Doc/library/turtle.rst

==================================
:mod:`!turtle` --- Turtle graphics
==================================

.. module:: turtle
   :synopsis: An educational framework for simple graphics applications

**Source code:** :source:`Lib/turtle.py`

.. testsetup:: default
   :skipif: _tkinter is None

   from turtle import *
   turtle = Turtle()

.. testcleanup::
   :skipif: _tkinter is None

   import os
   os.remove("my_drawing.ps")
   # Destroy the turtle window after tests are complete
   # Imported via star import in testsetup
   bye()

--------------

.. sidebar:: Turtle star

   Turtle can draw intricate shapes using programs that repeat simple
   moves.

   .. image:: turtle-star.png
      :alt: A yellow starburst of thin spikes with a red outline, drawn by turtle.
      :align: center

Imagine a robotic turtle starting at (0, 0) in the x-y plane.
After an ``import turtle``, give it the command ``turtle.forward(15)``, and it
moves (on-screen!) 15 pixels in the direction it is facing, drawing a line as
it moves. Give it the command ``turtle.right(25)``, and it rotates in-place 25
degrees clockwise.

Turtle graphics is an implementation of `the drawing tools introduced in Logo
<https://en.wikipedia.org/wiki/Turtle_(robot)>`__ in 1967. It was created as an
educational tool, and its instant, visible feedback makes it an effective way
for learners to encounter programming concepts. It is also a convenient way to
produce simple graphical output without bringing in external libraries.

This document includes four main sections:

* :ref:`turtle-tutorial` teaches the basics of turtle drawing.
* :ref:`turtle-reference` describes the functions, methods and classes this
  module defines.
* :ref:`turtle-howtos` detail how to handle specific tasks.
* :ref:`turtle-explanation` provides background on the object-oriented
  interface.

.. note::

   Turtle graphics requires the :mod:`tkinter` :term:`optional module`.
   The python.org installers for Windows and macOS include it, but some
   Linux distributions and other platforms may package it separately. If
   ``import turtle`` fails with an error mentioning ``_tkinter``, look for
   documentation from your distributor (that is, whoever provided Python to you).
   Check this in advance if you're planning to use turtle graphics with a learner.


.. _turtle-tutorial:
.. _get-started:
.. _get-started-as-quickly-as-possible:

Tutorial
========

New users should start here. In this tutorial we'll explore some of the
basics of turtle drawing.


Starting a turtle environment
-----------------------------

In a Python shell, import all the objects of the ``turtle`` module::

    from turtle import *

If you run into a ``Standard library module '_tkinter' was not found`` error,
you'll have to install the :mod:`Tk interface package <tkinter>` on your system.

Nothing appears yet. To open the turtle window, make the turtle visible::

    showturtle()

A new window opens, with the turtle in the middle, shown as an arrow
heading East.


Basic drawing
-------------

Send the turtle forward 100 steps::

   forward(100)

You should see a line drawn by the turtle, heading East. Change the
direction of the turtle, so that it turns 120 degrees left
(anti-clockwise)::

   left(120)

Let's continue by drawing a triangle::

   forward(100)
   left(120)
   forward(100)

Notice how the turtle, represented by an arrow, points in different
directions as you steer it.

Experiment with those commands, and also with ``backward()`` and
``right()``. Many commands also have shorter aliases, such as ``fd()`` for
:func:`forward`.


Pen control
^^^^^^^^^^^

Try changing the color - for example, ``color('blue')`` - and
width of the line - for example, ``width(3)`` - and then drawing again.

You can also move the turtle around without drawing, by lifting up the pen:
``up()`` before moving. To start drawing again, use ``down()``.


The turtle's position
^^^^^^^^^^^^^^^^^^^^^

Send your turtle back to its starting-point (useful if it has disappeared
off-screen)::

   home()

The home position is at the center of the turtle's screen. If you ever need to
know them, get the turtle's x-y coordinates with::

    pos()

Home is at ``(0, 0)``.

And after a while, it will probably help to clear the window so we can start
anew::

   clearscreen()


Making algorithmic patterns
---------------------------

Using loops, it's possible to build up geometric patterns::

    for steps in range(100):
        for c in ('blue', 'red', 'green'):
            color(c)
            forward(steps)
            right(30)


\ - which of course, are limited only by the imagination!

Let's draw the star shape at the top of this page. We want red lines,
filled in with yellow::

    color('red')
    fillcolor('yellow')

Just as ``up()`` and ``down()`` determine whether lines will be drawn,
filling can be turned on and off::

    begin_fill()

Next we'll create a loop::

    start = pos()

    while True:
        forward(200)
        left(170)
        if distance(start) < 1:
            break

``distance(start) < 1`` is a good way to know when the turtle is back at its
start position.

Finally, complete the filling::

    end_fill()

(Note that filling only actually takes place when you give the
``end_fill()`` command.)


.. _turtle-reference:
.. _turtle-graphics-reference:

Reference
=========

.. _turtle-methods:
.. _methods-of-rawturtle-turtle-and-corresponding-functions:

Turtle methods and functions
----------------------------

Most of the examples in this section refer to a Turtle instance called
``turtle``.

.. _turtle-motion:

Move and draw
^^^^^^^^^^^^^

.. function:: forward(distance)
              fd(distance)

   :param distance: a number

   Move the turtle forward by the specified *distance*, in the direction the
   turtle is headed.

   .. doctest::
      :skipif: _tkinter is None

      >>> turtle.position()
      (0.00,0.00)
      >>> turtle.forward(25)
      >>> turtle.position()
      (25.00,0.00)
      >>> turtle.forward(-75)
      >>> turtle.position()
      (-50.00,0.00)


.. function:: back(distance)
              bk(distance)
              backward(distance)

   :param distance: a number

   Move the turtle backward by *distance*, opposite to the direction the
   turtle is headed. The turtle's heading does not change.

   .. doctest::
      :skipif: _tkinter is None
      :hide:

      >>> turtle.goto(0, 0)

   .. doctest::
      :skipif: _tkinter is None

      >>> turtle.position()
      (0.00,0.00)
      >>> turtle.backward(30)
      >>> turtle.position()
      (-30.00,0.00)


.. function:: right(angle)
              rt(angle)

   :param angle: a number

   Turn the turtle right by the specified *angle*. The angle is measured in
   degrees by default; the unit can be changed with :func:`degrees` or
   :func:`radians`. How the heading is measured depends on the turtle mode,
   see :func:`mode`.

   .. doctest::
      :skipif: _tkinter is None
      :hide:

      >>> turtle.setheading(22)

   .. doctest::
      :skipif: _tkinter is None

      >>> turtle.heading()
      22.0
      >>> turtle.right(45)
      >>> turtle.heading()
      337.0


.. function:: left(angle)
              lt(angle)

   :param angle: a number

   Turn the turtle left by the specified *angle*. The angle is measured in
   degrees by default; the unit can be changed with :func:`degrees` or
   :func:`radians`. How the heading is measured depends on the turtle mode,
   see :func:`mode`.

   .. doctest::
      :skipif: _tkinter is None
      :hide:

      >>> turtle.setheading(22)

   .. doctest::
      :skipif: _tkinter is None

      >>> turtle.heading()
      22.0
      >>> turtle.left(45)
      >>> turtle.heading()
      67.0


.. function:: goto(x, y=None)
              setpos(x, y=None)
              setposition(x, y=None)

   :param x: a number or a pair/vector of numbers
   :param y: a number or ``None``

   Move the turtle to an absolute position. If *y* is ``None``, *x* must be a
   pair of coordinates or a :class:`Vec2D`, for example as returned by
   :func:`pos`. If the pen is down, a line is drawn. The turtle's heading does
   not change.

   .. doctest::
      :skipif: _tkinter is None
      :hide:

      >>> turtle.goto(0, 0)

   .. doctest::
      :skipif: _tkinter is None

      >>> tp = turtle.pos()
      >>> tp
      (0.00,0.00)
      >>> turtle.goto(60,30)
      >>> turtle.pos()
      (60.00,30.00)
      >>> turtle.goto((20,80))
      >>> turtle.pos()
      (20.00,80.00)
      >>> turtle.goto(tp)
      >>> turtle.pos()
      (0.00,0.00)


.. function:: teleport(x, y=None, *, fill_gap=False)

   :param x: a number or ``None``
   :param y: a number or ``None``
   :param fill_gap: a boolean

   Move turtle to an absolute position. Unlike goto(x, y), a line will not
   be drawn. The turtle's orientation does not change. If currently
   filling, the polygon(s) teleported from will be filled after leaving,
   and filling will begin again after teleporting. This can be disabled
   with fill_gap=True, which makes the imaginary line traveled during
   teleporting act as a fill barrier like in goto(x, y).

   .. doctest::
      :skipif: _tkinter is None
      :hide:

      >>> turtle.goto(0, 0)

   .. doctest::
      :skipif: _tkinter is None

      >>> tp = turtle.pos()
      >>> tp
      (0.00,0.00)
      >>> turtle.teleport(60)
      >>> turtle.pos()
      (60.00,0.00)
      >>> turtle.teleport(y=10)
      >>> turtle.pos()
      (60.00,10.00)
      >>> turtle.teleport(20, 30)
      >>> turtle.pos()
      (20.00,30.00)

   .. versionadded:: 3.12


.. function:: setx(x)

   :param x: a number

   Set the turtle's x coordinate to *x*. The y coordinate is unchanged.

   .. doctest::
      :skipif: _tkinter is None
      :hide:

      >>> turtle.goto(0, 240)

   .. doctest::
      :skipif: _tkinter is None

      >>> turtle.position()
      (0.00,240.00)
      >>> turtle.setx(10)
      >>> turtle.position()
      (10.00,240.00)


.. function:: sety(y)

   :param y: a number

   Set the turtle's y coordinate to *y*. The x coordinate is unchanged.

