Re: signal_button_press_event() not sending signal?

[Antonio Coralles <noche suapie reflex at>]

Matthew Ryan Hurne wrote:

> First of all, let me hint that I am very new to Gtkmm programming, and
> relatively new to C++ programming in general.
>
> I am trying to write a simple program that draws a bezier curve in a
> DrawingArea which can be manipulated by clicking and dragging its
> control points.
>
> Right now the program draws a curve, but I have not yet successfully
> implemented anything to manipulate it.  That's what I'm working on.
>
> I figured I'd start by figuring out how to detect a button click on the
> DrawingArea.  I know I'll need to get the coordinates of the mouse
> pointer as well.  From reading the tutorial, etc. it seemed that
> Widget::signal_button_press_event() is the appropriate method to use.  I
> have connected it to a signal handler in my MainWindow class.
> Everything compiles fine but the code in my signal handler doesn't seem
> to execute.
>
> Here's what code it seems you'd need.
> In MainWindow's constructor (curveArea is my DrawingArea):
>
> curveArea.signal_button_press_event().connect(sigc::mem_fun(*this,
> &MainWindow::on_curve_button_press_event));
>
> A protected member of MainWindow:
>
> bool MainWindow::on_curve_button_press_event(GdkEventButton* event)
> {
>         std::cout << "The drawing area was clicked" << std::endl;
>
>         return true;
> }
>
> I searched the web for a while trying to find any hints, and was only
> able to find something on a mailing list from 2002 that said it was a
> bug.  Seems like that wouldn't be relevant anymore.  Any help would be
> greatly appreciated.  If you want all my source code, I can attach it in
> a future e-mail.  I wasn't sure if that was proper mailing list
> etiquette so I figured I'd leave it out in this message.  Oh and one
> more thing...I'm having a lot of fun learning all this stuff.  :-)
>
> Matthew Hurne
>
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I would suggest you to read 
http://www.gtkmm.org/docs/gtkmm-2.4/docs/tutorial/html/ch14.html. To 
detect mouse clicks i would override bool 
Gtk::Widget::on_button_press_event(GdkEventButton*  event)  ... For 
further documentation for the various GdkEvent structs you may look at 
http://developer.gnome.org/doc/API/2.0/gdk/gdk-Event-Structures.html.

antonio