How to generate graphics in Python

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Reviewer Approved

Introduction

This articles demonstrates generation of graphics for S60 devices. The simplest mobile application development tool, PYS60,is used to develop this GraphicsGenerator.

Basically, the code snippet given in this article generates beautiful patterns (slide strokes for now) of the desired colour and latency (a parameter to interpret the pattern).

Features

Generates slide stroke patterns.
Supports all colours.
Support for random colours.
Supports 30 different patterns - all slide strokes.
Graphics generated can be saved.

Usage

The following modules are used when developing this application:

appuifw module
os module
graphics module
e32 module
key_codes module
random module
math module
time module

The following functions are used to create GraphicsGenerator:

save(): save the screenshots of Graphicsgenerator
draw_screen(): draw the screen on canvas
Start(): create a different pattern on canvas

These all functions are defined in source code in detail.

Source code

The code for the GraphicsGenerator is below.

#
# Graphics Generator
# 
 
'''
1.00 2009-07-05 Initial release
'''
 
VERSION = "1.00"
 
# importing the necessary modules
import e32,random
import time
import appuifw, os
import graphics, time
import math
 
# define color code
BLACK=(0,0,0)
RED=(255,0,0)
GREEN=(0,255,0)
BLUE=(0,0,255)
WHITE=(255,255,255)
running=1
 
#initializing  pattern
pattern=30
 
 
# Define the exit function
app_lock = e32.Ao_lock()
def quit():
	global running
	running=0
	app_lock.signal()
appuifw.app.exit_key_handler = quit
 
# Defining the save function for Screeenshots
def save():
	dirpath="C:\\GraphicsGenerator"
	try:
		os.mkdir(dirpath)
	except: pass
 
	# Sleep for 1 second
	e32.ao_sleep(1)
 
	# This function converts the current view to the new images
	image=graphics.screenshot()
 
	#current time is return by this function
	s = time.ctime()[11:19]
 
	# This is the path and name for storing the screenshots
	image.save(dirpath+"\\screenshot.jpg")
	appuifw.note(u"Saved to "+ unicode(dirpath))
 
#Define a function that will be called when the canvas needs to be redrawn
def handle_redraw(rect):    
   canvas.blit(img)
 
#define the draw function
def draw_screen():
 
       #Set the screen to full
       appuifw.app.screen = 'full' 
 
       #Global variable for application UI
       global canvas
 
       #Create an instance of Canvas and set it as the application's body
 
       canvas = appuifw.Canvas(redraw_callback=handle_redraw)    
       appuifw.app.body = canvas
       appuifw.app.exit_key_handler = quit
 
       #Global variable for application UI
       global img
       img = graphics.Image.new(canvas.size)
 
       #Clear the image
       img.clear(BLACK)
       handle_redraw(None)
 
def menu_about():
        ''' Callback for menu item About '''
 
	   appuifw.note(u"Graphics Generator  version 1.0"+"\n Developed by Nirpsis")	
 
#defining start function
 
def start():
	global running, pattern
	running=0
	UserWantRandom=0
 
	# Define x & y coordinate
	x=120
	y=160
	acelX=-1
	acelY=-1
	appuifw.note(u"Choose the colour of the pattern")
	L=[u"Red", u"Blue", u"Green", u"White", u"Random",u"Manual Colour"]
 
	#Selectionlist allows the user to select the list items
	i = appuifw.selection_list(L, search_field=1)
	if (i==0): COLOR=RED
	if (i==1): COLOR=BLUE
	if (i==2): COLOR=GREEN
	if (i==3): COLOR=WHITE
	if (i==4): UserWantRandom=1
	if (i==5): 
		a=appuifw.query(u"Enter Red concentration 0-255", "number")
		if a>255 or a<0:
			a=255
		b=appuifw.query(u"Enter Green concentration 0-255", "number")
		if b>255 or b<0:
			b=255
		c=appuifw.query(u"Enter Blue concentration 0-255", "number")
		if c>255 or c<0:
			c=255
		COLOR=(a,b,c)
	else: 
		quit()
 
	pattern=appuifw.query(u"Enter patter 1-30", "number")
	if pattern>30 or pattern<1:
		pattern=30
 
	# Calling the draw_screen function	
	draw_screen()
	running=1
 
	# Main loop
	while running:
		if x<0:
			if acelX==1:
				acelX=-1
			else:
				acelX=1
		if y<0:
			if acelY==1:
				acelY=-1
			else:
				acelY=1
		if x>240:
			if acelX==1:
				acelX=-1
			else:
				acelX=1
 
		if y>320:
			if acelY==1:
				acelY=-1
			else:
				acelY=1
 
		if(y <= 0):
			y = 0;
		if(y >= 320):
			y = 320;
		if(x <= 0):
			x = 0;
		if(x >= 240):
			x = 240;
 
        #defining the position of the points
 
		x = x * acelX
		y=y * acelY
		x=x+pattern
		y=y+pattern
		if UserWantRandom==1:
 
		        #below script draws random points
			#defining the colours of points
			a=random.randint( 0, 255)
			b=random.randint( 0, 255)
			c=random.randint( 0, 255)
			COLOR=(a,b,c)
 
	        # Drawing points		
		img.point((x,y),outline=COLOR,width=15)
 
		# Sleep for 0.01
		e32.ao_sleep(0.01)
		e32.ao_yield()
 
		# Main menu
		appuifw.app.menu = [(u"Save Graphics", save), (u"Start again", start),(u"About", menu_about), (u"Exit", quit)]
		handle_redraw(None)
start()
app_lock = e32.Ao_lock()
 
#Wait for the user to request the exit
app_lock.wait()