BUG: hit detection in gnome canvas text items

[Jeremy Henty <jeremy chaos org uk>]

It seems that hit detection for gnome canvas text items only works
when the anchor is north-west.  I am attaching a demo that creates a
text items for each possible anchor and configures them to turn blue
when the pointer is over them.  A little mouse wiggling determines
that the sensitive parts of the text widgets are: all of "North-West"
(as it should be), the right half of "North", the bottom half of
"West" and the bottom-right quarter of "Center".  The other five text
items are only sensitive along certain parts of their borders.  Unless
I am missing something this surely cannot be right.

Details:
gtk+-2.2.4
libart_lgpl_2.3.16
libgnomecanvas-2.4.0

Regards, 

Jeremy 

#include <stdio.h>
#include <gtk/gtk.h>
#include <libgnomecanvas/libgnomecanvas.h>

static void window_initialize(GtkWidget*);
static void canvas_initialize(GtkWidget*);

int
main(int argc,char **argv) 
{
  GtkWidget *window, *canvas;
  gtk_init(&argc,&argv);
  window = gtk_window_new(GTK_WINDOW_TOPLEVEL);
  window_initialize(window);
  canvas = gnome_canvas_new();
  canvas_initialize(canvas);
  gtk_container_add(GTK_CONTAINER(window),canvas);
  gtk_widget_show_all(window);
  gtk_main();
  return 0;
}

static void
window_destroy_handler(void)
{
  gtk_main_quit();
}

static void
window_initialize(GtkWidget* window)
{
  gtk_window_set_title(GTK_WINDOW(window),"Hot Text");
  g_signal_connect(window,"destroy",window_destroy_handler,(gpointer)NULL);
}

#define CANVAS_ITEM_COUNT 9

typedef struct {
  const char   *text;
  double        y;
  double        x;
  GtkAnchorType anchor;
} canvas_item_spec_t;

static const canvas_item_spec_t
canvas_item_specs[];

static void
canvas_item_event_handler(GnomeCanvasItem *text_item, 
			  GdkEvent *event,
			  const char *text
			  )
{
  printf("text: %s\n",text);
  switch (event->type)
    {
    case GDK_LEAVE_NOTIFY:
      g_object_set(text_item,
		   "fill_color","black",
		   0);
      break; 
    case GDK_ENTER_NOTIFY: 
      g_object_set(text_item,
		   "fill_color","blue",
		   0);
      break;
    default:
      break;
    }
}

static void
canvas_initialize(GtkWidget* canvas)
{
  GnomeCanvasGroup *canvas_root;
  int i;
  canvas_root = gnome_canvas_root(GNOME_CANVAS(canvas));
  for (i=0;i<CANVAS_ITEM_COUNT;i++) 
    {
      GnomeCanvasItem *text_item;
      const canvas_item_spec_t *canvas_item_spec;
      canvas_item_spec = &canvas_item_specs[i];
      text_item = gnome_canvas_item_new(canvas_root,
					GNOME_TYPE_CANVAS_TEXT,
					"font",       "Sans 20",
					"fill_color", "black",
					"text",   canvas_item_spec->text,
					"x",      canvas_item_spec->x,
					"y",      canvas_item_spec->y,
					"anchor", canvas_item_spec->anchor,
					0);
      g_signal_connect(G_OBJECT(text_item),"event",
		       G_CALLBACK(canvas_item_event_handler),
		       (gpointer)(canvas_item_spec->text)
		       );
    }
}

#define west     (0.0)
#define middle (200.0)
#define east   (400.0)
#define north    (0.0)
#define center  (50.0)
#define south  (100.0)

static const canvas_item_spec_t
canvas_item_specs[CANVAS_ITEM_COUNT] = {
  { "South-East", south,  east,   GTK_ANCHOR_SE,     },
  { "South",      south,  middle, GTK_ANCHOR_S,      },
  { "South-West", south,  west,   GTK_ANCHOR_SW,     },
  { "East",       center, east,   GTK_ANCHOR_E ,     },
  { "Center",     center, middle, GTK_ANCHOR_CENTER, },
  { "West",       center, west,   GTK_ANCHOR_W,      },
  { "North-East", north,  east,   GTK_ANCHOR_NE,     },
  { "North",      north,  middle, GTK_ANCHOR_N,      },
  { "North-West", north,  west,   GTK_ANCHOR_NW,     },
};