Add code components 366-385; ScrollArea Follow, editor sync

A terminal with history, a Go-colored code block, a log viewer that
follows, a hex viewer, a memory map, a JSON tree, a line diff, a GAME
OVER crash screen, an FPS meter, profiler bars, breakpoints,
variables, command history, a shortcut list, a debug grid, a pixel
editor that exports string art, a palette editor, a sprite sheet, a
glyph map and a 6502 register view.

layout.ScrollArea takes Follow, and ChatLog now uses it. data.TreeNode
takes a Value drawn in its Slot. pixel gains Has, and Sprite.Art
writes MustSprite art. pixel.Editor takes the caller's value at each
input event, so a value changed between frames is never typed onto.

code/code_test.go

@@ -0,0 +1,177 @@
+package code_test
+
+import (
+	"image"
+	"testing"
+	"time"
+
+	"github.com/egoist/mygo/ui"
+
+	"git.zacharyzhang.com/ZacharyZhang-NY/8bitMyGoUI/code"
+	"git.zacharyzhang.com/ZacharyZhang-NY/8bitMyGoUI/pixel"
+)
+
+type clock struct{ t time.Time }
+
+func (c *clock) now() time.Time { return c.t }
+
+// world is the settings a test view runs under.
+type world struct {
+	clk           *clock
+	reduce, inert bool
+}
+
+func newWorld() *world {
+	return &world{clk: &clock{time.Date(2026, 9, 2, 10, 30, 0, 0, time.UTC)}}
+}
+
+// view builds on a fake clock, two pixels a dot.
+func view(w, h int, wd *world, build func(c *ui.Context)) *ui.Tester {
+	tt := ui.NewTester(func(c *ui.Context) {
+		pixel.Use(c, pixel.Settings{Palette: pixel.SpringDay, Now: wd.clk.now, Inert: wd.inert})
+		build(c)
+	}, w, h)
+	if wd.reduce {
+		tt.SetPreferences(ui.Preferences{ReduceMotion: true, TextScale: 1})
+		tt.Frame()
+	}
+	return tt
+}
+
+// later moves the clock on and builds a frame.
+func later(tt *ui.Tester, wd *world, d time.Duration) {
+	wd.clk.t = wd.clk.t.Add(d)
+	tt.Frame()
+}
+
+func click(t *testing.T, tt *ui.Tester, label string) {
+	t.Helper()
+	if err := tt.Click(label); err != nil {
+		t.Fatalf("%v in %q", err, tt.Texts())
+	}
+}
+
+func find(t *testing.T, tt *ui.Tester, label string) ui.Rect {
+	t.Helper()
+	r, ok := tt.Find(label)
+	if !ok {
+		t.Fatalf("no %q in %q", label, tt.Texts())
+	}
+	return r
+}
+
+// none is a color outside the palette.
+const none pixel.Slot = 255
+
+// at is the slot at dot x, y, or none.
+func at(img *image.RGBA, x, y int) pixel.Slot {
+	c := img.RGBAAt(2*x, 2*y)
+	for s, want := range pixel.SpringDay.Colors {
+		if c.R == want.R && c.G == want.G && c.B == want.B {
+			return pixel.Slot(s)
+		}
+	}
+	return none
+}
+
+// count is how many dots in a box hold s.
+func count(img *image.RGBA, x, y, w, h int, s pixel.Slot) int {
+	n := 0
+	for j := y; j < y+h; j++ {
+		for i := x; i < x+w; i++ {
+			if at(img, i, j) == s {
+				n++
+			}
+		}
+	}
+	return n
+}
+
+// dots is a found box in dots.
+func dots(r ui.Rect) (x, y, w, h int) {
+	return int(r.X / 2), int(r.Y / 2), int(r.W / 2), int(r.H / 2)
+}
+
+func mustPanic(t *testing.T, name string, fn func()) {
+	t.Helper()
+	defer func() {
+		if recover() == nil {
+			t.Errorf("%s did not panic", name)
+		}
+	}()
+	fn()
+}
+
+func TestCodeBlockNumbersColorsAndCopies(t *testing.T) {
+	wd := newWorld()
+	copied := false
+	tt := view(500, 300, wd, func(c *ui.Context) {
+		copied = code.CodeBlock(c, "main.go", "package main\n\nfunc main() {\n\tprintln(1)\n}\n", code.CodeBlockOptions{}).Copied || copied
+	})
+	// Tabs become four spaces; each line is read alone.
+	for _, l := range []string{"package main", "func main() {", "    println(1)", "}"} {
+		find(t, tt, l)
+	}
+	x, y, w, h := dots(find(t, tt, "package main"))
+	img := tt.Image()
+	if count(img, x, y, w, h, pixel.Accent) == 0 || count(img, x, y, 10, h, pixel.Faint) == 0 {
+		t.Fatal("no Accent keyword or Faint line number on line 1")
+	}
+	click(t, tt, "COPY")
+	if !copied || tt.Clipboard() != "package main\n\nfunc main() {\n    println(1)\n}" {
+		t.Fatalf("copied %v: %q", copied, tt.Clipboard())
+	}
+	find(t, tt, "COPIED!")
+	later(tt, wd, 2*time.Second)
+	find(t, tt, "COPY")
+}
+
+func TestTerminalRunsAndRecalls(t *testing.T) {
+	wd := newWorld()
+	lines, input := []string{"READY."}, ""
+	var ran []string
+	tt := view(500, 300, wd, func(c *ui.Context) {
+		if r := code.Terminal(c, "Shell", lines, &input, code.TerminalOptions{}); r.Ran != "" {
+			ran = append(ran, r.Ran)
+			lines = append(lines, "$ "+r.Ran)
+		}
+	})
+	find(t, tt, "READY.")
+	click(t, tt, "COMMAND")
+	for _, cmd := range []string{"ls", "pwd", "pwd"} {
+		tt.Type(cmd)
+		tt.Key(0, ui.KeyEnter)
+	}
+	if len(ran) != 3 || ran[0] != "ls" || input != "" {
+		t.Fatalf("ran %q, input %q", ran, input)
+	}
+	find(t, tt, "$ pwd")
+	// A draft waits below the history; repeats are kept once.
+	tt.Type("ec")
+	steps := []struct {
+		key  ui.Key
+		want string
+	}{{ui.KeyUp, "pwd"}, {ui.KeyUp, "ls"}, {ui.KeyUp, "ls"}, {ui.KeyDown, "pwd"}, {ui.KeyDown, "ec"}, {ui.KeyDown, "ec"}}
+	for i, s := range steps {
+		tt.Key(0, s.key)
+		if input != s.want {
+			t.Fatalf("step %d: input %q, want %q", i, input, s.want)
+		}
+	}
+}
+
+func TestTerminalHoldsUnderInert(t *testing.T) {
+	wd := newWorld()
+	input := ""
+	tt := view(500, 300, wd, func(c *ui.Context) {
+		code.Terminal(c, "Shell", nil, &input, code.TerminalOptions{})
+	})
+	click(t, tt, "COMMAND")
+	tt.Type("ls")
+	tt.Key(0, ui.KeyEnter)
+	wd.inert = true
+	tt.Key(0, ui.KeyUp)
+	if input != "" {
+		t.Fatalf("an inert terminal recalled %q", input)
+	}
+}