Activities/Turtle Art/Programmable Brick

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Programmable Brick

The following feature—a block Pythoncodeblock.jpg 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. TAPippyButton.svg You can only have one type of Python block in your Turtle Art program.


TA-pippy.png

Another way to load the Python block, is to click the Python code block Pythoncodeblock.jpg 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 Loadpythonsamples.jpg 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.

Pythonsampleselector.jpg

loading code from the Journal

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

Pythonobjectselector.jpg

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

TA-dotted-line.png 

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.

TA-rgb.png 

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 these strings for the string in the program below.

  • /sys/devices/platform/olpc-battery.0/power_supply/olpc-battery/current_now
  • /sys/devices/platform/olpc-battery.0/power_supply/olpc-battery/voltage_now
  • /sys/devices/platform/dcon/backlight/dcon-bl/actual_brightness


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(int(string))  # append as integer value to heap
   else:
       tw.lc.heap.append(-1)

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

Understanding the structure of the Turtle Art program

Turtle Art offers two blocks for adding Python code,

  • the Python function block Pythonfunctionblock.jpg adds a single line of code,
  • the Python code block Pythoncodeblock.jpg 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 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
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