Using python, GTK+3, Vte libs. How to change the font size of a terminal?

Question

I made a program which shows four terminals in one window, but the font size is way too big. Here is my code:

#!/usr/bin/python shells.py

from gi.repository import Gtk, Vte, Gdk
from gi.repository import GLib
import os

class MainWindow(Gtk.Window):

    def __init__(self):
        Gtk.Window.__init__(self, title="shells")
        self.resize(1000, 1000)

        table = Gtk.Table(2, 2, True)
        self.add(table)

        palette = [Gdk.color_parse('red')] * 16
        terminal1 = Vte.Terminal()
        terminal2 = Vte.Terminal()
        terminal3 = Vte.Terminal()
        terminal4 = Vte.Terminal()

        scrolledwindow1 = Gtk.ScrolledWindow()
        scrolledwindow1.add(terminal1)

        scrolledwindow2 = Gtk.ScrolledWindow()
        scrolledwindow2.add(terminal2)

        scrolledwindow3 = Gtk.ScrolledWindow()
        scrolledwindow3.add(terminal3)

        scrolledwindow4 = Gtk.ScrolledWindow()
        scrolledwindow4.add(terminal4)

        terminal1.fork_command_full(Vte.PtyFlags.DEFAULT, os.environ['HOME'], ["/bin  /sh"], 
                                   [], GLib.SpawnFlags.DO_NOT_REAP_CHILD, None, None)
        terminal2.fork_command_full(Vte.PtyFlags.DEFAULT, os.environ['HOME'], ["/bin/sh"],
                                   [], GLib.SpawnFlags.DO_NOT_REAP_CHILD, None, None)
        terminal3.fork_command_full(Vte.PtyFlags.DEFAULT, os.environ['HOME'], ["/bin/sh"],
                                   [], GLib.SpawnFlags.DO_NOT_REAP_CHILD, None, None)
        terminal4.fork_command_full(Vte.PtyFlags.DEFAULT, os.environ['HOME'], ["/bin/sh"],
                                   [], GLib.SpawnFlags.DO_NOT_REAP_CHILD, None, None)

        terminal1.set_colors(Gdk.color_parse('red'), Gdk.color_parse('black'), palette)
        terminal2.set_colors(Gdk.color_parse('green'), Gdk.color_parse('black'), palette)
        terminal3.set_colors(Gdk.color_parse('yellow'), Gdk.color_parse('black'), palette)
        terminal4.set_colors(Gdk.color_parse('blue'), Gdk.color_parse('black'), palette)

        table.attach(scrolledwindow1, 0, 1, 0, 1)
        table.attach(scrolledwindow2, 1, 2, 0, 1)
        table.attach(scrolledwindow3, 0, 1, 1, 2)
        table.attach(scrolledwindow4, 1, 2, 1, 2)

win = MainWindow()
win.connect("delete-event", Gtk.main_quit)
win.show_all()
Gtk.main()

According to the documentation Vte set_font I used:

import pango
font = pango.FontDescription()
terminal1.set_font(font)

And I get the following error:

AttributeError: type object 'Context' has no attribute '__info__'

The example is from a stack overflow question: how to enable transparency in vte.Terminal

Then I used, according to this Vte 'decrease-font-size' signal :

terminal1.connect('decrease-font-size', function, data)
def function():
    print "press crtl -to decrease font-size"

Nothing happens with this one. And the rest also don't work. I also noticed that I can't really change the size of one terminal using:

terminal1.set_size(30, 29)

Seems to change nothing.

For these examples I used for the sake of simplicity only terminal1. Also one weird thing is that, when I do the "clear" command, it seems to rearrange itself and the font size becomes bigger. I apologize for weird English. It's not my native language, but I'll try my best. When it comes to programming, I have only experience with python and associated libraries or modules. I'm using a Linux Debian version as OS.

Greets

Answer 1

Connect to the realize signal of the Vte.Terminal as only then the Pango.FontDescription() is created, then get_font() on the terminal and set_size() on the Pango.FontDescription() returned by that:

#!/usr/bin/env python3


import os

from gi.repository import GLib
from gi.repository import Pango
from gi.repository import Gdk
from gi.repository import Gtk
from gi.repository import Vte


class MainWindow(Gtk.Window):
    def __init__(self):
        Gtk.Window.__init__(self, title="shells")
        self.resize(1000, 1000)

        table = Gtk.Table(2, 2, True)
        self.add(table)

        palette = [Gdk.color_parse('red')] * 16
        terminal1 = Vte.Terminal()
        terminal1.connect('realize', self.on_realize_terminal)
        terminal2 = Vte.Terminal()
        terminal2.connect('realize', self.on_realize_terminal)
        terminal3 = Vte.Terminal()
        terminal3.connect('realize', self.on_realize_terminal)
        terminal4 = Vte.Terminal()
        terminal4.connect('realize', self.on_realize_terminal)

        scrolledwindow1 = Gtk.ScrolledWindow()
        scrolledwindow1.add(terminal1)

        scrolledwindow2 = Gtk.ScrolledWindow()
        scrolledwindow2.add(terminal2)

        scrolledwindow3 = Gtk.ScrolledWindow()
        scrolledwindow3.add(terminal3)

        scrolledwindow4 = Gtk.ScrolledWindow()
        scrolledwindow4.add(terminal4)

        terminal1.fork_command_full(Vte.PtyFlags.DEFAULT, os.environ['HOME'], ["/bin/sh"], 
                                   [], GLib.SpawnFlags.DO_NOT_REAP_CHILD, None, None)
        terminal2.fork_command_full(Vte.PtyFlags.DEFAULT, os.environ['HOME'], ["/bin/sh"],
                                   [], GLib.SpawnFlags.DO_NOT_REAP_CHILD, None, None)
        terminal3.fork_command_full(Vte.PtyFlags.DEFAULT, os.environ['HOME'], ["/bin/sh"],
                                   [], GLib.SpawnFlags.DO_NOT_REAP_CHILD, None, None)
        terminal4.fork_command_full(Vte.PtyFlags.DEFAULT, os.environ['HOME'], ["/bin/sh"],
                                   [], GLib.SpawnFlags.DO_NOT_REAP_CHILD, None, None)

        terminal1.set_colors(Gdk.color_parse('red'), Gdk.color_parse('black'), palette)
        terminal2.set_colors(Gdk.color_parse('green'), Gdk.color_parse('black'), palette)
        terminal3.set_colors(Gdk.color_parse('yellow'), Gdk.color_parse('black'), palette)
        terminal4.set_colors(Gdk.color_parse('blue'), Gdk.color_parse('black'), palette)

        table.attach(scrolledwindow1, 0, 1, 0, 1)
        table.attach(scrolledwindow2, 1, 2, 0, 1)
        table.attach(scrolledwindow3, 0, 1, 1, 2)
        table.attach(scrolledwindow4, 1, 2, 1, 2)

    def on_realize_terminal(self, terminal):
        font = terminal.get_font()
        font.set_size(16 * Pango.SCALE)


if __name__ == '__main__':
    win = MainWindow()
    win.connect("delete-event", Gtk.main_quit)
    win.show_all()
    Gtk.main()