Applications can now manually call a screen redraw in a way that I think is thread safe

application.go

@@ -46,6 +46,11 @@ func (application *Application) Run () (
 	return
 }
 
+// Draw "commits" changes made in the buffer to the display.
+func (application *Application) Draw () {
+	application.backend.Draw()
+}
+
 // SetTitle sets the application's title. If in a window, it will appear as the
 // window's name.
 func (application *Application) SetTitle (title string) (err error) {

backend.go

@@ -7,6 +7,7 @@ type Backend interface {
 	Run      (channel chan(Event))
 	SetTitle (title string) (err error)
 	SetIcon  (icons []image.Image) (err error)
+	Draw     ()
 }
 
 type BackendFactory func (application *Application) (backend Backend, err error)

backends/x/x.go

@@ -1,6 +1,7 @@
 package x
 
 import "os"
+import "sync"
 import "image"
 import "image/draw"
 import "golang.org/x/image/font"
@@ -28,6 +29,8 @@ type Backend struct {
 	canvas      *xgraphics.Image
 	channel     chan(stone.Event)
 
+	drawLock sync.Mutex
+
 	ping struct {
 		before chan(struct { })
 		after  chan(struct { })
@@ -80,6 +83,17 @@ func (backend *Backend) Run (channel chan(stone.Event)) {
 	}
 }
 
+func (backend *Backend) Draw () {
+	backend.drawLock.Lock()
+	defer backend.drawLock.Unlock()
+	
+	backend.drawCells(true)
+	backend.canvas.XDraw()
+	backend.canvas.XPaint(backend.window.Id)
+	// FIXME use this instead once it works
+	// backend.updateWindowAreas(...)
+}
+
 func (backend *Backend) SetTitle (title string) (err error) {
 	err = ewmh.WmNameSet(backend.connection, backend.window.Id, title)
 	return
@@ -191,6 +205,9 @@ func (backend *Backend) calculateWindowSize () (x, y int) {
 }
 
 func (backend *Backend) reallocateCanvas () {
+	backend.drawLock.Lock()
+	defer backend.drawLock.Unlock()
+	
 	if backend.canvas != nil {
 		backend.canvas.Destroy()
 	}

examples/hello/main.go

@@ -8,8 +8,11 @@ import _ "image/png"
 import "git.tebibyte.media/sashakoshka/stone"
 import _ "git.tebibyte.media/sashakoshka/stone/backends/x"
 
+var application = &stone.Application { }
+var currentTime = time.Time { }
+var tickPing    = make(chan(struct { }))
+
 func main () {
-	application  := &stone.Application { }
 	application.SetTitle("hellorld")
 	application.SetSize(12, 2)
 
@@ -29,32 +32,51 @@ func main () {
 	channel, err := application.Run()
 	if err != nil { panic(err) }
 	
-	currentTime := time.Time { }
+	redraw()
+	application.Draw()
+	go tick()
 
 	for {
-		event := <- channel
-		switch event.(type) {
-		case stone.EventQuit:
-			os.Exit(0)
+		select {
+		case <- tickPing:
+			redraw()
+			application.Draw()
+		
+		case event := <- channel:
+			switch event.(type) {
+			case stone.EventQuit:
+				os.Exit(0)
 
-		case stone.EventResize:
-			currentTime = time.Now()
-
-			application.ResetDot()
-			fmt.Fprintln(application, "hellorld!")
-
-			hour   := currentTime.Hour()
-			minute := currentTime.Minute()
-			second := currentTime.Second()
-
-			application.SetRune(0, 1, rune(hour / 10 + 48))
-			application.SetRune(1, 1, rune(hour % 10 + 48))
-			application.SetRune(2, 1, ':')
-			application.SetRune(3, 1, rune(minute / 10 + 48))
-			application.SetRune(4, 1, rune(minute % 10 + 48))
-			application.SetRune(5, 1, ':')
-			application.SetRune(6, 1, rune(second / 10 + 48))
-			application.SetRune(7, 1, rune(second % 10 + 48))
+			case stone.EventResize:
+				redraw()
+			}
 		}
 	}
 }
+
+func redraw () {
+	currentTime = time.Now()
+
+	application.ResetDot()
+	fmt.Fprintln(application, "hellorld!")
+
+	hour   := currentTime.Hour()
+	minute := currentTime.Minute()
+	second := currentTime.Second()
+
+	application.SetRune(0, 1, rune(hour / 10 + 48))
+	application.SetRune(1, 1, rune(hour % 10 + 48))
+	application.SetRune(2, 1, ':')
+	application.SetRune(3, 1, rune(minute / 10 + 48))
+	application.SetRune(4, 1, rune(minute % 10 + 48))
+	application.SetRune(5, 1, ':')
+	application.SetRune(6, 1, rune(second / 10 + 48))
+	application.SetRune(7, 1, rune(second % 10 + 48))
+}
+
+func tick () {
+	for {
+		tickPing <- struct { } { }
+		time.Sleep(time.Second)
+	}
+}