Added Rect method to Control interface.

Fixed ContentScrollbar.
Added horizontal alignment to label.
Removed some dimensional constants.
Added several controls:
- Margin;
- Button;
- Columns;
- Scroll;
- Wrapper (reusable layout control) that wraps around existing control.

ui/button.go

@@ -0,0 +1,54 @@
+package ui
+
+import (
+	"opslag.de/schobers/galleg/allegro5"
+	"opslag.de/schobers/geom"
+)
+
+type Button struct {
+	ControlBase
+	Text                string
+	HorizontalAlignment allegro5.HorizontalAlignment
+}
+
+func NewButton(text string, click MouseClickFn) *Button {
+	return &Button{ControlBase: ControlBase{OnClick: click}, Text: text}
+}
+
+func NewButtonAlign(text string, click MouseClickFn, align allegro5.HorizontalAlignment) *Button {
+	return &Button{ControlBase: ControlBase{OnClick: click}, Text: text, HorizontalAlignment: align}
+}
+
+func (b *Button) DesiredSize(ctx Context) geom.PointF {
+	var fonts = ctx.Fonts()
+	var fnt = fonts.Get("default")
+	var w = fnt.TextWidth(b.Text)
+	var fntH = fnt.Height()
+	return geom.PtF(float64(w+fntH), float64(2*fntH))
+}
+
+func (b *Button) Render(ctx Context) {
+	var fonts = ctx.Fonts()
+
+	var min = b.Bounds.Min.To32()
+	var max = b.Bounds.Max.To32()
+
+	var fnt = fonts.Get("default")
+	var fntH = fnt.Height()
+
+	var back = ctx.Palette().Primary()
+	if b.IsOver && !b.IsPressed {
+		back = ctx.Palette().PrimaryHighlight()
+	}
+	allegro5.DrawFilledRectangle(min.X, min.Y, max.X, max.Y, back)
+	switch b.HorizontalAlignment {
+	case allegro5.AlignLeft:
+		fnt.Draw(min.X+.5*fntH, min.Y+.5*fntH, ctx.Palette().Lightest(), allegro5.AlignLeft, b.Text)
+	case allegro5.AlignCenter:
+		fnt.Draw(.5*(min.X+max.X), min.Y+.5*fntH, ctx.Palette().Lightest(), allegro5.AlignCenter, b.Text)
+	case allegro5.AlignRight:
+		fnt.Draw(min.X-.5*fntH, min.Y+.5*fntH, ctx.Palette().Lightest(), allegro5.AlignRight, b.Text)
+	}
+
+	b.ControlBase.Render(ctx)
+}

ui/checkbox.go

@@ -84,7 +84,7 @@ func (c *Checkbox) DesiredSize(ctx Context) geom.PointF {
 	var fonts = ctx.Fonts()
 	var fnt = fonts.Get("default")
 	var w = fnt.TextWidth(c.Text)
-	return geom.PtF(float64(w+checkboxSize+leftMargin), checkboxSize)
+	return geom.PtF(float64(w+checkboxSize), checkboxSize)
 }
 
