Re: how to prevent Gtk::Entry to "Pass on" key event?

[Kjell Ahlstedt <kjell ahlstedt bredband net>]

There is a section on event propagation in the gtkmm tutorial
http://developer.gnome.org/gtkmm-tutorial/stable/sec-keyboardevents-propagation.html.en

There you can also find a small program that you can compile and 
experiment with.

Yann is right in that you need to connect to the Entry's 
signal_key_press_event() and always return true from that signal 
handler. It will stop the event from propagating to the enclosing 
window. But you have connected IMWin::press_action() with the parameter 
after=false, which means that it will be called before any of the 
Entry's signal handlers.

If you remove 'false' in the call to connect() and connect to 
m_entry.signal_key_press_event(), your program will work as you want 
when the Entry has keyboard focus. But I suppose you added after=false 
for a good reason. Are there other widgets in your window that consume 
key presses and don't let them propagate to the enclosing window, 
although you want to handle them in IMWin::press_action()? If so, you 
probably must keep after=false, and test which widget has keyboard focus.

bool IMWin::press_action(GdkEventKey *e) {
  if (m_entry.has_focus())
    return false;
  ......

In this case there is no need to connect to 
m_entry.signal_key_press_event().

Kjell

2012-06-20 09:38, Yann Leydier skrev:
> The keypress event has a return value that tells if the signal must be 
> propagated:
> http://developer.gnome.org/gtk/stable/GtkWidget.html#GtkWidget-key-press-event 
>
>
> I hope this means that it can help to tell the entry not to propagate 
> the signal to the window. This should be something like adding :
>
> next_file_entry.signal_key_press_event().connect(sigc::mem_fun(this, 
> &TWin::no_key_propagate));
>
> bool TWin::no_key_propagate(GdkEventKey*)
> {
>     return true;
> }
>
> If this does not work, then we'll have to conclude that Gtk's doc is 
> cryptic on this point…
>
> yann
>
> On 20/06/12 09:23, jody wrote:
> > Hi Yann
> >
> > I'm not sure i exactlyx understand what you mean by "connect to the
> > entry's signal".
> >
> > In my window's constructor i have:
> >     signal_key_press_event().connect(sigc::mem_fun(*this,
> > &IMWin::press_action), false);
> >
> > where press_action method is:
> >
> > bool IMWin::press_action(GdkEventKey *e) {
> >      bool bReturn = false;
> > // call appropriate button if return is pressed
> >      if (e->keyval == GDK_Return) {
> >          if (m_txtColorTable.has_focus() || 
> > m_butColorBrowse.has_focus()) {
> >              on_button_color_table_clicked();
> >          }  else if (m_txtDataFile.has_focus() || 
> > m_butDataBrowse.has_focus()) {
> >              on_button_load_data_clicked();
> >          }
> >          bReturn = true;;
> >      } else if (e->keyval == GDK_f) {
> >          m_Image->flip();
> >      }
> >      return bReturn;
> > }
> >
> > Jody
> >
> >
> > On Wed, Jun 20, 2012 at 8:47 AM, Yann Leydier <yann leydier info> wrote:
> > > Hi,
> > >
> > > did you try to connect to the entry's signal and just return "true" 
> > > so that
> > > the event is not transmitted any further?
> > >
> > > yann
> > >
> > >
> > > On 20/06/12 08:40, jody wrote:
> > > > Hi
> > > > I have an application where i use keyboard events  ( with
> > > > signal_key_press_event().connect() ) to
> > > > control some simple actions nan image which is displayed (e.g.
> > > > flipping it when 'f' is pressed)
> > > > I also have a Gtk::Entry to type in the name of then next file to be
> > > > loaded.
> > > >
> > > > But whenever i type the key 'f' in the Gtk::Entry, the image is
> > > > flipped (and the character 'f' is written in the Gtk::Entry),
> > > > i.e. the key event has been used by by the Gtk::Entry and then been
> > > > passed on to the containing window.
> > > >
> > > > Is there a way to tell the entry to "destroy" the key press event
> > > > after using it?
> > > >
> > > > Thank You
> > > >    Jody
> > > > _______________________________________________
> > > > gtkmm-list mailing list
> > > > gtkmm-list gnome org
> > > > https://mail.gnome.org/mailman/listinfo/gtkmm-list
> > >
> > > _______________________________________________
> > > gtkmm-list mailing list
> > > gtkmm-list gnome org
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>
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