Re: locating a widget in a scrolled window

[Stephen Bach <9sjb qlink queensu ca>]

Hi Irtza, 

On Sun, Apr 10, 2005 at 09:48:24PM -0400, Irtza Sharif wrote:
> Thank you for your response.  Let me clarify my situation.
> 
> I have a Scrolled Window within which I add a vbox
> 
> The widgets inside the vbox are held in a linked list that I have
> setup.  New widgets can be created and added to this vbox within the
> scrolled window while the program is running.  When these new widgets
> are created and added, I would like to shift the scrolled window to
> show this widget.

If the new widgets are direct children of the vbox (which is a direct
child of the scrolled window's viewport), you should be able to do
something like this:

void scroll_to(GtkWidget* scrolled_window, GtkWidget* widget) {

	gdouble page_inc, step_inc, upper, lower, pos;

	GtkAdjustment* vadj = gtk_scrolled_window_get_vadjustment(
			GTK_SCROLLED_WINDOW(scrolled_window));

	page_inc = vadj->page_increment;
	step_inc = vadj->step_increment;
	lower = vadj->lower;

	/* Otherwise we sometimes scroll down into a page of black. */
	upper = vadj->upper - page_inc - step_inc;

	/* Center on the widget. */
	pos = (gdouble)widget->allocation.y - page_inc/2;

	gtk_adjustment_set_value(vadj, CLAMP(pos, lower, upper));
}


This only takes into account the vertical, but I think the horizontal
could be done similarly.

If the new widgets aren't direct children of the vbox, you could still
probably do this by recursing up through widget->parent until you get to
the vbox, remapping the coordinates along the way.

Hope this helps,

Stephen