 func (c *Checkbox) box() *allegro5.Bitmap {

ui/columns.go

@@ -0,0 +1,114 @@
+package ui
+
+import (
+	"math"
+
+	"opslag.de/schobers/geom"
+)
+
+type columns struct {
+	ContainerBase
+	cols []*column
+	col  int
+}
+
+type column struct {
+	p DockPanel
+}
+
+func (c *column) Append(ctrl Control) {
+	c.p.Append(DockTop, ctrl)
+}
+
+func (c *column) AppendCreate(ctx Context, ctrl Control) {
+	c.p.AppendCreate(ctx, DockTop, ctrl)
+}
+
+type Columns interface {
+	Container
+	Columns() []Column
+	Append(Control)
+	AppendCreate(Context, Control)
+}
+
+type Column interface {
+	Append(Control)
+	AppendCreate(Context, Control)
+}
+
+func NewColumns(cols int, ctrls ...Control) Columns {
+	var c = &columns{}
+	for i := 0; i < cols; i++ {
+		c.addColumn()
+	}
+	for _, ctrl := range ctrls {
+		c.Append(ctrl)
+	}
+	return c
+}
+
+func (c *columns) addColumn() {
+	var p = NewDockPanel(c)
+	c.ContainerBase.Append(p)
+	c.cols = append(c.cols, &column{p})
+}
+
+func (c *columns) next() {
+	c.col = (c.col + 1) % len(c.cols)
+}
+
+func (c *columns) Columns() []Column {
+	var cols = make([]Column, len(c.cols))
+	for i, col := range c.cols {
+		cols[i] = col
+	}
+	return cols
+}
+
+func (c *columns) Append(ctrl Control) {
+	c.cols[c.col].Append(ctrl)
+	c.next()
+}
+
+func (c *columns) AppendCreate(ctx Context, ctrl Control) {
+	c.cols[c.col].AppendCreate(ctx, ctrl)
+	c.next()
+}
+
+func (c *columns) DesiredSize(ctx Context) geom.PointF {
+	var w float64
+	var h float64
+	for _, col := range c.cols {
+		var sz = col.p.DesiredSize(ctx)
+		if !math.IsNaN(w) {
+			if math.IsNaN(sz.X) {
+				w = sz.X
+			} else {
+				w += sz.X
+			}
+		}
+		if !math.IsNaN(h) {
+			if math.IsNaN(sz.Y) {
+				h = sz.Y
+			} else {
+				h = math.Max(h, sz.Y)
+			}
+		}
+	}
+	return geom.PtF(w, h)
+}
+
+func (c *columns) Arrange(ctx Context, rect geom.RectangleF) {
+	c.ContainerBase.SetRect(rect)
+	var w, h = rect.Dx(), rect.Dy()
+	var cols = float64(len(c.cols))
+	for i, col := range c.cols {
+		var ii = float64(i)
+		var colH = col.p.DesiredSize(ctx).Y
+		if colH > h {
+			colH = h
+		}
+		var colR = geom.RectF(rect.Min.X+ii*w/cols, rect.Min.Y, rect.Min.X+(ii+1)*w/cols, rect.Min.Y+colH)
+		Arrange(ctx, col.p, colR)
+	}
+}

ui/contentscrollbar.go

@@ -18,6 +18,8 @@ type ContentScrollbar struct {
 	Orientation    Orientation
 	OnChanged      ContentScrollbarValueChangedFn
 	handle         *contentScrollbarHandle
+	barLength      float64
+	scrollDistance float64
 }
 
 type contentScrollbarHandle struct {
@@ -47,17 +49,21 @@ func (s *ContentScrollbar) Destroyed(ctx Context) {
 	s.handle.Destroyed(ctx)
 }
 
-func (s *ContentScrollbar) barViewRange() (float64, float64) {
+func (s *ContentScrollbar) length() (float64, float64) {
 	var min, max float64
 	switch s.Orientation {
 	case OrientationHorizontal:
 		min = s.Bounds.Min.X
 		max = s.Bounds.Max.X
 	default:
-		min = s.Bounds.Max.Y
-		max = s.Bounds.Min.Y
+		min = s.Bounds.Min.Y
+		max = s.Bounds.Max.Y
 	}
-	var length = (max - min)
+	return max - min, min
+}
+
+func (s *ContentScrollbar) updateBarLength() {
+	var length, _ = s.length()
 	var bar = length
 	if s.Length > length {
 		bar = length * length / s.Length
@@ -69,7 +75,12 @@ func (s *ContentScrollbar) barViewRange() (float64, float64) {
 			bar = 20
 		}
 	}
-	return min + .5*bar, max - .5*bar
+	s.barLength = bar
+	var d = s.Length - length
+	if d < 0 {
+		d = 0
+	}
+	s.scrollDistance = d
 }
 
 func (s *ContentScrollbar) barViewCenter() float64 {
@@ -82,23 +93,21 @@ func (s *ContentScrollbar) barViewCenter() float64 {
 }
 
