x backend has an event loop

backends/x/x.go

@@ -4,25 +4,49 @@ import "image"
 
 import "github.com/jezek/xgbutil"
 // import "github.com/jezek/xgbutil/ewmh"
-// import "github.com/jezek/xgbutil/xevent"
+import "github.com/jezek/xgbutil/xevent"
 import "github.com/jezek/xgbutil/xwindow"
 import "github.com/jezek/xgbutil/xgraphics"
 
 import "git.tebibyte.media/sashakoshka/stone"
 
 type Backend struct {
-	connection *xgbutil.Conn
-	window     *xwindow.Window
-	canvas     *xgraphics.Image
+	application *stone.Application
+	config      *stone.Config
+	connection  *xgbutil.XUtil
+	window      *xwindow.Window
+	canvas      *xgraphics.Image
+	channel     chan(stone.Event)
+
+	ping struct {
+		before chan(struct { })
+		after  chan(struct { })
+		quit   chan(struct { })
+	}
+	
+	metrics struct {
+		cellWidth  int
+		cellHeight int
+		padding    int
+		paddingX   int
+		paddingY   int
+		descent    int
+	}
 }
 
 func (backend *Backend) Run (channel chan(stone.Event)) {
-	// TODO: setup
-	go backend.mainLoop(channel)
-}
-
-func (backend *Backend) mainLoop (channel chan(stone.Event)) {
+	backend.channel = channel
 	
+	for {
+		select {
+		case <- backend.ping.before:
+			<- backend.ping.after
+
+		case <- backend.ping.quit:
+			backend.shutDown()
+			return
+		}
+	}
 }
 
 func (backend *Backend) SetTitle (title string) {
@@ -32,3 +56,72 @@ func (backend *Backend) SetTitle (title string) {
 func (backend *Backend) SetIcon (icons []image.Image) {
 	
 }
+
+func (backend *Backend) shutDown () {
+	backend.channel <- stone.EventQuit { }
+}
+
+// calculateWindowSize calculates window bounds based on the internal buffer
+// size.
+func (backend *Backend) calculateWindowSize () (x, y int) {
+	width, height := backend.application.Size()
+	x =
+		width * backend.metrics.cellWidth +
+		backend.metrics.padding * 2
+	y =
+		height * backend.metrics.cellHeight +
+		backend.metrics.padding * 2
+	return
+}
+
+
+// factory instantiates an X backend.
+func factory (application *stone.Application) (output stone.Backend, err error) {
+	backend := &Backend {
+		application: application,
+		config:      application.Config(),
+	}
+
+	// calculate metrics
+	// TODO: base these off of font metrics
+	backend.metrics.cellWidth  = 8
+	backend.metrics.cellHeight = 16
+	backend.metrics.padding =
+		backend.config.Padding() *
+		backend.metrics.cellHeight
+	backend.metrics.paddingX = backend.metrics.padding
+	backend.metrics.paddingY = backend.metrics.padding
+
+	// connect to X
+	backend.connection, err = xgbutil.NewConn()
+	if err != nil { return }
+	backend.window, err = xwindow.Generate(backend.connection)
+	if err != nil { return }
+
+	// create the window
+	windowWidth, windowHeight := backend.calculateWindowSize()
+	backend.window.Create (
+		backend.connection.RootWin(),
+		0, 0, windowWidth, windowHeight,
+		0)
+	backend.window.Map()
+
+	// attatch graceful close handler
+	backend.window.WMGracefulClose (func (window *xwindow.Window) {
+		backend.window.Destroy()
+		backend.shutDown()
+	})
+
+	// start event loop
+	backend.ping.before,
+	backend.ping.after,
+	backend.ping.quit = xevent.MainPing(backend.connection)
+	
+	output = backend
+	return
+}
+
+// init registers this backend when the program starts.
+func init () {
+	stone.RegisterBackend(factory)
+}