[pygtk] checking the clipboard for changes

[Khiraly]

Hi!

Im writing an application, where I need to display the changes of the
clipboard.
So if the text of the clipboard are changed, the application need to
display it.

I didnt find any gtk function to provide me this automatically(so the
Gtk itself trigger an events, when the clipboard changes), am I right?

Or do I need the check the clipboard periodically? (for example every
100 ms, and if it is changed, launch the appropriate function)

What is the best approach the handle this problem (new timer thread
which check the clipboard periodically?)?

Any pointer for the right docs is really appreciated!


Best regards, 
 Khiraly

ps:
For the curious, here is the program which display the clipboard on
anotification area (but only once, bottom-right corner):
#! /usr/bin/python

import pygtk
pygtk.require("2.0")
import gtk,gobject
import egg.trayicon

class TrayDemonstration:
  def close_balloon(self,a,b):
    print "closing balloon..."
    self.balloon.destroy();
    return True
  def set_label(self,text):
    #text = text + "hmm"
    self.label.set_text(text)
    size = self.label.size_request()
    self.rect.x =  size[0]
    self.rect.y = size[1]
    self.balloon.resize(self.rect.x,self.rect.y)
    self.balloon.move(self.width-self.rect.x,self.height-self.rect.y)
    return
  def clipboard_text_received(self, clipboard, text, data):
    self.set_label(text)
    return
  def __init__(self):
    window = gtk.Window(gtk.WINDOW_POPUP);
    self.balloon = window;
    self.label = gtk.Label("Balloon!! \n another row!\n es meg egy");
    eventbox = gtk.EventBox()
    eventbox.set_events (gtk.gdk.BUTTON_PRESS_MASK)
    eventbox.connect("button-press-event",self.close_balloon)
    # close balloon is for closing the balloon,
    # the status icon is kept in self.trayicon
    # so it could be used in the whole class

    eventbox.add(self.label)
    window.add(eventbox);

    ty = egg.trayicon.TrayIcon("TrayIconDemo")

    eventbox2 = gtk.EventBox()
    pixbuf = gtk.gdk.pixbuf_new_from_file
("/usr/share/icons/gnome/scalable/emblems/emblem-favorite.svg")

    image = gtk.Image()
    image.set_from_pixbuf(pixbuf)
    eventbox2.add(image)
    ty.add(eventbox2)
    ty.show_all()
    #window.resize(200,200)
    size = self.label.size_request()
    self.rect = rect_class(size[0],size[1]);
    window.resize(self.rect.x,self.rect.y)
    print "x: %s, y: %s" % (self.rect.x,self.rect.y)
    self.height = gtk.gdk.screen_height()
    self.width  = gtk.gdk.screen_width()
    window.move(self.width-self.rect.x,self.height-self.rect.y)

    gobject.timeout_add(6000, window.destroy) # simple timeout
    # to close the balloon after 6 secs
    self.clipboard = gtk.clipboard_get(gtk.gdk.SELECTION_PRIMARY)
    self.clipboard.request_text(self.clipboard_text_received)
    szoveg ="alma"
    gobject.timeout_add(3000, self.set_label, szoveg)
    window.show_all();

class rect_class:
  def __init__(self,x,y):
    self.x = x
    self.y = y
def main():
  gtk.main()
  return 0

if __name__ == '__main__':
  program = TrayDemonstration()
  main()