Add event handling capability to all the widgets

box.cxx

@@ -2,31 +2,13 @@
 
 #include <FL/Fl_Box.H>
 
-#include "_cgo_export.h"
+#include "event_handler.h"
 
 
-class GBox : public Fl_Box {
+class GBox : public EventHandler<Fl_Box> {
 public:
   GBox(int boxType, int x, int y, int w, int h, const char* label)
-    : Fl_Box((Fl_Boxtype)boxType, x, y, w, h, label) {
-  }
-
-  int handle(int event) final {
-    if (m_eventHandlerId >= 0) {
-      const int ret = _go_eventHandler(m_eventHandlerId, event);
-      if (ret != 0) {
-	return ret;
-      }
-    }
-    return Fl_Box::handle(event);
-  }
-
-  void set_event_handler(int handlerId) {
-    m_eventHandlerId = handlerId;
-  }
-
-private:
-  int m_eventHandlerId = -1;
+    : EventHandler<Fl_Box>((Fl_Boxtype)boxType, x, y, w, h, label) {}
 };
 
 GBox *go_fltk_new_Box(int boxType, int x, int y, int w, int h, const char* label) {

box.go

@@ -8,18 +8,10 @@ import "unsafe"
 
 type Box struct {
 	widget
-	eventHandler int
 }
 
 func NewBox(boxType BoxType, x, y, w, h int, text ...string) *Box {
 	b := &Box{}
 	initWidget(b, unsafe.Pointer(C.go_fltk_new_Box(C.int(boxType), C.int(x), C.int(y), C.int(w), C.int(h), cStringOpt(text))))
 	return b
 }
-func (b *Box) SetEventHandler(handler func(Event) bool) {
-	if b.eventHandler > 0 {
-		globalEventHandlerMap.unregister(b.eventHandler)
-	}
-	b.eventHandler = globalEventHandlerMap.register(handler)
-	C.go_fltk_Box_set_event_handler((*C.GBox)(b.ptr), C.int(b.eventHandler))
-}

button.cxx

@@ -7,36 +7,75 @@
 #include <FL/Fl_Return_Button.H>
 #include <FL/Fl_Radio_Round_Button.H>
 
-Fl_Button *go_fltk_new_Button(int x, int y, int w, int h, const char *label) {
-  return new Fl_Button(x, y, w, h, label);
+#include "event_handler.h"
+
+
+class GButton : public EventHandler<Fl_Button> {
+public:
+  GButton(int x, int y, int w, int h, const char *label)
+    : EventHandler<Fl_Button>(x, y, w, h, label) {}
+};
+
+GButton *go_fltk_new_Button(int x, int y, int w, int h, const char *label) {
+  return new GButton(x, y, w, h, label);
 }
 
-char go_fltk_Button_value(Fl_Button *b) {
+char go_fltk_Button_value(GButton *b) {
   return b->value();
 }
-void go_fltk_Button_set_value(Fl_Button *b, int val) {
+void go_fltk_Button_set_value(GButton *b, int val) {
   b->value(val);
 }
-void go_fltk_Button_set_down_box(Fl_Button *b, int val) {
+void go_fltk_Button_set_down_box(GButton *b, int val) {
   b->down_box((Fl_Boxtype)val);
 }
 
-Fl_Check_Button *go_fltk_new_Check_Button(int x, int y, int w, int h, const char *label) {
-  return new Fl_Check_Button(x, y, w, h, label);
+class GCheck_Button : public EventHandler<Fl_Check_Button> {
+public:
+  GCheck_Button(int x, int y, int w, int h, const char *label)
+    : EventHandler<Fl_Check_Button>(x, y, w, h, label) {}
+};
+
+GCheck_Button *go_fltk_new_Check_Button(int x, int y, int w, int h, const char *label) {
+  return new GCheck_Button(x, y, w, h, label);
 }
 
