# ComboBox (Python)

Marta Maria Casetti
mmcasetti@gmail.com 2012
A widget used to choose from a list of items
Mario Blättermann
mario.blaettermann@gmail.com 2011, 2013, 2016, 2018

# ComboBox (zweispaltig)

This ComboBox prints to the terminal your selection when you change it.

# Code used to generate this example

from gi.repository import Gtk import sys

actions = [["Select", None], ["New", Gtk.STOCK_NEW], ["Open", Gtk.STOCK_OPEN], ["Save", Gtk.STOCK_SAVE]]

class MyWindow(Gtk.ApplicationWindow):

def __init__(self, app): Gtk.Window.__init__(self, title="Welcome to GNOME", application=app) self.set_default_size(200, -1) self.set_border_width(10)

# the data in the model, of type string on two columns listmodel = Gtk.ListStore(str, str) # append the data for i in range(len(actions)): listmodel.append(actions[i])

# a combobox to see the data stored in the model combobox = Gtk.ComboBox(model=listmodel)

# cellrenderers to render the data renderer_pixbuf = Gtk.CellRendererPixbuf() renderer_text = Gtk.CellRendererText()

# we pack the cell into the beginning of the combobox, allocating # no more space than needed; # first the image, then the text; # note that it does not matter in which order they are in the model, # the visualization is decided by the order of the cellrenderers combobox.pack_start(renderer_pixbuf, False) combobox.pack_start(renderer_text, False)

# associate a property of the cellrenderer to a column in the model # used by the combobox combobox.add_attribute(renderer_text, "text", 0) combobox.add_attribute(renderer_pixbuf, "stock_id", 1)

# the first row is the active one at the beginning combobox.set_active(0)

# connect the signal emitted when a row is selected to the callback # function combobox.connect("changed", self.on_changed)

# add the combobox to the window self.add(combobox)

def on_changed(self, combo): # if the row selected is not the first one, write on the terminal # the value of the first column in the model if combo.get_active() != 0: print("You chose " + str(actions[combo.get_active()][0]) + "\n") return True

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 ComboBox widget

The ComboBox widget is designed around a Model/View/Controller design: the Model stores the data; the View gets change notifications and displays the content of the model; the Controller, finally, changes the state of the model and notifies the view of these changes. For more information and for a list of useful methods for ComboBox see .

In line 45 the `"changed"` signal is connected to the callback function `on_changed()` using `widget.connect(signal, callback function)`. See for a more detailed explanation.

# API-Referenzen

In this sample we used the following:

GtkComboBox

GtkListStore

GtkCellRendererText

GtkCellRendererPixbuf

Stock Items

pygobject - Python bindings for GObject Introspection