# Button (Python)

Marta Maria Casetti
mmcasetti@gmail.com 2012
A button widget which emits a signal when clicked
Rafael Fontenelle
rafaelff@gnome.org 2013, 2018

# Button

A button widget connected to a simple callback function.

# Code used to generate this example

from gi.repository import Gtk import sys

class MyWindow(Gtk.ApplicationWindow): # a window

def __init__(self, app): Gtk.Window.__init__(self, title="GNOME Button", application=app) self.set_default_size(250, 50)

# a button button = Gtk.Button() # with a label button.set_label("Click me") # connect the signal "clicked" emitted by the button # to the callback function do_clicked button.connect("clicked", self.do_clicked) # add the button to the window self.add(button)

# callback function connected to the signal "clicked" of the button def do_clicked(self, button): print("You clicked me!")

class MyApplication(Gtk.Application):

def __init__(self): Gtk.Application.__init__(self)

def do_activate(self): win = MyWindow(self) win.show_all()

def do_startup(self): Gtk.Application.do_startup(self)

app = MyApplication() exit_status = app.run(sys.argv) sys.exit(exit_status)

# Useful methods for a Button widget

In line 16 the `"clicked"` signal from the button is connected to the callback function `do_clicked()` using `widget.connect(signal, callback function)`. See for a more detailed explanation.

`set_relief(Gtk.ReliefStyle.NONE)` sets to none the relief style of the edges of the Gtk.Button - as opposed to `Gtk.ReliefStyle.NORMAL`.

If the label of the button is a stock icon, `set_use_stock(True)` sets the label as the name of the corresponding stock icon.

To set an image (e.g. a stock image) for the button `button`:

image = Gtk.Image() image.set_from_stock(Gtk.STOCK_ABOUT, Gtk.IconSize.BUTTON) button.set_image(image)

You should not set a label for the button after this, otherwise it will show the label and not the image.

If we use `set_focus_on_click(False)` the button will not grab focus when it is clicked by the mouse. This could be useful in places like toolbars, so that the keyboard focus is not removed from the main area of the application.

# Referências da API

In this sample we used the following:

GtkButton

GtkWindow