Add data components 151-175; clear MyGo row highlights

Lists, tables, trees, grids, inventories and records in data/.
Outline and GridView build on ui.List: ui.Outline strokes its arrows
and ui.GridView spaces and tints items. The pixel theme keeps MyGo's
row highlights clear so scrolled rows stay on whole dots; off lists
take a veil against the wheel. Adds Canvas.Silhouette, SwitchOptions
Label and exports Rarity.Slot.

data/tree.go

@@ -0,0 +1,130 @@
+package data
+
+import (
+	"log/slog"
+	"strconv"
+
+	"github.com/egoist/mygo/ui"
+
+	"git.zacharyzhang.com/ZacharyZhang-NY/8bitMyGoUI/pixel"
+)
+
+type TreeNode struct {
+	Label    string
+	Children []TreeNode
+}
+
+type TreeOptions struct {
+	// Width is in dots; zero means 160.
+	Width    int
+	Disabled bool
+}
+
+type TreeResult struct {
+	Element          *ui.Element
+	Changed, Toggled bool
+}
+
+type treeKey struct{}
+
+// Tree of ▸▾ items; *selected is a path, "0/2".
+func Tree(c *ui.Context, text string, roots []TreeNode, selected *string, o TreeOptions) TreeResult {
+	k := pixel.K(c)
+	nodes := map[string]TreeNode{}
+	var index func(ns []TreeNode, at string)
+	index = func(ns []TreeNode, at string) {
+		for i, n := range ns {
+			p := at + strconv.Itoa(i)
+			nodes[p] = n
+			index(n.Children, p+"/")
+		}
+	}
+	index(roots, "")
+	children := func(p string) []string {
+		var out []string
+		for i := range nodes[p].Children {
+			out = append(out, p+"/"+strconv.Itoa(i))
+		}
+		return out
+	}
+	var tops []string
+	for i := range roots {
+		tops = append(tops, strconv.Itoa(i))
+	}
+	shell, base, st := pixel.Shell(c, func() *ui.Element {
+		return ui.Box(c).Focusable().Role(ui.RoleTree).Label(text).Disabled(o.Disabled)
+	})
+	opened := ui.Local(base, treeKey{}, func() map[string]bool { return map[string]bool{} })
+	rows := flatten(tops, children, *opened)
+	if len(rows) == 0 {
+		return TreeResult{Element: shell}
+	}
+	at := 0
+	for i, r := range rows {
+		if r.key == *selected {
+			at = i
+		}
+	}
+	old := *selected
+	res := TreeResult{Element: shell}
+	if base.Shortcut(0, ui.KeyDown) {
+		at = min(at+1, len(rows)-1)
+	}
+	if base.Shortcut(0, ui.KeyUp) {
+		at = max(at-1, 0)
+	}
+	right, left := base.Shortcut(0, ui.KeyRight), base.Shortcut(0, ui.KeyLeft)
+	if right || left {
+		at, res.Toggled = steer(rows, at, *opened, right)
+	}
+	enter, space := base.Shortcut(0, ui.KeyEnter), base.Shortcut(0, ui.KeySpace)
+	toggle := func(i int) {
+		if key := rows[i].key; rows[i].branch {
+			(*opened)[key], res.Toggled = !(*opened)[key], true
+		}
+	}
+	if enter || space {
+		toggle(at)
+	}
+	// Enter and Space are taken, so clicks come from pointers.
+	if base.Clicked() {
+		x, y, _ := base.PointerPosition()
+		if i := int(y/k.Dot()) / pixel.LineHeight; i >= 0 && i < len(rows) {
+			at = i
+			if int(x/k.Dot()) < rows[i].depth*10+12 {
+				toggle(i)
+			}
+		}
+	}
+	if res.Toggled {
+		rows = flatten(tops, children, *opened)
+		at = min(at, len(rows)-1)
+	}
+	*selected = rows[at].key
+	res.Changed = *selected != old
+	base.Description(nodes[*selected].Label)
+	shown := rows
+	shell.Size(k.D(pixel.Or("Tree Width", o.Width, 160)), k.D(len(shown)*pixel.LineHeight)).Draw(func(p *ui.Painter, r ui.Rect) {
+		g := k.Canvas(p, r)
+		for i, rw := range shown {
+			y, x, ink := i*pixel.LineHeight, rw.depth*10, pixel.Ink
+			if i == at {
+				g.Rect(0, y, g.W, pixel.LineHeight, pixel.Accent)
+				ink = pixel.AccentInk
+			}
+			if rw.branch {
+				if (*opened)[rw.key] {
+					g.Sprite(x+3, y+6, down, 0, ink, 1)
+				} else {
+					g.Sprite(x+4, y+5, pointer, 0, ink, 1)
+				}
+			}
+			g.Text(x+12, y, nodes[rw.key].Label, ink, 1)
+		}
+		g.Finish(st)
+	})
+	if res.Changed || res.Toggled {
+		slog.Debug("8bit: tree", "label", text, "path", *selected, "toggled", res.Toggled)
+	}
+	return res
+}