qedit/pkg/ui/menu.go
2021-04-15 11:59:25 -05:00

469 lines
12 KiB
Go

package ui
import (
"fmt"
"strings"
"github.com/gdamore/tcell/v2"
runewidth "github.com/mattn/go-runewidth"
)
// Item is an interface implemented by ItemEntry and ItemMenu to be listed in Menus.
type Item interface {
GetName() string
// Returns a character/rune index of the name of the item.
GetQuickCharIdx() int
// A Shortcut is a string of the modifiers+key name of the action that must be pressed
// to trigger the shortcut. For example: "Ctrl+Alt+X". The order of the modifiers is
// very important. Letters are case-sensitive. See the KeyEvent.Name() function of tcell
// for information. An empty string implies no shortcut.
GetShortcut() string
}
// An ItemSeparator is like a blank Item that cannot actually be selected. It is useful
// for separating items in a Menu.
type ItemSeparator struct{}
// GetName returns an empty string.
func (i *ItemSeparator) GetName() string {
return ""
}
func (i *ItemSeparator) GetQuickCharIdx() int {
return 0
}
func (i *ItemSeparator) GetShortcut() string {
return ""
}
// ItemEntry is a listing in a Menu with a name and callback.
type ItemEntry struct {
Name string
QuickChar int // Character/rune index of Name
Shortcut string
Callback func()
}
// GetName returns the name of the ItemEntry.
func (i *ItemEntry) GetName() string {
return i.Name
}
func (i *ItemEntry) GetQuickCharIdx() int {
return i.QuickChar
}
func (i *ItemEntry) GetShortcut() string {
return i.Shortcut
}
// GetName returns the name of the Menu.
func (m *Menu) GetName() string {
return m.Name
}
func (m *Menu) GetQuickCharIdx() int {
return m.QuickChar
}
func (m *Menu) GetShortcut() string {
return ""
}
// A MenuBar is a horizontal list of menus.
type MenuBar struct {
menus []*Menu
selected int // Index of selection in MenuBar
menusVisible bool // Whether to draw the selected menu
baseComponent
}
func NewMenuBar(theme *Theme) *MenuBar {
return &MenuBar{
menus: make([]*Menu, 0, 6),
baseComponent: baseComponent{theme: theme},
}
}
func (b *MenuBar) AddMenu(menu *Menu) {
menu.itemSelectedCallback = func() {
b.menusVisible = false
menu.SetFocused(false)
}
b.menus = append(b.menus, menu)
}
// GetMenuXPos returns the X position of the name of Menu at `idx` visually.
func (b *MenuBar) GetMenuXPos(idx int) int {
x := 1
for i := 0; i < idx; i++ {
x += len(b.menus[i].Name) + 2 // two for padding
}
return x
}
func (b *MenuBar) ActivateMenuUnderCursor() {
b.menusVisible = true // Show menus
menu := &b.menus[b.selected]
(*menu).SetPos(b.GetMenuXPos(b.selected), b.y+1)
(*menu).SetFocused(true)
}
func (b *MenuBar) CursorLeft() {
if b.menusVisible {
b.menus[b.selected].SetFocused(false) // Unfocus current menu
}
if b.selected <= 0 {
b.selected = len(b.menus) - 1 // Wrap to end
} else {
b.selected--
}
if b.menusVisible {
// Update position of new menu after changing menu selection
b.menus[b.selected].SetPos(b.GetMenuXPos(b.selected), b.y+1)
b.menus[b.selected].SetFocused(true) // Focus new menu
}
}
func (b *MenuBar) CursorRight() {
if b.menusVisible {
b.menus[b.selected].SetFocused(false)
}
if b.selected >= len(b.menus)-1 {
b.selected = 0 // Wrap to beginning
} else {
b.selected++
}
if b.menusVisible {
// Update position of new menu after changing menu selection
b.menus[b.selected].SetPos(b.GetMenuXPos(b.selected), b.y+1)
b.menus[b.selected].SetFocused(true) // Focus new menu
}
}
// Draw renders the MenuBar and its sub-menus.
