Re: Gtk::Image and mouse click

[Paul Davis <pjdavis engineering uiowa edu>]

Petr,

This type of error is generally caused by your call back not having the 
appropriate signature.

In your case it should be:

bool
MainWindow::on_image2_button_press( GdkEvent* event ) ;

And another gotchya to remember is to enable mouse events to be captured 
by the widget. I'm not sure that Gtk::Image has them on by default.

But its something like:

Gdk::EventMask events = image.get_events() ;
events |= Gdk::BUTTON_PRESS_MASK ;
image.set_events( events ) ;

Or, you can wrap your image in an event box and connect your call back 
to the event box.

Paul

Petr Hracek wrote:

> Hi everybody,
> I want to click on the image widget and get coors.
> I used following:
> Gtk::Image image;
> image.signal_button_press_event().connect(sigc::mem_fun(*this, 
> &MainWindow::on_image2_button_press));
> but it shows me error message:
>
> /usr/include/sigc++-2.0/sigc++/functors/slot.h: In static member 
> function ‘static T_return sigc::internal::slot_call1<T_functor, 
> T_return, T_arg1>::call_it(sigc::internal::slot_rep*, typename 
> sigc::type_trait<T_arg3>::take) [with T_functor = 
> sigc::bound_mem_functor0<void, MainWindow>, T_return = bool, T_arg1 = 
> GdkEventButton*]’:
> /usr/include/sigc++-2.0/sigc++/functors/slot.h:144: instantiated from 
> ‘static void* (* sigc::internal::slot_call1<T_functor, T_return, 
> T_arg1>::address())(void*) [with T_functor = 
> sigc::bound_mem_functor0<void, MainWindow>, T_return = bool, T_arg1 = 
> GdkEventButton*]’
> /usr/include/sigc++-2.0/sigc++/functors/slot.h:529: instantiated from 
> ‘sigc::slot1<T_return, T_arg1>::slot1(const T_functor&) [with 
> T_functor = sigc::bound_mem_functor0<void, MainWindow>, T_return = 
> bool, T_arg1 = GdkEventButton*]’
> /usr/include/sigc++-2.0/sigc++/functors/slot.h:1157: instantiated from 
> ‘sigc::slot<T_return, T_arg1, sigc::nil, sigc::nil, sigc::nil, 
> sigc::nil, sigc::nil, sigc::nil>::slot(const T_functor&) [with 
> T_functor = sigc::bound_mem_functor0<void, MainWindow>, T_return = 
> bool, T_arg1 = GdkEventButton*]’
> MainWindow.cpp:198: instantiated from here
> /usr/include/sigc++-2.0/sigc++/functors/slot.h:137: error: void value 
> not ignored as it ought to be
> /usr/include/sigc++-2.0/sigc++/adaptors/adaptor_trait.h: In member 
> function ‘typename 
> sigc::adaptor_functor<T_functor>::deduce_result_type<T_arg1, void, 
> void, void, void, void, void>::type 
> sigc::adaptor_functor<T_functor>::operator()(T_arg1) const [with 
> T_arg1 = GdkEventButton* const&, T_functor = 
> sigc::bound_mem_functor0<void, MainWindow>]’:
> /usr/include/sigc++-2.0/sigc++/functors/slot.h:137: instantiated from 
> ‘static T_return sigc::internal::slot_call1<T_functor, T_return, 
> T_arg1>::call_it(sigc::internal::slot_rep*, typename 
> sigc::type_trait<T_arg3>::take) [with T_functor = 
> sigc::bound_mem_functor0<void, MainWindow>, T_return = bool, T_arg1 = 
> GdkEventButton*]’
> /usr/include/sigc++-2.0/sigc++/functors/slot.h:144: instantiated from 
> ‘static void* (* sigc::internal::slot_call1<T_functor, T_return, 
> T_arg1>::address())(void*) [with T_functor = 
> sigc::bound_mem_functor0<void, MainWindow>, T_return = bool, T_arg1 = 
> GdkEventButton*]’
> /usr/include/sigc++-2.0/sigc++/functors/slot.h:529: instantiated from 
> ‘sigc::slot1<T_return, T_arg1>::slot1(const T_functor&) [with 
> T_functor = sigc::bound_mem_functor0<void, MainWindow>, T_return = 
> bool, T_arg1 = GdkEventButton*]’
> /usr/include/sigc++-2.0/sigc++/functors/slot.h:1157: instantiated from 
> ‘sigc::slot<T_return, T_arg1, sigc::nil, sigc::nil, sigc::nil, 
> sigc::nil, sigc::nil, sigc::nil>::slot(const T_functor&) [with 
> T_functor = sigc::bound_mem_functor0<void, MainWindow>, T_return = 
> bool, T_arg1 = GdkEventButton*]’
> MainWindow.cpp:198: instantiated from here
> /usr/include/sigc++-2.0/sigc++/adaptors/adaptor_trait.h:84: error: no 
> match for call to ‘(sigc::bound_mem_functor0<void, MainWindow>) 
> (GdkEventButton* const&)’
> /usr/include/sigc++-2.0/sigc++/functors/mem_fun.h:1786: note: 
> candidates are: T_return sigc::bound_mem_functor0<T_return, 
> T_obj>::operator()() const [with T_return = void, T_obj = MainWindow]
> /usr/include/sigc++-2.0/sigc++/adaptors/adaptor_trait.h:84: error: 
> return-statement with a value, in function returning 'void'
>
> can you help me with this problem?
> regards
> Petr Hracek
>
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