   .. doctest::
      :skipif: _tkinter is None
      :hide:

      >>> turtle.goto(0, 40)

   .. doctest::
      :skipif: _tkinter is None

      >>> turtle.position()
      (0.00,40.00)
      >>> turtle.sety(-10)
      >>> turtle.position()
      (0.00,-10.00)


.. function:: setheading(to_angle)
              seth(to_angle)

   :param to_angle: a number

   Set the turtle's heading to *to_angle*. Here are some common directions in
   degrees:

   =================== ====================
    standard mode           logo mode
   =================== ====================
      0 - east                0 - north
     90 - north              90 - east
    180 - west              180 - south
    270 - south             270 - west
   =================== ====================

   .. doctest::
      :skipif: _tkinter is None

      >>> turtle.setheading(90)
      >>> turtle.heading()
      90.0


.. function:: home()

   Move the turtle to the origin, coordinates (0,0). The turtle's heading is
   set to its start orientation, which depends on the turtle mode, see
   :func:`mode`.

   .. doctest::
      :skipif: _tkinter is None
      :hide:

      >>> turtle.setheading(90)
      >>> turtle.goto(0, -10)

   .. doctest::
      :skipif: _tkinter is None

      >>> turtle.heading()
      90.0
      >>> turtle.position()
      (0.00,-10.00)
      >>> turtle.home()
      >>> turtle.position()
      (0.00,0.00)
      >>> turtle.heading()
      0.0


.. function:: circle(radius, extent=None, steps=None)

   :param radius: a number
   :param extent: a number or ``None``
   :param steps: an integer or ``None``

   Draw a circle with the given *radius*. The center is *radius* units left
   of the turtle; *extent*, an angle, determines which part of the circle is
   drawn. If *extent* is not given, draw the entire circle. If *extent* is
   not a full circle, one endpoint of the arc is the current pen position.
   Draw the arc in counterclockwise direction if *radius* is positive,
   otherwise in clockwise direction. Finally, the turtle's heading is changed
   by *extent*.

   As the circle is approximated by an inscribed regular polygon, *steps*
   determines the number of steps to use. If not given, it will be calculated
   automatically. May be used to draw regular polygons.

   .. doctest::
      :skipif: _tkinter is None

      >>> turtle.home()
      >>> turtle.position()
      (0.00,0.00)
      >>> turtle.heading()
      0.0
      >>> turtle.circle(50)
      >>> turtle.position()
      (-0.00,0.00)
      >>> turtle.heading()
      0.0
      >>> turtle.circle(120, 180)  # draw a semicircle
      >>> turtle.position()
      (0.00,240.00)
      >>> turtle.heading()
      180.0


.. function:: dot()
              dot(size)
              dot(color, /)
              dot(size, color, /)
              dot(size, r, g, b, /)

   :param size: an integer >= 1 (if given)
   :param color: a colorstring or a numeric color tuple

   Draw a circular dot with diameter *size*, using *color*.  If *size* is
   not given, the maximum of ``pensize+4`` and ``2*pensize`` is used.


   .. doctest::
      :skipif: _tkinter is None

      >>> turtle.home()
      >>> turtle.dot()
      >>> turtle.fd(50); turtle.dot(20, "blue"); turtle.fd(50)
      >>> turtle.position()
      (100.00,-0.00)
      >>> turtle.heading()
      0.0


.. function:: stamp()

   Stamp a copy of the turtle shape onto the canvas at the current turtle
   position.  Return a stamp_id for that stamp, which can be used to delete
   it by calling ``clearstamp(stamp_id)``.

   .. doctest::
      :skipif: _tkinter is None

      >>> turtle.color("blue")
      >>> stamp_id = turtle.stamp()
      >>> turtle.fd(50)


.. function:: clearstamp(stampid)

   :param stampid: an integer, must be return value of previous
                   :func:`stamp` call

   Delete stamp with given *stampid*.

   .. doctest::
      :skipif: _tkinter is None

      >>> turtle.position()
      (150.00,-0.00)
      >>> turtle.color("blue")
      >>> astamp = turtle.stamp()
      >>> turtle.fd(50)
      >>> turtle.position()
      (200.00,-0.00)
      >>> turtle.clearstamp(astamp)
      >>> turtle.position()
      (200.00,-0.00)


.. function:: clearstamps(n=None)

   :param n: an integer (or ``None``)

   Delete all or first/last *n* of turtle's stamps.  If *n* is ``None``, delete
   all stamps, if *n* > 0 delete first *n* stamps, else if *n* < 0 delete
   last *n* stamps.

   .. doctest::
      :skipif: _tkinter is None

      >>> for i in range(8):
      ...     unused_stamp_id = turtle.stamp()
      ...     turtle.fd(30)
      >>> turtle.clearstamps(2)
      >>> turtle.clearstamps(-2)
      >>> turtle.clearstamps()


.. function:: undo()

   Undo (repeatedly) the last turtle action(s).  Number of available
   undo actions is determined by the size of the undobuffer.

   .. doctest::
      :skipif: _tkinter is None

      >>> for i in range(4):
      ...     turtle.fd(50); turtle.lt(80)
      ...
      >>> for i in range(8):
      ...     turtle.undo()


.. function:: speed(speed=None)

   :param speed: an integer in the range 0..10 or a speedstring (see below)

   Set the turtle's speed to an integer value in the range 0..10.  If no
   argument is given, return current speed.

   If input is a number greater than 10 or smaller than 0.5, speed is set
   to 0.  Speedstrings are mapped to speedvalues as follows:

   * "fastest":  0
   * "fast":  10
   * "normal":  6
   * "slow":  3
   * "slowest":  1

   Speeds from 1 to 10 enforce increasingly faster animation of line drawing
   and turtle turning.

   Attention: *speed* = 0 means that *no* animation takes
   place. forward/back makes turtle jump and likewise left/right make the
   turtle turn instantly.

   .. doctest::
      :skipif: _tkinter is None

      >>> turtle.speed()
      3
      >>> turtle.speed('normal')
      >>> turtle.speed()
      6
      >>> turtle.speed(9)
      >>> turtle.speed()
      9


Tell Turtle's state
^^^^^^^^^^^^^^^^^^^

.. function:: position()
              pos()

   Return the turtle's current location (x,y) as a :class:`Vec2D` vector.

   .. doctest::
      :skipif: _tkinter is None

      >>> turtle.pos()
      (440.00,-0.00)


.. function:: towards(x, y=None)

   :param x: a number or a pair/vector of numbers or a turtle instance
   :param y: a number if *x* is a number, else ``None``

   Return the angle of the line from the turtle's position to (x,y). If *y* is
   ``None``, *x* must be a pair of coordinates, a :class:`Vec2D`, for example
   as returned by :func:`pos`, or another turtle. The angle is measured from
   the turtle's start orientation, which depends on the turtle mode, see
   :func:`mode`.

   .. doctest::
      :skipif: _tkinter is None

      >>> turtle.goto(10, 10)
      >>> turtle.towards(0,0)
      225.0


.. function:: xcor()

   Return the turtle's x coordinate.

   .. doctest::
      :skipif: _tkinter is None

      >>> turtle.home()
      >>> turtle.left(50)
      >>> turtle.forward(100)
      >>> turtle.pos()
      (64.28,76.60)
      >>> print(round(turtle.xcor(), 5))
      64.27876


.. function:: ycor()

   Return the turtle's y coordinate.

   .. doctest::
      :skipif: _tkinter is None

      >>> turtle.home()
      >>> turtle.left(60)
      >>> turtle.forward(100)
      >>> print(turtle.pos())
      (50.00,86.60)
      >>> print(round(turtle.ycor(), 5))
      86.60254


.. function:: heading()

   Return the turtle's current heading. The value depends on the turtle mode,
   see :func:`mode`.

   .. doctest::
      :skipif: _tkinter is None

      >>> turtle.home()
      >>> turtle.left(67)
      >>> turtle.heading()
      67.0


.. function:: distance(x, y=None)

   :param x: a number or a pair/vector of numbers or a turtle instance
   :param y: a number if *x* is a number, else ``None``

   Return the distance from the turtle to (x,y) in turtle step units. If *y* is
   ``None``, *x* must be a pair of coordinates, a :class:`Vec2D`, for example
   as returned by :func:`pos`, or another turtle.

   .. doctest::
      :skipif: _tkinter is None

      >>> turtle.home()
      >>> turtle.distance(30,40)
      50.0
      >>> turtle.distance((30,40))
      50.0
      >>> joe = Turtle()
      >>> joe.forward(77)
      >>> turtle.distance(joe)
      77.0


Settings for measurement
^^^^^^^^^^^^^^^^^^^^^^^^

.. function:: degrees(fullcircle=360.0)

   :param fullcircle: a number

   Set the angle measurement units to degrees. The number of degrees in a full
   circle is set to *fullcircle*, which defaults to 360.

   .. doctest::
      :skipif: _tkinter is None

      >>> turtle.home()
      >>> turtle.left(90)
      >>> turtle.heading()
      90.0

      >>> # Change angle measurement unit to grad (also known as gon,
      >>> # grade, or gradian and equals 1/100-th of the right angle.)
      >>> turtle.degrees(400.0)
      >>> turtle.heading()
      100.0
      >>> turtle.degrees(360)
      >>> turtle.heading()
      90.0


.. function:: radians()

   Set the angle measurement units to radians.  Equivalent to
   ``degrees(2 * math.pi)``.

