Add layout components 001-020 with demos and behavior tests

layout/grid.go

@@ -0,0 +1,68 @@
+package layout
+
+import (
+	"fmt"
+
+	"github.com/egoist/mygo/ui"
+
+	"git.zacharyzhang.com/ZacharyZhang-NY/8bitMyGoUI/pixel"
+)
+
+type GridLines uint8
+
+const (
+	NoLines GridLines = iota
+	SolidLines
+	DottedLines
+)
+
+type GridOptions struct {
+	// Columns is zero for 2.
+	Columns int
+	// Pad is around each cell's content; zero means 4.
+	Pad   int
+	Lines GridLines
+}
+
+// Grid lays n cells in equal columns, lines between them.
+func Grid(c *ui.Context, n int, o GridOptions, cell func(i int)) *ui.Element {
+	k := pixel.K(c)
+	cols := orDef("Grid Columns", o.Columns, 2)
+	pad := orDef("Grid Pad", o.Pad, 4)
+	orDef("Grid n", n, 0)
+	if o.Lines > DottedLines {
+		panic(fmt.Sprintf("layout: unknown grid lines %d", o.Lines))
+	}
+	grid := ui.Grid(c).FillWidth()
+	w, check := pixel.WrapWidth(c, grid)
+	tracks := make([]ui.Track, cols)
+	for i, d := range shares(w, cols) {
+		tracks[i] = ui.Fixed(k.D(d))
+	}
+	return grid.ColumnTracks(tracks...).Draw(func(p *ui.Painter, r ui.Rect) { check(r) }).Children(func() {
+		for i := range n {
+			right, below := edges(i, n, cols)
+			ui.Box(c).Padding(k.D(pad)).Draw(func(p *ui.Painter, r ui.Rect) {
+				g := k.Canvas(p, r)
+				line := func(x, y, w, h int) {
+					if o.Lines == DottedLines {
+						g.Checker(x, y, w, h, pixel.Edge)
+					} else if o.Lines == SolidLines {
+						g.Rect(x, y, w, h, pixel.Edge)
+					}
+				}
+				if right {
+					line(g.W-1, 0, 1, g.H)
+				}
+				if below {
+					line(0, g.H-1, g.W, 1)
+				}
+			}).Children(func() { cell(i) })
+		}
+	})
+}
+
+// edges reports neighbors right of and below cell i.
+func edges(i, n, cols int) (right, below bool) {
+	return i%cols != cols-1 && i != n-1, i < (n-1)/cols*cols
+}