macOS: simpler handling of GL windows when first displayed.

tested on macOS versions 10.3, 10.6, 10.9, 10.14

src/Fl_Gl_Window.cxx

@@ -72,7 +72,7 @@ int Fl_Gl_Window::can_do(int a, const int *b) {
 }
 
 void Fl_Gl_Window::show() {
-  int need_redraw = 0;
+  int need_after = 0;
   if (!shown()) {
     if (!g) {
       g = pGlWindowDriver->find(mode_,alist);
@@ -86,10 +86,10 @@ void Fl_Gl_Window::show() {
 	return;
       }
     }
-    pGlWindowDriver->before_show(need_redraw);
+    pGlWindowDriver->before_show(need_after);
   }
   Fl_Window::show();
-  pGlWindowDriver->after_show(need_redraw);
+  if (need_after) pGlWindowDriver->after_show();
 }
 
 
@@ -513,13 +513,13 @@ Fl_Gl_Window_Driver *Fl_Gl_Window_Driver::newGlWindowDriver(Fl_Gl_Window *w)
   return new Fl_Cocoa_Gl_Window_Driver(w);
 }
 
-void Fl_Cocoa_Gl_Window_Driver::before_show(int& need_redraw) {
-  if( ! pWindow->parent() ) need_redraw=1;
+void Fl_Cocoa_Gl_Window_Driver::before_show(int& need_after) {
+  need_after = 1;
 }
 
-void Fl_Cocoa_Gl_Window_Driver::after_show(int need_redraw) {
-  pWindow->set_visible();
-  if(need_redraw) pWindow->redraw();//necessary only after creation of a top-level GL window
+void Fl_Cocoa_Gl_Window_Driver::after_show() {
+  // Makes sure the GL context is created to avoid drawing twice the window when first shown
+  pWindow->make_current();
 }
 
 float Fl_Cocoa_Gl_Window_Driver::pixels_per_unit()
@@ -703,7 +703,7 @@ Fl_Gl_Window_Driver *Fl_Gl_Window_Driver::newGlWindowDriver(Fl_Gl_Window *w)
   return new Fl_X11_Gl_Window_Driver(w);
 }
 
-void Fl_X11_Gl_Window_Driver::before_show(int& need_redraw) {
+void Fl_X11_Gl_Window_Driver::before_show(int&) {
   Fl_X::make_xid(pWindow, g()->vis, g()->colormap);
   if (overlay() && overlay() != pWindow) ((Fl_Gl_Window*)overlay())->show();
 }

src/Fl_Gl_Window_Driver.H

@@ -52,8 +52,8 @@ public:
   static Fl_Gl_Window_Driver *newGlWindowDriver(Fl_Gl_Window *w);
   static Fl_Gl_Window_Driver *global();
   virtual float pixels_per_unit() {return 1;}
-  virtual void before_show(int& need_redraw) {}
-  virtual void after_show(int need_redraw) {}
+  virtual void before_show(int& need_after) {}
+  virtual void after_show() {}
   virtual void invalidate();
   virtual int mode_(int m, const int *a) {return 0;}
   virtual void make_current_before() {}
@@ -105,8 +105,8 @@ class Fl_Cocoa_Gl_Window_Driver : public Fl_Gl_Window_Driver {
   friend class Fl_OpenGL_Display_Device;
   Fl_Cocoa_Gl_Window_Driver(Fl_Gl_Window *win) : Fl_Gl_Window_Driver(win) {}
   virtual float pixels_per_unit();
-  virtual void before_show(int& need_redraw);
-  virtual void after_show(int need_redraw);
+  virtual void before_show(int& need_after);
+  virtual void after_show();
   virtual int mode_(int m, const int *a);
   virtual void make_current_before();
   virtual void swap_buffers();
@@ -161,7 +161,7 @@ class Fl_X11_Gl_Window_Driver : public Fl_Gl_Window_Driver {
   friend class Fl_Gl_Window_Driver;
   Fl_X11_Gl_Window_Driver(Fl_Gl_Window *win) : Fl_Gl_Window_Driver(win) {}
   virtual float pixels_per_unit();
-  virtual void before_show(int& need_redraw);
+  virtual void before_show(int& need_after);
   virtual int mode_(int m, const int *a);
   virtual void swap_buffers();
   virtual void resize(int is_a_resize, int w, int h);

src/Fl_cocoa.mm

@@ -2186,10 +2186,6 @@ static FLTextInputContext* fltextinputcontext_instance = nil;
   Fl_Cocoa_Window_Driver *d = Fl_Cocoa_Window_Driver::driver(window);
   [self did_view_resolution_change];
   if (d->wait_for_expose_value) { // 1st drawing of layer-backed GL window
-    Fl_Device_Plugin *plugin = Fl_Device_Plugin::opengl_plugin();
-    if (plugin) {
-      [plugin->context(window) update]; // layer-backed GL windows may be empty without this
-    }
     d->wait_for_expose_value = 0;
   }
   window->clear_damage(FL_DAMAGE_ALL);
@@ -2336,13 +2332,6 @@ static FLTextInputContext* fltextinputcontext_instance = nil;
   through_drawRect = YES;
   Fl_Cocoa_Window_Driver *d = Fl_Cocoa_Window_Driver::driver(window);
   [self did_view_resolution_change];
-  if (window->as_gl_window() && d->wait_for_expose_value) { // 1st drawing of GL window
-    Fl_Device_Plugin *plugin = Fl_Device_Plugin::opengl_plugin();
-    if (plugin) {
-      [plugin->context(window) update]; // GL windows may be empty without this
-    }
-  }
-
   d->wait_for_expose_value = 0;
   Fl_X *i = Fl_X::i(window);
   if ( i->region ) {
@@ -3661,6 +3650,7 @@ int Fl_Darwin_System_Driver::clipboard_contains(const char *type) {
 }
 
 void Fl_Cocoa_Window_Driver::destroy(FLWindow *xid) {
+  [[xid parentWindow] removeChildWindow:xid]; // necessary until 10.6 at least
   if (fl_sys_menu_bar && Fl_Sys_Menu_Bar_Driver::window_menu_style())
     Fl_MacOS_Sys_Menu_Bar_Driver::driver()->remove_window([xid getFl_Window]);
   [xid close];

src/glut_compatibility.cxx

@@ -243,14 +243,20 @@ int glutCreateWindow(const char *title) {
   W->valid(0);
   W->context_valid(0);
   W->make_current();
+  // some platforms (e.g., macOS 10.9) draw the window while show() runs
+  // but the window's draw function is not yet set when this function runs
+  W->redraw();
   return W->number;
 }
 
 int glutCreateSubWindow(int win, int x, int y, int w, int h) {
   Fl_Glut_Window *W = new Fl_Glut_Window(x,y,w,h,0);
   windows[win]->add(W);
-  if (windows[win]->shown()) W->show();
-  W->make_current();
+  if (windows[win]->shown()) {
+    W->show();
+    W->make_current();
+    W->redraw();
+  }
   return W->number;
 }
 /** Destroys the glut window, first unregister it from the glut windows list */