Add layout components 001-020 with demos and behavior tests

layout/resizable.go

@@ -0,0 +1,83 @@
+package layout
+
+import (
+	"fmt"
+	"log/slog"
+
+	"github.com/egoist/mygo/ui"
+
+	"git.zacharyzhang.com/ZacharyZhang-NY/8bitMyGoUI/pixel"
+)
+
+type ResizableOptions struct {
+	// MinW and MinH are zero for 24.
+	MinW, MinH int
+	// MaxW and MaxH are zero for no limit.
+	MaxW, MaxH int
+	Label      string
+	Disabled   bool
+}
+
+type ResizableResult struct {
+	Element *ui.Element
+	Changed bool
+}
+
+// Resizable is a *w×*h dot box with a ◢ grip.
+func Resizable(c *ui.Context, w, h *int, o ResizableOptions, children func()) ResizableResult {
+	k := pixel.K(c)
+	minW, minH := orDef("Resizable MinW", o.MinW, 24), orDef("Resizable MinH", o.MinH, 24)
+	maxW, maxH := orDef("Resizable MaxW", o.MaxW, 0), orDef("Resizable MaxH", o.MaxH, 0)
+	if maxW > 0 && maxW < minW || maxH > 0 && maxH < minH {
+		panic(fmt.Sprintf("layout: Resizable max %d×%d under min %d×%d", maxW, maxH, minW, minH))
+	}
+	clamp := func(v, lo, hi int) int {
+		if hi > 0 {
+			v = min(v, hi)
+		}
+		return max(v, lo)
+	}
+	was := [2]int{*w, *h}
+	e := ui.Box(c).Clip()
+	e.Children(func() {
+		children()
+		shell, base, st := pixel.Shell(c, func() *ui.Element {
+			return ui.Box(c).Focusable().Role(ui.RoleSplitter).Label(label(k, o.Label, "resize")).Disabled(o.Disabled).Cursor(ui.CursorResizeNWSE)
+		})
+		if dx, dy, ok := drag(k, base); ok {
+			*w, *h = *w+dx, *h+dy
+		}
+		for key, d := range map[ui.Key][2]int{ui.KeyLeft: {-4, 0}, ui.KeyRight: {4, 0}, ui.KeyUp: {0, -4}, ui.KeyDown: {0, 4}} {
+			if !o.Disabled && base.Shortcut(0, key) {
+				*w, *h = *w+d[0], *h+d[1]
+			}
+		}
+		shell.Absolute().Right(0).Bottom(0).Size(k.D(9), k.D(9)).Draw(func(p *ui.Painter, r ui.Rect) { corner(k.Canvas(p, r), st) })
+	})
+	*w, *h = clamp(*w, minW, maxW), clamp(*h, minH, maxH)
+	e.Size(k.D(*w), k.D(*h))
+	res := ResizableResult{Element: e, Changed: [2]int{*w, *h} != was}
+	if res.Changed {
+		slog.Debug("8bit: resizable", "w", *w, "h", *h)
+	}
+	return res
+}
+
+// corner is a ◢ of three ridges in the bottom-right.
+func corner(g pixel.Canvas, st pixel.State) {
+	for _, s := range []int{2, 5, 8} {
+		for i := 0; i <= s; i++ {
+			x, y := g.W-1-s+i, g.H-1-i
+			g.Dot(x, y, pixel.Shade)
+			if x > 0 && y > 0 {
+				g.Dot(x-1, y-1, pixel.Lit)
+			}
+		}
+	}
+	if st.Disabled {
+		g.Checker(0, 0, g.W, g.H, pixel.Face)
+	}
+	if st.Focus {
+		g.FocusMark(0, 0, g.W, g.H)
+	}
+}