Re: Get position of cursor in widget?

[Chris Vine <chris cvine freeserve co uk>]

On Tue, 2007-07-17 at 13:53 +0200, CÃdric Lucantis wrote:
> Le lundi 16 juillet 2007 12:50, charlesvpacker a Ãcrit :
> > I'm a GTK newbie who has successfully taken the very first
> > steps toward building a custom image processing application.
> > I've figured out how to read and display an image using
> > a GtkImage and GtkPixbuf. I've also modified a block of pixels
> > in the existing pixbuf and updated the displayed image
> > via gtk_image_set_from_pixbuf. Now I want to get the pixel
> > position of the mouse cursor resting on the image. I don't recall
> > seeing a GTK tutorial on capturing pointer position or motion.
> > Could somebody, um, point me to one?
>
> If you want this from within a mouse event handler, you can use the 
> (x,y) and (x_root,y_root) members provided by all the mouse event 
> types. The first pair gives the position of the mouse relative to the 
> event window and the second the position relative to the screen origin. 
>
> If you're not in a handler, you still have gdk_window_get_pointer() and 
> gdk_display_get_pointer(). See the Gdk reference manual for more infos 
> (sections 'Event structures', 'Windows' and 'Display').

You can also use gtk_widget_get_pointer(), which has the advantage of
providing the position in widget co-ordinates.  The gdk functions,
including the gdk event callbacks, provide it in (Gdk/X) window
co-ordinates.  The two can be different in, for example, TreeView
columns with headers, and some Gtk functions (such as for example
gtk_tree_view_get_dest_row_at_pos()) expect widget co-ordinates.

Chris