Add layout components 001-020 with demos and behavior tests

layout/split.go

@@ -0,0 +1,117 @@
+package layout
+
+import (
+	"log/slog"
+
+	"github.com/egoist/mygo/ui"
+
+	"git.zacharyzhang.com/ZacharyZhang-NY/8bitMyGoUI/pixel"
+)
+
+const gripW = 6
+
+type SplitOptions struct {
+	// Vertical stacks the panes top and bottom.
+	Vertical bool
+	// Min is the smallest pane in dots; zero means 24.
+	Min      int
+	Label    string
+	Disabled bool
+}
+
+type SplitResult struct {
+	Element *ui.Element
+	Changed bool
+}
+
+// Split shows two panes and a grip moving *size dots.
+func Split(c *ui.Context, size *int, o SplitOptions, first, second func()) SplitResult {
+	k := pixel.K(c)
+	least := orDef("Split Min", o.Min, 24)
+	var e *ui.Element
+	var total float32
+	back, fwd := ui.KeyLeft, ui.KeyRight
+	if o.Vertical {
+		e = ui.Column(c)
+		total, back, fwd = e.Bounds().H, ui.KeyUp, ui.KeyDown
+	} else {
+		e = ui.Row(c)
+		total = e.Bounds().W
+	}
+	limit := func(n int) int {
+		if total > 0 {
+			n = min(n, int(total/k.Dot())-gripW-least)
+		}
+		return max(n, least)
+	}
+	start := *size
+	e.AlignItems(ui.Stretch).Children(func() {
+		pane := ui.Box(c).Clip().Children(first)
+		shell, base, st := pixel.Shell(c, func() *ui.Element {
+			cur := ui.CursorResizeEW
+			if o.Vertical {
+				cur = ui.CursorResizeNS
+			}
+			return ui.Box(c).Focusable().Role(ui.RoleSplitter).Label(label(k, o.Label, "resize")).Disabled(o.Disabled).Cursor(cur)
+		})
+		if dx, dy, ok := drag(k, base); ok {
+			if o.Vertical {
+				dx = dy
+			}
+			*size += dx
+		}
+		if !o.Disabled && base.Shortcut(0, back) {
+			*size -= 4
+		}
+		if !o.Disabled && base.Shortcut(0, fwd) {
+			*size += 4
+		}
+		*size = limit(*size)
+		if o.Vertical {
+			pane.FillWidth().Height(k.D(*size))
+			shell.FillWidth().Height(k.D(gripW))
+		} else {
+			pane.FillHeight().Width(k.D(*size))
+			shell.FillHeight().Width(k.D(gripW))
+		}
+		shell.Draw(func(p *ui.Painter, r ui.Rect) { grip(k.Canvas(p, r), st, o.Vertical) })
+		ui.Box(c).Grow(1).Clip().Children(second)
+	})
+	e.Draw(func(p *ui.Painter, r ui.Rect) {
+		now := r.W
+		if o.Vertical {
+			now = r.H
+		}
+		if now != total {
+			c.Invalidate()
+		}
+	})
+	res := SplitResult{Element: e, Changed: *size != start}
+	if res.Changed {
+		slog.Debug("8bit: split moved", "size", *size)
+	}
+	return res
+}
+
+// grip is a bar with three bumps across its length.
+func grip(g pixel.Canvas, st pixel.State, vertical bool) {
+	fill := pixel.Face
+	if st.Hover || st.Press {
+		fill = pixel.Lit
+	}
+	g.Rect(0, 0, g.W, g.H, fill)
+	for i := -1; i <= 1; i++ {
+		x, y := g.W/2-1, g.H/2-1+i*4
+		if vertical {
+			x, y = g.W/2-1+i*4, g.H/2-1
+		}
+		g.Dot(x, y, pixel.Lit)
+		g.Dot(x+1, y+1, pixel.Shade)
+	}
+	if st.Disabled {
+		g.Checker(0, 0, g.W, g.H, pixel.Face)
+	}
+	if st.Focus {
+		g.FocusMark(0, 0, g.W, g.H)
+	}
+}