 func (s *ContentScrollbar) toValue(x, y float64) float64 {
-	var n = y
+	var pos = y
 	if OrientationHorizontal == s.Orientation {
-		n = x
+		pos = x
 	}
-	var min, max = s.barViewRange()
-	if min == max {
+	var length, min = s.length()
+	if length == 0 {
 		return 0
 	}
-	var delta = s.Length - (max - min)
-	var off = (n - min) / (max - min)
-	var v = off * (s.Length - (max - min))
-	if v < 0 {
-		v = 0
-	} else if v > delta {
-		v = delta
+	var offset = (pos - .5*s.barLength - min) / (length - s.barLength)
+	if offset < 0 {
+		return 0
+	} else if offset > 1 {
+		return s.scrollDistance
 	}
-	return v
+	return s.scrollDistance * offset
 }
 
 func (s *ContentScrollbar) change(v float64) {
@@ -117,13 +126,16 @@ func (s *ContentScrollbar) snapTo(x, y int) {
 }
 
 func (s *ContentScrollbar) increment(d int) {
-	// var val = s.Value + d
-	// if val < s.Minimum {
-	// 	val = s.Minimum
-	// } else if val > s.Maximum {
-	// 	val = s.Maximum
-	// }
-	// s.change(val)
+	if s.Orientation == OrientationVertical {
+		d *= -1
+	}
+	var val = s.Value + float64(d)*ScrollbarWidth
+	if val < 0 {
+		val = 0
+	} else if val > s.scrollDistance {
+		val = s.scrollDistance
+	}
+	s.change(val)
 }
 
 func (s *ContentScrollbar) Handle(ctx Context, ev allegro5.Event) {
@@ -168,19 +180,21 @@ func (s *ContentScrollbar) SetRect(rect geom.RectangleF) {
 		}
 	}
 	s.ControlBase.SetRect(rect)
+	s.updateBarLength()
 
-	// var min, max = s.barViewRange()
-	// var off = float64(s.Value-s.Minimum) / float64(s.Maximum-s.Minimum)
-	// var centerH = min + (max-min)*off
-	// var r = 0.5 * float64(s.handles[0].Width())
-
-	// var center = s.barViewCenter()
-	// switch s.Orientation {
-	// case OrientationHorizontal:
-	// 	s.handle.SetRect(geom.RectF(centerH-r, center-r, centerH+r, center+r))
-	// default:
-	// 	s.handle.SetRect(geom.RectF(center-r, centerH-r, center+r, centerH+r))
-	// }
+	var offset float64
+	if 0 < s.scrollDistance {
+		offset = s.Value / s.scrollDistance
+	}
+	var length, min = s.length()
+	var begin = min + (length-s.barLength)*offset
+	var end = begin + s.barLength
+	switch s.Orientation {
+	case OrientationHorizontal:
+		s.handle.SetRect(geom.RectF(begin, rect.Min.Y, end, rect.Max.Y))
+	default:
+		s.handle.SetRect(geom.RectF(rect.Min.X, begin, rect.Max.X, end))
+	}
 }
 
 func (s *ContentScrollbar) Render(ctx Context) {

ui/control.go

@@ -14,6 +14,7 @@ type Control interface {
 	Update(Context, time.Duration)
 	Handle(Context, allegro5.Event)
 	DesiredSize(Context) geom.PointF
+	Rect() geom.RectangleF
 	SetRect(geom.RectangleF)
 	Render(Context)
 }

ui/dimensions.go

@@ -1,7 +1,5 @@
 package ui
 
-const topMargin = 4
 const leftMargin = 8
-const lineHeight = 16
 const checkboxMargin = 4
 const checkboxSize = 24

ui/dockpanel.go

@@ -30,6 +30,14 @@ func NewDockPanel(parent Container) DockPanel {
 	return &dockPanel{ContainerBase: ContainerBase{parent: parent}}
 }
 
