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Editorial Team
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Asked: 2026-05-29T09:39:13+00:00

I’m trying to compile a gtkmm application that uses cairomm for drawing. It compiles

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I’m trying to compile a gtkmm application that uses cairomm for drawing.
It compiles fine using gtkmm3.0 but when I try to compile it using gtkmm2.4 i get:

error: ‘signal_draw’ was not declared in this scope

I’m using g++.

It seems that there is no signal_draw in gtkmm2.4(Am I wrong?). Is there any function/signal that can be used instead?

Thanks in advance.

Sorry for my bad English.

Some code:

class egclass: public Gtk::DrawingArea

{

public:

egclass();

virtual ~egclass();

virtual bool on_draw(const Cairo::RefPtr<Cairo::Context>& cr);

};

egclass::egclass()

{

#ifndef GLIBMM_DEFAULT_SIGNAL_HANDLERS_ENABLED

signal_draw().connect(sigc::mem_fun(*this, &egclass::on_draw), false);

#endif

}

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1 Answer

  1. Editorial Team

    The older gtkmm 2.4 has on_expose_event instead:

    virtual bool on_expose_event(GdkEventExpose* event);

    If you need to create a cairo context for drawing, with the GTK+ C API it goes something like this:

    cairo_t *cr;

cr = gdk_cairo_create (event->window);
gdk_cairo_region (cr, event->region);
cairo_clip (cr);

/* do your drawing */

cairo_destroy (cr);

    … translating the snippet above to gtkmm is left as an exercise to the reader.

    Also see the following links:

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