text: /////////////////////////////////////////////////////////////////////////////
  // Name:        src/gtk/glcanvas.cpp
  // Purpose:     wxGLCanvas, for using OpenGL/Mesa with wxWidgets and GTK
  // Author:      Robert Roebling
  // Modified by:
  // Created:     17/08/98
  // Copyright:   (c) Robert Roebling
  // Licence:     wxWindows licence
  /////////////////////////////////////////////////////////////////////////////
  
  // For compilers that support precompilation, includes "wx.h".
  #include "wx/wxprec.h"
  
  #if wxUSE_GLCANVAS
  
  #include "wx/glcanvas.h"
  
  #include <gtk/gtk.h>
  #include <gdk/gdkx.h>
  #include "wx/gtk/private/gtk2-compat.h"
  
  #if WXWIN_COMPATIBILITY_2_8
  
  //-----------------------------------------------------------------------------
  // "realize" from m_wxwindow: used to create m_glContext implicitly
  //-----------------------------------------------------------------------------
  
  extern "C" {
  static void
  gtk_glwindow_realized_callback( GtkWidget *WXUNUSED(widget), wxGLCanvas *win )
  {
      win->GTKInitImplicitContext();
  }
  }
  
  #endif // WXWIN_COMPATIBILITY_2_8
  
  //-----------------------------------------------------------------------------
  // "map" from m_wxwindow
  //-----------------------------------------------------------------------------
  
  #ifndef __WXGTK3__
  extern "C" {
  static void
  gtk_glwindow_map_callback( GtkWidget * WXUNUSED(widget), wxGLCanvas *win )
  {
      wxPaintEvent event( win->GetId() );
      event.SetEventObject( win );
      win->HandleWindowEvent( event );
  
      win->m_exposed = false;
      win->GetUpdateRegion().Clear();
  }
  }
  #endif
  
  //-----------------------------------------------------------------------------
  // "expose_event" of m_wxwindow
  //-----------------------------------------------------------------------------
  
  extern "C" {
  #ifdef __WXGTK3__
  static gboolean draw(GtkWidget*, cairo_t* cr, wxGLCanvas* win)
  {
      win->m_exposed = true;
      if (win->m_cairoPaintContext == NULL)
      {
          win->m_cairoPaintContext = cr;
          cairo_reference(cr);
      }
      double x1, y1, x2, y2;
      cairo_clip_extents(cr, &x1, &y1, &x2, &y2);
      win->GetUpdateRegion().Union(int(x1), int(y1), int(x2 - x1), int(y2 - y1));
      return false;
  }
  #else
  static gboolean
  gtk_glwindow_expose_callback( GtkWidget *WXUNUSED(widget), GdkEventExpose *gdk_event, wxGLCanvas *win )
  {
      win->m_exposed = true;
  
      win->GetUpdateRegion().Union( gdk_event->area.x,
                                    gdk_event->area.y,
                                    gdk_event->area.width,
                                    gdk_event->area.height );
      return false;
  }
  #endif
  }
  
  //-----------------------------------------------------------------------------
  // "size_allocate" of m_wxwindow
  //-----------------------------------------------------------------------------
  
  extern "C" {
  static void
  gtk_glcanvas_size_callback(GtkWidget *WXUNUSED(widget),
                             GtkAllocation * WXUNUSED(alloc),
                             wxGLCanvas *win)
  {
      wxSizeEvent event( wxSize(win->m_width,win->m_height), win->GetId() );
      event.SetEventObject( win );
      win->HandleWindowEvent( event );
  }
  }
  
  //-----------------------------------------------------------------------------
  // emission hook for "parent-set"
  //-----------------------------------------------------------------------------
  
  extern "C" {
  static gboolean
  parent_set_hook(GSignalInvocationHint*, guint, const GValue* param_values, void* data)
  {
      wxGLCanvas* win = (wxGLCanvas*)data;
      if (g_value_peek_pointer(&param_values[0]) == win->m_wxwindow)
      {
          const XVisualInfo* xvi = win->GetXVisualInfo();
          GdkVisual* visual = gtk_widget_get_visual(win->m_wxwindow);
          if (GDK_VISUAL_XVISUAL(visual)->visualid != xvi->visualid)
          {
              GdkScreen* screen = gtk_widget_get_screen(win->m_wxwindow);
              visual = gdk_x11_screen_lookup_visual(screen, xvi->visualid);
  #ifdef __WXGTK3__
              gtk_widget_set_visual(win->m_wxwindow, visual);
  #else
              GdkColormap* colormap = gdk_colormap_new(visual, false);
              gtk_widget_set_colormap(win->m_wxwindow, colormap);
              g_object_unref(colormap);
  #endif
          }
          // remove hook
          return false;
      }
      return true;
  }
  }
  
  //---------------------------------------------------------------------------
  // wxGlCanvas
  //---------------------------------------------------------------------------
  
  IMPLEMENT_CLASS(wxGLCanvas, wxWindow)
  
  wxGLCanvas::wxGLCanvas(wxWindow *parent,
                         wxWindowID id,
                         const int *attribList,
                         const wxPoint& pos,
                         const wxSize& size,
                         long style,
                         const wxString& name,
                         const wxPalette& palette)
  #if WXWIN_COMPATIBILITY_2_8
      : m_createImplicitContext(false)
  #endif
  {
      Create(parent, id, pos, size, style, name, attribList, palette);
  }
  
