Replace obsolete Gtk symbols

This update replaces depreciated Gtk1.x symbols with Gtk2.x symbols in
preparation for adding Gtk3 support. These edits aim to be fully
compatible with Gtk2.x, allowing backward compatibility.

The following symbols have been replaced in this commit:

Gtk symbols that have been moved to the Gdk library:
 - GtkType -> Gtype
 - GTK_CHECK_CAST -> G_TYPE_CHECK_INSTANCE_CAST
 - GTK_CHECK_TYPE -> G_TYPE_CHECK_INSTANCE_TYPE
 - gtk_signal_connect -> g_signal_connect
 - GTK_SIGNAL_FUNC -> G_CALLBACK
 - gtk_type_class -> g_type_class_peek
 - gtk_type_new-> g_object_new
 - GtkTypeInfo -> GtypeInfo (Not required for
   g_type_register_static_simple)
 - gtk_type_unique -> g_type_register_static_simple
 - gdk_draw_image_rgb -> replaced by gdk_cairo_source_pixbuf
   NB: This requires porting to use cairo contexts and GdkPixbufs.

The following gtk symbols are changed for their modern equivalent:
 - GTK_WIDGET_REALIZED -> gtk_widget_get_realized
 - GTK_OBJECT_FLAGS -> gtk_widget_set_realized

Symbols without replacement:
 - gtk_range_set_update_policy -> No replacement; as default policy is
   set to continuous we can delete this line.

modules/highgui/src/window_gtk.cpp

@@ -47,6 +47,7 @@
 
 #include "gtk/gtk.h"
 #include "gdk/gdkkeysyms.h"
+#include <gdk-pixbuf/gdk-pixbuf.h>
 #include <stdio.h>
 
 #ifdef HAVE_OPENGL
@@ -88,14 +89,14 @@ GtkWidget*     cvImageWidgetNew      (int flags);
 void           cvImageWidgetSetImage(CvImageWidget * widget, const CvArr *arr);
 
 // standard GTK object macros
-#define CV_IMAGE_WIDGET(obj)          GTK_CHECK_CAST (obj, cvImageWidget_get_type (), CvImageWidget)
+#define CV_IMAGE_WIDGET(obj)          G_TYPE_CHECK_INSTANCE_CAST (obj, cvImageWidget_get_type (), CvImageWidget)
 #define CV_IMAGE_WIDGET_CLASS(klass)  GTK_CHECK_CLASS_CAST (klass, cvImageWidget_get_type (), CvImageWidgetClass)
-#define CV_IS_IMAGE_WIDGET(obj)       GTK_CHECK_TYPE (obj, cvImageWidget_get_type ())
+#define CV_IS_IMAGE_WIDGET(obj)       G_TYPE_CHECK_INSTANCE_TYPE (obj, cvImageWidget_get_type ())
 
 /////////////////////////////////////////////////////////////////////////////
 // Private API ////////////////////////////////////////////////////////
 /////////////////////////////////////////////////////////////////////////////
-GtkType        cvImageWidget_get_type (void);
+GType        cvImageWidget_get_type (void);
 
 static GtkWidgetClass * parent_class = NULL;
 
@@ -135,7 +136,7 @@ cvImageWidgetNew (int flags)
 {
   CvImageWidget *image_widget;
 
-  image_widget = CV_IMAGE_WIDGET( gtk_type_new (cvImageWidget_get_type ()) );
+  image_widget = CV_IMAGE_WIDGET( gtk_widget_new (cvImageWidget_get_type (), NULL) );
   image_widget->original_image = 0;
   image_widget->scaled_image = 0;
   image_widget->flags = flags | CV_WINDOW_NO_IMAGE;
@@ -153,7 +154,7 @@ cvImageWidget_realize (GtkWidget *widget)
   g_return_if_fail (widget != NULL);
   g_return_if_fail (CV_IS_IMAGE_WIDGET (widget));
 
-  GTK_WIDGET_SET_FLAGS (widget, GTK_REALIZED);
+  gtk_widget_set_realized(widget, true);
 
   attributes.x = widget->allocation.x;
   attributes.y = widget->allocation.y;
@@ -270,7 +271,7 @@ cvImageWidget_size_allocate (GtkWidget     *widget,
       cvResize( image_widget->original_image, image_widget->scaled_image, CV_INTER_AREA );
   }
 
