On Wed, 2008-05-21 at 19:40 +0300, Dov Grobgeld wrote: > For what it is worth, the DovImageViewer (which is part of giv), does > a single redraw based on a call to: > > gint dov_image_viewer_zoom_around_fixed_point (DovImageViewer * > self, > double new_scale_x, > double new_scale_y, > double old_x, > double old_y, > double new_x, > double new_y); > > It will transfer the old widget coordinate (old_x,old_y) to > (new_x,new_y) while zooming in (or out) to (new_scale_x, new_scale_y). > If adjustments have been attached to the widget, then these are > updated as well. > > Since the entire GdkPixbuf is prepared before it is being exposed in > the window through a call to gdk_draw_pixbuf() the result is quite > smooth. (At this point the user of the widget can connect to a signal > and add annotations to the pixbuf, before it is being shipped to the > screen.) > > Am I still missing something? I agree it wasn't easy to get coordinate > systems correct in the widget implementation, but there is nothing > intrinsic in gtk that hinders it. no, thats precisely what i mean. existing GTK widgets do not provide this function, and instead use gdk_move_window() (because they don't realize that a complete redraw is to follow). that is, when you zoom around, say, the center of a GtkLayout or GtkViewPort, you end up first doing a scroll to reposition the visible part of the child window, and then, ***duh*** you redraw the entire child window. your custom widget does the right thing, and this is what other widgets that could potentially be the site of zoom-around-fixed-point need to do. _______________________________________________ gtk-list mailing list gtk-list@xxxxxxxxx http://mail.gnome.org/mailman/listinfo/gtk-list