func (b *MenuBar) Draw(s tcell.Screen) {
var normalStyle tcell.Style
if b.focused {
normalStyle = b.theme.GetOrDefault("MenuBarFocused")
} else {
normalStyle = b.theme.GetOrDefault("MenuBar")
}
// Draw menus based on whether b.focused and which is selected
DrawRect(s, b.x, b.y, b.width, 1, ' ', normalStyle)
col := b.x + 1
for i, item := range b.menus {
sty := normalStyle
if b.focused && b.selected == i {
fg, bg, attr := normalStyle.Decompose()
sty = tcell.Style{}.Foreground(bg).Background(fg).Attributes(attr)
}
str := fmt.Sprintf(" %s ", item.Name)
cols := DrawQuickCharStr(s, col, b.y, str, item.QuickChar+1, sty)
col += cols
}
if b.menusVisible {
menu := b.menus[b.selected]
menu.Draw(s) // Draw menu when it is expanded / visible
}
}
// SetFocused highlights the MenuBar and focuses any sub-menus.
func (b *MenuBar) SetFocused(v bool) {
b.focused = v
b.menus[b.selected].SetFocused(v)
if !v {
b.selected = 0 // Reset cursor position every time component is unfocused
if b.menusVisible {
b.menusVisible = false
}
}
}
func (b *MenuBar) GetMinSize() (int, int) {
return 0, 1
}
// HandleEvent will propogate events to sub-menus and returns true if
// any of them handled the event.
func (b *MenuBar) HandleEvent(event tcell.Event) bool {
switch ev := event.(type) {
case *tcell.EventKey:
// Shortcuts (Ctrl-s or Ctrl-A, for example)
if ev.Modifiers() != 0 { // If there is a modifier on the key...
// tcell names it "Ctrl+(Key)" so we want to remove the "Ctrl+"
// prefix, and use the remaining part of the string as the shortcut.
keyName := ev.Name()
// Find who the shortcut key belongs to
for i := range b.menus {
handled := b.menus[i].handleShortcut(keyName)
if handled {
return true
}
}
return false // The shortcut key was not handled by any menus
}
switch ev.Key() {
case tcell.KeyEnter:
if !b.menusVisible { // If menus are not visible...
b.ActivateMenuUnderCursor()
} else { // The selected Menu is visible, send the event to it
return b.menus[b.selected].HandleEvent(event)
}
case tcell.KeyLeft:
b.CursorLeft()
case tcell.KeyRight:
b.CursorRight()
case tcell.KeyTab:
if b.menusVisible {
return b.menus[b.selected].HandleEvent(event)
} else {
b.CursorRight()
}
// Quick char
case tcell.KeyRune: // Search for the matching quick char in menu names
if !b.menusVisible { // If the selected Menu is not open/visible
for i, m := range b.menus {
r := QuickCharInString(m.Name, m.QuickChar)
if r != 0 && r == ev.Rune() {
b.selected = i // Select menu at i
b.ActivateMenuUnderCursor() // Show menu
break
}
}
} else {
return b.menus[b.selected].HandleEvent(event) // Have menu handle quick char event
}
default:
if b.menusVisible {
return b.menus[b.selected].HandleEvent(event)
} else {
return false // Nobody to propogate our event to
}
}
return true
}
return false
}
// A Menu contains one or more ItemEntry or ItemMenus.
type Menu struct {
Name string
QuickChar int // Character/rune index of Name
Items []Item
selected int // Index of selected Item
itemSelectedCallback func() // Used internally to hide menus on selection
baseComponent
}
// New creates a new Menu. `items` can be `nil`.
func NewMenu(name string, quickChar int, theme *Theme) *Menu {
return &Menu{
Name: name,
QuickChar: quickChar,
Items: make([]Item, 0, 6),
baseComponent: baseComponent{theme: theme},
}
}
func (m *Menu) AddItem(item Item) {
switch typ := item.(type) {
case *Menu:
typ.itemSelectedCallback = func() {
m.itemSelectedCallback()
}
}
m.Items = append(m.Items, item)
}
func (m *Menu) AddItems(items []Item) {
for _, item := range items {
m.AddItem(item)
}
}
func (m *Menu) ActivateItemUnderCursor() {
switch item := m.Items[m.selected].(type) {
case *ItemEntry:
item.Callback()
m.itemSelectedCallback()
case *Menu:
// TODO: implement sub-menus ...
