Activities/Turtle Art/Programmable Brick

Programmable Brick

The following feature—a block that can be programmed by the Pippy activity—is available in versions 44+ of Turtle Art.

Version 44 to 103

A copy of the tamyblock.py module is stored in the Journal when you first launch Turtle Art. All the sample modules are in this one file but all except one are commented out with #

You can edit the tamyblock.py module in Pippy. Then load the Python code into the Python block using the Pippy button on the Project toolbar. You can only have one type of Python block in your Turtle Art program.

Another way to load the Python block, is to click the Python code block found on the the Extras palette.

Version 104 onwards

There are two ways to create Python blocks: by loading sample code provided with Turtle Art or by loading Python code the your Journal.

loading sample code

A number of individual sample programs are provided. Clicking on the Load Python Block button on the Load/Save Toolbar will invoke a file-selector dialog. Select the sample that you want and it will be both copied to the Journal and loaded into a Python block.

loading code from the Journal

Clicking on a Python block that has been dragged onto the canvas from the Extras palette will invoke an object-selector dialog.

Select the Python code that that you want and that code will be loaded into the selected block.

You can't run a Python block by clicking on it, as that opens the object selector; instead attach the block to another one and click elsewhere on the stack you have created.

Which ever way you create them, multiple Python blocks can have different code loaded in them.

Sample code

def myblock(lc, x):
   ###########################################################################
   #
   # Draw a dotted line of length x.
   #
   ###########################################################################
   try:  # make sure x is a number
      x = float(x)
   except ValueError:
       return
   if lc.tw.canvas.pendown:
       dist = 0
       while dist+lc.tw.canvas.pensize < x:   # repeat drawing dots
           lc.tw.canvas.setpen(True)
           lc.tw.canvas.forward(1)
           lc.tw.canvas.setpen(False)
           lc.tw.canvas.forward((lc.tw.canvas.pensize*2)-1)
           dist += (lc.tw.canvas.pensize*2)
       lc.tw.canvas.forward(x-dist)           # make sure we have moved exactly x
       lc.tw.canvas.setpen(True)
   else:
       lc.tw.canvas.forward(x)
   return

You can pass a list of up to three arguments to tamyblock.py as in the example below that converts the input to an rgb value.

def myblock(lc, x):
   ###########################################################################
   #
   # Set rgb color
   #
   ###########################################################################
   r = int(x[0])
   while r < 0:
       r += 256
   while r > 255:
       r -= 256
   g = int(x[1])
   while g < 0:
       g += 256
   while g > 255:
       g -= 256
   b = int(x[0])
   while b < 0:
       b += 256
   while b > 255:
       b -= 256
   rgb = "#%02x%02x%02x" % (r,g,b)
   lc.tw.fgcolor = lc.tw.canvas.cm.alloc_color(rgb)
   return

def myblock(lc, x):
   ###########################################################################
   #
   # Push an uppercase version of a string onto the heap.
   # Use a 'pop' block to use the new string.
   #
   ###########################################################################
   if type(x) != str:
       X = str(x).upper()
   else:
       X = x.upper()
   lc.heap.append(X)
   return

def myblock(lc, x):
   ###########################################################################
   #
   # Push hours, minutes, seconds onto the FILO.
   # Use three 'pop' blocks to retrieve these values.
   # Note: because we use a FILO (first in, last out heap),
   # the first value you will pop will be seconds.
   #
   ###########################################################################
   lc.heap.append(localtime().tm_hour)
   lc.heap.append(localtime().tm_min)
   lc.heap.append(localtime().tm_sec)
   return

def myblock(lc, x):
   ###########################################################################
   #
   # Add a third dimension (gray) to the color model.
   #
   ###########################################################################
   val = 0.3 * lc.tw.rgb[0] + 0.6 * lc.tw.rgb[1] + 0.1 * lc.tw.rgb[2]
   if x != 100:
       x = int(x)%100
   r = int((val*(100-x) + lc.tw.rgb[0]*x)/100)
   g = int((val*(100-x) + lc.tw.rgb[1]*x)/100)
   b = int((val*(100-x) + lc.tw.rgb[2]*x)/100)
   # reallocate current color
   rgb = "#%02x%02x%02x" % (r,g,b)
   lc.tw.fgcolor = lc.tw.canvas.cm.alloc_color(rgb)
   return

def myblock(lc, x):
   ###########################################################################
   #
   # Save an image named x to the Sugar Journal.
   #
   ###########################################################################
   lc.tw.save_as_image(str(x))
   return

def myblock(lc, x):

