Re: Is there ways to make a atk factory only used for some instances

[Bolian Yin <bolian yin sun com>]

Hi Bill and Padraig,

Please see the attached picture. The "jump button" (the little yellow rectangle) is the gnome-canvas-item in question, more accurately, it is a gnome-canvas-item-pixbuf.  The "jump button" is used to indicate that there are more events that are not displayed in the day.  Now I have make it focusable, can jump to the day on receving a Enter Key, then all the events of the day can be displayed.  This is the action that I want to export through the atk action interface.

In the current implementation of the jump button in evolution, there are no new subclass to GnomeCanvasPixbuf, see the code below:

-- code snip begins -----------------------------------------------------------------------------------

    /* Create the buttons to jump to each days. */
    pixbuf = gdk_pixbuf_new_from_xpm_data ((const char**) jump_xpm);

    for (i = 0; i < E_WEEK_VIEW_MAX_WEEKS * 7; i++) {
        week_view->jump_buttons[i] = gnome_canvas_item_new
            (canvas_group,
             gnome_canvas_pixbuf_get_type (),
             "GnomeCanvasPixbuf::pixbuf", pixbuf,
             NULL);

        g_signal_connect (week_view->jump_buttons[i], "event",
                  G_CALLBACK (e_week_view_on_jump_button_event), week_view);
    }

/* ... omitted */

e_week_view_on_jump_button_event (GnomeCanvasItem *item,
                  GdkEvent *event,
                  EWeekView *week_view)
{

    /* ... omitted */

    else if (event->type == GDK_KEY_PRESS) {
        /* return, if Tab, Control or Alt is pressed */
        if ((event->key.keyval == GDK_Tab) ||
            (event->key.state & (GDK_CONTROL_MASK | GDK_MOD1_MASK)))
            return FALSE;
        /* with a return key or a simple character, jump to the day */
        if ((event->key.keyval == GDK_Return) ||
            ((event->key.keyval >= 0x20) &&
             (event->key.keyval <= 0xFF))) {
            e_week_view_jump_to_button_item (week_view, item);
            return TRUE;
        }
    }

    /* ... omitted */
}
-- code snip end -----------------------------------------------------------------------------------


So, the "action" is only supported through the signal handler to GnomeCanvasPixbuf "event" signal, not in a new subclass. My aim is to support this action only in the jumpbutton instances, not in any other instances of GnomeCanvasPixbuf.

Thanks,
-Bolian


Bill Haneman wrote:

Bolian:

The best way to ensure that an AtkFactory is used only with certain
instances of a GObject type is to create a new subtype.  In your case,
this means that GnomeCanvasItem should be subclassed, and an appropriate
AtkFactory registered for the new type or types.  

GnomeCanvasItem is already an abstract class, so you must already be
using subclasses.  If your GnomeCanvasItems are instances of existing
GnomeCanvas subtypes, for instance GnomeCanvasWidget instances, you may
need to create something like a GnomeCanvasActiveWidget type which is
used for your 'actionable' canvas items.

regards

Bill

On Thu, 2003-09-04 at 08:06, Bolian Yin wrote:
  

Hi Padraig,

I met the problem in gnome-canvas-item. Gail has impl for 
gnome-canvas-item, but programmers can add many functions to a 
gnome-canvas-item.

For example, a gnome-canvas-item support an action in some context, and 
want to add a action interface to the atkobject creates for it. In this 
case, I cannot register a new factory to create the atk object, or all 
the gnome-canvas-items will create their atk objects using the new factory.
Is there ways to make a atk factory only used for some instances of 
gnome-canvas-item, and in other case the default (gail) factory will be 
used?

Thanks,
Bolian