refactor menu into subpackage

widgets/menu/main.go

@@ -0,0 +1,121 @@
+package menu
+
+import (
+	"sort"
+
+	ui "github.com/gizak/termui"
+)
+
+type Padding [2]int // x,y padding
+
+type Menu struct {
+	ui.Block
+	SortItems   bool // enable automatic sorting of menu items
+	TextFgColor ui.Attribute
+	TextBgColor ui.Attribute
+	Selectable  bool
+	CursorPos   int
+	items       Items
+	padding     Padding
+}
+
+func NewMenu() *Menu {
+	return &Menu{
+		Block:       *ui.NewBlock(),
+		TextFgColor: ui.ThemeAttr("par.text.fg"),
+		TextBgColor: ui.ThemeAttr("par.text.bg"),
+		CursorPos:   0,
+		padding:     Padding{4, 2},
+	}
+}
+
+func (m *Menu) AddItems(items ...Item) {
+	for _, i := range items {
+		m.items = append(m.items, i)
+	}
+	m.refresh()
+}
+
+// Remove menu item by value or label
+func (m *Menu) DelItem(s string) (success bool) {
+	for n, i := range m.items {
+		if i.Val == s || i.Label == s {
+			m.items = append(m.items[:n], m.items[n+1:]...)
+			success = true
+			m.refresh()
+			break
+		}
+	}
+	return success
+}
+
+// Sort menu items(if enabled) and re-calculate window size
+func (m *Menu) refresh() {
+	if m.SortItems {
+		sort.Sort(m.items)
+	}
+	m.calcSize()
+	ui.Render(m)
+}
+
+func (m *Menu) SelectedItem() Item {
+	return m.items[m.CursorPos]
+}
+
+func (m *Menu) Buffer() ui.Buffer {
+	var cell ui.Cell
+	buf := m.Block.Buffer()
+
+	for n, item := range m.items {
+		x := m.padding[0]
+		for _, ch := range item.Text() {
+			// invert bg/fg colors on currently selected row
+			if m.Selectable && n == m.CursorPos {
+				cell = ui.Cell{Ch: ch, Fg: m.TextBgColor, Bg: m.TextFgColor}
+			} else {
+				cell = ui.Cell{Ch: ch, Fg: m.TextFgColor, Bg: m.TextBgColor}
+			}
+			buf.Set(x, n+m.padding[1], cell)
+			x++
+		}
+	}
+
+	return buf
+}
+
+func (m *Menu) Up(ui.Event) {
+	if m.CursorPos > 0 {
+		m.CursorPos--
+		ui.Render(m)
+	}
+}
+
+func (m *Menu) Down(ui.Event) {
+	if m.CursorPos < (len(m.items) - 1) {
+		m.CursorPos++
+		ui.Render(m)
+	}
+}
+
+// Setup some default handlers for menu navigation
+func (m *Menu) NavigationHandlers() {
+	ui.Handle("/sys/kbd/<up>", m.Up)
+	ui.Handle("/sys/kbd/<down>", m.Down)
+	ui.Handle("/sys/kbd/q", func(ui.Event) { ui.StopLoop() })
+}
+
+// Set width and height based on menu items
+func (m *Menu) calcSize() {
+	m.Width = 8 // minimum width
+
+	items := m.items
+	for _, i := range m.items {
+		s := i.Text()
+		if len(s) > m.Width {
+			m.Width = len(s)
+		}
+	}
+
+	m.Width += (m.padding[0] * 2)
+	m.Height = len(items) + (m.padding[1] * 2)
+}