   ###########################################################################
   #
   # Push mouse event to stack
   #
   ###########################################################################
 
   if lc.tw.mouse_flag == 1:
       # push y first so x will be popped first
       lc.heap.append((lc.tw.canvas.height / 2) - lc.tw.mouse_y)
       lc.heap.append(lc.tw.mouse_x - (lc.tw.canvas.width / 2))
       lc.heap.append(1) # mouse event
       lc.tw.mouse_flag = 0
   else:
       lc.heap.append(0) # no mouse event

Device I/O

This Python block returns with the brightness sensor value in the heap. A range of parameters can be measured, for example, substitute any of the path strings in the table for the 'device' in the program below.

device	path	notes
battery current	/sys/devices/platform/olpc-battery.0/power_supply/olpc-battery/current_now	OLPC XO
battery voltage	/sys/devices/platform/olpc-battery.0/power_supply/olpc-battery/voltage_now	OLPC XO
screen brightness	/sys/devices/platform/dcon/backlight/dcon-bl/actual_brightness	OLPC XO
light sensor	/sys/devices/platform/olpc-ols.0/power_state	OLPC XO 1.75
screen mode	/sys/devices/platform/dcon/monochrome

def myblock(tw, x):  # ignores second argument
   import os
  
   # The light sensor is only available on the XO 1.75
   device = '/sys/devices/platform/olpc-ols.0/power_state'
   
   if os.path.exists(device):
       fh = open(device)
       string = fh.read()
       fh.close()
       tw.lc.heap.append(float(string))  # append as float value to heap
   else:
       tw.lc.heap.append(-1)

Look in /sys/devices on your computer to find other devices you may be able to access. Also, if you can work out how to use them...

• accelerometer: /dev/input/event0 ???
• power button: /dev/input/event1
• lid switch: /dev/input/event2
• ebook: /dev/input/event3
• headphone jack: /dev/input/event7
• microphone jack: /dev/input/event8
• rotate, cursor, and game pad keys: /dev/input/event10

def myblock(tw, x):  # ignores second argument
  
  import os
  devicestr='/dev/input/event3'              #the ebook switch
  cmd='sudo chmod 777 {!s}'.format(devicestr)
  os.system(cmd)                             #caution! changing system file permissions
  fd =open(devicestr, 'rb')
  for x in range(12):
     fd.read(1)                              #does not return till the switch state changes
  tw.lc.heap.append( ord(fd.read(1)))        #push ebook switch state to heap
  fd.close

Understanding the structure of the Turtle Art program

Turtle Art offers two blocks for adding Python code,

• the Python function block adds a single line of code,
• the Python code block supports multi-line code.

Python function block

The Python function block is processed through tajail.py. For security reasons, it cannot access Turtle Art objects. It can it only access the Python language and the time and math libraries as the following extract from tajail.py shows.

from time import *
from math import *

For more information on allowable syntax for this block:

• Python language, see http://docs.python.org/tutorial/
• math library, see http://docs.python.org/library/math.html
• time library, see http://docs.python.org/library/time.html
• Numpy library, see numpy.scipy.org/ (Not supported as of v104)

Python code block

Turtle Art is created in object oriented Python code. This is based around the definition of classes and the creation of object(s) which are instance(s) of that class. These objects then have properties and methods which are defined by their class.

See http://docs.python.org/tutorial/classes.html for a description of classes in Python.

