() []tui.View {
+	s := make([]tui.View, 0, len(g.views))
+	for _, view := range g.views {
+		s = append(s, view)
+	}
+	return s
+}
+
+func (g *BorderGroup) SetView(v tui.View, slot Slot) {
+	g.views[slot] = v
+}
+
+func (g *BorderGroup) View(slot Slot) tui.View {
+	return g.views[slot]
+}
+
+func (g *BorderGroup) Draw(buf *tui.ViewBuffer) {
+	g.ViewTmpl.Draw(buf)
+
+	if g.verticalLayout == nil {
+		g.Layout()
+	}
+	verticalLayout := g.verticalLayout
+
+	if g.horizontalLayout == nil {
+		g.Layout()
+	}
+	horizontalLayout := g.horizontalLayout
+
+	remainingVerticalSpacePerView := (buf.Height() - verticalLayout.Sum.Height)
+	if verticalLayout.VerticalNegativeCount > 0 {
+		remainingVerticalSpacePerView /= verticalLayout.VerticalNegativeCount
+	}
+
+	remainingHorizontalSpacePerView := (buf.Width() - horizontalLayout.Sum.Width)
+	if horizontalLayout.HorizontalNegativeCount > 0 {
+		remainingHorizontalSpacePerView /= horizontalLayout.HorizontalNegativeCount
+	}
+
+	fitsVertically := buf.Height() >= verticalLayout.Sum.Height
+	fitsHorizontally := buf.Width() >= horizontalLayout.Sum.Width
+
+	var topHeight int
+	var bottomHeight int
+	var leftWidth int
+	var rightWidth int
+
+	if view, ok := g.views[Top]; ok {
+		_, topHeight = view.Layout()
+
+		if fitsVertically {
+			topHeight = iff(topHeight < 0, remainingVerticalSpacePerView, topHeight)
+		} else {
+			topHeight = int(float64(buf.Height()) * float64(topHeight) / float64(verticalLayout.Sum.Height))
+		}
+
+		view.Draw(buf.Sub(0, 0, buf.Width(), topHeight))
+	}
+
+	if view, ok := g.views[Bottom]; ok {
+		_, bottomHeight = view.Layout()
+
+		if fitsVertically {
+			bottomHeight = iff(bottomHeight < 0, remainingVerticalSpacePerView, bottomHeight)
+		} else {
+			bottomHeight = int(float64(buf.Height()) * float64(bottomHeight) / float64(verticalLayout.Sum.Height))
+		}
+
+		view.Draw(buf.Sub(0, buf.Height()-bottomHeight, buf.Width(), bottomHeight))
+	}
+
+	if view, ok := g.views[Left]; ok {
+		leftWidth, _ = view.Layout()
+
+		if fitsHorizontally {
+			leftWidth = iff(leftWidth < 0, remainingHorizontalSpacePerView, leftWidth)
+		} else {
+			leftWidth = int(float64(buf.Width()) * float64(leftWidth) / float64(horizontalLayout.Sum.Width))
+		}
+
+		view.Draw(buf.Sub(0, topHeight, leftWidth, buf.Height()-topHeight-bottomHeight))
+	}
+
+	if view, ok := g.views[Right]; ok {
+		rightWidth, _ = view.Layout()
+
+		if fitsHorizontally {
+			rightWidth = iff(rightWidth < 0, remainingHorizontalSpacePerView, rightWidth)
+		} else {
+			rightWidth = int(float64(buf.Width()) * float64(rightWidth) / float64(horizontalLayout.Sum.Width))
+		}
+
+		view.Draw(buf.Sub(buf.Width()-rightWidth, topHeight, rightWidth, buf.Height()-topHeight-bottomHeight))
+	}
+
+	if view, ok := g.views[Center]; ok {
+		view.Draw(buf.Sub(leftWidth, topHeight, buf.Width()-leftWidth-rightWidth, buf.Height()-topHeight-bottomHeight))
+	}
+
+	g.verticalLayout = nil
+	g.horizontalLayout = nil
+}
+
+func (g *BorderGroup) Layout() (prefWidth, prefHeight int) {
+	g.verticalLayout = CalculateLayoutResult([]tui.View{g.View(Top), g.View(Center), g.View(Bottom)})
+	g.horizontalLayout = CalculateLayoutResult([]tui.View{g.View(Left), g.View(Center), g.View(Right)})
+	return -1, -1
+}
+
+func (g *BorderGroup) OnKeyPressed(event *tui.KeyEvent) (consumed bool) {
+	for _, view := range g.Views() {
+		if view.OnKeyPressed(event) {
+			return true
+		}
+	}
+	return false
+}
+
+type Slot uint8
+
+const (
+	Top Slot = iota
+	Bottom
+	Left
+	Right
+	Center
+)