  #if WXWIN_COMPATIBILITY_2_8
  
  wxGLCanvas::wxGLCanvas(wxWindow *parent,
                         wxWindowID id,
                         const wxPoint& pos,
                         const wxSize& size,
                         long style,
                         const wxString& name,
                         const int *attribList,
                         const wxPalette& palette)
      : m_createImplicitContext(true)
  {
      m_sharedContext = NULL;
      m_sharedContextOf = NULL;
  
      Create(parent, id, pos, size, style, name, attribList, palette);
  }
  
  wxGLCanvas::wxGLCanvas(wxWindow *parent,
                         const wxGLContext *shared,
                         wxWindowID id,
                         const wxPoint& pos,
                         const wxSize& size,
                         long style,
                         const wxString& name,
                         const int *attribList,
                         const wxPalette& palette)
      : m_createImplicitContext(true)
  {
      m_sharedContext = const_cast<wxGLContext *>(shared);
  
      Create(parent, id, pos, size, style, name, attribList, palette);
  }
  
  wxGLCanvas::wxGLCanvas(wxWindow *parent,
                         const wxGLCanvas *shared,
                         wxWindowID id,
                         const wxPoint& pos, const wxSize& size,
                         long style, const wxString& name,
                         const int *attribList,
                         const wxPalette& palette )
      : m_createImplicitContext(true)
  {
      m_sharedContext = NULL;
      m_sharedContextOf = const_cast<wxGLCanvas *>(shared);
  
      Create(parent, id, pos, size, style, name, attribList, palette);
  }
  
  #endif // WXWIN_COMPATIBILITY_2_8
  
  bool wxGLCanvas::Create(wxWindow *parent,
                          wxWindowID id,
                          const wxPoint& pos,
                          const wxSize& size,
                          long style,
                          const wxString& name,
                          const int *attribList,
                          const wxPalette& palette)
  {
  #if wxUSE_PALETTE
      wxASSERT_MSG( !palette.IsOk(), wxT("palettes not supported") );
  #endif // wxUSE_PALETTE
      wxUnusedVar(palette); // Unused when wxDEBUG_LEVEL==0
  
      m_exposed = false;
      m_noExpose = true;
      m_nativeSizeEvent = true;
  #ifdef __WXGTK3__
      m_cairoPaintContext = NULL;
      m_backgroundStyle = wxBG_STYLE_PAINT;
  #endif
  
      if ( !InitVisual(attribList) )
          return false;
  
      // watch for the "parent-set" signal on m_wxwindow so we can set colormap
      // before m_wxwindow is realized (which will occur before
      // wxWindow::Create() returns if parent is already visible)
      unsigned sig_id = g_signal_lookup("parent-set", GTK_TYPE_WIDGET);
      g_signal_add_emission_hook(sig_id, 0, parent_set_hook, this, NULL);
  
      wxWindow::Create( parent, id, pos, size, style, name );
  
      gtk_widget_set_double_buffered(m_wxwindow, false);
  
  #if WXWIN_COMPATIBILITY_2_8
      g_signal_connect(m_wxwindow, "realize",       G_CALLBACK(gtk_glwindow_realized_callback), this);
  #endif // WXWIN_COMPATIBILITY_2_8
  #ifdef __WXGTK3__
      g_signal_connect(m_wxwindow, "draw", G_CALLBACK(draw), this);
  #else
      g_signal_connect(m_wxwindow, "map",           G_CALLBACK(gtk_glwindow_map_callback),      this);
      g_signal_connect(m_wxwindow, "expose_event",  G_CALLBACK(gtk_glwindow_expose_callback),   this);
  #endif
      g_signal_connect(m_widget,   "size_allocate", G_CALLBACK(gtk_glcanvas_size_callback),     this);
  
  #if WXWIN_COMPATIBILITY_2_8
      // if our parent window is already visible, we had been realized before we
      // connected to the "realize" signal and hence our m_glContext hasn't been
      // initialized yet and we have to do it now
      if (gtk_widget_get_realized(m_wxwindow))
          gtk_glwindow_realized_callback( m_wxwindow, this );
  #endif // WXWIN_COMPATIBILITY_2_8
  
  #ifndef __WXGTK3__
      if (gtk_widget_get_mapped(m_wxwindow))
          gtk_glwindow_map_callback( m_wxwindow, this );
  #endif
  
      return true;
  }
  
  bool wxGLCanvas::SetBackgroundStyle(wxBackgroundStyle /* style */)
  {
      return false;
  }
  
  Window wxGLCanvas::GetXWindow() const
  {
      GdkWindow* window = GTKGetDrawingWindow();
      return window ? GDK_WINDOW_XID(window) : 0;
  }
  
  void wxGLCanvas::OnInternalIdle()
  {
      if (m_exposed)
      {
  #ifdef __WXGTK3__
          GTKSendPaintEvents(m_cairoPaintContext);
          cairo_destroy(m_cairoPaintContext);
          m_cairoPaintContext = NULL;
  #else
          wxPaintEvent event( GetId() );
          event.SetEventObject( this );
          HandleWindowEvent( event );
  #endif
  
          m_exposed = false;
          GetUpdateRegion().Clear();
      }
  
      wxWindow::OnInternalIdle();
  }
  
  #if WXWIN_COMPATIBILITY_2_8
  
  void wxGLCanvas::GTKInitImplicitContext()
  {
      if ( !m_glContext && m_createImplicitContext )
      {
          wxGLContext *share = m_sharedContext;
          if ( !share && m_sharedContextOf )
              share = m_sharedContextOf->m_glContext;
  
          m_glContext = new wxGLContext(this, share);
      }
  }
  
  #endif // WXWIN_COMPATIBILITY_2_8
  
  #endif // wxUSE_GLCANVAS
  