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#!/usr/bin/env python
"""Text Widget/Automatic scrolling
This example demonstrates how to use the gravity of
GtkTextMarks to keep a text view scrolled to the bottom
while appending text."""
import gobject
import gtk
class AutomaticScrollingDemo(gtk.Window):
def __init__(self, parent=None):
# Create the toplevel window
gtk.Window.__init__(self)
try:
self.set_screen(parent.get_screen())
except AttributeError:
self.connect('destroy', lambda *w: gtk.main_quit())
self.set_title(self.__class__.__name__)
self.set_default_size(600, 400)
self.set_border_width(0)
hbox = gtk.HBox(True, 6)
self.add(hbox)
self.create_text_view(hbox, True)
self.create_text_view(hbox, False)
self.count_sb = 0
self.count_se = 0
self.show_all()
def create_text_view(self, hbox, scroll_to_end):
swindow = gtk.ScrolledWindow()
hbox.pack_start(swindow)
textview = gtk.TextView()
swindow.add(textview)
timeout = self.setup_scroll(textview, scroll_to_end)
# Remove the timeout in destroy handler, so we don't try to
# scroll destroyed widget.
textview.connect("destroy", lambda widget: gobject.source_remove(timeout))
def setup_scroll(self, textview, scroll_to_end):
buf = textview.get_buffer()
itr = buf.get_end_iter()
if scroll_to_end:
# If we want to scroll to the end, including horizontal scrolling,
# then we just create a mark with right gravity at the end of the
# buffer. It will stay at the end unless explicitely moved with
# gtk_text_buffer_move_mark.
buf.create_mark("end", itr, False)
# Add scrolling timeout.
return gobject.timeout_add(50, self.scroll_to_end, textview)
else:
# If we want to scroll to the bottom, but not scroll horizontally,
# then an end mark won't do the job. Just create a mark so we can
# use it with gtk_text_view_scroll_mark_onscreen, we'll position it
# explicitely when needed. Use left gravity so the mark stays where
# we put it after inserting new text.
buf.create_mark("scroll", itr, True)
# Add scrolling timeout.
return gobject.timeout_add(100, self.scroll_to_bottom, textview)
""" Scroll to the end of the buffer. """
def scroll_to_end(self, textview):
buf = textview.get_buffer()
# Get the "end" mark. It's located at the end of buffer because
# of right gravity
mark = buf.get_mark("end")
itr = buf.get_iter_at_mark(mark)
# and insert some text at its position, the iter will be
# revalidated after insertion to point to the end of inserted text
buf.insert(itr, "\n")
buf.insert(itr, " " * self.count_se)
buf.insert(itr, "Scroll to end scroll to end scroll to end scroll to end ")
# Now scroll the end mark onscreen.
textview.scroll_mark_onscreen(mark)
# Emulate typewriter behavior, shift to the left if we
# are far enough to the right.
self.count_se += 1
if self.count_se > 150:
self.count_se = 0
return True
""" Scroll to the bottom of the buffer. """
def scroll_to_bottom(self, textview):
buf = textview.get_buffer()
# Get the end iterator
itr = buf.get_end_iter()
# and insert some text at it, the iter will be revalidated
# after insertion to point to the end of inserted text
buf.insert(itr, "\n")
buf.insert(itr, " " * self.count_sb)
buf.insert(itr, "Scroll to bottom scroll to bottom scroll to bottom scroll to bottom")
# Move the iterator to the beginning of line, so we don't scroll
# in horizontal direction
itr.set_line_offset(0)
# and place the mark at iter. the mark will stay there after we
# insert some text at the end because it has right gravity.
mark = buf.get_mark("scroll")
buf.move_mark(mark, itr)
# Scroll the mark onscreen.
textview.scroll_mark_onscreen(mark)
# Shift text back if we got enough to the right.
self.count_sb += 1
if self.count_sb > 40:
self.count_sb = 0
return True
def main():
AutomaticScrollingDemo()
gtk.main()
if __name__ == '__main__':
main()
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