Made event dispatch asynchronous to avoid deadlocks; right now events that cannot be dispatched get dropped.

3 files changed, 23 insertions, 16 deletions

diff --git a/stdwndclass_windows.go b/stdwndclass_windows.go
index 2824746..3c9861f 100644
--- a/stdwndclass_windows.go
+++ b/stdwndclass_windows.go
@@ -32,7 +32,7 @@ func stdWndProc(s *sysData) func(hwnd _HWND, uMsg uint32, wParam _WPARAM, lParam
 			switch ss.ctype {
 			case c_button:
 				if wParam.HIWORD() == _BN_CLICKED {
-					ss.event <- struct{}{}
+					ss.signal()
 				}
 			}
 			return 0
@@ -58,9 +58,7 @@ func stdWndProc(s *sysData) func(hwnd _HWND, uMsg uint32, wParam _WPARAM, lParam
 			}
 			return 0
 		case _WM_CLOSE:
-			if s.event != nil {
-				s.event <- struct{}{}
-			}
+			s.signal()
 			return 0
 		default:
 			r1, _, _ := defWindowProc.Call(
diff --git a/sysdata.go b/sysdata.go
index e4885ac..da94766 100644
--- a/sysdata.go
+++ b/sysdata.go
@@ -55,6 +55,19 @@ func (c *cSysData) delete(int) error {
 	panic(runtime.GOOS + " sysData does not define delete()")
 }
 
+// signal sends the event signal. This raise is done asynchronously to avoid deadlocking the UI task.
+// Thanks skelterjohn for this techinque: if we can't queue any more events, drop them; TODO this would be best if the channel is buffered
+func (s *cSysData) signal() {
+	if s.event != nil {
+		go func() {
+			select {
+			case s.event <- struct{}{}:
+			default:
+			}
+		}()
+	}
+}
+
 const (
 	c_window = iota
 	c_button
diff --git a/sysdata_unix.go b/sysdata_unix.go
index 3c13b8c..3250b6d 100644
--- a/sysdata_unix.go
+++ b/sysdata_unix.go
@@ -35,19 +35,17 @@ var classTypes = [nctypes]*classData{
 		setText:	gtk_window_set_title,
 		text:		gtk_window_get_title,
 		signals:	map[string]func(*sysData) func() bool{
-			"delete-event":		func(w *sysData) func() bool {
+			"delete-event":		func(s *sysData) func() bool {
 				return func() bool {
-					if w.event != nil {
-						w.event <- struct{}{}
-					}
+					s.signal()
 					return true		// do not close the window
 				}
 			},
-			"configure-event":	func(w *sysData) func() bool {
+			"configure-event":	func(s *sysData) func() bool {
 				return func() bool {
-					if w.container != nil && w.resize != nil {		// wait for init
-						width, height := gtk_window_get_size(w.widget)
-						err := w.resize(0, 0, width, height)
+					if s.container != nil && s.resize != nil {		// wait for init
+						width, height := gtk_window_get_size(s.widget)
+						err := s.resize(0, 0, width, height)
 						if err != nil {
 							panic("child resize failed: " + err.Error())
 						}
@@ -64,11 +62,9 @@ var classTypes = [nctypes]*classData{
 		setText:	gtk_button_set_label,
 		text:		gtk_button_get_label,
 		signals:	map[string]func(*sysData) func() bool{
-			"clicked":		func(w *sysData) func() bool {
+			"clicked":		func(s *sysData) func() bool {
 				return func() bool {
-					if w.event != nil {
-						w.event <- struct{}{}
-					}
+					s.signal()
 					return true		// do not close the window
 				}
 			},