   .. doctest::
      :skipif: _tkinter is None

      >>> turtle.home()
      >>> turtle.left(90)
      >>> turtle.heading()
      90.0
      >>> turtle.radians()
      >>> turtle.heading()
      1.5707963267948966

   .. doctest::
      :skipif: _tkinter is None
      :hide:

      >>> turtle.degrees(360)


Pen control
^^^^^^^^^^^

Drawing state
~~~~~~~~~~~~~

.. function:: pendown()
              pd()
              down()

   Pull the pen down -- drawing when moving.


.. function:: penup()
              pu()
              up()

   Pull the pen up -- no drawing when moving.


.. function:: pensize(width=None)
              width(width=None)

   :param width: a positive number

   Set the line thickness to *width* or return it.  If resizemode is set to
   "auto" and turtleshape is a polygon, that polygon is drawn with the same line
   thickness.  If no argument is given, the current pensize is returned.

   .. doctest::
      :skipif: _tkinter is None

      >>> turtle.pensize()
      1
      >>> turtle.pensize(10)   # from here on lines of width 10 are drawn


.. function:: pen(pen=None, **pendict)

   :param pen: a dictionary with some or all of the below listed keys
   :param pendict: one or more keyword-arguments with the below listed keys as keywords

   Return or set the pen's attributes in a "pen-dictionary" with the following
   key/value pairs:

   * "shown": True/False
   * "pendown": True/False
   * "pencolor": color-string or color-tuple
   * "fillcolor": color-string or color-tuple
   * "pensize": positive number
   * "speed": number in range 0..10
   * "resizemode": "auto" or "user" or "noresize"
   * "stretchfactor": (positive number, positive number)
   * "outline": positive number
   * "tilt": number

   This dictionary can be used as argument for a subsequent call to :func:`pen`
   to restore the former pen-state.  Moreover one or more of these attributes
   can be provided as keyword-arguments.  This can be used to set several pen
   attributes in one statement.

   .. doctest::
      :skipif: _tkinter is None
      :options: +NORMALIZE_WHITESPACE

      >>> turtle.pen(fillcolor="black", pencolor="red", pensize=10)
      >>> sorted(turtle.pen().items())
      [('fillcolor', 'black'), ('outline', 1), ('pencolor', 'red'),
       ('pendown', True), ('pensize', 10), ('resizemode', 'noresize'),
       ('shearfactor', 0.0), ('shown', True), ('speed', 9),
       ('stretchfactor', (1.0, 1.0)), ('tilt', 0.0)]
      >>> penstate=turtle.pen()
      >>> turtle.color("yellow", "")
      >>> turtle.penup()
      >>> sorted(turtle.pen().items())[:3]
      [('fillcolor', ''), ('outline', 1), ('pencolor', 'yellow')]
      >>> turtle.pen(penstate, fillcolor="green")
      >>> sorted(turtle.pen().items())[:3]
      [('fillcolor', 'green'), ('outline', 1), ('pencolor', 'red')]

.. function:: isdown()

   Return ``True`` if pen is down, ``False`` if it's up.

   .. doctest::
      :skipif: _tkinter is None

      >>> turtle.penup()
      >>> turtle.isdown()
      False
      >>> turtle.pendown()
      >>> turtle.isdown()
      True


Color control
~~~~~~~~~~~~~

.. function:: pencolor()
              pencolor(color, /)
              pencolor(r, g, b, /)

   Return or set the pencolor.

   Four input formats are allowed:

   ``pencolor()``
      Return the current pencolor as color specification string or
      as a tuple (see example).  May be used as input to another
      :func:`color`, :func:`pencolor`, :func:`fillcolor` or :func:`bgcolor`
      call.

   ``pencolor(colorstring)``
      Set pencolor to *colorstring*, which is a Tk color specification string,
      such as ``"red"``, ``"yellow"``, or ``"#33cc8c"``.

   ``pencolor((r, g, b))``
      Set pencolor to the RGB color represented by the tuple of *r*, *g*, and
      *b*.  Each of *r*, *g*, and *b* must be in the range 0..colormode, where
      colormode is either 1.0 or 255 (see :func:`colormode`).

   ``pencolor(r, g, b)``
      Set pencolor to the RGB color represented by *r*, *g*, and *b*.  Each of
      *r*, *g*, and *b* must be in the range 0..colormode.

   If turtleshape is a polygon, the outline of that polygon is drawn with the
   newly set pencolor.

   .. doctest::
      :skipif: _tkinter is None

      >>> colormode()
      1.0
      >>> turtle.pencolor()
      'red'
      >>> turtle.pencolor("brown")
      >>> turtle.pencolor()
      'brown'
      >>> tup = (0.2, 0.8, 0.55)
      >>> turtle.pencolor(tup)
      >>> turtle.pencolor()
      (0.2, 0.8, 0.5490196078431373)
      >>> colormode(255)
      >>> turtle.pencolor()
      (51.0, 204.0, 140.0)
      >>> turtle.pencolor('#32c18f')
      >>> turtle.pencolor()
      (50.0, 193.0, 143.0)


.. function:: fillcolor()
              fillcolor(color, /)
              fillcolor(r, g, b, /)

   Return or set the fillcolor.

   Four input formats are allowed:

   ``fillcolor()``
      Return the current fillcolor as color specification string, possibly
      in tuple format (see example).  May be used as input to another
      :func:`color`, :func:`pencolor`, :func:`fillcolor` or :func:`bgcolor`
      call.

   ``fillcolor(colorstring)``
      Set fillcolor to *colorstring*, which is a Tk color specification string,
      such as ``"red"``, ``"yellow"``, or ``"#33cc8c"``.

   ``fillcolor((r, g, b))``
      Set fillcolor to the RGB color represented by the tuple of *r*, *g*, and
      *b*.  Each of *r*, *g*, and *b* must be in the range 0..colormode, where
      colormode is either 1.0 or 255 (see :func:`colormode`).

   ``fillcolor(r, g, b)``
      Set fillcolor to the RGB color represented by *r*, *g*, and *b*.  Each of
      *r*, *g*, and *b* must be in the range 0..colormode.

   If turtleshape is a polygon, the interior of that polygon is drawn
   with the newly set fillcolor.

   .. doctest::
      :skipif: _tkinter is None

      >>> turtle.fillcolor("violet")
      >>> turtle.fillcolor()
      'violet'
      >>> turtle.pencolor()
      (50.0, 193.0, 143.0)
      >>> turtle.fillcolor((50, 193, 143))  # Integers, not floats
      >>> turtle.fillcolor()
      (50.0, 193.0, 143.0)
      >>> turtle.fillcolor('#ffffff')
      >>> turtle.fillcolor()
      (255.0, 255.0, 255.0)


.. function:: color()
              color(color, /)
              color(r, g, b, /)
              color(pencolor, fillcolor, /)

   Return or set pencolor and fillcolor.

   Several input formats are allowed.  They use 0 to 3 arguments as
   follows:

   ``color()``
      Return the current pencolor and the current fillcolor as a pair of color
      specification strings or tuples as returned by :func:`pencolor` and
      :func:`fillcolor`.

   ``color(colorstring)``, ``color((r,g,b))``, ``color(r,g,b)``
      Inputs as in :func:`pencolor`, set both, fillcolor and pencolor, to the
      given value.

   ``color(colorstring1, colorstring2)``, ``color((r1,g1,b1), (r2,g2,b2))``
      Equivalent to ``pencolor(colorstring1)`` and ``fillcolor(colorstring2)``
      and analogously if the other input format is used.

   If turtleshape is a polygon, outline and interior of that polygon is drawn
   with the newly set colors.

   .. doctest::
      :skipif: _tkinter is None

      >>> turtle.color("red", "green")
      >>> turtle.color()
      ('red', 'green')
      >>> color("#285078", "#a0c8f0")
      >>> color()
      ((40.0, 80.0, 120.0), (160.0, 200.0, 240.0))


See also: Screen method :func:`colormode`.


Filling
~~~~~~~

.. doctest::
   :skipif: _tkinter is None
   :hide:

   >>> turtle.home()

.. function:: filling()

   Return fillstate (``True`` if filling, ``False`` else).

   .. doctest::
      :skipif: _tkinter is None

      >>> turtle.begin_fill()
      >>> if turtle.filling():
      ...    turtle.pensize(5)
      ... else:
      ...    turtle.pensize(3)

.. function:: fill()

   Fill the shape drawn in the ``with turtle.fill():`` block.

   .. doctest::
      :skipif: _tkinter is None

      >>> turtle.color("black", "red")
      >>> with turtle.fill():
      ...     turtle.circle(80)

   Using :func:`!fill` is equivalent to adding the :func:`begin_fill` before the
   fill-block and :func:`end_fill` after the fill-block:

   .. doctest::
      :skipif: _tkinter is None

      >>> turtle.color("black", "red")
      >>> turtle.begin_fill()
      >>> turtle.circle(80)
      >>> turtle.end_fill()

   .. versionadded:: 3.14


.. function:: begin_fill()

   To be called just before drawing a shape to be filled.


.. function:: end_fill()

   Fill the shape drawn after the last call to :func:`begin_fill`.

   Whether or not overlap regions for self-intersecting polygons
   or multiple shapes are filled depends on the operating system graphics,
   type of overlap, and number of overlaps.  For example, the Turtle star
   above may be either all yellow or have some white regions.

   .. doctest::
      :skipif: _tkinter is None

      >>> turtle.color("black", "red")
      >>> turtle.begin_fill()
      >>> turtle.circle(80)
      >>> turtle.end_fill()


More drawing control
~~~~~~~~~~~~~~~~~~~~

.. function:: reset()

   Delete the turtle's drawings and re-center the turtle. The turtle's
   settings are restored to their default values.

   .. doctest::
      :skipif: _tkinter is None

      >>> turtle.goto(0,-22)
      >>> turtle.left(100)
      >>> turtle.position()
      (0.00,-22.00)
      >>> turtle.heading()
      100.0
      >>> turtle.reset()
      >>> turtle.position()
      (0.00,0.00)
      >>> turtle.heading()
      0.0


.. function:: clear()

   Delete the turtle's drawings from the screen. The state and position of the
   turtle as well as the drawings of other turtles are not affected.


