Dialogs
In this part of the Ruby GTK programming tutorial, we will introduce dialogs.
Dialog windows or dialogs are an indispensable part of most modern GUI applications. A dialog is defined as a conversation between two or more persons. In a computer application a dialog is a window which is used to "talk" to the application. A dialog is used to input data, modify data, change the application settings etc. Dialogs are important means of communication between a user and a computer program.
Message boxes
Message dialogs are convenient dialogs that provide messages to the user of the application. The message consists of textual and image data.
#!/usr/bin/ruby
# ZetCode Ruby GTK tutorial
#
# This example shows message
# dialogs
#
# author: jan bodnar
# website: www.zetcode.com
# last modified: June 2009
require 'gtk2'
class RubyApp < Gtk::Window
def initialize
super
set_title "Messages"
signal_connect "destroy" do
Gtk.main_quit
end
init_ui
set_default_size 250, 100
set_window_position Gtk::Window::POS_CENTER
show_all
end
def init_ui
table = Gtk::Table.new 2, 2, true
info = Gtk::Button.new "Information"
warn = Gtk::Button.new "Warning"
ques = Gtk::Button.new "Question"
erro = Gtk::Button.new "Error"
info.signal_connect "clicked" do
on_info
end
warn.signal_connect "clicked" do
on_warn
end
ques.signal_connect "clicked" do
on_ques
end
erro.signal_connect "clicked" do
on_erro
end
table.attach info, 0, 1, 0, 1
table.attach warn, 1, 2, 0, 1
table.attach ques, 0, 1, 1, 2
table.attach erro, 1, 2, 1, 2
add table
end
def on_info
md = Gtk::MessageDialog.new(self,
Gtk::Dialog::DESTROY_WITH_PARENT, Gtk::MessageDialog::INFO,
Gtk::MessageDialog::BUTTONS_CLOSE, "Download completed")
md.run
md.destroy
end
def on_erro
md = Gtk::MessageDialog.new(self, Gtk::Dialog::MODAL |
Gtk::Dialog::DESTROY_WITH_PARENT, Gtk::MessageDialog::ERROR,
Gtk::MessageDialog::BUTTONS_CLOSE, "Error loading file")
md.run
md.destroy
end
def on_ques
md = Gtk::MessageDialog.new(self,
Gtk::Dialog::DESTROY_WITH_PARENT, Gtk::MessageDialog::QUESTION,
Gtk::MessageDialog::BUTTONS_CLOSE, "Are you sure to quit?")
md.run
md.destroy
end
def on_warn
md = Gtk::MessageDialog.new(self,
Gtk::Dialog::DESTROY_WITH_PARENT, Gtk::MessageDialog::WARNING,
Gtk::MessageDialog::BUTTONS_CLOSE, "Unallowed operation")
md.run
md.destroy
end
end
Gtk.init
window = RubyApp.new
Gtk.main
In our example, we will show four kinds of message dialogs. Information, Warning, Question and Error message dialogs.
info = Gtk::Button.new "Information" warn = Gtk::Button.new "Warning" ques = Gtk::Button.new "Question" erro = Gtk::Button.new "Error"
We have four buttons. Each of these buttons will show a different kind of message dialog.
def on_info
md = Gtk::MessageDialog.new(self,
Gtk::Dialog::DESTROY_WITH_PARENT, Gtk::MessageDialog::INFO,
Gtk::MessageDialog::BUTTONS_CLOSE, "Download completed")
md.run
md.destroy
end
If we click on the info button, the Information dialog is displayed. The Gtk::MessageDialog::INFO specifies the type of the dialog. The Gtk::MessageDialog::BUTTONS_CLOSE specifies the button to be displayed in the dialog. The last parameter is the message dislayed. The dialog is displayed with the run method. The programmer must also call either the destroy or the hide method.
AboutDialog
The AboutDialog displays information about the application. AboutDialog can display a logo, the name of the application, version, copyright, website or licence information. It is also possible to give credits to the authors, documenters, translators and artists.
