ruby and Gtk::FontChooserDialog.new font size

Question

I am using ruby 2.6.3, installed by compiling the source. When using Gtk::FontChooserDialog.new, the default font size given is 10. Is it possible to call Gtk::FontChooserDialog.new with a different size, such as 24, so that I can avoid having to change the size each time I select a font. Here is how I am doing things:

dialog = Gtk::FontChooserDialog.new(:title => "Select font",
                                          :parent => self,                                         
                                          :action =>  Gtk::FileChooserAction::OPEN,
                                      :buttons => [[Gtk::Stock::OPEN, Gtk::ResponseType::ACCEPT], [Gtk::Stock::CANCEL, Gtk::ResponseType::CANCEL]])

I have tried (in the argument list) :size => 24, :default_size => 24, etc. This does not work. I'm just guessing here. I have searched a lot, with no luck. I also looked in the gem sample dirs at test-gtk-font-chooser-dialog.rb and other files but no luck.

I am using Linux Mint Mate 19.1, installed a couple of weeks ago.

Answer 1

You need to set the size through a Pango.FontDescription. A short example in Python would be:

font_chooser = Gtk.FontChooserDialog.new(title = "Select font", parent = self)
font_description = Pango.FontDescription.new()
font_description.set_size(24 * Pango.SCALE)
font_chooser.set_font_desc(font_description)

EDIT And here is a complete example in Ruby:

#!/usr/bin/ruby

'''
ZetCode Ruby GTK tutorial

This program runs a font dialog with a default (settable) font size.

Author: Jan Bodnar
Website: www.zetcode.com
Last modified: May 2014
'''

require 'gtk3'
require 'pango'

class RubyApp < Gtk::Window

    def initialize
        super
        init_ui
    end

    def init_ui

        set_title "Center"
        signal_connect "destroy" do 
            Gtk.main_quit 
        end

        button = Gtk::Button.new
        button.set_label "Font"    
        button.signal_connect "clicked" do 
            dialog = Gtk::FontChooserDialog.new(:title => "Select font", :parent => self, :action =>  Gtk::FileChooserAction::OPEN, :buttons => [[Gtk::Stock::OPEN, Gtk::ResponseType::ACCEPT], [Gtk::Stock::CANCEL, Gtk::ResponseType::CANCEL]])
            font_description = Pango::FontDescription.new
            font_description.set_size 24 * Pango::SCALE
            dialog.set_font_desc font_description
            dialog.run
        end

        add button
        set_default_size 300, 200
        set_window_position Gtk::WindowPosition::CENTER
        show_all
    end   
end


window = RubyApp.new
Gtk.main