views/borderview.go

@@ -0,0 +1,93 @@
+package views
+
+import "git.tordarus.net/Tordarus/tui"
+
+// BorderView is a tui.Wrapper which draws an ASCII border around its view.
+// Be aware that box drawing characters must share the same tui.Style with the next character.
+// This can lead to color artifacts when using BorderView with colored styles.
+type BorderView struct {
+	tui.WrapperTmpl
+	Border BorderBox
+}
+
+var _ tui.View = &BorderView{}
+
+func NewBorderView(view tui.View) *BorderView {
+	v := new(BorderView)
+	v.SetView(view)
+	v.Border = ThinBorder()
+	return v
+}
+
+func (g *BorderView) Draw(buf *tui.ViewBuffer) {
+	g.View().Draw(buf.Sub(1, 1, buf.Width()-2, buf.Height()-2))
+
+	buf.Set(0, 0, tui.Rune{Rn: g.Border.TopLeft, Style: g.Style()})
+	buf.Set(buf.Width()-1, 0, tui.Rune{Rn: g.Border.TopRight, Style: g.Style()})
+
+	buf.Set(0, buf.Height()-1, tui.Rune{Rn: g.Border.BottomLeft, Style: g.Style()})
+	buf.Set(buf.Width()-1, buf.Height()-1, tui.Rune{Rn: g.Border.BottomRight, Style: g.Style()})
+
+	for x := 1; x < buf.Width()-1; x++ {
+		buf.Set(x, 0, tui.Rune{Rn: g.Border.Horizontal, Style: g.Style()})
+		buf.Set(x, buf.Height()-1, tui.Rune{Rn: g.Border.Horizontal, Style: g.Style()})
+	}
+
+	for y := 1; y < buf.Height()-1; y++ {
+		buf.Set(0, y, tui.Rune{Rn: g.Border.Vertical, Style: g.Style()})
+		buf.Set(buf.Width()-1, y, tui.Rune{Rn: g.Border.Vertical, Style: g.Style()})
+	}
+}
+
+func (v *BorderView) Layout() (prefWidth, prefHeight int) {
+	w, h := v.View().Layout()
+	w = iff(w > 0, w+2, w)
+	h = iff(h > 0, h+2, h)
+	return w, h
+}
+
+func (v *BorderView) Style() tui.Style {
+	return v.ViewTmpl.Style()
+}
+
+type BorderBox struct {
+	TopLeft     rune
+	TopRight    rune
+	BottomLeft  rune
+	BottomRight rune
+	Horizontal  rune
+	Vertical    rune
+}
+
+func ThickBorder() BorderBox {
+	return BorderBox{
+		TopLeft:     '┏',
+		TopRight:    '┓',
+		BottomLeft:  '┗',
+		BottomRight: '┛',
+		Horizontal:  '━',
+		Vertical:    '┃',
+	}
+}
+
+func ThinBorder() BorderBox {
+	return BorderBox{
+		TopLeft:     '┌',
+		TopRight:    '┐',
+		BottomLeft:  '└',
+		BottomRight: '┘',
+		Horizontal:  '─',
+		Vertical:    '│',
+	}
+}
+
+func DoubleBorder() BorderBox {
+	return BorderBox{
+		TopLeft:     '╔',
+		TopRight:    '╗',
+		BottomLeft:  '╚',
+		BottomRight: '╝',
+		Horizontal:  '═',
+		Vertical:    '║',
+	}
+}

