Gtk (mm) limit width of combobox - gtk

Question

Because I use Comboboxes that may contain text entries of very long size,
which leads to the combobox increasing its width far beyond reasonable size,
I am trying to give a maximum width to the combobox.
If I am doing this like this:
class MyCombo : public Gtk::ComboBox {
private:
CellRendererText render;
public:
MyCombo() {
render.property_width_chars() = 10;
render.property_ellipsize() = Pango::ELLIPSIZE_END;
pack_start(render, true);
}
};
The result will be an empty cell of the desired width, which seems logical since I did not specify which column to show. But how can I do this with that attempt? Using pack_start will just bypass the renderer...
Another approach is this one:
class MyCombo : public Gtk::ComboBox {
private:
CellRendererText render;
public:
MyCombo() {
pack_start(render, true);
set_cell_data_func(render, sigc::mem_fun(*this, &MyCombo::render_iter));
}
void render_iter(const TreeModel::const_iterator& iter) {
Glib::ustring data = get_string_from_iter(iter);
int desired_width_chars = 10; //for example
render.property_text() = ellipsize_string(data, desired_width_chars);
}
};
Using that approach, it works, but the text in the popup (what opens up when u click the combobox) is also shortened which is not what I want (obviously the user should be able to read the whole string and I dont care about the popup widht.)
Can you please help me with this? I would be happy for any advice/alternative solutions.
Regards tagelicht

Answer 1

NOTE: set_wrap_width is a function that wraps the total number of entries in the combo box over a number of columns specified; it does not answer the question.
Using set_wrap_width(1) | Using set_wrap_width(5)
Following Noup's answer as a guide I managed to get the below code; which directly answers the question and its requirements (C++/Gtkmm).
// Get the first cell renderer of the ComboBox.
auto v_cellRenderer = (Gtk::CellRendererText*)v_comboBox.get_first_cell();
// Probably obsolete; Sets character width to 1.
v_cellRenderer->property_width_chars() = 1;
// Sets the ellipses ("...") to be at the end, where text overflows.
// See Pango::ELLIPSIZE enum for other values.
v_cellRenderer->property_ellipsize() = Pango::ELLIPSIZE_END;
// Sets the size of the box, change this to suit your needs.
// -1 sets it to automatic scaling: (width, height).
v_cellRenderer->set_fixed_size(200, -1);
Result (image):
Result of code
BE AWARE: Depending on where you perform the above code; either all the cells will be the same size, or just the box itself (intended).
From experimenting, I've found:
In the parent object constructor: All cell sizes are the same.
In a separate function: Only the first cell (the box) is affected.
I'd recommend you put the code in a function that's connected to the comboBox's changed signal, such as:
v_comboBox.signal_changed().connect(sigc::mem_fun(*this, &YourClass::comboBox_changedFunction));

Answer 2

This may be what you are looking for:
cell_renderer_text.set_wrap_width(10)
This is for Python, but you get the idea :-)
Unfortunately, the documentation is scarce. I found this by poking around in Anjuta/Glade.
Edit:
the docs are here. They are not overly helpful, but they do exist.

Answer 3

As an alternative, the following works for me without having to set wrap_width nor to subclass ComboBox (in Gtk#):
ComboBoxText cb = new ComboBoxText();
cb.Hexpand = true; //If there's available space, we use it
CellRendererText renderer = (cb.Cells[0] as CellRendererText); //Get the ComboBoxText only renderer
renderer.WidthChars = 20; //Always show at least 20 chars
renderer.Ellipsize = Pango.EllipsizeMode.End;
Note: I'm using Expand to use space if it's available. If you just want to keep the combo box on a fixed width, just remove that bit.