Hi, Anyone interested? Vote! Hi Hendrik, I can't answer the question. I suggest you read some samples, e.g. the code of the canvas widget, and follow their way to implement a scrollable customized drawing widget. Thanks, Gang 2011/7/8 Hendrik Tews <tews@xxxxxxxxxxxxxxxxxxxx>: > Hi, > > what is the preferred way to reposition a GtkDrawingArea inside a > GtkScrollbar just after the GtkDrawingArea has been enlarged? > > In detail: I have a DrawingArea (in Gtk 2.20 in Debian squeeze) > that gets now and then enlarged when new elements are drawn on > it. For enlarging it I use gtk_widget_set_size_request. The > DrawingArea sits inside a Scrollbar. After enlarging the > DrawingArea I want to make sure that the new element, which I've > just drawn in the new region, is visible. I therefore call > gtk_adjustment_clamp_page on both scroll bars with appropriate > lower and upper values. I then call gtk_widget_queue_clear on the > DrawingArea and let it redraw when the exposure event arrives. > > The trouble is that the new element is often outside the visible > portion of the DrawingArea. So gtk_adjustment_clamp_page does not > work in this case. AFAICS the problem is that the size does not > change immediately when I call gtk_widget_set_size_request and > therefore the call of gtk_adjustment_clamp_page works with the > old size. When the adjustments finally get the new size they > forgot about my clamp_page request and the new region with the > new element in it remains invisible. > > When and how should I change the adjustments so that the new > region in the DrawingArea becomes visible? > > Using the size-allocate signal does not work, because apparently > it is only emitted if my size request is larger then the current > size. (Sometimes I also delete elements and shrink the > DrawingArea. But also in these cases I want to ensure that a > certain current element is visible). > > Changing the adjustment in the handler of the exposure event does > also not work reliably. Sometimes the DrawingArea receives > exposure events before the size has changed. Therefore I would > have to set the adjustment on every exposure event, which would > break the function of the scroll bars. > > For screen shots of my application visit > http://askra.de/software/prooftree/ . > > I posted this already on gtk-app-devel, but got no replies there. > > Bye, > > Hendrik Tews > _______________________________________________ > 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