.. function:: write(arg, move=False, align="left", font=("Arial", 8, "normal"))

   :param arg: object to be written to the TurtleScreen
   :param move: True/False
   :param align: one of the strings "left", "center" or right"
   :param font: a triple (fontname, fontsize, fonttype)

   Write text - the string representation of *arg* - at the current turtle
   position according to *align* ("left", "center" or "right") and with the given
   font.  If *move* is true, the pen is moved to the bottom-right corner of the
   text.  By default, *move* is ``False``.

   .. doctest::
      :skipif: _tkinter is None

      >>> turtle.write("Home = ", True, align="center")
      >>> turtle.write((0,0), True)


Turtle state
^^^^^^^^^^^^

Visibility
~~~~~~~~~~

.. function:: hideturtle()
              ht()

   Make the turtle invisible. If the pen is down, movement still draws.


.. function:: showturtle()
              st()

   Make the turtle visible.


.. function:: isvisible()

   Return ``True`` if the turtle is shown, ``False`` if it's hidden.

   .. doctest::
      :skipif: _tkinter is None

      >>> turtle.hideturtle()
      >>> turtle.isvisible()
      False
      >>> turtle.showturtle()
      >>> turtle.isvisible()
      True


Appearance
~~~~~~~~~~

.. function:: shape(name=None)

   :param name: a string which is a valid shapename

   Set turtle shape to shape with given *name* or, if name is not given, return
   name of current shape.  Shape with *name* must exist in the TurtleScreen's
   shape dictionary.  Initially there are the following polygon shapes: "arrow",
   "turtle", "circle", "square", "triangle", "classic".  To learn about how to
   deal with shapes see Screen method :func:`register_shape`.

   .. doctest::
      :skipif: _tkinter is None

      >>> turtle.shape()
      'classic'
      >>> turtle.shape("turtle")
      >>> turtle.shape()
      'turtle'


.. function:: resizemode(rmode=None)

   :param rmode: one of the strings "auto", "user", "noresize"

   Set resizemode to one of the values: "auto", "user", "noresize".  If *rmode*
   is not given, return current resizemode.  Different resizemodes have the
   following effects:

   - "auto": adapts the appearance of the turtle corresponding to the value of pensize.
   - "user": adapts the appearance of the turtle according to the values of
     stretchfactor and outlinewidth (outline), which are set by
     :func:`shapesize`.
   - "noresize": no adaption of the turtle's appearance takes place.

   ``resizemode("user")`` is called by :func:`shapesize` when used with arguments.

   .. doctest::
      :skipif: _tkinter is None

      >>> turtle.resizemode()
      'noresize'
      >>> turtle.resizemode("auto")
      >>> turtle.resizemode()
      'auto'


.. function:: shapesize(stretch_wid=None, stretch_len=None, outline=None)
              turtlesize(stretch_wid=None, stretch_len=None, outline=None)

   :param stretch_wid: positive number
   :param stretch_len: positive number
   :param outline: positive number

   Return or set the pen's attributes x/y-stretchfactors and/or outline.  Set
   resizemode to "user".  If and only if resizemode is set to "user", the turtle
   will be displayed stretched according to its stretchfactors: *stretch_wid* is
   stretchfactor perpendicular to its orientation, *stretch_len* is
   stretchfactor in direction of its orientation, *outline* determines the width
   of the shape's outline.

   .. doctest::
      :skipif: _tkinter is None

      >>> turtle.shapesize()
      (1.0, 1.0, 1)
      >>> turtle.resizemode("user")
      >>> turtle.shapesize(5, 5, 12)
      >>> turtle.shapesize()
      (5, 5, 12)
      >>> turtle.shapesize(outline=8)
      >>> turtle.shapesize()
      (5, 5, 8)


.. function:: shearfactor(shear=None)

   :param shear: number (optional)

   Set or return the current shearfactor. Shear the turtleshape according to
   the given shearfactor shear, which is the tangent of the shear angle.
   Do *not* change the turtle's heading (direction of movement).
   If shear is not given: return the current shearfactor, i. e. the
   tangent of the shear angle, by which lines parallel to the
   heading of the turtle are sheared.

   .. doctest::
      :skipif: _tkinter is None

      >>> turtle.shape("circle")
      >>> turtle.shapesize(5,2)
      >>> turtle.shearfactor(0.5)
      >>> turtle.shearfactor()
      0.5


.. function:: tilt(angle)

   :param angle: a number

   Rotate the turtleshape by *angle* from its current tilt-angle, but do *not*
   change the turtle's heading (direction of movement).

   .. doctest::
      :skipif: _tkinter is None

      >>> turtle.reset()
      >>> turtle.shape("circle")
      >>> turtle.shapesize(5,2)
      >>> turtle.tilt(30)
      >>> turtle.fd(50)
      >>> turtle.tilt(30)
      >>> turtle.fd(50)


.. function:: tiltangle(angle=None)

   :param angle: a number (optional)

   Set or return the current tilt-angle. If angle is given, rotate the
   turtleshape to point in the direction specified by angle,
   regardless of its current tilt-angle. Do *not* change the turtle's
   heading (direction of movement).
   If angle is not given: return the current tilt-angle, i. e. the angle
   between the orientation of the turtleshape and the heading of the
   turtle (its direction of movement).

   .. doctest::
      :skipif: _tkinter is None

      >>> turtle.reset()
      >>> turtle.shape("circle")
      >>> turtle.shapesize(5,2)
      >>> turtle.tilt(45)
      >>> turtle.tiltangle()
      45.0


.. function:: shapetransform(t11=None, t12=None, t21=None, t22=None)

   :param t11: a number (optional)
   :param t12: a number (optional)
   :param t21: a number (optional)
   :param t12: a number (optional)

   Set or return the current transformation matrix of the turtle shape.

   If none of the matrix elements are given, return the transformation
   matrix as a tuple of 4 elements.
   Otherwise set the given elements and transform the turtleshape
   according to the matrix consisting of first row t11, t12 and
   second row t21, t22. The determinant t11 * t22 - t12 * t21 must not be
   zero, otherwise an error is raised.
   Modify stretchfactor, shearfactor and tiltangle according to the
   given matrix.

   .. doctest::
      :skipif: _tkinter is None

      >>> turtle = Turtle()
      >>> turtle.shape("square")
      >>> turtle.shapesize(4,2)
      >>> turtle.shearfactor(-0.5)
      >>> turtle.shapetransform()
      (4.0, -1.0, -0.0, 2.0)


.. function:: get_shapepoly()

   Return the current shape polygon as tuple of coordinate pairs. This
   can be used to define a new shape or components of a compound shape.

   .. doctest::
      :skipif: _tkinter is None

      >>> turtle.shape("square")
      >>> turtle.shapetransform(4, -1, 0, 2)
      >>> turtle.get_shapepoly()
      ((50, -20), (30, 20), (-50, 20), (-30, -20))


Using events
^^^^^^^^^^^^

.. function:: onclick(fun, btn=1, add=None)
   :noindex:

   :param fun: a function with two arguments or ``None``
   :param btn: an integer
   :param add: a boolean or ``None``

   Bind *fun* to mouse-click events on this turtle. *fun* is called with the
   coordinates of the clicked point on the canvas. If *fun* is ``None``,
   existing bindings are removed. *btn* is the number of the mouse button and
   defaults to 1, the left mouse button. If *add* is ``True``, a new binding
   is added, otherwise it replaces a former binding. Example for the
   anonymous turtle, that is, the procedural way:

   .. doctest::
      :skipif: _tkinter is None

      >>> def turn(x, y):
      ...     left(180)
      ...
      >>> onclick(turn)  # Now clicking into the turtle will turn it.
      >>> onclick(None)  # event-binding will be removed


.. function:: onrelease(fun, btn=1, add=None)

   :param fun: a function with two arguments which will be called with the
               coordinates of the clicked point on the canvas
   :param btn: number of the mouse-button, defaults to 1 (left mouse button)
   :param add: ``True`` or ``False`` -- if ``True``, a new binding will be
               added, otherwise it will replace a former binding

   Bind *fun* to mouse-button-release events on this turtle.  If *fun* is
   ``None``, existing bindings are removed.

   .. doctest::
      :skipif: _tkinter is None

      >>> class MyTurtle(Turtle):
      ...     def glow(self,x,y):
      ...         self.fillcolor("red")
      ...     def unglow(self,x,y):
      ...         self.fillcolor("")
      ...
      >>> turtle = MyTurtle()
      >>> turtle.onclick(turtle.glow)     # clicking on turtle turns fillcolor red,
      >>> turtle.onrelease(turtle.unglow) # releasing turns it to transparent.


.. function:: ondrag(fun, btn=1, add=None)

   :param fun: a function with two arguments which will be called with the
               coordinates of the clicked point on the canvas
   :param btn: number of the mouse-button, defaults to 1 (left mouse button)
   :param add: ``True`` or ``False`` -- if ``True``, a new binding will be
               added, otherwise it will replace a former binding

   Bind *fun* to mouse-move events on this turtle.  If *fun* is ``None``,
   existing bindings are removed.

   Remark: Every sequence of mouse-move-events on a turtle is preceded by a
   mouse-click event on that turtle.

   .. doctest::
      :skipif: _tkinter is None

      >>> turtle.ondrag(turtle.goto)

   Subsequently, clicking and dragging the Turtle will move it across
   the screen thereby producing handdrawings (if pen is down).


Special Turtle methods
^^^^^^^^^^^^^^^^^^^^^^


.. function:: poly()

   Record the vertices of a polygon drawn in the ``with turtle.poly():`` block.
   The first and last vertices will be connected.

   .. doctest::
      :skipif: _tkinter is None

      >>> with turtle.poly():
      ...     turtle.forward(100)
      ...     turtle.right(60)
      ...     turtle.forward(100)

   .. versionadded:: 3.14


.. function:: begin_poly()

   Start recording the vertices of a polygon. The current turtle position is
   the first vertex of the polygon.


