Add project components 421-435; Checkbox turns only when on

Fifteen project components: QuestBoard, TaskItem, TaskList, Milestones,
Burndown, Pomodoro, Priority, AssigneePicker, LabelPicker, TimeTracker,
Roadmap, SprintPanel, IssueCard, Checklist and WorkloadBar.

QuestBoard is one base that draws TODO, DOING and DONE; arrows move,
Alt with an arrow carries a card, and a drag carries it live. Priority
draws 12x12 bars, and Critical is on fire. Pomodoro banks time on PAUSE
and the tomato sleeps through the rest. Extreme inputs fail fast or
saturate instead of wrapping.

MyGo's CheckboxBase turns its value before Disabled is set, so
input.Checkbox now hands it a copy and keeps only turns of an enabled
base. The home scene test checks the sky row, not one pixel that
falling snow can cover.

project/roadmap.go

@@ -0,0 +1,112 @@
+package project
+
+import (
+	"fmt"
+	"strings"
+	"time"
+
+	"github.com/egoist/mygo/ui"
+
+	"git.zacharyzhang.com/ZacharyZhang-NY/8bitMyGoUI/pixel"
+)
+
+// Bar is work on a lane from Start to End.
+type Bar struct {
+	Title      string
+	Start, End time.Time
+	// Slot colors the bar's cap; zero picks one by order.
+	Slot pixel.Slot
+}
+
+// Lane is a row of bars: a team or theme.
+type Lane struct {
+	Name string
+	Bars []Bar
+}
+
+type RoadmapOptions struct {
+	// Months shown; zero means 6.
+	Months int
+	// MonthWidth is in dots; zero means 44.
+	MonthWidth int
+}
+
+var capSlots = []pixel.Slot{pixel.Info, pixel.Good, pixel.Warn, pixel.Magic, pixel.Bad}
+
+const laneH = pixel.LineHeight + 8
+
+// Roadmap lays bars on lanes under months, from from's.
+func Roadmap(c *ui.Context, text string, from time.Time, lanes []Lane, o RoadmapOptions) *ui.Element {
+	k := pixel.K(c)
+	months, mw := pixel.Or("Roadmap Months", o.Months, 6), pixel.Or("Roadmap MonthWidth", o.MonthWidth, 44)
+	if len(lanes) == 0 || months > 120 {
+		panic(fmt.Sprintf("project: Roadmap of %d lanes over %d months", len(lanes), months))
+	}
+	nameW, said := 0, make([]string, len(lanes))
+	for i, l := range lanes {
+		var bs []string
+		for _, b := range l.Bars {
+			if b.Title == "" || !b.Start.Before(b.End) {
+				panic(fmt.Sprintf("project: Roadmap bar %q runs %v to %v", b.Title, b.Start, b.End))
+			}
+			bs = append(bs, b.Title+" "+b.Start.Format("01-02")+"–"+b.End.Format("01-02"))
+		}
+		if l.Name == "" {
+			panic("project: Roadmap has a lane with no name")
+		}
+		nameW, said[i] = max(nameW, pixel.Measure(l.Name)), l.Name+": "+strings.Join(bs, ", ")
+	}
+	nameW += 8
+	start := time.Date(from.Year(), from.Month(), 1, 0, 0, 0, 0, from.Location())
+	end := start.AddDate(0, months, 0)
+	// x places a time in its month's column, within view.
+	x := func(t time.Time) int {
+		if !start.Before(t) {
+			return nameW
+		}
+		if !t.Before(end) {
+			return nameW + months*mw
+		}
+		m := (t.Year()-start.Year())*12 + int(t.Month()-start.Month())
+		from := start.AddDate(0, m, 0)
+		f := float64(t.Sub(from)) / float64(from.AddDate(0, 1, 0).Sub(from))
+		return nameW + m*mw + int(f*float64(mw))
+	}
+	top := pixel.LineHeight + 4
+	w, h, now := nameW+months*mw, top+len(lanes)*laneH, k.Now()
+	return ui.Box(c).Size(k.D(w), k.D(h)).Role(ui.RoleImage).Label(text).Description(strings.Join(said, "; ")).Draw(func(p *ui.Painter, r ui.Rect) {
+		g := k.Canvas(p, r)
+		for m := range months {
+			mx := nameW + m*mw
+			g.Text(mx+3, 0, month(k, start.AddDate(0, m, 0).Month()), pixel.Faint, 1)
+			for y := top; y < h; y += 2 {
+				g.Dot(mx, y, pixel.Shade)
+			}
+		}
+		g.HLine(nameW, top-2, months*mw, pixel.Shade)
+		for i, l := range lanes {
+			y := top + i*laneH
+			g.Text(0, y+4, l.Name, pixel.Ink, 1)
+			for j, b := range l.Bars {
+				// Bars outside the months shrink to nothing.
+				x0, x1 := x(b.Start), x(b.End)
+				if x1-x0 < 4 {
+					continue
+				}
+				slot := b.Slot
+				if slot == 0 {
+					slot = capSlots[j%len(capSlots)]
+				}
+				g.Frame(x0, y+2, x1-x0, laneH-4, pixel.Raised, pixel.Face)
+				g.Rect(x0+2, y+4, 3, laneH-8, slot)
+				g.Clip(x0+7, y+2, x1-x0-9, laneH-4, func() { g.Text(x0+7, y+4, b.Title, pixel.Ink, 1) })
+			}
+		}
+		// Today is a dashed Accent line, while in view.
+		if !now.Before(start) && now.Before(end) {
+			for tx, y := x(now), top-2; y < h; y += 3 {
+				g.Rect(tx, y, 1, 2, pixel.Accent)
+			}
+		}
+	})
+}