Thanks John,
Your response is very helpful. The one key question that remains for me is: How do I draw a "floating crosshair"? Thanks. Jim ________________________________ Dr. James C. Tilton Voice: 301-286-9510 NASA Goddard Space Flight Center FAX: 301-286-1776 Mail Code 606.3 E-Mail: james.c.til...@nasa.gov<mailto:james.c.til...@nasa.gov> (Computational & Information Sciences and Technology Office) Greenbelt, MD 20771 URLs: http://ipp.gsfc.nasa.gov/ft_tech_rhseg.shtm and http://science.gsfc.nasa.gov/606.3/TILTON/ -----Original Message----- From: jcup...@gmail.com [mailto:jcup...@gmail.com] Sent: Wednesday, April 04, 2012 4:00 AM To: Tilton, James C. (GSFC-6063) Cc: gtk-app-devel-list@gnome.org Subject: Re: Making a cursor (cross hair) track between image displays Hi Jim, On 2 April 2012 17:00, Tilton, James C. (GSFC-6063) <james.c.til...@nasa.gov> wrote: > When I place the cursor in one of the display images, I would like to have a > cross hair appear at the cursor location of the window in which the cursor is > placed at the location currently pointed to by the cursor. I would ALSO like > to have a similar cross hair appear in each of the other associated display > images. Add an event handler to the eventbox and listen for GDK_MOTION_NOTIFY. You need to use gtk_widget_add_events() and turn on motion events with GDK_POINTER_MOTION_MASK, gtk will not deliver motion events to windows by default to try to cut down on unnecessary signalling. (gtk used to support motion event compression, where it would just report the most recent position rather than all positions since the last event delivery, but I think this has been deprecated ... perhaps an expert knows) Once you have a motion events, use motion.x and motion.y to get the mouse position, map this to image space, then map out to the coordinate space for your other image windows. On those other displays, draw a floating crosshair at the right spot. My program does something like this, you're welcome to look at the source if it might help. Though it's a large, hairy thing and perhaps not a clear example. http://www.vips.ecs.soton.ac.uk/index.php?title=VIPS John _______________________________________________ gtk-app-devel-list mailing list gtk-app-devel-list@gnome.org http://mail.gnome.org/mailman/listinfo/gtk-app-devel-list