.. function:: end_poly()

   Stop recording the vertices of a polygon. The current turtle position is
   the last vertex of the polygon. This will be connected with the first vertex.


.. function:: get_poly()

   Return the last recorded polygon.

   .. doctest::
      :skipif: _tkinter is None

      >>> turtle.home()
      >>> turtle.begin_poly()
      >>> turtle.fd(100)
      >>> turtle.left(20)
      >>> turtle.fd(30)
      >>> turtle.left(60)
      >>> turtle.fd(50)
      >>> turtle.end_poly()
      >>> p = turtle.get_poly()
      >>> register_shape("myFavouriteShape", p)


.. function:: clone()

   Create and return a clone of the turtle with same position, heading and
   turtle properties.

   .. doctest::
      :skipif: _tkinter is None

      >>> mick = Turtle()
      >>> joe = mick.clone()


.. function:: getturtle()
              getpen()

   Return the Turtle object itself.  Only reasonable use: as a function to
   return the "anonymous turtle":

   .. doctest::
      :skipif: _tkinter is None

      >>> pet = getturtle()
      >>> pet.fd(50)
      >>> pet
      <turtle.Turtle object at 0x...>


.. function:: getscreen()

   Return the :class:`TurtleScreen` object the turtle is drawing on.
   TurtleScreen methods can then be called for that object.

   .. doctest::
      :skipif: _tkinter is None

      >>> ts = turtle.getscreen()
      >>> ts
      <turtle._Screen object at 0x...>
      >>> ts.bgcolor("pink")


.. function:: setundobuffer(size)

   :param size: an integer or ``None``

   Set or disable undobuffer.  If *size* is an integer, an empty undobuffer of
   given size is installed.  *size* gives the maximum number of turtle actions
   that can be undone by the :func:`undo` method/function.  If *size* is
   ``None``, the undobuffer is disabled.

   .. doctest::
      :skipif: _tkinter is None

      >>> turtle.setundobuffer(42)


.. function:: undobufferentries()

   Return number of entries in the undobuffer.

   .. doctest::
      :skipif: _tkinter is None

      >>> while undobufferentries():
      ...     undo()



.. _compoundshapes:

Compound shapes
^^^^^^^^^^^^^^^

To use compound turtle shapes, which consist of several polygons of different
color, you must use the helper class :class:`Shape` explicitly as described
below:

1. Create an empty Shape object of type "compound".
2. Add as many components to this object as desired, using the
   :meth:`~Shape.addcomponent` method.

   For example:

   .. doctest::
      :skipif: _tkinter is None

      >>> s = Shape("compound")
      >>> poly1 = ((0,0),(10,-5),(0,10),(-10,-5))
      >>> s.addcomponent(poly1, "red", "blue")
      >>> poly2 = ((0,0),(10,-5),(-10,-5))
      >>> s.addcomponent(poly2, "blue", "red")

3. Now add the Shape to the Screen's shapelist and use it:

   .. doctest::
      :skipif: _tkinter is None

      >>> register_shape("myshape", s)
      >>> shape("myshape")


.. note::

   The :class:`Shape` class is used internally by the :func:`register_shape`
   method in different ways.  The application programmer has to deal with the
   Shape class *only* when using compound shapes like shown above!


.. _methods-of-turtlescreen-screen:
.. _methods-of-turtlescreen-screen-and-corresponding-functions:

Screen methods and functions
----------------------------

Most of the examples in this section refer to a TurtleScreen instance called
``screen``.

.. doctest::
   :skipif: _tkinter is None
   :hide:

   >>> screen = Screen()

Window control
^^^^^^^^^^^^^^

.. function:: bgcolor()
              bgcolor(color, /)
              bgcolor(r, g, b, /)

   Return or set the background color of the TurtleScreen.

   Four input formats are allowed:

   ``bgcolor()``
      Return the current background color as a color specification string or
      as a tuple (see example).  May be used as input to another
      :func:`color`, :func:`pencolor`, :func:`fillcolor` or :func:`bgcolor`
      call.

   ``bgcolor(colorstring)``
      Set the background color to *colorstring*, which is a Tk color
      specification string, such as ``"red"``, ``"yellow"``, or ``"#33cc8c"``.

   ``bgcolor((r, g, b))``
      Set the background color to the RGB color represented by the tuple of
      *r*, *g*, and *b*.
      Each of *r*, *g*, and *b* must be between 0 and colormode, where
      colormode is either 1.0 or 255 (see :func:`colormode`).

   ``bgcolor(r, g, b)``
      Set the background color to the RGB color represented by *r*, *g*, and
      *b*. Each of *r*, *g*, and *b* must be between 0 and colormode.

   .. doctest::
      :skipif: _tkinter is None

      >>> screen.bgcolor("orange")
      >>> screen.bgcolor()
      'orange'
      >>> screen.bgcolor("#800080")
      >>> screen.bgcolor()
      (128.0, 0.0, 128.0)


.. function:: bgpic(picname=None)

   :param picname: a string, name of an image file (PNG, GIF, PGM, and PPM)
                   or ``"nopic"``, or ``None``

   Set background image or return name of current backgroundimage.  If *picname*
   is a filename, set the corresponding image as background.  If *picname* is
   ``"nopic"``, delete background image, if present.  If *picname* is ``None``,
   return the filename of the current backgroundimage. ::

      >>> screen.bgpic()
      'nopic'
      >>> screen.bgpic("landscape.gif")
      >>> screen.bgpic()
      "landscape.gif"


.. function:: clear()
   :noindex:

   .. note::
      This TurtleScreen method is available as a global function only under the
      name ``clearscreen``.  The global function ``clear`` is a different one
      derived from the Turtle method ``clear``.


.. function:: clearscreen()

   Delete all drawings and all turtles from the TurtleScreen.  Reset the now
   empty TurtleScreen to its initial state: white background, no background
   image, no event bindings and tracing on.


.. function:: reset()
   :noindex:

   .. note::
      This TurtleScreen method is available as a global function only under the
      name ``resetscreen``.  The global function ``reset`` is another one
      derived from the Turtle method ``reset``.


.. function:: resetscreen()

   Reset all turtles on the screen to their initial state.


.. function:: screensize(canvwidth=None, canvheight=None, bg=None)

   :param canvwidth: positive integer, new width of canvas in pixels
   :param canvheight: positive integer, new height of canvas in pixels
   :param bg: colorstring or color-tuple, new background color

   If no arguments are given, return current (canvaswidth, canvasheight).  Else
   resize the canvas the turtles are drawing on.  Do not alter the drawing
   window.  To observe hidden parts of the canvas, use the scrollbars. With this
   method, one can make visible those parts of a drawing which were outside the
   canvas before.

   .. doctest::
      :skipif: _tkinter is None

      >>> screen.screensize()
      (400, 300)
      >>> screen.screensize(2000,1500)
      >>> screen.screensize()
      (2000, 1500)

   e.g. to search for an erroneously escaped turtle ;-)


.. function:: setworldcoordinates(llx, lly, urx, ury)

   :param llx: a number
   :param lly: a number
   :param urx: a number
   :param ury: a number

   Set up a user-defined coordinate system. *llx* and *lly* are the x and y
   coordinates of the lower left corner of the canvas. *urx* and *ury* are the
   x and y coordinates of the upper right corner. Switch to mode "world" if
   necessary, which performs a reset. If mode "world" is already active, all
   drawings are redrawn according to the new coordinates. In user-defined
   coordinate systems, angles may appear distorted, see :func:`mode`.

   .. doctest::
      :skipif: _tkinter is None

      >>> screen.reset()
      >>> screen.setworldcoordinates(-50,-7.5,50,7.5)
      >>> for _ in range(72):
      ...     left(10)
      ...
      >>> for _ in range(8):
      ...     left(45); fd(2)   # a regular octagon

   .. doctest::
      :skipif: _tkinter is None
      :hide:

      >>> screen.reset()
      >>> for t in turtles():
      ...      t.reset()


Animation control
^^^^^^^^^^^^^^^^^

.. function:: no_animation()

   Temporarily turn off turtle animation. The code inside the :keyword:`with`
   block is not animated. Once the block is exited, the drawing appears. This
   is useful for drawing complex shapes where even the fastest speed setting
   is too slow.

   .. doctest::
      :skipif: _tkinter is None

      >>> with screen.no_animation():
      ...     for dist in range(2, 400, 2):
      ...         fd(dist)
      ...         rt(90)

   .. versionadded:: 3.14


.. function:: delay(delay=None)

   :param delay: a nonnegative integer or ``None``

   Return or set the drawing delay in milliseconds. This is approximately the
   time interval between two consecutive canvas updates. The longer the
   drawing delay, the slower the animation.

   .. doctest::
      :skipif: _tkinter is None

      >>> screen.delay()
      10
      >>> screen.delay(5)
      >>> screen.delay()
      5


.. function:: tracer(n=None, delay=None)

   :param n: a nonnegative integer or ``None``
   :param delay: a nonnegative integer or ``None``

   Turn turtle animation on or off and set the drawing delay. If *n* is given,
   only every n-th regular screen update is performed, which can be used to
   speed up the drawing of complex graphics. If *n* is 0, animation is turned
   off and the screen is only updated by calling :func:`update`. If *delay* is
   given, it sets the drawing delay, see :func:`delay`. When called without
   arguments, return the current value of *n*.

   .. doctest::
      :skipif: _tkinter is None

      >>> screen.tracer(8, 25)
      >>> dist = 2
      >>> for i in range(200):
      ...     fd(dist)
      ...     rt(90)
      ...     dist += 2


.. function:: update()

   Perform a TurtleScreen update. To be used when tracer is turned off.

See also the RawTurtle/Turtle method :func:`speed`.


