Question

I am using this code:

class editbook
{
  GtkWidget* _nbook;
  std::vector<GtkWidget*> _srcset; //and so on...

……………………………………………………………………………….

void editbook::add_page()
{
    GtkWidget* tmp = gtk_source_view_new();
    _srcset.push_back(tmp);
    gtk_notebook_append_page(GTK_NOTEBOOK(_nbook),tmp,gtk_label_new("untitled"));
}

……………………………………………………………………………….

void editbook::set_text(const std::string& text)
{
    int index = gtk_notebook_get_current_page(GTK_NOTEBOOK(_nbook));
    GtkTextBuffer* tbuffer = gtk_text_view_get_buffer(GTK_TEXT_VIEW(_srcset[index]));
    gtk_text_buffer_set_text(GTK_TEXT_BUFFER(tbuffer),text.c_str(),-1);
}

Compiles fine. But gives this weird runtime error:

Segementation Fault: return 139

I have traced down the problem to: gtk_text_view_get_buffer(GTK_TEXT_VIEW(_srcset[index]));

NOTE: I am using GtkSourceView instead of GtkTextView, but that may not be a problem because I am gettin the same error when I try GtkTextView.

NOTE: I am using Gtk 2x

NOTE: I am not sure whether to tag this question with C or C++. bec. Gtk+ is a C lib. But I am using C++. So I’ll just tag both for now.

Answer 1

The problem in your code could be that the child widget added to GtkNotebook through gtk_notebook_append_page is not visible, try showing the child widget through gtk_widget_show call. Something on these lines :

void editbook::add_page()
{
    GtkWidget* tmp = gtk_source_view_new();
    _srcset.push_back(tmp);
    gtk_widget_show(tmp); //Show the child widget to make it visible
    gtk_notebook_append_page(GTK_NOTEBOOK(_nbook),tmp,gtk_label_new("untitled"));
}

When you use gtk_notebook_get_current_page if none of the child widget are visible then it returns -1, which I think might be happening in your case & as index is -1 when you use operator[] which doesn’t check for bounds the program crashes. I strongly suggest you use vector::at instead of using operator[] so that you get std::out_of_range exception during run time to indicate the problem. You could use:

void editbook::set_text(const std::string& text)
{
    int index = gtk_notebook_get_current_page(GTK_NOTEBOOK(_nbook));
    GtkTextBuffer* tbuffer = gtk_text_view_get_buffer(GTK_TEXT_VIEW(_srcset.at(index)));
    gtk_text_buffer_set_text(GTK_TEXT_BUFFER(tbuffer),text.c_str(),-1);
}

Hope this helps!