views/constrainview.go

@@ -0,0 +1,29 @@
+package views
+
+import (
+	"git.tordarus.net/Tordarus/tui"
+)
+
+// ConstrainView is a tui.Wrapper which constrains the dimensions of its View
+type ConstrainView struct {
+	tui.WrapperTmpl
+	MaxWidth  int
+	MaxHeight int
+}
+
+var _ tui.View = &ConstrainView{}
+
+func NewConstrainView(view tui.View) *ConstrainView {
+	v := new(ConstrainView)
+	v.SetView(view)
+	v.Constrain(-1, -1)
+	return v
+}
+
+func (v *ConstrainView) Constrain(maxWidth, maxHeight int) {
+	v.MaxWidth, v.MaxHeight = maxWidth, maxHeight
+}
+
+func (v *ConstrainView) Layout() (prefWidth, prefHeight int) {
+	return v.MaxWidth, v.MaxHeight
+}

views/coordgroup.go

@@ -0,0 +1,49 @@
+package views
+
+import "git.tordarus.net/Tordarus/tui"
+
+// CoordGroup is a tui.Group which places its children on predefined coordinates
+type CoordGroup struct {
+	tui.ViewTmpl
+	views map[tui.View]tui.Dimension
+}
+
+var _ tui.Group = &CoordGroup{}
+
+func NewCoordGroup() *CoordGroup {
+	return &CoordGroup{
+		views: map[tui.View]tui.Dimension{},
+	}
+}
+
+func (g *CoordGroup) Views() []tui.View {
+	s := make([]tui.View, 0, len(g.views))
+	for v := range g.views {
+		s = append(s, v)
+	}
+	return s
+}
+
+// SetView places v at the given coordinates with the given dimensions.
+// v will be added to g's children if not already added before
+func (g *CoordGroup) SetView(v tui.View, x, y, width, height int) {
+	g.views[v] = tui.Dimension{Point: tui.Point{X: x, Y: y}, Size: tui.Size{Width: width, Height: height}}
+}
+func (g *CoordGroup) Draw(buf *tui.ViewBuffer) {
+	for v, d := range g.views {
+		v.Draw(buf.Sub(d.X, d.Y, d.Width, d.Height))
+	}
+}
+
+func (v *CoordGroup) Layout() (prefWidth, prefHeight int) {
+	return -1, -1
+}
+
+func (g *CoordGroup) OnKeyPressed(event *tui.KeyEvent) (consumed bool) {
+	for _, view := range g.Views() {
+		if view.OnKeyPressed(event) {
+			return true
+		}
+	}
+	return false
+}

views/eventview.go

@@ -1,27 +0,0 @@
-package views
-
-import (
-	"git.tordarus.net/Tordarus/tui"
-)
-
-type EventView struct {
-	tui.WrapperTmpl
-
-	View       tui.View
-	KeyPressed func(event *tui.KeyEvent) (consumed bool)
-}
-
-func NewEventView(view tui.View) *EventView {
-	return &EventView{View: view}
-}
-
-func (v *EventView) OnKeyPressed(event *tui.KeyEvent) (consumed bool) {
-	if v.KeyPressed != nil {
-		return v.KeyPressed(event)
-	}
-	return v.ViewTmpl.OnKeyPressed(event)
-}
-
-func (v *EventView) Draw(buf *tui.ViewBuffer) {
-	v.View.Draw(buf)
-}

