import sys
import cairo, gi

USE_GTK2 = True

if USE_GTK2:
    gi.require_version('Gtk', '2.0')
    gi.require_version('Gdk', '2.0')
    gi.require_version('WebKit', '1.0')
from gi.repository import Gtk, Gdk, WebKit

DEFAULT_SIZE = 800, 480

if len(sys.argv) != 3:
    print 'usage: %s url filename'%sys.argv[0]
    sys.exit(-1)

uri, filename = sys.argv[1:]

for scheme in ('http://', 'https://', 'ftp://', 'file://'):
    if uri.startswith(scheme):
        break
else:
    uri = 'http://' + uri

window = Gtk.OffscreenWindow()
view = WebKit.WebView()
settings = view.get_settings()
settings.props.auto_resize_window = True
settings.props.enable_plugins = False
view.set_settings(settings)
window.add(view)

def capture_window(window):
    w, h = window.get_size()
    if w < 50 or h < 50:
        # window is too small.
        # resize window and reload
        window.set_default_size(*DEFAULT_SIZE)
        view.reload()
        return

    dst = cairo.ImageSurface(cairo.FORMAT_ARGB32, w, h)
    ctx = cairo.Context(dst)
    surface = Gdk.cairo_create(window.get_window()).get_target()
    ctx.set_source_surface(surface)
    ctx.paint()
    dst.write_to_png(filename)
    Gtk.main_quit()

def load_cb(webview, pspec, window):
    if webview.get_load_status() == WebKit.LoadStatus.FINISHED:
        capture_window(window)

view.connect('notify::load-status', load_cb, window)
view.load_uri(uri)
window.show_all()

Gtk.main()