package ui
import (
"sync/atomic"
"github.com/gdamore/tcell/v2"
)
const (
// nominal state, UI is up to date
CLEAN int32 = iota
// UI render has been queued in Redraw channel
DIRTY
)
// State of the UI. Any value other than 0 means the UI is in a dirty state.
// This should only be accessed via atomic operations to maintain thread safety
var uiState int32
var Callbacks = make(chan func(), 50)
// QueueFunc queues a function to be called in the main goroutine. This can be
// used to prevent race conditions from delayed functions
func QueueFunc(fn func()) {
Callbacks <- fn
}
// Use a buffered channel of size 1 to avoid blocking callers of Invalidate()
var Redraw = make(chan bool, 1)
// Invalidate marks the entire UI as invalid and request a redraw as soon as
// possible. Invalidate can be called from any goroutine and will never block.
func Invalidate() {
if atomic.SwapInt32(&uiState, DIRTY) != DIRTY {
Redraw <- true
}
}
type UI struct {
Content DrawableInteractive
Quit chan struct{}
Events chan tcell.Event
ctx *Context
screen tcell.Screen
popover *Popover
}
func Initialize(content DrawableInteractive) (*UI, error) {
screen, err := tcell.NewScreen()
if err != nil {
return nil, err
}
if err = screen.Init(); err != nil {
return nil, err
}
screen.Clear()
screen.HideCursor()
screen.EnablePaste()
width, height := screen.Size()
state := UI{
Content: content,
screen: screen,
// Use unbuffered channels (always blocking unless somebody can
// read immediately) We are merely using this as a proxy to
// tcell screen internal event channel.
Events: make(chan tcell.Event),
Quit: make(chan struct{}),
}
state.ctx = NewContext(width, height, screen, state.onPopover)
Invalidate()
if beeper, ok := content.(DrawableInteractiveBeeper); ok {
beeper.OnBeep(screen.Beep)
}
content.Focus(true)
if root, ok := content.(RootDrawable); ok {
root.Initialize(&state)
}
go state.screen.ChannelEvents(state.Events, state.Quit)
return &state, nil
}
func (state *UI) onPopover(p *Popover) {
state.popover = p
}
func (state *UI) Exit() {
close(state.Quit)
}
func (state *UI) Close() {
state.screen.Fini()
}
func (state *UI) Render() {
if atomic.SwapInt32(&uiState, CLEAN) != CLEAN {
// reset popover for the next Draw
state.popover = nil
state.Content.Draw(state.ctx)
if state.popover != nil {
// if the Draw resulted in a popover, draw it
state.popover.Draw(state.ctx)
}
state.screen.Show()
}
}
func (state *UI) EnableMouse() {
state.screen.EnableMouse()
}
func (state *UI) HandleEvent(event tcell.Event) {
if event, ok := event.(*tcell.EventResize); ok {
state.screen.Clear()
width, height := event.Size()
state.ctx = NewContext(width, height, state.screen, state.onPopover)
Invalidate()
}
// if we have a popover, and it can handle the event, it does so
if state.popover == nil || !state.popover.Event(event) {
// otherwise, we send the event to the main content
state.Content.Event(event)
}
}
