add optional tooltip to menu widget

widgets/menu/tooltip.go

@@ -0,0 +1,55 @@
+package menu
+
+import (
+	ui "github.com/gizak/termui"
+)
+
+type ToolTip struct {
+	ui.Block
+	Lines       []string
+	TextFgColor ui.Attribute
+	TextBgColor ui.Attribute
+	padding     Padding
+}
+
+func NewToolTip(lines ...string) *ToolTip {
+	t := &ToolTip{
+		Block:       *ui.NewBlock(),
+		Lines:       lines,
+		TextFgColor: ui.ThemeAttr("menu.text.fg"),
+		TextBgColor: ui.ThemeAttr("menu.text.bg"),
+		padding:     Padding{2, 1},
+	}
+	t.BorderFg = ui.ThemeAttr("menu.border.fg")
+	t.BorderLabelFg = ui.ThemeAttr("menu.label.fg")
+	t.X = 1
+	t.Align()
+	return t
+}
+
+func (t *ToolTip) Buffer() ui.Buffer {
+	var cell ui.Cell
+	buf := t.Block.Buffer()
+
+	y := t.Y + t.padding[1]
+
+	for n, line := range t.Lines {
+		x := t.X + t.padding[0]
+		for _, ch := range line {
+			cell = ui.Cell{Ch: ch, Fg: t.TextFgColor, Bg: t.TextBgColor}
+			buf.Set(x, y+n, cell)
+			x++
+		}
+	}
+
+	return buf
+}
+
+// Set width and height based on screen size
+func (t *ToolTip) Align() {
+	t.Width = ui.TermWidth() - (t.padding[0] * 2)
+	t.Height = len(t.Lines) + (t.padding[1] * 2)
+	t.Y = ui.TermHeight() - t.Height
+
+	t.Block.Align()
+}