16.4 turtle -- Turtle graphics for Tk

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16.4 `turtle` -- Turtle graphics for Tk

Availability: Tk.

The turtle module provides turtle graphics primitives, in both an object-oriented and procedure-oriented ways. Because it uses Tkinter for the underlying graphics, it needs a version of python installed with Tk support.

The procedural interface uses a pen and a canvas which are automagically created when any of the functions are called.

The turtle module defines the following functions:

degrees( ): Set angle measurement units to degrees.

radians( ): Set angle measurement units to radians.

reset( ): Clear the screen, re-center the pen, and set variables to the default values.

clear( ): Clear the screen.

tracer( flag): Set tracing on/off (according to whether flag is true or not). Tracing means line are drawn more slowly, with an animation of an arrow along the line.

forward( distance): Go forward distance steps.

backward( distance): Go backward distance steps.

left( angle): Turn left angle units. Units are by default degrees, but can be set via the degrees() and radians() functions.

right( angle): Turn right angle units. Units are by default degrees, but can be set via the degrees() and radians() functions.

up( ): Move the pen up -- stop drawing.

down( ): Move the pen down -- draw when moving.

width( width): Set the line width to width.

color( s)
color( (r, g, b))
color( r, g, b): Set the pen color. In the first form, the color is specified as a Tk color specification as a string. The second form specifies the color as a tuple of the RGB values, each in the range [0..1]. For the third form, the color is specified giving the RGB values as three separate parameters (each in the range [0..1]).

write( text[, move]): Write text at the current pen position. If move is true, the pen is moved to the bottom-right corner of the text. By default, move is false.

fill( flag): The complete specifications are rather complex, but the recommended usage is: call fill(1) before drawing a path you want to fill, and call fill(0) when you finish to draw the path.

circle( radius[, extent]): Draw a circle with radius radius whose center-point is radius units left of the turtle. extent determines which part of a circle is drawn: if not given it defaults to a full circle.
If extent is not a full circle, one endpoint of the arc is the current pen position. The arc is drawn in a counter clockwise direction if radius is positive, otherwise in a clockwise direction. In the process, the direction of the turtle is changed by the amount of the extent.

goto( x, y)
goto( (x, y)): Go to co-ordinates x, y. The co-ordinates may be specified either as two separate arguments or as a 2-tuple.

This module also does from math import *, so see the documentation for the math module for additional constants and functions useful for turtle graphics.

demo( ): Exercise the module a bit.

exception Error: Exception raised on any error caught by this module.

For examples, see the code of the demo() function.

This module defines the following classes:

class Pen( ): Define a pen. All above functions can be called as a methods on the given pen. The constructor automatically creates a canvas do be drawn on.

class RawPen( canvas): Define a pen which draws on a canvas canvas. This is useful if you want to use the module to create graphics in a ``real'' program.

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