Re: Multitouch in goocanvasmm

[Kjell Ahlstedt <kjell ahlstedt bredband net>]

Gtk::Widget::signal_touch_event() exists since gtkmm 3.3.20.

Den 2014-12-12 21:58, Klaus Rudolph skrev:
> Hi all,
>
> I want to use goocanvasmm to recognize touch events. I did the following:
>
>
> m_canvas->add_events( Gdk::BUTTON_PRESS_MASK | Gdk::BUTTON_RELEASE_MASK | Gdk::POINTER_MOTION_MASK | 
> Gdk::TOUCH_MASK);
> sigc::connection conn_t1 = m_canvas->signal_event().connect( sigc::ptr_fun( &AnyEvent));
>
> My event handler starts like this:
>
> bool AnyEvent( GdkEvent* ev)
> {
>      switch( ev->type )
>      {
>          case GDK_TOUCH_BEGIN:
>              {
>              GdkEventTouch* tev = (GdkEventTouch*)ev;
>              cout << "Begin" << endl;
>
>              cout << tev->x << " " << tev->y << endl;
>              }
>              break;
>
> ...
>
> All that work fine! I see the events GDK_TOUCH(BEGIN/UPDATE/END) coming in the canvas signal handler!
>
> Well, here is my question:
>
> What I would like to do now is something like:
> sigc::connection conn1 = m_rect->signal_???????_event().connect( sigc::ptr_fun( &TouchFunc ));
>
> I believe that there is no function which can directly see the touch events. Is this right? If not,
> which signal_?????_event() method can I use to connect the touch signals from an item drawn on the canvas to 
> the touch event?
>   
> If there is actually no method which can deal with touch events directly for the canvas items, is there a way to forward the
> catched events again into the canvas, maybe as button events, which then will be forwarded to the correct 
> item of the canvas?
> I have no idea if there is a send_event or any other function which could do the job. The only thing I would 
> achieve is, that from the received
> coordinates on the canvas window the correct canvas item would be found and then the event is forwarded 
> exactly on only to this item.
>
> As additional information: Yes, the first touch event is also recognized as key_press_event by the item. But 
> there is no way to get additional
> touch events there from more then the first finger tipped on the touch.
> Maybe it is also a solution to enable multiple press/move/release events. But I have no idea how to do this. 
> It would be nice if someone can point me to the
> information.
>
> Thanks
>   Klaus