Dov Grobgeld wrote: > Here's another idea that I use in my program giv. Whenever I am painting > an object on screen, I am painting the same object in an off-screen > image with the same drawing commands but with "color" that is a > combination of R,G,B that encode the index of the object. The important > catch is that you have to turn off anti-aliasing for this to work. > During motion events I then extract the corresponding pixel from the > off-screen image, decode the R,G, and B to get the index of the object, > which points to a vector of properties that I show. I always had this idea of using cairo for hit detection in this way. Didn't know you have already implemented it Dov. Great! Cheers, behdad > Regards, > Dov > > 2009/2/7 Fabio Mariotti <mariotti.fabio@xxxxxxxxx > <mailto:mariotti.fabio@xxxxxxxxx>> > > Ok I have 2 partial answers to myself: > > > I need to draw triangles (and circles) on the screen (any drawable) > and have active events on each object I draw: namely mouse_over, > click.. etc.. > [they can overlap] > > Is there any alternative to gnome-canvas? > In particular gnome-canvas was working nicely up to 20000 objects > but a bit heavy with 40000. (I would guess that an equivalent > canvas solution will suffer the same problem..) > > Is there a simple way to "recode" a simple z-buffer using > existing tools? > With simple I mean that I do not have to recalculate exposed pixels. > > > 1) There is no simple coding or otherwise I would be doing a canvas! > > 2) for my little application I have a possible solution: > I set up a z-buffer as simple integers vector. I store 2 doubles > at least for each figure so an integer shouldn't harm the memory. > Due to the type of application, on an click at x,y, I can guess > a limited number of triangles which might be present in the area. > I can redraw the area in the style of a canvas and propagate > the event. Grab it. destroy the canvas-like object. and redraw > in normal style. > I am not sure if I can actually do it... more over I'll still need > the canvas part. > The advantage is that (of course I do not have to code again > the pixel stuff) I can change shape of my > objects at will (ok twice) and moreover I can simply use the event > stuff which exists already. > The overload on the users side shouldn't e that big They will stare > at the screen anyway.. ;). > On which widget can I draw a canvas at arbitrary coordinates? > I'll find it out ;) > [ > I got the idea from an old post... > http://mail.gnome.org/archives/gtk-list/2006-September/msg00275.html > Where I discussed the problem in different terms. > I didn't actually try it. The first reason was that on win > machines it would > have made no difference. > ] > > A note: would it be a possibility to have a gdk widget named > shape(for example) > which simply draw itself and gets events? > It is just the same problem of shaped windows and the like. > > sorry again for the long post.. > Faio > > > _______________________________________________ > gtk-list mailing list > gtk-list@xxxxxxxxx <mailto:gtk-list@xxxxxxxxx> > http://mail.gnome.org/mailman/listinfo/gtk-list > > > > ------------------------------------------------------------------------ > > _______________________________________________ > gtk-list mailing list > gtk-list@xxxxxxxxx > http://mail.gnome.org/mailman/listinfo/gtk-list _______________________________________________ gtk-list mailing list gtk-list@xxxxxxxxx http://mail.gnome.org/mailman/listinfo/gtk-list
