Question

In this part of the PyGTK programming tutorial, we will explore the Pango library.

Pango is a free and open source computing library for rendering internationalised texts in high quality. Different font backends can be used, allowing cross-platform support. (wikipedia)

Pango provides advanced font and text handling that is used for Gdk and Gtk .

Simple example

In our first example, we show, how to change font for our label widget.

quotes.py

#!/usr/bin/python

# ZetCode PyGTK tutorial 
#
# This example shows how to modify
# the font of a label
#
# author: jan bodnar
# website: zetcode.com 
# last edited: February 2009


import gtk
import pango

quotes = """Excess of joy is harder to bear than any amount of sorrow.
The more one judges, the less one loves.
There is no such thing as a great talent without great will power. 
"""


class PyApp(gtk.Window): 
  def __init__(self):
    super(PyApp, self).__init__()
    
    self.connect("destroy", gtk.main_quit)
    self.set_title("Quotes")
    
    label = gtk.Label(quotes)
    gtk.gdk.beep()

    fontdesc = pango.FontDescription("Purisa 10")
    label.modify_font(fontdesc)

    fix = gtk.Fixed()

    fix.put(label, 5, 5)
    
    self.add(fix)
    self.set_position(gtk.WIN_POS_CENTER)
    self.show_all()

PyApp()
gtk.main()

In the above code example, we have a label widget with three quotations. We change its font to Purisa 10.

 quotes = """Excess of joy is harder to bear than any amount of sorrow.
 The more one judges, the less one loves.
 There is no such thing as a great talent without great will power. 
"""

This is the text to show in the label.

fontdesc = pango.FontDescription("Purisa 10")

The FontDescription is used to specify the characteristics of a font.

label.modify_font(fontdesc)

We change the font of the label widget to Purisa 10.

Figure: Quotations

System fonts

The next code example shows all available fonts in a TreeView widget.

systemfonts.py

#!/usr/bin/python

# ZetCode PyGTK tutorial 
#
# This example lists all available
# fonts on a system in a TreeView widget
#
# author: jan bodnar
# website: zetcode.com 
# last edited: February 2009

import gtk
import pango


class PyApp(gtk.Window): 
  def __init__(self):
    super(PyApp, self).__init__()
    
    self.set_size_request(350, 250)
    self.set_border_width(8)
    self.connect("destroy", gtk.main_quit)
    self.set_title("System fonts")
    
    sw = gtk.ScrolledWindow()
    sw.set_shadow_type(gtk.SHADOW_ETCHED_IN)
    sw.set_policy(gtk.POLICY_AUTOMATIC, gtk.POLICY_AUTOMATIC)
    
    context = self.create_pango_context()
    self.fam = context.list_families()

    store = self.create_model()

    treeView = gtk.TreeView(store)
    treeView.set_rules_hint(True)
    sw.add(treeView)

    self.create_column(treeView)

    self.add(sw)
    
    self.set_position(gtk.WIN_POS_CENTER)
    self.show_all()


  def create_column(self, treeView):
    rendererText = gtk.CellRendererText()
    column = gtk.TreeViewColumn("FontName", rendererText, text=0)
    column.set_sort_column_id(0)  
    treeView.append_column(column)
  
  def create_model(self):
    store = gtk.ListStore(str)

    for ff in self.fam:
      store.append([ff.get_name()])

    return store
  

PyApp()
gtk.main()

The code example shows all available fonts on a system.

context = self.create_pango_context()

This code line creates a pango context object. It contains global information about the rendering process of text.

self.fam = context.list_families()

From the context object, we retrieve all available font families.

for ff in self.fam:
  store.append([ff.get_name()])

During the model creation of the TreeView widget, we get all font names from the array of font families and put them into the list store.

Figure: System fonts

Unicode

Pango is used to work with internationalised text.

unicode.py

#!/usr/bin/python
# -*- coding: utf-8 -*-

# ZetCode PyGTK tutorial 
#
# This example displays text
# in azbuka
#
# author: jan bodnar
# website: zetcode.com 
# last edited: February 2009

import gtk
import pango


obj = unicode(u'''Фёдор Михайлович Достоевский родился 30 октября (11 ноября)
1821 года в Москве. Был вторым из 7 детей. Отец, Михаил Андреевич, 
работал вгоспитале для бедных. Мать, Мария Фёдоровна 
(в девичестве Нечаева), происходила из купеческого рода.''')


class PyApp(gtk.Window): 
  def __init__(self):
    super(PyApp, self).__init__()
    
    self.connect("destroy", gtk.main_quit)
    self.set_title("Unicode")
    
    label = gtk.Label(obj.encode('utf-8'))

    fontdesc = pango.FontDescription("Purisa 10")
    label.modify_font(fontdesc)

    fix = gtk.Fixed()

    fix.put(label, 5, 5)
    
    self.add(fix)
    self.set_position(gtk.WIN_POS_CENTER)
    self.show_all()

PyApp()
gtk.main()

We show some text in azbuka.

# -*- coding: utf-8 -*-

In order to work directly with internationalized text in the source code, we must provide this magic comment. Note that it must be on the first or the second line.

 obj = unicode(u'''Фёдор Михайлович Достоевский родился 30 октября (11 ноября)
1821 года в Москве. Был вторым из 7 детей. Отец, Михаил Андреевич, 
работал вгоспитале для бедных. Мать, Мария Фёдоровна 
(в девичестве Нечаева), происходила из купеческого рода.''')

This is text in azbuka.

Label label = new Label(text);

We put encoded text into the label.

Figure: Unicode

Attributes

Pango attribute is an attribute that applies to a section of text.

attributes.py

#!/usr/bin/python

# ZetCode PyGTK tutorial 
#
# In this program we work with
# pango attributes
#
# author: jan bodnar
# website: zetcode.com 
# last edited: February 2009

import gtk
import pango

text = "Valour fate kinship darkness"


class PyApp(gtk.Window): 
  def __init__(self):
    super(PyApp, self).__init__()
    
    self.connect("destroy", gtk.main_quit)
    self.set_title("Attributes")
    
    label = gtk.Label(text)

    attr = pango.AttrList()
    
    fg_color = pango.AttrForeground(65535, 0, 0, 0, 6)
    underline = pango.AttrUnderline(pango.UNDERLINE_DOUBLE, 7, 11)
    bg_color = pango.AttrBackground(40000, 40000, 40000, 12, 19)
    strike = pango.AttrStrikethrough(True, 20, 29)
    size = pango.AttrSize(30000, 0, -1)

    attr.insert(fg_color)
    attr.insert(underline)
    attr.insert(bg_color)
    attr.insert(size)
    attr.insert(strike)

    label.set_attributes(attr)

    fix = gtk.Fixed()

    fix.put(label, 5, 5)
    
    self.add(fix)
    self.set_position(gtk.WIN_POS_CENTER)
    self.show_all()

PyApp()
gtk.main()

In the code example we show four different attributes applied on the text.

attr = pango.AttrList()

Pango attribute list is an object for holding attributes.

fg_color = pango.AttrForeground(65535, 0, 0, 0, 6)

Here we create an attribute that will render text in red color. The first three parameters are the R, G, B values of a color. The last two parameters are the start and end indexes of the text, to which we apply this attribute.

label.set_attributes(attr)

We set the list of attributes for the label.

Figure: Pango attributes

In this chapter of the PyGTK programming library, we worked with pango library.