See the file TurtleArtActivity.py. This is where it starts. When an instance of TurtleArtActivity is created, setup_canvas() creates an instance of TurtleArtWindow: self.tw This instance of TurtleArtWindow creates an instance of LogoCode: self.tw.lc and an instance of TurtleGraphics: self.tw.canvas

tamyblock.py gets passed a LogoCode instance, lc, and everything is relative to that instance. tw is passed to lc and set as an instance data object at init. This allows referral back to tw when needed. Consequently, Class TurtleArtWindow is accessed through lc.tw. and Class TurtleGraphics is accessed through lc.tw.canvas

Class	Defined in	Instance	Created in
TurtleArtActivity	TurtleArtActivity.py		inherits from sugar.activity
TurtleArtWindow	tawindow.py	tw	TurtleArtActivity.py
LogoCode	talogo.py	lc	tawindow.py
TurtleGraphics	tacanvas.py	canvas	tawindow.py
Turtles, Turtle	taturtle.py	turtles	tawindow.py, tacanvas.py
Blocks, Block	tablock.py	block_list	tawindow.py

Class TurtleArtWindow – useful properties and methods (from within tamyblock.py, lc.tw is the class instance)

Methods and data attributes	Example	Notes
set_fullscreen(self)	lc.tw.set_fullscreen()	Hides the Sugar toolbar
set_cartesian(self, flag)	lc.tw.set_cartesian(True)	True will make the overlay visible; False will make it invisible
set_polar(self, flag)	lc.tw.set_polar(True)	True will make the overlay visible; False will make it invisible
hideshow_button(self, flag)	lc.tw.hideshow_button()	Toggles visibility of blocks and palettes
self.active_turtle	lc.tw.active_turtle	The active turtle instance

Class TurtleGraphics – useful properties and methods (from within tamyblock.py, lc.tw.canvas is the class instance)

Methods and data attributes	Example	Notes
clearscreen(self)	lc.tw.canvas.clearscreen()	Clears the screen and resets all turtle and pen attributes to default values
setpen(self, flag)	lc.tw.canvas.setpen(True)	True will set the pen "down", enabling drawing; False will set the pen "up"
forward(self, n)	lc.tw.canvas.forward(100)	Move the turtle forward 100 units
arc(self, a, r)	lc.tw.canvas.arc(120, 50)	Move the turtle along an arc of 120 degrees (clockwise) and radius of 50 units
setheading(self, a)	lc.tw.canvas.setheading(180)	Set the turtle heading to 180 (towards the bottom of the screen)
self.heading	lc.tw.canvas.heading	The current heading
setpensize(self, n)	lc.tw.canvas.setpensize(25)	Set the turtle pensize to 25 units
self.pensize	lc.tw.canvas.pensize	The current pensize
setcolor(self, c)	lc.tw.canvas.color(70)	Set the pen color to 70 (blue)
self.color	lc.tw.canvas.color	The current pen color
setshade(self, s)	lc.tw.canvas.shade(50)	Set the pen shade to 50
self.shade	lc.tw.canvas.shade	The current pen shade
fillscreen(self, c, s)	lc.tw.canvas.fillscreen(70, 90)	Fill the screen with color 70, shade 90 (light blue)
setxy(self, x, y)	lc.tw.canvas.setxy(100,100)	Move the turtle to position (100, 100)
self.xcor	lc.tw.canvas.xcor	The current x coordinate of the turtle (scaled to current units)
self.ycor	lc.tw.canvas.ycor	The current y coordinate of the turtle (scaled to current units)
self.set_turtle(name)	lc.tw.canvas.set_turtle(1)	Set the current turtle to turtle '1'

Other useful Python functions

Module	Methods and data attributes	Example	Notes
from math import pow	pow(2,3)	returns 2 to the 3rd power (8)	See http://docs.python.org/library/math.html
from math import sin, pi	sin(45*pi/180)	returns sin of 45 (0.707)	See http://docs.python.org/library/math.html
from time import localtime	localtime().tm_hour	returns the current hour	See http://docs.python.org/library/time.html
	lc.heap.append(data)	add data to the FILO	See http://docs.python.org/tutorial/datastructures.html
	data = lc.heap.pop(-1)	pop data off of the FILO	See http://docs.python.org/tutorial/datastructures.html