-  if (GTK_WIDGET_REALIZED (widget))
+  if (gtk_widget_get_realized (widget))
     {
       image_widget = CV_IMAGE_WIDGET (widget);
 
@@ -321,7 +322,7 @@ static void cvImageWidget_class_init (CvImageWidgetClass * klass)
   object_class = (GtkObjectClass*) klass;
   widget_class = (GtkWidgetClass*) klass;
 
-  parent_class = GTK_WIDGET_CLASS( gtk_type_class (gtk_widget_get_type ()) );
+  parent_class = GTK_WIDGET_CLASS( g_type_class_peek (gtk_widget_get_type ()) );
 
   object_class->destroy = cvImageWidget_destroy;
 
@@ -341,24 +342,18 @@ cvImageWidget_init (CvImageWidget *image_widget)
     image_widget->flags=0;
 }
 
-GtkType cvImageWidget_get_type (void){
-  static GtkType image_type = 0;
+GType cvImageWidget_get_type (void){
+  static GType image_type = 0;
 
   if (!image_type)
     {
-      static const GtkTypeInfo image_info =
-      {
-        (gchar*)"CvImageWidget",
-        sizeof (CvImageWidget),
-        sizeof (CvImageWidgetClass),
-        (GtkClassInitFunc) cvImageWidget_class_init,
-        (GtkObjectInitFunc) cvImageWidget_init,
-        /* reserved_1 */ NULL,
-        /* reserved_1 */ NULL,
-        (GtkClassInitFunc) NULL
-      };
-
-      image_type = gtk_type_unique (GTK_TYPE_WIDGET, &image_info);
+      image_type = g_type_register_static_simple( GTK_TYPE_WIDGET,
+                           (gchar*) "CvImageWidget",
+                           sizeof(CvImageWidgetClass),
+                           (GClassInitFunc) cvImageWidget_class_init,
+                           sizeof(CvImageWidget),
+                           (GInstanceInitFunc) cvImageWidget_init,
+                           (GTypeFlags)NULL);
     }
 
   return image_type;
@@ -758,7 +753,9 @@ static gboolean cvImageWidget_expose(GtkWidget* widget, GdkEventExpose* event, g
     (void)data;
 #endif
 
-  CvImageWidget *image_widget;
+  CvImageWidget *image_widget = NULL;
+  cairo_t *cr = NULL;
+  GdkPixbuf *pixbuf = NULL;
 
   g_return_val_if_fail (widget != NULL, FALSE);
   g_return_val_if_fail (CV_IS_IMAGE_WIDGET (widget), FALSE);
@@ -767,29 +764,30 @@ static gboolean cvImageWidget_expose(GtkWidget* widget, GdkEventExpose* event, g
   if (event->count > 0)
     return FALSE;
 
+  cr = gdk_cairo_create(widget->window);
   image_widget = CV_IMAGE_WIDGET (widget);
 
-  gdk_window_clear_area (widget->window,
-                         0, 0,
-                         widget->allocation.width,
-                         widget->allocation.height);
   if( image_widget->scaled_image ){
       // center image in available region
       int x0 = (widget->allocation.width - image_widget->scaled_image->cols)/2;
       int y0 = (widget->allocation.height - image_widget->scaled_image->rows)/2;
 
-      gdk_draw_rgb_image( widget->window, widget->style->fg_gc[GTK_STATE_NORMAL],
-          x0, y0, MIN(image_widget->scaled_image->cols, widget->allocation.width),
+      pixbuf = gdk_pixbuf_new_from_data(image_widget->scaled_image->data.ptr, GDK_COLORSPACE_RGB, false,
+          8, MIN(image_widget->scaled_image->cols, widget->allocation.width),
           MIN(image_widget->scaled_image->rows, widget->allocation.height),
-          GDK_RGB_DITHER_MAX, image_widget->scaled_image->data.ptr, image_widget->scaled_image->step );
+          image_widget->scaled_image->step, NULL, NULL);
+      gdk_cairo_set_source_pixbuf(cr, pixbuf, x0, y0);
   }
   else if( image_widget->original_image ){
-      gdk_draw_rgb_image( widget->window, widget->style->fg_gc[GTK_STATE_NORMAL],
-          0, 0,
-          MIN(image_widget->original_image->cols, widget->allocation.width),
-           MIN(image_widget->original_image->rows, widget->allocation.height),
-          GDK_RGB_DITHER_MAX, image_widget->original_image->data.ptr, image_widget->original_image->step );
+      pixbuf = gdk_pixbuf_new_from_data(image_widget->original_image->data.ptr, GDK_COLORSPACE_RGB, false,
+          8, MIN(image_widget->original_image->cols, widget->allocation.width),
+          MIN(image_widget->original_image->rows, widget->allocation.height),
+          image_widget->original_image->step, NULL, NULL);
+      gdk_cairo_set_source_pixbuf(cr, pixbuf, 0, 0);
   }
+
+  cairo_paint(cr);
+  cairo_destroy(cr);
   return TRUE;
 }
 
