Added margins control.

alui/margins.go

@@ -0,0 +1,51 @@
+package alui
+
+import (
+	"opslag.de/schobers/geom"
+)
+
+var _ Control = &Margins{}
+
+type Margins struct {
+	Proxy
+
+	Top, Left, Bottom, Right float32
+
+	bounds geom.RectangleF32
+}
+
+func NewMargins(target Control, margins ...float32) *Margins {
+	m := &Margins{Proxy: Proxy{Target: target}}
+	switch len(margins) {
+	case 1:
+		m.Top, m.Left, m.Bottom, m.Right = margins[0], margins[0], margins[0], margins[0]
+	case 2:
+		m.Top, m.Left, m.Bottom, m.Right = margins[0], margins[1], margins[0], margins[1]
+	case 4:
+		m.Top, m.Left, m.Bottom, m.Right = margins[0], margins[1], margins[2], margins[3]
+	default:
+		panic("expected 1 (all same), 2 (vertical, horizontal) or 4 margins (all separately specified)")
+	}
+	return m
+}
+
+func (m *Margins) Bounds() geom.RectangleF32 { return m.bounds }
+
+func (m *Margins) DesiredSize(ctx *Context) geom.PointF32 {
+	return m.Proxy.DesiredSize(ctx).Add2D(m.Left+m.Right, m.Top+m.Bottom)
+}
+
+func (m *Margins) inset(bounds geom.RectangleF32) geom.RectangleF32 {
+	return geom.RectF32(bounds.Min.X+m.Left, bounds.Min.Y+m.Top, bounds.Max.X-m.Right, bounds.Max.Y-m.Bottom)
+}
+
+func (m *Margins) Layout(ctx *Context, bounds geom.RectangleF32) {
+	m.bounds = bounds
+	target := m.inset(bounds)
+	m.Proxy.Layout(ctx, target)
+}
+
+func (m *Margins) Render(ctx *Context, bounds geom.RectangleF32) {
+	target := m.inset(bounds)
+	m.Proxy.Render(ctx, target)
+}

alui/proxy.go

@@ -31,14 +31,14 @@ func (p *Proxy) Handle(e allg5.Event) {
 	}
 }
 
-func (p *Proxy) Render(ctx *Context, bounds geom.RectangleF32) {
-	if p.Target != nil {
-		p.Target.Render(ctx, bounds)
-	}
-}
-
 func (p *Proxy) Layout(ctx *Context, bounds geom.RectangleF32) {
 	if p.Target != nil {
 		p.Target.Layout(ctx, bounds)
 	}
 }
+
+func (p *Proxy) Render(ctx *Context, bounds geom.RectangleF32) {
+	if p.Target != nil {
+		p.Target.Render(ctx, bounds)
+	}
+}

cmd/krampus19/changesettings.go

@@ -181,22 +181,7 @@ type settingsHeader struct {
 func newSettingsHeader(label string) alui.Control {
 	header := &settingsHeader{}
 	header.Text = label
-	return header
-}
-
-func (h *settingsHeader) DesiredSize(ctx *alui.Context) geom.PointF32 {
-	size := h.Label.DesiredSize(ctx)
-	size.Y += 5 * margin
-	return size
-}
-
-func (h *settingsHeader) Layout(ctx *alui.Context, bounds geom.RectangleF32) {
-	var label = bounds
-	if label.Dy() > 5*margin {
-		label.Min.Y = bounds.Min.Y + 3*margin
-		label.Max.Y = bounds.Max.Y - 2*margin
-	}
-	h.Label.Layout(ctx, label)
+	return alui.NewMargins(header, 3*margin, 0, 2*margin, 0)
 }
 
 type settingsRow struct {