views/flowgroup.go

@@ -0,0 +1,114 @@
+package views
+
+import (
+	"git.tordarus.net/Tordarus/tui"
+)
+
+// FlowGroup ia a tui.Group which places its children in a linear layout
+type FlowGroup struct {
+	tui.ViewTmpl
+	views           []tui.View
+	lastLayoutPhase *LayoutResult
+
+	// Orientation defines in which direction the children will be placed
+	Orientation tui.Orientation
+}
+
+var _ tui.Group = &FlowGroup{}
+
+func NewFlowGroup(orientation tui.Orientation) *FlowGroup {
+	return &FlowGroup{
+		views:       make([]tui.View, 0),
+		Orientation: orientation,
+	}
+}
+
+func (g *FlowGroup) Views() []tui.View {
+	return g.views[:]
+}
+
+func (g *FlowGroup) AppendViews(v ...tui.View) {
+	g.views = append(g.views, v...)
+}
+
+func (g *FlowGroup) PrependViews(v ...tui.View) {
+	g.views = append(v, g.views...)
+}
+
+func (g *FlowGroup) InsertView(v tui.View, index int) {
+	g.views = append(g.views[:index], append([]tui.View{v}, g.views[index:]...)...)
+}
+
+func (g *FlowGroup) Draw(buf *tui.ViewBuffer) {
+	g.ViewTmpl.Draw(buf)
+
+	if g.lastLayoutPhase == nil {
+		g.Layout()
+	}
+	layout := g.lastLayoutPhase
+
+	if g.Orientation == tui.Horizontal {
+		remainingSpacePerView := buf.Width() - layout.Sum.Width
+		if layout.HorizontalNegativeCount > 0 {
+			remainingSpacePerView /= layout.HorizontalNegativeCount
+		}
+
+		x := 0
+		for _, view := range g.views {
+			size := layout.Sizes[view]
+
+			size.Height = iff(size.Height < 0, buf.Height(), size.Height)
+			if size.Width < 0 {
+				size.Width = iff(layout.Sum.Width > buf.Width(), 0, remainingSpacePerView)
+			}
+
+			view.Draw(buf.Sub(x, 0, size.Width, size.Height))
+			x += size.Width
+		}
+	} else if g.Orientation == tui.Vertical {
+		remainingSpacePerView := buf.Height() - layout.Sum.Height
+		if layout.VerticalNegativeCount > 0 {
+			remainingSpacePerView /= layout.VerticalNegativeCount
+		}
+
+		y := 0
+		for _, view := range g.views {
+			size := layout.Sizes[view]
+
+			size.Width = iff(size.Width < 0, buf.Width(), size.Width)
+			if size.Height < 0 {
+				size.Height = iff(layout.Sum.Height > buf.Height(), 0, remainingSpacePerView)
+			}
+
+			view.Draw(buf.Sub(0, y, size.Width, size.Height))
+			y += size.Height
+		}
+	}
+
+	g.lastLayoutPhase = nil
+}
+
+func (g *FlowGroup) Layout() (prefWidth, prefHeight int) {
+	layout := CalculateLayoutResult(g.Views())
+	g.lastLayoutPhase = layout
+
+	if g.Orientation == tui.Horizontal {
+		prefWidth = iff(layout.HorizontalNegativeCount == 0, layout.Sum.Width, -1)
+		prefHeight = iff(layout.VerticalNegativeCount == 0, layout.Max.Height, -1)
+	} else if g.Orientation == tui.Vertical {
+		prefWidth = iff(layout.HorizontalNegativeCount == 0, layout.Max.Width, -1)
+		prefHeight = iff(layout.VerticalNegativeCount == 0, layout.Sum.Width, -1)
+	}
+
+	layout.Pref = tui.Size{Width: prefWidth, Height: prefHeight}
+	return
+}
+
+func (g *FlowGroup) OnKeyPressed(event *tui.KeyEvent) (consumed bool) {
+	for _, view := range g.Views() {
+		if view.OnKeyPressed(event) {
+			return true
+		}
+	}
+	return false
+}

views/growview.go

@@ -0,0 +1,20 @@
+package views
+
+import (
+	"git.tordarus.net/Tordarus/tui"
+)
+
+// GrowView is a tui.View which always demands all available space
+type GrowView struct {
+	tui.ViewTmpl
+}
+
+var _ tui.View = &GrowView{}
+
+func NewGrowView() *GrowView {
+	return &GrowView{}
+}
+
+func (v *GrowView) Layout() (prefWidth, prefHeight int) {
+	return -1, -1
+}

