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/skillbutton.go

@@ -0,0 +1,66 @@
+package game
+
+import (
+	"fmt"
+	"log/slog"
+	"math"
+	"strconv"
+
+	"github.com/egoist/mygo/ui"
+
+	"git.zacharyzhang.com/ZacharyZhang-NY/8bitMyGoUI/pixel"
+)
+
+type SkillButtonOptions struct {
+	Disabled bool
+}
+
+type SkillButtonResult struct {
+	Element *ui.Element
+	// Clicked is a press while the skill is ready.
+	Clicked bool
+}
+
+// SkillButton shows a skill, its key and a cooldown wipe.
+func SkillButton(c *ui.Context, text string, sprite *pixel.Sprite, key string, cooldown float64, o SkillButtonOptions) SkillButtonResult {
+	k := pixel.K(c)
+	if sprite == nil || !(cooldown >= 0 && cooldown <= 1) || !pixel.MicroOK(key) {
+		panic(fmt.Sprintf("game: SkillButton %q needs a sprite, a micro key %q, a cooldown in 0–1 (%v)", text, key, cooldown))
+	}
+	shell, base, st := pixel.Shell(c, func() *ui.Element { return ui.ButtonBase(c).Label(text).Disabled(o.Disabled) })
+	res := SkillButtonResult{Element: shell, Clicked: base.Clicked() && cooldown == 0}
+	if res.Clicked {
+		slog.Debug("8bit: skill", "label", text)
+	}
+	state := k.Msg("ready")
+	if cooldown > 0 {
+		state = strconv.Itoa(int(math.Ceil(cooldown*100))) + "%"
+	}
+	base.Description(state)
+	shell.Size(k.D(24), k.D(24)).Draw(func(p *ui.Painter, r ui.Rect) {
+		g := k.Canvas(p, r)
+		style := pixel.Raised
+		if st.Press {
+			style = pixel.Sunken
+		}
+		g.Frame(0, 0, 24, 24, style, pixel.Face)
+		g.Sprite((24-sprite.W)/2, (24-sprite.H)/2, sprite, 0, pixel.Ink, 1)
+		// The wipe clears from twelve, clockwise, as the cooldown ends.
+		for y := 2; y < 22; y++ {
+			for x := 2; x < 22; x++ {
+				a := math.Atan2(float64(x)-11.5, 11.5-float64(y)) / (2 * math.Pi)
+				if a < 0 {
+					a++
+				}
+				if a >= 1-cooldown {
+					g.Veil(x, y, 1, 1, pixel.Edge, 11)
+				}
+			}
+		}
+		kw := pixel.MicroWidth(key)
+		g.Rect(1, 1, kw+3, 8, pixel.Lit)
+		g.Micro(2, 2, key, pixel.Ink, 1)
+		g.Finish(st)
+	})
+	return res
+}