-Fl_Toggle_Button *go_fltk_new_Toggle_Button(int x, int y, int w, int h, const char *label) {
-  return new Fl_Toggle_Button(x, y, w, h, label);
+class GToggle_Button : public EventHandler<Fl_Toggle_Button> {
+public:
+  GToggle_Button(int x, int y, int w, int h, const char *label)
+    : EventHandler<Fl_Toggle_Button>(x, y, w, h, label) {}
+};
+
+GToggle_Button *go_fltk_new_Toggle_Button(int x, int y, int w, int h, const char *label) {
+  return new GToggle_Button(x, y, w, h, label);
 }
 
-Fl_Radio_Button *go_fltk_new_Radio_Button(int x, int y, int w, int h, const char *label) {
-  return new Fl_Radio_Button(x, y, w, h, label);
+class GRadio_Button : public EventHandler<Fl_Radio_Button> {
+public:
+  GRadio_Button(int x, int y, int w, int h, const char *label)
+    : EventHandler<Fl_Radio_Button>(x, y, w, h, label) {}
+};
+
+GRadio_Button *go_fltk_new_Radio_Button(int x, int y, int w, int h, const char *label) {
+  return new GRadio_Button(x, y, w, h, label);
 }
 
-Fl_Return_Button *go_fltk_new_Return_Button(int x, int y, int w, int h, const char *label) {
-  return new Fl_Return_Button(x, y, w, h, label);
+class GReturn_Button : public EventHandler<Fl_Return_Button> {
+public:
+  GReturn_Button(int x, int y, int w, int h, const char *label)
+    : EventHandler<Fl_Return_Button>(x, y, w, h, label) {}
+};
+
+GReturn_Button *go_fltk_new_Return_Button(int x, int y, int w, int h, const char *label) {
+  return new GReturn_Button(x, y, w, h, label);
 }
 
-Fl_Radio_Round_Button *go_fltk_new_Radio_Round_Button(int x, int y, int w, int h, const char *label) {
-  return new Fl_Radio_Round_Button(x, y, w, h, label);
+class GRadio_Round_Button : public EventHandler<Fl_Radio_Round_Button> {
+public:
+  GRadio_Round_Button(int x, int y, int w, int h, const char *label)
+    : EventHandler<Fl_Radio_Round_Button>(x, y, w, h, label) {}
+};
+
+GRadio_Round_Button *go_fltk_new_Radio_Round_Button(int x, int y, int w, int h, const char *label) {
+  return new GRadio_Round_Button(x, y, w, h, label);
 }

button.go

@@ -17,17 +17,17 @@ func NewButton(x, y, w, h int, text ...string) *Button {
 }
 
 func (b *Button) Value() bool {
-	return C.go_fltk_Button_value((*C.Fl_Button)(b.ptr)) != C.char(0)
+	return C.go_fltk_Button_value((*C.GButton)(b.ptr)) != C.char(0)
 }
 func (b *Button) SetValue(val bool) {
 	if val {
-		C.go_fltk_Button_set_value((*C.Fl_Button)(b.ptr), 1)
+		C.go_fltk_Button_set_value((*C.GButton)(b.ptr), 1)
 	} else {
-		C.go_fltk_Button_set_value((*C.Fl_Button)(b.ptr), 0)
+		C.go_fltk_Button_set_value((*C.GButton)(b.ptr), 0)
 	}
 }
 func (b *Button) SetDownBox(box BoxType) {
-	C.go_fltk_Button_set_down_box((*C.Fl_Button)(b.ptr), C.int(box))
+	C.go_fltk_Button_set_down_box((*C.GButton)(b.ptr), C.int(box))
 }
 
 type CheckButton struct {

button.h

@@ -4,22 +4,22 @@
 extern "C" {
 #endif
 
-  typedef struct Fl_Button Fl_Button;
-  typedef struct Fl_Check_Button Fl_Check_Button;
-  typedef struct Fl_Radio_Button Fl_Radio_Button;
-  typedef struct Fl_Toggle_Button Fl_Toggle_Button;
-  typedef struct Fl_Return_Button Fl_Return_Button;
-  typedef struct Fl_Radio_Round_Button Fl_Radio_Round_Button;
+  typedef struct GButton GButton;
+  typedef struct GCheck_Button GCheck_Button;
+  typedef struct GRadio_Button GRadio_Button;
+  typedef struct GToggle_Button GToggle_Button;
+  typedef struct GReturn_Button GReturn_Button;
+  typedef struct GRadio_Round_Button GRadio_Round_Button;
 