Using screen events
^^^^^^^^^^^^^^^^^^^

.. function:: listen(xdummy=None, ydummy=None)

   Set focus on TurtleScreen (in order to collect key-events).  Dummy arguments
   are provided in order to be able to pass :func:`listen` to the onclick method.


.. function:: onkey(fun, key)
              onkeyrelease(fun, key)

   :param fun: a function with no arguments or ``None``
   :param key: a string: key (e.g. "a") or key-symbol (e.g. "space")

   Bind *fun* to key-release event of key.  If *fun* is ``None``, event bindings
   are removed. Remark: in order to be able to register key-events, TurtleScreen
   must have the focus. (See method :func:`listen`.)

   .. doctest::
      :skipif: _tkinter is None

      >>> def f():
      ...     fd(50)
      ...     lt(60)
      ...
      >>> screen.onkey(f, "Up")
      >>> screen.listen()


.. function:: onkeypress(fun, key=None)

   :param fun: a function with no arguments or ``None``
   :param key: a string: key (e.g. "a") or key-symbol (e.g. "space")

   Bind *fun* to key-press event of key if key is given,
   or to any key-press-event if no key is given.
   Remark: in order to be able to register key-events, TurtleScreen
   must have focus. (See method :func:`listen`.)

   .. doctest::
      :skipif: _tkinter is None

      >>> def f():
      ...     fd(50)
      ...
      >>> screen.onkey(f, "Up")
      >>> screen.listen()


.. function:: onclick(fun, btn=1, add=None)
              onscreenclick(fun, btn=1, add=None)

   :param fun: a function with two arguments or ``None``
   :param btn: an integer
   :param add: a boolean or ``None``

   Bind *fun* to mouse-click events on this screen. *fun* is called with the
   coordinates of the clicked point on the canvas. If *fun* is ``None``,
   existing bindings are removed. *btn* is the number of the mouse button and
   defaults to 1, the left mouse button. If *add* is ``True``, a new binding
   is added, otherwise it replaces a former binding.

   Example for a TurtleScreen instance named ``screen`` and a Turtle instance
   named ``turtle``:

   .. doctest::
      :skipif: _tkinter is None

      >>> screen.onclick(turtle.goto) # Subsequently clicking into the TurtleScreen will
      >>>                             # make the turtle move to the clicked point.
      >>> screen.onclick(None)        # remove event binding again

   .. note::
      This TurtleScreen method is available as a global function only under the
      name ``onscreenclick``.  The global function ``onclick`` is another one
      derived from the Turtle method ``onclick``.


.. function:: ontimer(fun, t=0)

   :param fun: a function with no arguments
   :param t: a number >= 0

   Install a timer that calls *fun* after *t* milliseconds.

   .. doctest::
      :skipif: _tkinter is None

      >>> running = True
      >>> def f():
      ...     if running:
      ...         fd(50)
      ...         lt(60)
      ...         screen.ontimer(f, 250)
      >>> f()   ### makes the turtle march around
      >>> running = False


.. function:: mainloop()
              done()

   Start the event loop by calling Tkinter's :meth:`~tkinter.Misc.mainloop`
   method. Must be the last statement in a turtle graphics program. Must
   *not* be used if a script is run from within IDLE in -n mode (see
   :ref:`idle-no-subprocess`).


Input methods
^^^^^^^^^^^^^

.. function:: textinput(title, prompt)

   :param title: a string
   :param prompt: a string

   Pop up a dialog window for input of a string. *title* is the title of the
   dialog window and *prompt* is a text describing what information to input.
   Return the string entered. If the dialog is canceled, return ``None``. ::

      >>> screen.textinput("NIM", "Name of first player:")


.. function:: numinput(title, prompt, default=None, minval=None, maxval=None)

   :param title: a string
   :param prompt: a string
   :param default: a number or ``None``
   :param minval: a number or ``None``
   :param maxval: a number or ``None``

   Pop up a dialog window for input of a number. *title* is the title of the
   dialog window and *prompt* is a text describing what numerical information
   to input. *default* is the default value, *minval* and *maxval* are the
   minimum and maximum values for input. If these are given, the number
   entered must be between *minval* and *maxval*. If not, a hint is issued
   and the dialog remains open for correction. Return the number entered. If
   the dialog is canceled, return ``None``. ::

      >>> screen.numinput("Poker", "Your stakes:", 1000, minval=10, maxval=10000)


Settings and special methods
^^^^^^^^^^^^^^^^^^^^^^^^^^^^

.. function:: mode(mode=None)

   :param mode: a string or ``None``

   Set the turtle mode and perform a reset. *mode* is one of the strings
   "standard", "logo" or "world". If *mode* is not given, return the current
   mode.

   Mode "standard" is compatible with the old :mod:`!turtle` module. Mode
   "logo" is compatible with most Logo turtle graphics. Mode "world" uses
   user-defined world coordinates, see :func:`setworldcoordinates`. In this
   mode, angles appear distorted if the x and y units are not of equal length.

   ============ ========================= ===================
       Mode      Initial turtle heading     positive angles
   ============ ========================= ===================
    "standard"    to the right (east)       counterclockwise
      "logo"        upward    (north)         clockwise
   ============ ========================= ===================

   .. doctest::
      :skipif: _tkinter is None

      >>> mode("logo")  # resets turtle heading to north
      >>> mode()
      'logo'


.. function:: colormode(cmode=None)

   :param cmode: a number or ``None``

   Return the colormode or set it to 1.0 or 255. After setting it, the *r*,
   *g* and *b* values of color triples have to be between 0 and *cmode*.

   .. doctest::
      :skipif: _tkinter is None

      >>> screen.colormode(1)
      >>> turtle.pencolor(240, 160, 80)
      Traceback (most recent call last):
           ...
      TurtleGraphicsError: bad color sequence: (240, 160, 80)
      >>> screen.colormode()
      1.0
      >>> screen.colormode(255)
      >>> screen.colormode()
      255
      >>> turtle.pencolor(240,160,80)


.. function:: getcanvas()

   Return the Canvas of this TurtleScreen.  Useful for insiders who know what to
   do with a Tkinter Canvas.

   .. doctest::
      :skipif: _tkinter is None

      >>> cv = screen.getcanvas()
      >>> cv
      <turtle.ScrolledCanvas object ...>


.. function:: getshapes()

   Return a list of names of all currently available turtle shapes.

   .. doctest::
      :skipif: _tkinter is None

      >>> screen.getshapes()
      ['arrow', 'blank', 'circle', ..., 'turtle']


.. function:: register_shape(name, shape=None)
              addshape(name, shape=None)

   :param name: a string
   :param shape: a string, a tuple of pairs of numbers, a :class:`Shape`
                 object or ``None``

   Add a turtle shape to the TurtleScreen's shape list. It can be called in
   four different ways:

   (1) *name* is the name of an image file (PNG, GIF, PGM, and PPM) and
       *shape* is ``None``: Install the corresponding image shape. ::

       >>> screen.register_shape("turtle.gif")

   (2) *name* is an arbitrary string and *shape* is the name of an image file
       (PNG, GIF, PGM, and PPM): Install the corresponding image shape. ::

       >>> screen.register_shape("turtle", "turtle.gif")

   (3) *name* is an arbitrary string and *shape* is a tuple of pairs of
       coordinates: Install the corresponding polygon shape.

       .. doctest::
          :skipif: _tkinter is None

          >>> screen.register_shape("triangle", ((5,-3), (0,5), (-5,-3)))

   (4) *name* is an arbitrary string and *shape* is a (compound) :class:`Shape`
       object: Install the corresponding compound shape.

   Image shapes do not rotate when turning the turtle, so they do not display
   the heading of the turtle. To use a registered shape, call :func:`shape`
   with its name.

   .. versionchanged:: 3.14
      Added support for PNG, PGM, and PPM image formats.
      Both a shape name and an image file name can be specified.


.. function:: turtles()

   Return the list of turtles on the screen.

   .. doctest::
      :skipif: _tkinter is None

      >>> for turtle in screen.turtles():
      ...     turtle.color("red")


.. function:: window_height()

   Return the height of the turtle window. ::

      >>> screen.window_height()
      480


.. function:: window_width()

   Return the width of the turtle window. ::

      >>> screen.window_width()
      640


.. _screenspecific:
.. _methods-specific-to-screen-not-inherited-from-turtlescreen:

Screen-only methods
^^^^^^^^^^^^^^^^^^^

.. function:: bye()

   Close the turtle graphics window.


.. function:: exitonclick()

   Bind ``bye()`` method to mouse clicks on the Screen.


   If the value "using_IDLE" in the configuration dictionary is ``False``
   (default value), also enter mainloop.  Remark: If IDLE with the ``-n`` switch
   (no subprocess) is used, this value should be set to ``True`` in
   :file:`turtle.cfg`.  In this case IDLE's own mainloop is active also for the
   client script.


.. function:: save(filename, overwrite=False)

   Save the current turtle drawing (and turtles) as a PostScript file.

   :param filename: the path of the saved PostScript file
   :param overwrite: if ``False`` and there already exists a file with the given
                     filename, then the function will raise a
                     ``FileExistsError``. If it is ``True``, the file will be
                     overwritten.

   .. doctest::
      :skipif: _tkinter is None

      >>> screen.save("my_drawing.ps")
      >>> screen.save("my_drawing.ps", overwrite=True)

   .. versionadded:: 3.14

.. function:: setup(width=_CFG["width"], height=_CFG["height"], startx=_CFG["leftright"], starty=_CFG["topbottom"])

   Set the size and position of the main window.  Default values of arguments
   are stored in the configuration dictionary and can be changed via a
   :file:`turtle.cfg` file.

