import sys
import cairo
import gi
gi.require_version("Gtk", "3.0")
from gi.repository import Gtk
def draw_event(widget, ctx, surface):
ctx.set_source_surface(surface, 0, 0)
ctx.paint()
if len(sys.argv) != 2:
raise SystemExit('usage: png_view.py png_file')
filename = sys.argv[1]
surface = cairo.ImageSurface.create_from_png(filename)
width = surface.get_width()
height = surface.get_height()
win = Gtk.Window()
win.connect('destroy', Gtk.main_quit)
drawingarea = Gtk.DrawingArea()
win.add(drawingarea)
drawingarea.connect('draw', draw_event, surface)
drawingarea.set_size_request(width, height)
win.show_all()
Gtk.main()