1 files changed, 79 insertions, 0 deletions
diff --git a/gui/ui/menu.go b/gui/ui/menu.go
new file mode 100644
index 0000000..7fe7ff8
--- /dev/null
+++ b/gui/ui/menu.go
@@ -0,0 +1,79 @@
+package ui
+
+import "9front/gui/draw"
+
+// An Item is one line of a menu.
+type Item struct {
+	Label string
+	Do    func()
+}
+
+// Menu pops up at p and tracks until button 3 comes back up, the way
+// page(1) and vdir(1) do it: press 3, drag, release on an item.
+//
+// It keeps itself on the screen, which is the detail everyone forgets
+// until the menu opens near the bottom edge and half of it is missing.
+// redraw is called if the menu is dismissed without a choice.
+func (u *UI) Menu(items []Item, at draw.Point, mc *draw.Mousectl, redraw func()) {
+	if len(items) == 0 {
+		return
+	}
+
+	lh := int32(u.F.Height) + 4
+	var w int32
+	for _, it := range items {
+		if x := u.F.Width(it.Label) + 20; x > w {
+			w = x
+		}
+	}
+	h := lh*int32(len(items)) + 4
+	win := u.Win.Rect()
+	r := draw.Rect(at.X, at.Y, at.X+w, at.Y+h)
+	if r.Max.X > win.Max.X {
+		r = r.Add(draw.Point{X: win.Max.X - r.Max.X})
+	}
+	if r.Max.Y > win.Max.Y {
+		r = r.Add(draw.Point{Y: win.Max.Y - r.Max.Y})
+	}
+
+	sel := -1
+	paint := func() {
+		u.Fill(r, "tag")
+		u.Border(r, "border")
+		for i, it := range items {
+			ir := draw.Rect(r.Min.X+1, r.Min.Y+2+int32(i)*lh,
+				r.Max.X-1, r.Min.Y+2+int32(i+1)*lh)
+			if i == sel {
+				u.Fill(ir, "today")
+			}
+			u.Text(draw.Point{X: ir.Min.X + 8, Y: ir.Min.Y + 2}, "ink", it.Label)
+		}
+		u.D.Flush()
+	}
+	itemAt := func(p draw.Point) int {
+		if p.X < r.Min.X || p.X >= r.Max.X {
+			return -1
+		}
+		i := int((p.Y - r.Min.Y - 2) / lh)
+		if i < 0 || i >= len(items) || p.Y < r.Min.Y+2 {
+			return -1
+		}
+		return i
+	}
+	paint()
+
+	for m := range mc.C {
+		if n := itemAt(m.Point); n != sel {
+			sel = n
+			paint()
+		}
+		if m.Buttons&4 == 0 {
+			if sel >= 0 {
+				items[sel].Do()
+			} else {
+				redraw()
+			}
+			return
+		}
+	}
+}