   :param width: if an integer, a size in pixels, if a float, a fraction of the
                 screen; default is 50% of screen
   :param height: if an integer, the height in pixels, if a float, a fraction of
                  the screen; default is 75% of screen
   :param startx: if positive, starting position in pixels from the left
                  edge of the screen, if negative from the right edge, if ``None``,
                  center window horizontally
   :param starty: if positive, starting position in pixels from the top
                  edge of the screen, if negative from the bottom edge, if ``None``,
                  center window vertically

   .. doctest::
      :skipif: _tkinter is None

      >>> screen.setup (width=200, height=200, startx=0, starty=0)
      >>>              # sets window to 200x200 pixels, in upper left of screen
      >>> screen.setup(width=.75, height=0.5, startx=None, starty=None)
      >>>              # sets window to 75% of screen by 50% of screen and centers


.. function:: title(titlestring)

   :param titlestring: a string

   Set the title of the turtle window to *titlestring*. The title is shown in
   the title bar of the turtle graphics window.

   .. doctest::
      :skipif: _tkinter is None

      >>> screen.title("Welcome to the turtle zoo!")


Public classes
--------------


.. class:: RawTurtle(canvas)
           RawPen(canvas)

   :param canvas: a :class:`!tkinter.Canvas`, a :class:`ScrolledCanvas` or a
                  :class:`TurtleScreen`

   Create a turtle.  The turtle has all methods described above as "methods of
   Turtle/RawTurtle".


.. class:: Turtle()

   Subclass of RawTurtle, has the same interface but draws on a default
   :class:`Screen` object created automatically when needed for the first time.


.. class:: TurtleScreen(cv)

   :param cv: a :class:`!tkinter.Canvas`

   Provides screen oriented methods like :func:`bgcolor` etc. that are described
   above.

.. class:: Screen()

   Subclass of :class:`TurtleScreen`, with :ref:`four methods added
   <screenspecific>`. Calling ``Screen()`` returns the single screen object.
   If it does not exist yet, it is created. Otherwise the existing one is
   returned.


.. class:: ScrolledCanvas(master)

   :param master: some Tkinter widget to contain the ScrolledCanvas, i.e.
      a Tkinter-canvas with scrollbars added

   Used by class Screen, which thus automatically provides a ScrolledCanvas as
   playground for the turtles.

.. class:: Shape(type_, data)

   :param type\_: a string
   :param data: depends on *type_*

   Data structure modeling shapes. *type_* is one of the strings "polygon",
   "image" or "compound". What *data* must be depends on *type_*: for
   "polygon" a tuple of pairs of coordinates, for "image" an image (only used
   internally), and for "compound" ``None``, as a compound shape is built up
   using the :meth:`addcomponent` method.

   .. method:: addcomponent(poly, fill, outline=None)

      :param poly: a tuple of pairs of numbers
      :param fill: a color
      :param outline: a color or ``None``

      Add a component to a shape of type "compound". *poly* is a polygon, a
      tuple of pairs of numbers. *fill* is the color the polygon is filled
      with and *outline* is the color of its outline. If *outline* is not
      given, *fill* is used for it as well.

      Example:

      .. doctest::
         :skipif: _tkinter is None

         >>> poly = ((0,0), (10,-5), (0,10), (-10,-5))
         >>> s = Shape("compound")
         >>> s.addcomponent(poly, "red", "blue")
         >>> # ... add more components and then use register_shape()

      See :ref:`compoundshapes`.


.. class:: Vec2D(x, y)

   A two-dimensional vector class, used as a helper class for implementing
   turtle graphics.  May be useful for turtle graphics programs too.  Derived
   from tuple, so a vector is a tuple!

   Provides (for *a*, *b* vectors, *k* number):

   * ``a + b`` vector addition
   * ``a - b`` vector subtraction
   * ``a * b`` inner product
   * ``k * a`` and ``a * k`` multiplication with scalar
   * ``abs(a)`` absolute value of a
   * ``a.rotate(angle)`` rotation


Exceptions
----------

The :mod:`!turtle` module defines the following exception:

.. exception:: TurtleGraphicsError

   Raised for invalid arguments or operations.
   For example, a malformed color string:

   .. doctest::
      :skipif: _tkinter is None

      >>> turtle.color("blau")
      Traceback (most recent call last):
          ...
      turtle.TurtleGraphicsError: bad color string: blau


.. _turtle-howtos:
.. _turtle-how-to:
.. _how-to:

How-to guides
=============

This section covers some typical turtle use-cases and approaches.


Automatically begin and end filling
-----------------------------------

Starting with Python 3.14, you can use the :func:`fill` :term:`context manager`
instead of :func:`begin_fill` and :func:`end_fill` to automatically begin and
end fill. Here is an example::

   with fill():
       for i in range(4):
           forward(100)
           right(90)

   forward(200)

The code above is equivalent to::

   begin_fill()
   for i in range(4):
       forward(100)
       right(90)
   end_fill()

   forward(200)


Use the ``turtle`` module namespace
-----------------------------------

Using ``from turtle import *`` is convenient - but be warned that it imports a
rather large collection of objects, and if you're doing anything but turtle
graphics you run the risk of a name conflict (this becomes even more an issue
if you're using turtle graphics in a script where other modules might be
imported).

The solution is to use ``import turtle`` - ``fd()`` becomes
``turtle.fd()``, ``width()`` becomes ``turtle.width()`` and so on. (If typing
"turtle" over and over again becomes tedious, use for example ``import turtle
as t`` instead.)


Use turtle graphics in a script
-------------------------------

It's recommended to use the ``turtle`` module namespace as described
immediately above, for example::

    import turtle as t
    from random import random

    for i in range(100):
        steps = int(random() * 100)
        angle = int(random() * 360)
        t.right(angle)
        t.fd(steps)

Another step is also required though - as soon as the script ends, Python
will also close the turtle's window. Add::

    t.mainloop()

to the end of the script. The script will now wait to be dismissed and
will not exit until it is terminated, for example by closing the turtle
graphics window.


Use object-oriented turtle graphics
-----------------------------------

.. seealso:: :ref:`Explanation of the object-oriented interface <turtle-explanation>`

Other than for very basic introductory purposes, or for trying things out
as quickly as possible, it's more usual and much more powerful to use the
object-oriented approach to turtle graphics. For example, this allows
multiple turtles on screen at once.

In this approach, the various turtle commands are methods of objects (mostly of
``Turtle`` objects). You *can* use the object-oriented approach in the shell,
but it would be more typical in a Python script.

The example above then becomes::

    from turtle import Turtle
    from random import random

    t = Turtle()
    for i in range(100):
        steps = int(random() * 100)
        angle = int(random() * 360)
        t.right(angle)
        t.fd(steps)

    t.screen.mainloop()

Note the last line. ``t.screen`` is an instance of the :class:`Screen`
that a Turtle instance exists on; it's created automatically along with
the turtle.

The turtle's screen can be customised, for example::

    t.screen.title('Object-oriented turtle demo')
    t.screen.bgcolor("orange")


.. _help-and-configuration:

How to use help
---------------

The public methods of the Screen and Turtle classes are documented extensively
via docstrings.  So these can be used as online-help via the Python help
facilities:

- When using IDLE, tooltips show the signatures and first lines of the
  docstrings of typed in function-/method calls.

- Calling :func:`help` on methods or functions displays the docstrings::

     >>> help(Screen.bgcolor)
     Help on method bgcolor in module turtle:

     bgcolor(self, *args) unbound turtle.Screen method
         Set or return backgroundcolor of the TurtleScreen.

         Arguments (if given): a color string or three numbers
         in the range 0..colormode or a 3-tuple of such numbers.


         >>> screen.bgcolor("orange")
         >>> screen.bgcolor()
         "orange"
         >>> screen.bgcolor(0.5,0,0.5)
         >>> screen.bgcolor()
         "#800080"

     >>> help(Turtle.penup)
     Help on method penup in module turtle:

     penup(self) unbound turtle.Turtle method
         Pull the pen up -- no drawing when moving.

         Aliases: penup | pu | up

         No argument

         >>> turtle.penup()

- The docstrings of the functions which are derived from methods have a modified
  form::

     >>> help(bgcolor)
     Help on function bgcolor in module turtle:

     bgcolor(*args)
         Set or return backgroundcolor of the TurtleScreen.

         Arguments (if given): a color string or three numbers
         in the range 0..colormode or a 3-tuple of such numbers.

         Example::

           >>> bgcolor("orange")
           >>> bgcolor()
           "orange"
           >>> bgcolor(0.5,0,0.5)
           >>> bgcolor()
           "#800080"

     >>> help(penup)
     Help on function penup in module turtle:

     penup()
         Pull the pen up -- no drawing when moving.

         Aliases: penup | pu | up

         No argument

         Example:
         >>> penup()

These modified docstrings are created automatically together with the function
definitions that are derived from the methods at import time.


.. _turtle-docstring-translation:

Translation of docstrings into different languages
--------------------------------------------------

The docstrings of the public methods of the Screen and Turtle classes, and of
the corresponding functions, can be replaced with translations, so that
:func:`help` and IDE tooltips are shown in another language. However, only the help
text is translated, the names of the functions and methods stay the same.

Translations are distributed on PyPI in the :pypi:`turtle-translations`
package. To use them, install the package with :program:`pip` and select the
language with the :envvar:`PYTHON_TURTLE_LANG` environment variable. For
example, to show the help text in Spanish:

.. code-block:: console

   $ python -m pip install turtle-translations
   $ PYTHON_TURTLE_LANG=es python
   >>> import turtle
   >>> help(turtle.forward)

The language can also be set permanently with the *language* entry of the
:file:`turtle.cfg` file (see :ref:`turtle-configuration`). If no translation
is found for the selected language, the English docstrings are kept.

To add a new language or improve an existing translation, see the
contribution instructions in the :pypi:`turtle-translations` project.

