Add layout components 001-020 with demos and behavior tests

layout/window.go

@@ -0,0 +1,42 @@
+package layout
+
+import (
+	"github.com/egoist/mygo/ui"
+
+	"git.zacharyzhang.com/ZacharyZhang-NY/8bitMyGoUI/pixel"
+)
+
+const tabH = pixel.LineHeight + 2
+
+type WindowOptions struct {
+	// Title shows in a tab above the body.
+	Title string
+	// Padding is inside the bevel; zero means 6.
+	Padding int
+}
+
+// Window is a beveled window with an optional title tab.
+func Window(c *ui.Context, o WindowOptions, children func()) *ui.Element {
+	k := pixel.K(c)
+	pad := 3 + orDef("Window Padding", o.Padding, 6)
+	top := 0
+	e := ui.Column(c)
+	if o.Title != "" {
+		top = tabH - 1
+		e.Role(ui.RoleGroup).Label(o.Title)
+	}
+	return e.Padding(k.D(top+pad), k.D(pad), k.D(pad), k.D(pad)).Draw(func(p *ui.Painter, r ui.Rect) {
+		g := k.Canvas(p, r)
+		if g.W < 12 || g.H < top+6 {
+			return
+		}
+		g.Frame(0, top, g.W, g.H-top, pixel.Window, pixel.Face)
+		if o.Title == "" {
+			return
+		}
+		w := min(pixel.Measure(o.Title)+12, g.W-8)
+		g.Frame(4, 0, w, tabH, pixel.Raised, pixel.Face)
+		g.Rect(5, tabH-2, w-2, 4, pixel.Face)
+		g.Clip(4, 0, w-2, tabH, func() { g.Text(10, 1, o.Title, pixel.Ink, 1) })
+	}).Children(children)
+}