Add game components 246-268; data.DrawSlot, Canvas.TextVeil

Health, mana and experience bars, quarter hearts, lives, a spinning
coin counter, score board, stage timer, minimap with fog, compass,
hotbar, paper-doll equipment, skill tree, skill buttons with cooldown
wipes, status effects, a boss bar, damage numbers, quest log and
tracker, party frames, character sheet, level-up screen and shop.
data exports DrawSlot so every slot looks alike; pixel adds TextVeil
for dissolving text. Messages the font cannot draw are fixed and
TestMessagesHaveGlyphs holds every message to the font.

game/timerhud.go

@@ -0,0 +1,39 @@
+package game
+
+import (
+	"fmt"
+	"math"
+	"time"
+
+	"github.com/egoist/mygo/ui"
+
+	"git.zacharyzhang.com/ZacharyZhang-NY/8bitMyGoUI/pixel"
+)
+
+type TimerHUDOptions struct{}
+
+// TimerHUD shows TIME in seconds; under 30 it blinks red.
+func TimerHUD(c *ui.Context, left time.Duration, o TimerHUDOptions) *ui.Element {
+	k := pixel.K(c)
+	if left < 0 {
+		panic(fmt.Sprintf("game: TimerHUD %v left", left))
+	}
+	secs := int(math.Ceil(left.Seconds()))
+	name, n := k.Msg("time"), fmt.Sprintf("%03d", secs)
+	hurry := left < 30*time.Second
+	top := tagH(name) + 2
+	w := max(tagW(name), 2*pixel.Measure(n))
+	return ui.Box(c).Role(ui.RoleText).Label(name+" "+n).Size(k.D(w), k.D(top+2*pixel.LineHeight)).Draw(func(p *ui.Painter, r ui.Rect) {
+		g := k.Canvas(p, r)
+		tag(g, 0, 0, name, pixel.Faint)
+		ink := pixel.Ink
+		if hurry {
+			ink = pixel.Bad
+			// It blinks at 2 Hz; reduced, it holds steady.
+			if !k.Reduce() && g.Busy(4)%2 == 1 {
+				return
+			}
+		}
+		g.Text(0, top-2, n, ink, 2)
+	})
+}