@@ -854,18 +852,18 @@ CV_IMPL int cvNamedWindow( const char* name, int flags )
     //
     // configure event handlers
     // TODO -- move this to CvImageWidget ?
-    gtk_signal_connect( GTK_OBJECT(window->frame), "key-press-event",
-                        GTK_SIGNAL_FUNC(icvOnKeyPress), window );
-    gtk_signal_connect( GTK_OBJECT(window->widget), "button-press-event",
-                        GTK_SIGNAL_FUNC(icvOnMouse), window );
-    gtk_signal_connect( GTK_OBJECT(window->widget), "button-release-event",
-                        GTK_SIGNAL_FUNC(icvOnMouse), window );
-    gtk_signal_connect( GTK_OBJECT(window->widget), "motion-notify-event",
-                        GTK_SIGNAL_FUNC(icvOnMouse), window );
-    gtk_signal_connect( GTK_OBJECT(window->frame), "delete-event",
-                        GTK_SIGNAL_FUNC(icvOnClose), window );
-    gtk_signal_connect( GTK_OBJECT(window->widget), "expose-event",
-                        GTK_SIGNAL_FUNC(cvImageWidget_expose), window );
+    g_signal_connect( window->frame, "key-press-event",
+                        G_CALLBACK(icvOnKeyPress), window );
+    g_signal_connect( window->widget, "button-press-event",
+                        G_CALLBACK(icvOnMouse), window );
+    g_signal_connect( window->widget, "button-release-event",
+                        G_CALLBACK(icvOnMouse), window );
+    g_signal_connect( window->widget, "motion-notify-event",
+                        G_CALLBACK(icvOnMouse), window );
+    g_signal_connect( window->frame, "delete-event",
+                        G_CALLBACK(icvOnClose), window );
+    g_signal_connect( window->widget, "expose-event",
+                        G_CALLBACK(cvImageWidget_expose), window );
 
     gtk_widget_add_events (window->widget, GDK_BUTTON_RELEASE_MASK | GDK_BUTTON_PRESS_MASK | GDK_POINTER_MOTION_MASK) ;
 
@@ -1225,7 +1223,6 @@ icvCreateTrackbar( const char* trackbar_name, const char* window_name,
         GtkWidget* hscale_box = gtk_hbox_new( FALSE, 10 );
         GtkWidget* hscale_label = gtk_label_new( trackbar_name );
         GtkWidget* hscale = gtk_hscale_new_with_range( 0, count, 1 );
-        gtk_range_set_update_policy( GTK_RANGE(hscale), GTK_UPDATE_CONTINUOUS );
         gtk_scale_set_digits( GTK_SCALE(hscale), 0 );
         //gtk_scale_set_value_pos( hscale, GTK_POS_TOP );
         gtk_scale_set_draw_value( GTK_SCALE(hscale), TRUE );
@@ -1256,8 +1253,8 @@ icvCreateTrackbar( const char* trackbar_name, const char* window_name,
     trackbar->notify = on_notify;
     trackbar->notify2 = on_notify2;
     trackbar->userdata = userdata;
-    gtk_signal_connect( GTK_OBJECT(trackbar->widget), "value-changed",
-                        GTK_SIGNAL_FUNC(icvOnTrackbar), trackbar );
+    g_signal_connect( trackbar->widget, "value-changed",
+                        G_CALLBACK(icvOnTrackbar), trackbar );
 
     // queue a widget resize to trigger a window resize to
     // compensate for the addition of trackbars