A translation is a docstring dictionary. It is a top-level module named
:samp:`turtle_docstringdict_{language}.py` on :data:`sys.path` defining a
dictionary named ``docsdict``, the keys of which are method names such as
``Turtle.forward`` and the values of which are the translated docstrings. It is
read in at import time. Entries naming a method which does not exist in the
running version are ignored.

.. versionchanged:: 3.16
   Entries naming an unknown method are ignored instead of reported.

.. envvar:: PYTHON_TURTLE_LANG

   The name of the language to read the translation for. It takes precedence
   over the *language* entry of the :file:`turtle.cfg` file.

   .. versionadded:: 3.16

.. function:: write_docstringdict(filename="turtle_docstringdict")

   :param filename: a string, used as filename

   Create and write docstring-dictionary to a Python script with the given
   filename.  This function has to be called explicitly (it is not used by the
   turtle graphics classes).  The docstring dictionary will be written to the
   Python script :file:`{filename}.py`.  It is intended to serve as a template
   for translation of the docstrings into different languages.


.. _turtle-configuration:

How to configure Screen and Turtles
-----------------------------------

The built-in default configuration mimics the appearance and behaviour of the
old turtle module in order to retain best possible compatibility with it.

If you want to use a different configuration which better reflects the features
of this module or which better fits to your needs, e.g. for use in a classroom,
you can prepare a configuration file ``turtle.cfg`` which will be read at import
time and modify the configuration according to its settings.

The built in configuration would correspond to the following ``turtle.cfg``:

.. code-block:: ini

   width = 0.5
   height = 0.75
   leftright = None
   topbottom = None
   canvwidth = 400
   canvheight = 300
   mode = standard
   colormode = 1.0
   delay = 10
   undobuffersize = 1000
   shape = classic
   pencolor = black
   fillcolor = black
   resizemode = noresize
   visible = True
   language = english
   exampleturtle = turtle
   examplescreen = screen
   title = Python Turtle Graphics
   using_IDLE = False

Short explanation of selected entries:

- The first four lines correspond to the arguments of the :func:`Screen.setup <setup>`
  method.
- Line 5 and 6 correspond to the arguments of the method
  :func:`Screen.screensize <screensize>`.
- *shape* can be any of the built-in shapes, e.g: arrow, turtle, etc.  For more
  info try ``help(shape)``.
- If you want to use no fill color (i.e. make the turtle transparent), you have
  to write ``fillcolor = ""`` (but all nonempty strings must not have quotes in
  the cfg file).
- If you want to reflect the turtle its state, you have to use ``resizemode =
  auto``.
- The *language* entry selects the language of the docstrings, unless the
  :envvar:`PYTHON_TURTLE_LANG` environment variable is set. See
  :ref:`turtle-docstring-translation` for more information.
- The entries *exampleturtle* and *examplescreen* define the names of these
  objects as they occur in the docstrings.  The transformation of
  method-docstrings to function-docstrings will delete these names from the
  docstrings.
- *using_IDLE*: Set this to ``True`` if you regularly work with IDLE and its ``-n``
  switch ("no subprocess").  This will prevent :func:`exitonclick` to enter the
  mainloop.

There can be a :file:`turtle.cfg` file in the directory where :mod:`!turtle` is
stored and an additional one in the current working directory.  The latter will
override the settings of the first one.

The :file:`Lib/turtledemo` directory contains a :file:`turtle.cfg` file.  You can
study it as an example and see its effects when running the demos (preferably
not from within the demo-viewer).


.. _turtle-explanation:

Explanation
===========

A turtle object draws on a screen object, and there a number of key classes in
the turtle object-oriented interface that can be used to create them and relate
them to each other.

A :class:`Turtle` instance will automatically create a :class:`Screen`
instance if one is not already present.

``Turtle`` is a subclass of :class:`RawTurtle`, which *doesn't* automatically
create a drawing surface - a *canvas* will need to be provided or created for
it. The *canvas* can be a :class:`!tkinter.Canvas`, :class:`ScrolledCanvas`
or :class:`TurtleScreen`.


:class:`TurtleScreen` is the basic drawing surface for a
turtle. :class:`Screen` is a subclass of ``TurtleScreen``, and
includes :ref:`some additional methods <screenspecific>` for managing its
appearance (including size and title) and behaviour. ``TurtleScreen``'s
constructor needs a :class:`!tkinter.Canvas` or a
:class:`ScrolledCanvas` as an argument.

The functional interface for turtle graphics uses the various methods of
``Turtle`` and ``TurtleScreen``/``Screen``. Behind the scenes, a screen
object is automatically created whenever a function derived from a ``Screen``
method is called. Similarly, a turtle object is automatically created
whenever any of the functions derived from a Turtle method is called.

To use multiple turtles on a screen, the object-oriented interface must be
used.


:mod:`!turtledemo` --- Demo scripts
===================================

.. module:: turtledemo
   :synopsis: A viewer for example turtle scripts

The :mod:`!turtledemo` package includes a set of demo scripts.  These
scripts can be run and viewed using the supplied demo viewer as follows::

   python -m turtledemo

Alternatively, you can run the demo scripts individually.  For example, ::

   python -m turtledemo.bytedesign

The :mod:`!turtledemo` package directory contains:

- A demo viewer :file:`__main__.py` which can be used to view the sourcecode
  of the scripts and run them at the same time.
- Multiple scripts demonstrating different features of the :mod:`!turtle`
  module.  Examples can be accessed via the Examples menu.  They can also
  be run standalone.
- A :file:`turtle.cfg` file which serves as an example of how to write
  and use such files.

The demo scripts are:

.. currentmodule:: turtle

.. tabularcolumns:: |l|L|L|

+------------------------+------------------------------+--------------------------------------+
| Name                   | Description                  | Features                             |
+========================+==============================+======================================+
| ``bytedesign``         | complex classical            | :func:`tracer`, :func:`delay`,       |
|                        | turtle graphics pattern      | :func:`update`                       |
+------------------------+------------------------------+--------------------------------------+
| ``chaos``              | graphs Verhulst dynamics,    | world coordinates                    |
|                        | shows that computer's        |                                      |
|                        | computations can generate    |                                      |
|                        | results sometimes against the|                                      |
|                        | common sense expectations    |                                      |
+------------------------+------------------------------+--------------------------------------+
| ``clock``              | analog clock showing time    | turtles as clock's                   |
|                        | of your computer             | hands, :func:`ontimer`               |
+------------------------+------------------------------+--------------------------------------+
| ``colormixer``         | experiment with r, g, b      | :func:`ondrag`                       |
+------------------------+------------------------------+--------------------------------------+
| ``forest``             | 3 breadth-first trees        | randomization                        |
+------------------------+------------------------------+--------------------------------------+
| ``fractalcurves``      | Hilbert & Koch curves        | recursion                            |
+------------------------+------------------------------+--------------------------------------+
| ``lindenmayer``        | ethnomathematics             | L-System                             |
|                        | (indian kolams)              |                                      |
+------------------------+------------------------------+--------------------------------------+
| ``minimal_hanoi``      | Towers of Hanoi              | Rectangular Turtles                  |
|                        |                              | as Hanoi discs                       |
|                        |                              | (:func:`shape`, :func:`shapesize`)   |
+------------------------+------------------------------+--------------------------------------+
| ``nim``                | play the classical nim game  | turtles as nimsticks,                |
|                        | with three heaps of sticks   | event driven (mouse,                 |
|                        | against the computer.        | keyboard)                            |
+------------------------+------------------------------+--------------------------------------+
| ``paint``              | super minimalistic           | :func:`onclick`                      |
|                        | drawing program              |                                      |
+------------------------+------------------------------+--------------------------------------+
| ``peace``              | elementary                   | turtle: appearance                   |
|                        |                              | and animation                        |
+------------------------+------------------------------+--------------------------------------+
| ``penrose``            | aperiodic tiling with        | :func:`stamp`                        |
|                        | kites and darts              |                                      |
+------------------------+------------------------------+--------------------------------------+
| ``planet_and_moon``    | simulation of                | compound shapes,                     |
|                        | gravitational system         | :class:`Vec2D`                       |
+------------------------+------------------------------+--------------------------------------+
| ``rosette``            | a pattern from the wikipedia | :func:`clone`,                       |
|                        | article on turtle graphics   | :func:`undo`                         |
+------------------------+------------------------------+--------------------------------------+
| ``round_dance``        | dancing turtles rotating     | compound shapes, :func:`clone`       |
|                        | pairwise in opposite         | :func:`shapesize`, :func:`tilt`,     |
|                        | direction                    | :func:`get_shapepoly`, :func:`update`|
+------------------------+------------------------------+--------------------------------------+
| ``sorting_animate``    | visual demonstration of      | simple alignment,                    |
|                        | different sorting methods    | randomization                        |
+------------------------+------------------------------+--------------------------------------+
| ``tree``               | a (graphical) breadth        | :func:`clone`                        |
|                        | first tree (using generators)|                                      |
+------------------------+------------------------------+--------------------------------------+
| ``two_canvases``       | simple design                | turtles on two                       |
|                        |                              | canvases                             |
+------------------------+------------------------------+--------------------------------------+
| ``yinyang``            | another elementary example   | :func:`circle`                       |
+------------------------+------------------------------+--------------------------------------+

Have fun!


.. doctest::
   :skipif: _tkinter is None
   :hide:

   >>> for turtle in turtles():
   ...      turtle.reset()
   >>> turtle.penup()
   >>> turtle.goto(-200,25)
   >>> turtle.pendown()
   >>> turtle.write("No one expects the Spanish Inquisition!",
   ...      font=("Arial", 20, "normal"))
   >>> turtle.penup()
   >>> turtle.goto(-100,-50)
   >>> turtle.pendown()
   >>> turtle.write("Our two chief Turtles are...",
   ...      font=("Arial", 16, "normal"))
   >>> turtle.penup()
   >>> turtle.goto(-450,-75)
   >>> turtle.write(str(turtles()))