views/marginview.go

@@ -0,0 +1,48 @@
+package views
+
+import "git.tordarus.net/Tordarus/tui"
+
+// MarginView is a tui.Wrapper which applies margin around its view
+type MarginView struct {
+	tui.WrapperTmpl
+	Margin map[tui.Side]int
+}
+
+var _ tui.View = &MarginView{}
+
+func NewMarginView(view tui.View) *MarginView {
+	v := new(MarginView)
+	v.SetView(view)
+	v.SetMargin(0, 0, 0, 0)
+	return v
+}
+
+func (g *MarginView) Draw(buf *tui.ViewBuffer) {
+	x := g.Margin[tui.Left]
+	y := g.Margin[tui.Top]
+	w := buf.Width() - x - g.Margin[tui.Right]
+	h := buf.Height() - y - g.Margin[tui.Bottom]
+
+	g.ViewTmpl.Draw(buf)
+	g.View().Draw(buf.Sub(x, y, w, h))
+}
+
+func (v *MarginView) Layout() (prefWidth, prefHeight int) {
+	w, h := v.View().Layout()
+	w = iff(w > 0, w+v.Margin[tui.Left]+v.Margin[tui.Right], w)
+	h = iff(h > 0, h+v.Margin[tui.Top]+v.Margin[tui.Bottom], h)
+	return w, h
+}
+
+func (v *MarginView) Style() tui.Style {
+	return v.ViewTmpl.Style()
+}
+
+func (v *MarginView) SetMargin(top, right, bottom, left int) {
+	v.Margin = map[tui.Side]int{
+		tui.Top:    top,
+		tui.Right:  right,
+		tui.Bottom: bottom,
+		tui.Left:   left,
+	}
+}

views/textview.go

@@ -4,6 +4,7 @@ import (
 	"git.tordarus.net/Tordarus/tui"
 )
 
+// TextView is a tui.View which prints text
 type TextView struct {
 	tui.ViewTmpl
 	Text string
@@ -20,3 +21,7 @@ func NewTextView(text string) *TextView {
 		Text: text,
 	}
 }
+
+func (v *TextView) Layout() (prefWidth, prefHeight int) {
+	return tui.MeasureMultiLineString(v.Text)
+}

views/utils.go

@@ -0,0 +1,86 @@
+package views
+
+import (
+	"math"
+
+	"git.tordarus.net/Tordarus/tui"
+)
+
+func min(x, y int) int {
+	if x < y {
+		return x
+	}
+	return y
+}
+
+func max(x, y int) int {
+	if x > y {
+		return x
+	}
+	return y
+}
+
+func iff[T any](condition bool, trueValue, falseValue T) T {
+	if condition {
+		return trueValue
+	}
+	return falseValue
+}
+
+type LayoutResult struct {
+	Sizes map[tui.View]tui.Size
+
+	Sum  tui.Size
+	Min  tui.Size
+	Max  tui.Size
+	Pref tui.Size
+
+	Count int
+
+	VerticalNegativeCount   int
+	HorizontalNegativeCount int
+}
+
+func CalculateLayoutResult(views []tui.View) *LayoutResult {
+	result := &LayoutResult{
+		Sizes: map[tui.View]tui.Size{},
+
+		Sum: tui.Size{Width: 0, Height: 0},
+		Min: tui.Size{Width: math.MaxInt, Height: math.MaxInt},
+		Max: tui.Size{Width: -1, Height: -1},
+
+		Count: 0,
+
+		VerticalNegativeCount:   0,
+		HorizontalNegativeCount: 0,
+	}
+
+	for _, view := range views {
+		if view == nil {
+			continue
+		}
+
+		result.Count++
+
+		width, height := view.Layout()
+		result.Sizes[view] = tui.Size{Width: width, Height: height}
+
+		if width > 0 {
+			result.Sum.Width += width
+			result.Min.Width = min(result.Min.Width, width)
+			result.Max.Width = max(result.Max.Width, width)
+		} else if width < 0 {
+			result.HorizontalNegativeCount++
+		}
+
+		if height > 0 {
+			result.Sum.Height += height
+			result.Min.Height = min(result.Min.Height, height)
+			result.Max.Height = max(result.Max.Height, height)
+		} else if height < 0 {
+			result.VerticalNegativeCount++
+		}
+	}
+
+	return result
+}