+func NewDockPanelContent(parent Container, d Dock, controls ...Control) DockPanel {
+	var p = NewDockPanel(parent)
+	for _, c := range controls {
+		p.Append(d, c)
+	}
+	return p
+}
+
 func (p *dockPanel) Append(d Dock, children ...Control) error {
 	for _, child := range children {
 		p.ContainerBase.Append(child)

ui/label.go

@@ -1,10 +1,21 @@
 package ui
 
-import "opslag.de/schobers/galleg/allegro5"
+import (
+	"opslag.de/schobers/galleg/allegro5"
+	"opslag.de/schobers/geom"
+)
 
 type Label struct {
 	ControlBase
 	Text                string
+	HorizontalAlignment allegro5.HorizontalAlignment
+}
+
+func (l *Label) DesiredSize(ctx Context) geom.PointF {
+	var fonts = ctx.Fonts()
+	var fnt = fonts.Get("default")
+	var _, _, w, h = fnt.TextDimensions(l.Text)
+	return geom.PtF(float64(w), float64(h))
 }
 
 func (l *Label) Render(ctx Context) {
@@ -13,7 +24,7 @@ func (l *Label) Render(ctx Context) {
 	var min = l.Bounds.Min.To32()
 
 	var fnt = fonts.Get("default")
-	fnt.Draw(min.X+leftMargin, min.Y+lineHeight-fnt.Ascent(), ctx.Palette().Darkest(), allegro5.AlignLeft, l.Text)
+	fnt.Draw(min.X, min.Y+fnt.Height()-fnt.Ascent(), ctx.Palette().Darkest(), l.HorizontalAlignment, l.Text)
 
 	l.ControlBase.Render(ctx)
 }

ui/margin.go

@@ -0,0 +1,50 @@
+package ui
+
+import "opslag.de/schobers/geom"
+
+type margin struct {
+	Wrapper
+	Left, Top, Right, Bottom float64
+}
+
+func Margin(c Control, m float64) Control {
+	return &margin{Wrap(c), m, m, m, m}
+}
+
+func LeftMargin(c Control, m float64) Control {
+	return &margin{Wrap(c), m, 0, 0, 0}
+}
+
+func TopMargin(c Control, m float64) Control {
+	return &margin{Wrap(c), 0, m, 0, 0}
+}
+
+func HorizontalMargin(c Control, m float64) Control {
+	return &margin{Wrap(c), m, 0, m, 0}
+}
+
+func VerticalMargin(c Control, m float64) Control {
+	return &margin{Wrap(c), 0, m, 0, m}
+}
+
+func (m *margin) DesiredSize(ctx Context) geom.PointF {
+	var sz = m.Wrapper.DesiredSize(ctx)
+	return geom.PtF(sz.X+m.Left+m.Right, sz.Y+m.Top+m.Bottom)
+}
+
+func (m *margin) Arrange(ctx Context, rect geom.RectangleF) {
+	m.Wrapper.SetRect(rect)
+	rect.Min.X += m.Left
+	rect.Min.Y += m.Top
+	rect.Max.X -= m.Right
+	rect.Max.Y -= m.Bottom
+	if rect.Min.X > rect.Max.X {
+		var x = .5 * (rect.Min.X + rect.Max.X)
+		rect.Min.X, rect.Max.X = x, x
+	}
+	if rect.Min.Y > rect.Max.Y {
+		var y = .5 * (rect.Min.Y + rect.Max.Y)
+		rect.Min.Y, rect.Max.Y = y, y
+	}
+	Arrange(ctx, m.Wrapped, rect)
+}