-  extern Fl_Button* go_fltk_new_Button(int x, int y, int w, int h, const char* label);
-  extern char go_fltk_Button_value(Fl_Button* b);
-  extern void go_fltk_Button_set_value(Fl_Button* b, int value);
-  extern void go_fltk_Button_set_down_box(Fl_Button* b, int value);
-  extern Fl_Check_Button *go_fltk_new_Check_Button(int x, int y, int w, int h, const char *label);
-  extern Fl_Radio_Button *go_fltk_new_Radio_Button(int x, int y, int w, int h, const char *label);
-  extern Fl_Toggle_Button *go_fltk_new_Toggle_Button(int x, int y, int w, int h, const char *label);
-  extern Fl_Return_Button *go_fltk_new_Return_Button(int x, int y, int w, int h, const char *label);
-  extern Fl_Radio_Round_Button *go_fltk_new_Radio_Round_Button(int x, int y, int w, int h, const char *label);
+  extern GButton* go_fltk_new_Button(int x, int y, int w, int h, const char* label);
+  extern char go_fltk_Button_value(GButton* b);
+  extern void go_fltk_Button_set_value(GButton* b, int value);
+  extern void go_fltk_Button_set_down_box(GButton* b, int value);
+  extern GCheck_Button *go_fltk_new_Check_Button(int x, int y, int w, int h, const char *label);
+  extern GRadio_Button *go_fltk_new_Radio_Button(int x, int y, int w, int h, const char *label);
+  extern GToggle_Button *go_fltk_new_Toggle_Button(int x, int y, int w, int h, const char *label);
+  extern GReturn_Button *go_fltk_new_Return_Button(int x, int y, int w, int h, const char *label);
+  extern GRadio_Round_Button *go_fltk_new_Radio_Round_Button(int x, int y, int w, int h, const char *label);
 
 #ifdef __cplusplus
 }

choice.cxx

@@ -2,8 +2,15 @@
 
 #include <FL/Fl_Choice.H>
 
+#include "event_handler.h"
 
-Fl_Choice *go_fltk_new_Choice(int x, int y, int w, int h, const char *label) {
-  return new Fl_Choice(x, y, w, h, label);
+class GChoice : public EventHandler<Fl_Choice> {
+public:
+  GChoice(int x, int y, int w, int h, const char *label)
+    : EventHandler<Fl_Choice>(x, y, w, h, label) {}
+};
+
+GChoice *go_fltk_new_Choice(int x, int y, int w, int h, const char *label) {
+  return new GChoice(x, y, w, h, label);
 }
 

choice.h

@@ -4,9 +4,9 @@
 extern "C" {
 #endif
 
-  typedef struct Fl_Choice Fl_Choice;
+  typedef struct GChoice GChoice;
 
-  extern Fl_Choice *go_fltk_new_Choice(int x, int y, int w, int h, const char *label);
+  extern GChoice *go_fltk_new_Choice(int x, int y, int w, int h, const char *label);
 
 #ifdef __cplusplus
 }

event_handler.h

@@ -0,0 +1,35 @@
+#pragma once
+
+#include "_cgo_export.h"
+
+
+class WidgetWithEventHandler {
+public:
+  virtual void set_event_handler(int handlerId) = 0;
+};
+
+template<class BaseWidget>
+class EventHandler : public BaseWidget, public WidgetWithEventHandler {
+public:
+  template<class... Arg>
+  EventHandler(Arg... args)
+    : BaseWidget(args...) {}
+
+  int handle(int event) final {
+    if (m_eventHandlerId >= 0) {
+      const int ret = _go_eventHandler(m_eventHandlerId, event);
+      if (ret != 0) {
+	return ret;
+      }
+    }
+    return BaseWidget::handle(event);
+  }
+
+  void set_event_handler(int handlerId) final {
+    m_eventHandlerId = handlerId;
+  }
+
+protected:
+  int m_eventHandlerId = -1;
+
+};

gl_window.cxx

@@ -2,48 +2,35 @@
 
 #include <FL/Fl_Gl_Window.H>
 
+#include "event_handler.h"
+
 #include "_cgo_export.h"
 