}
}
func (m *Menu) CursorUp() {
if m.selected <= 0 {
m.selected = len(m.Items) - 1 // Wrap to end
} else {
m.selected--
}
switch m.Items[m.selected].(type) {
case *ItemSeparator:
m.CursorUp() // Recursion; stack overflow if the only item in a Menu is a separator.
default:
}
}
func (m *Menu) CursorDown() {
if m.selected >= len(m.Items)-1 {
m.selected = 0 // Wrap to beginning
} else {
m.selected++
}
switch m.Items[m.selected].(type) {
case *ItemSeparator:
m.CursorDown() // Recursion; stack overflow if the only item in a Menu is a separator.
default:
}
}
// Draw renders the Menu at its position.
func (m *Menu) Draw(s tcell.Screen) {
defaultStyle := m.theme.GetOrDefault("Menu")
m.GetSize() // Call this to update internal width and height
DrawRect(s, m.x, m.y, m.width, m.height, ' ', defaultStyle) // Fill background
DrawRectOutlineDefault(s, m.x, m.y, m.width, m.height, defaultStyle) // Draw outline
// Draw items based on whether m.focused and which is selected
for i, item := range m.Items {
switch item.(type) {
case *ItemSeparator:
str := fmt.Sprintf("%s%s%s", "├", strings.Repeat("─", m.width-2), "┤")
DrawStr(s, m.x, m.y+1+i, str, defaultStyle)
default: // Handle sub-menus and item entries the same
var sty tcell.Style
if m.selected == i {
sty = m.theme.GetOrDefault("MenuSelected")
} else {
sty = defaultStyle
}
nameCols := DrawQuickCharStr(s, m.x+1, m.y+1+i, item.GetName(), item.GetQuickCharIdx(), sty)
str := strings.Repeat(" ", m.width-2-nameCols) // Fill space after menu names to border
DrawStr(s, m.x+1+nameCols, m.y+1+i, str, sty)
if shortcut := item.GetShortcut(); len(shortcut) > 0 { // If the item has a shortcut...
str := " " + shortcut + " "
DrawStr(s, m.x+m.width-1-runewidth.StringWidth(str), m.y+1+i, str, sty)
}
}
}
}
// SetFocused does not do anything for a Menu.
func (m *Menu) SetFocused(v bool) {
// TODO: when adding sub-menus, set all focus to v
if !v {
m.selected = 0
}
}
func (m *Menu) GetMinSize() (int, int) {
maxNameLen := 0
var widestShortcut int = 0 // Will contribute to the width
for i := range m.Items {
nameLen := len(m.Items[i].GetName())
if nameLen > maxNameLen {
maxNameLen = nameLen
}
if key := m.Items[i].GetShortcut(); runewidth.StringWidth(key) > widestShortcut {
widestShortcut = runewidth.StringWidth(key) // For the sake of good unicode
}
}
shortcutsWidth := 0
if widestShortcut > 0 {
shortcutsWidth = 1 + widestShortcut + 1 // " Ctrl+X " (with one cell padding surrounding)
}
m.width = 1 + maxNameLen + shortcutsWidth + 1 // Add two for padding
m.height = 1 + len(m.Items) + 1 // And another two for the same reason ...
return m.width, m.height
}
// GetSize returns the size of the Menu.
func (m *Menu) GetSize() (int, int) {
return m.GetMinSize()
}
// SetSize sets the size of the Menu.
func (m *Menu) SetSize(width, height int) {
// Cannot set the size of a Menu
}
func (m *Menu) handleShortcut(key string) bool {
for i := range m.Items {
switch typ := m.Items[i].(type) {
case *ItemSeparator:
continue
case *Menu:
return typ.handleShortcut(key) // Have the sub-menu handle the shortcut
case *ItemEntry:
if typ.Shortcut == key { // If this item matches the shortcut we're finding...
m.selected = i
m.ActivateItemUnderCursor() // Activate it
return true
}
}
}
return false
}
// HandleEvent will handle events for a Menu and may propogate them
// to sub-menus. Returns true if the event was handled.
func (m *Menu) HandleEvent(event tcell.Event) bool {
// TODO: simplify this function
switch ev := event.(type) {
case *tcell.EventKey:
switch ev.Key() {
case tcell.KeyEnter:
m.ActivateItemUnderCursor()
case tcell.KeyUp:
m.CursorUp()
case tcell.KeyTab:
fallthrough
case tcell.KeyDown:
m.CursorDown()
case tcell.KeyRune:
// TODO: support quick chars for sub-menus
for i, item := range m.Items {
if m.selected == i {
continue // Skip the item we're on
}
r := QuickCharInString(item.GetName(), item.GetQuickCharIdx())
if r != 0 && r == ev.Rune() {
m.selected = i
break
}
}
default:
return false
}
return true
}
return false
}