viewtmpl.go

@@ -1,44 +1,30 @@
 package tui
 
-import "github.com/gdamore/tcell"
-
 type ViewTmpl struct {
-	foreground *Color
+	style *Style
-	background *Color
 }
 
 var _ View = &ViewTmpl{}
 
 func (v *ViewTmpl) Draw(buf *ViewBuffer) {
-	buf.Fill(DefaultRune)
+	buf.Fill(Rune{' ', v.Style()})
+}
+
+func (v *ViewTmpl) Layout() (prefWidth, prefHeight int) {
+	return -1, -1
 }
 
 func (v *ViewTmpl) OnKeyPressed(event *KeyEvent) (consumed bool) {
 	return false
 }
 
+func (v *ViewTmpl) SetStyle(s Style) {
+	v.style = &s
+}
+
 func (v *ViewTmpl) Style() Style {
-	return StyleDefault.Background(v.Background()).Foreground(v.Foreground())
+	if v.style == nil {
-}
+		return StyleDefault
-
-func (v *ViewTmpl) Foreground() Color {
-	if v.foreground == nil {
-		return tcell.ColorDefault
 	}
-	return *v.foreground
+	return *v.style
-}
-
-func (v *ViewTmpl) SetForeground(color Color) {
-	v.foreground = &color
-}
-
-func (v *ViewTmpl) Background() Color {
-	if v.background == nil {
-		return tcell.ColorDefault
-	}
-	return *v.background
-}
-
-func (v *ViewTmpl) SetBackground(color Color) {
-	v.background = &color
 }

wrappertmpl.go

@@ -1,7 +1,5 @@
 package tui
 
-import "github.com/gdamore/tcell"
-
 type WrapperTmpl struct {
 	ViewTmpl
 	view View
@@ -17,6 +15,13 @@ func (v *WrapperTmpl) Draw(buf *ViewBuffer) {
 	}
 }
 
+func (v *WrapperTmpl) Layout() (prefWidth, prefHeight int) {
+	if v.view != nil {
+		return v.view.Layout()
+	}
+	return v.ViewTmpl.Layout()
+}
+
 func (v *WrapperTmpl) OnKeyPressed(event *KeyEvent) (consumed bool) {
 	if v.view != nil {
 		return v.view.OnKeyPressed(event)
@@ -24,6 +29,14 @@ func (v *WrapperTmpl) OnKeyPressed(event *KeyEvent) (consumed bool) {
 	return v.ViewTmpl.OnKeyPressed(event)
 }
 
+func (v *WrapperTmpl) SetStyle(s Style) {
+	if v.view != nil {
+		v.view.SetStyle(s)
+		return
+	}
+	v.ViewTmpl.SetStyle(s)
+}
+
 func (v *WrapperTmpl) Style() Style {
 	if v.view != nil {
 		return v.view.Style()
@@ -31,37 +44,7 @@ func (v *WrapperTmpl) Style() Style {
 	return v.ViewTmpl.Style()
 }
 
-func (v *WrapperTmpl) Foreground() Color {
+func (v *WrapperTmpl) Views() []View {
-	if v.view != nil {
-		return v.view.Foreground()
-	}
-	return v.ViewTmpl.Foreground()
-}
-
-func (v *WrapperTmpl) SetForeground(color Color) {
-	if v.view != nil {
-		v.view.SetForeground(color)
-	} else {
-		v.ViewTmpl.SetForeground(color)
-	}
-}
-
-func (v *WrapperTmpl) Background() Color {
-	if v.background == nil {
-		return tcell.ColorDefault
-	}
-	return *v.background
-}
-
-func (v *WrapperTmpl) SetBackground(color Color) {
-	if v.view != nil {
-		v.view.SetBackground(color)
-	} else {
-		v.ViewTmpl.SetBackground(color)
-	}
-}
-
-func (v *WrapperTmpl) Children() []View {
 	return []View{v.view}
 }