 
-class GGlWindow : public Fl_Gl_Window {
+class GGlWindow : public EventHandler<Fl_Gl_Window> {
 public:
   GGlWindow(int x, int y, int w, int h, uintptr_t drawFunId)
-    : Fl_Gl_Window(x, y, w, h)
+    : EventHandler<Fl_Gl_Window>(x, y, w, h)
     , m_drawFunId(drawFunId) {
     mode(FL_OPENGL3 | FL_MULTISAMPLE);
   }
   void draw() final {
     _go_callbackHandler(m_drawFunId);
   }
 
-  int handle(int event) final {
-    if (m_eventHandlerId >= 0) {
-      const int ret = _go_eventHandler(m_eventHandlerId, event);
-      if (ret != 0) {
-	return ret;
-      }
-    }
-    return Fl_Gl_Window::handle(event);
-  }
-
   void resize(int x, int y, int w, int h) final {
     Fl_Gl_Window::resize(x, y, w, h);
     if (m_resizeHandlerId != 0) {
       _go_callbackHandler(m_resizeHandlerId);
     }
   }
 
-  void set_event_handler(int handlerId) {
-    m_eventHandlerId = handlerId;
-  }
-
   void set_resize_handler(uintptr_t resizeHandlerId) {
     m_resizeHandlerId = resizeHandlerId;
   }
 
 private:
   uintptr_t const m_drawFunId;
-  int m_eventHandlerId = -1;
   uintptr_t m_resizeHandlerId = 0;
 };
 

gl_window.go

@@ -4,17 +4,18 @@ package fltk
 #include "gl_window.h"
 */
 import "C"
-import "unsafe"
+import (
+	"unsafe"
+)
 
 type GlWindow struct {
 	Window
 	drawFunId       uintptr
 	resizeHandlerId uintptr
-	eventHandler    int
 }
 
 func NewGlWindow(x, y, w, h int, drawFun func()) *GlWindow {
-	win := &GlWindow{eventHandler: -1}
+	win := &GlWindow{}
 	win.drawFunId = globalCallbackMap.register(drawFun)
 	initWidget(win, unsafe.Pointer(C.go_fltk_new_GlWindow(C.int(x), C.int(y), C.int(w), C.int(h), C.uintptr_t(win.drawFunId))))
 	return win
@@ -32,10 +33,6 @@ func (w *GlWindow) Destroy() {
 		globalCallbackMap.unregister(w.resizeHandlerId)
 	}
 	w.resizeHandlerId = 0
-	if w.eventHandler > 0 {
-		globalEventHandlerMap.unregister(w.eventHandler)
-	}
-	w.eventHandler = 0
 	w.Window.Destroy()
 }
 func (w *GlWindow) ContextValid() bool {
@@ -47,13 +44,6 @@ func (w *GlWindow) Valid() bool {
 func (w *GlWindow) CanDo() bool {
 	return C.go_fltk_Gl_Window_can_do((*C.GGlWindow)(w.ptr)) != 0
 }
-func (w *GlWindow) SetEventHandler(handler func(Event) bool) {
-	if w.eventHandler > 0 {
-		globalEventHandlerMap.unregister(w.eventHandler)
-	}
-	w.eventHandler = globalEventHandlerMap.register(handler)
-	C.go_fltk_Gl_Window_set_event_handler((*C.GGlWindow)(w.ptr), C.int(w.eventHandler))
-}
 
 func (w *GlWindow) SetResizeHandler(handler func()) {
 	if w.resizeHandlerId > 0 {