#!/usr/bin/ruby
# ZetCode Ruby GTK tutorial
#
# This example demonstrates the
# AboutDialog dialog
#
# author: jan bodnar
# website: www.zetcode.com
# last modified: June 2009
require 'gtk2'
class RubyApp < Gtk::Window
def initialize
super
set_title "About dialog"
signal_connect "destroy" do
Gtk.main_quit
end
init_ui
set_default_size 300, 150
set_window_position Gtk::Window::POS_CENTER
show_all
end
def init_ui
button = Gtk::Button.new "About"
button.set_size_request 80, 30
button.signal_connect "clicked" do
on_clicked
end
fix = Gtk::Fixed.new
fix.put button, 20, 20
add fix
end
def on_clicked
about = Gtk::AboutDialog.new
about.set_program_name "Battery"
about.set_version "0.1"
about.set_copyright "(c) Jan Bodnar"
about.set_comments "Battery is a simple tool for battery checking"
about.set_website "http://www.zetcode.com"
about.set_logo Gdk::Pixbuf.new "battery.png"
about.run
about.destroy
end
end
Gtk.init
window = RubyApp.new
Gtk.main
The code example uses a AboutDialog with some of its features.
about = Gtk::AboutDialog.new
We create an AboutDialog.
about.set_program_name "Battery" about.set_version "0.1" about.set_copyright "(c) Jan Bodnar"
Here we specify the name, the version and the copyright.
about.set_logo Gdk::Pixbuf.new "battery.png"
This line creates a logo.
FontSelectionDialog
The FontSelectionDialog is a dialog for selecting fonts. It is typically used in applications, that do some text editing or formatting.
#!/usr/bin/ruby
# ZetCode Ruby GTK tutorial
#
# This example works with the
# FontSelectionDialog
#
# author: jan bodnar
# website: www.zetcode.com
# last modified: June 2009
require 'gtk2'
class RubyApp < Gtk::Window
def initialize
super
set_title "FontSelectionDialog"
signal_connect "destroy" do
Gtk.main_quit
end
init_ui
set_default_size 300, 150
set_window_position Gtk::Window::POS_CENTER
show_all
end
def init_ui
set_border_width 10
@label = Gtk::Label.new "The only victory over love is flight."
button = Gtk::Button.new "Select font"
button.signal_connect "clicked" do
on_clicked
end
fix = Gtk::Fixed.new
fix.put button, 100, 30
fix.put @label, 30, 90
add fix
end
def on_clicked
fdia = Gtk::FontSelectionDialog.new "Select font name"
response = fdia.run
if response == Gtk::Dialog::RESPONSE_OK
font_desc = Pango::FontDescription.new fdia.font_name
if font_desc
@label.modify_font font_desc
end
end
fdia.destroy
end
end
Gtk.init
window = RubyApp.new
Gtk.main
In the code example, we have a button and a label. We show the FontSelectionDialog by clicking on the button.
fdia = Gtk::FontSelectionDialog.new "Select font name"
We create the FontSelectionDialog.
if response == Gtk::Dialog::RESPONSE_OK
font_desc = Pango::FontDescription.new fdia.font_name
if font_desc
@label.modify_font font_desc
end
end
If we click on the OK button, the font of the label widget changes to the one, that we selected in the dialog.
ColorSelectionDialog
ColorSelectionDialog is a dialog for selecting a color.
#!/usr/bin/ruby
# ZetCode Ruby GTK tutorial
#
# This example works with the
# ColorSelectionDialog
#
# author: jan bodnar
# website: www.zetcode.com
# last modified: June 2009
require 'gtk2'
class RubyApp < Gtk::Window
def initialize
super
set_title "ColorSelectionDialog"
signal_connect "destroy" do
Gtk.main_quit
end
init_ui
set_default_size 350, 150
set_window_position Gtk::Window::POS_CENTER
show_all
end
def init_ui
set_border_width 10
@label = Gtk::Label.new "The only victory over love is flight."
button = Gtk::Button.new "Select color"
button.signal_connect "clicked" do
on_clicked
end
fix = Gtk::Fixed.new
fix.put button, 100, 30
fix.put @label, 30, 90
add fix
end
def on_clicked
cdia = Gtk::ColorSelectionDialog.new "Select color"
response = cdia.run
if response == Gtk::Dialog::RESPONSE_OK
colorsel = cdia.colorsel
color = colorsel.current_color
@label.modify_fg Gtk::STATE_NORMAL, color
end
cdia.destroy
end
end
Gtk.init
window = RubyApp.new
Gtk.main
The example is very similar to the previous one. This time we change the color of the label.
cdia = Gtk::ColorSelectionDialog.new "Select color"
We create the ColorSelectionDialog.
if response == Gtk::Dialog::RESPONSE_OK
colorsel = cdia.colorsel
color = colorsel.current_color
@label.modify_fg Gtk::STATE_NORMAL, color
end
If the user pressed OK, we get the color value and modify the label's color.
In this part of the Ruby GTK tutorial, we presented dialogs.