ui/scroll.go

@@ -0,0 +1,77 @@
+package ui
+
+import (
+	"opslag.de/schobers/galleg/allegro5"
+	"opslag.de/schobers/geom"
+)
+
+type scroll struct {
+	Wrapper
+	Content Control
+	Bar     *ContentScrollbar
+}
+
+func Scroll(c Control, o Orientation) Control {
+	var dock = NewDockPanel(nil)
+	var bar = &ContentScrollbar{Orientation: o}
+	switch o {
+	case OrientationHorizontal:
+		dock.Append(DockBottom, TopMargin(bar, ScrollbarWidth))
+		dock.Append(DockBottom, c)
+	case OrientationVertical:
+		dock.Append(DockRight, LeftMargin(bar, ScrollbarWidth))
+		dock.Append(DockRight, c)
+	}
+	var s = &scroll{Wrap(dock), c, bar}
+	bar.OnChanged = func(v float64) {
+
+	}
+	return s
+}
+
+func (s *scroll) Handle(ctx Context, ev allegro5.Event) {
+	s.Wrapper.Handle(ctx, ev)
+	switch e := ev.(type) {
+	case *allegro5.MouseMoveEvent:
+		if 0 != e.DeltaZ && !s.Bar.IsOver && geom.PtF(float64(e.X), float64(e.Y)).In(s.Bounds) {
+			var d = e.DeltaZ
+			if allegro5.IsAnyKeyDown(allegro5.KeyLShift, allegro5.KeyRShift) {
+				d *= 10
+			}
+			s.Bar.increment(d)
+		}
+	}
+}
+
+func (s *scroll) Render(ctx Context) {
+	var bounds = s.Content.Rect()
+	var w, h = bounds.Dx(), bounds.Dy()
+	var bmp, err = allegro5.NewVideoBitmap(int(w), int(h))
+	if nil != err {
+		return
+	}
+	defer bmp.Destroy()
+	bmp.SetAsTarget()
+	switch s.Bar.Orientation {
+	case OrientationHorizontal:
+		Arrange(ctx, s.Content, geom.RectF(-s.Bar.Value, 0, w, h))
+	case OrientationVertical:
+		Arrange(ctx, s.Content, geom.RectF(0, -s.Bar.Value, w, h))
+	}
+	s.Content.Render(ctx)
+	ctx.Display().SetAsTarget()
+	var min = s.Bounds.Min.To32()
+	bmp.Draw(min.X, min.Y)
+	s.Bar.Render(ctx)
+}
+
+func (s *scroll) Arrange(ctx Context, rect geom.RectangleF) {
+	var sz = s.Content.DesiredSize(ctx)
+	switch s.Bar.Orientation {
+	case OrientationHorizontal:
+		s.Bar.Length = sz.X
+	case OrientationVertical:
+		s.Bar.Length = sz.Y
+	}
+	s.Wrapper.Arrange(ctx, rect)
+}

ui/state.go

@@ -18,6 +18,7 @@ type State interface {
 
 type StateBase struct {
 	Control  Control
+	ChangeTo State
 }
 
 func (s *StateBase) Enter(ctx Context) error {
@@ -42,7 +43,7 @@ func (s *StateBase) Update(ctx Context, dt time.Duration) (State, error) {
 	if nil != s.Control {
 		s.Control.Update(ctx, dt)
 	}
-	return nil, nil
+	return s.ChangeTo, nil
 }
 
 func (s *StateBase) Handle(ctx Context, ev allegro5.Event) error {

ui/wrapper.go

@@ -0,0 +1,58 @@
+package ui
+
+import (
+	"time"
+
+	"opslag.de/schobers/galleg/allegro5"
+	"opslag.de/schobers/geom"
+)
+
+type Wrapper struct {
+	Wrapped Control
+	Bounds  geom.RectangleF
+}
+
+func Wrap(c Control) Wrapper {
+	return Wrapper{Wrapped: c}
+}
+
+func (w *Wrapper) Created(ctx Context, p Container) error {
+	return w.Wrapped.Created(ctx, p)
+}
+
+func (w *Wrapper) Destroyed(ctx Context) {
+	w.Wrapped.Destroyed(ctx)
+}
+
+func (w *Wrapper) Update(ctx Context, d time.Duration) {
+	w.Wrapped.Update(ctx, d)
+}
+
+func (w *Wrapper) Handle(ctx Context, ev allegro5.Event) {
+	w.Wrapped.Handle(ctx, ev)
+}
+
+func (w *Wrapper) DesiredSize(ctx Context) geom.PointF {
+	return w.Wrapped.DesiredSize(ctx)
+}
+
+func (w *Wrapper) Rect() geom.RectangleF {
+	return w.Bounds
+}
+
+func (w *Wrapper) SetRect(rect geom.RectangleF) {
+	w.Bounds = rect
+}
+
+func (w *Wrapper) Render(ctx Context) {
+	w.Wrapped.Render(ctx)
+}
+
+func (w *Wrapper) Children() []Control {
+	return []Control{w.Wrapped}
+}
+
+func (w *Wrapper) Arrange(ctx Context, rect geom.RectangleF) {
+	w.Bounds = rect
+	Arrange(ctx, w.Wrapped, rect)
+}