Python Code for creating Screen saver

This is the Python code for creating a screensaver of a moving ball. The ball will bee moving along the screen and when it hits any of the edges it will bounce back. If Python is installed in your mobile you can edit this code and create your own screen savers.

import appuifw
from graphics import *
import e32
from key_codes import *

class Keyboard(object):
    def __init__(self,onevent=lambda:None):
        self._keyboard_state={}
        self._downs={}
        self._onevent=onevent
    def handle_event(self,event):
        if event['type'] == appuifw.EEventKeyDown:
            code=event['scancode']
            if not self.is_down(code):
                self._downs[code]=self._downs.get(code,0)+1
            self._keyboard_state[code]=1
        elif event['type'] == appuifw.EEventKeyUp:
            self._keyboard_state[event['scancode']]=0
        self._onevent()
    def is_down(self,scancode):
        return self._keyboard_state.get(scancode,0)
    def pressed(self,scancode):
        if self._downs.get(scancode,0):
            self._downs[scancode]-=1
            return True
        return False
keyboard=Keyboard()


appuifw.app.screen='full'
img=None
def handle_redraw(rect):
    if img:
        canvas.blit(img)
appuifw.app.body=canvas=appuifw.Canvas(
    event_callback=keyboard.handle_event,
    redraw_callback=handle_redraw)
img=Image.new(canvas.size)


running=1
def quit():
    global running
    running=0
appuifw.app.exit_key_handler=quit

location=[img.size[0]/2,img.size[1]/2]
speed=[0.,0.]
blobsize=16
xs,ys=img.size[0]-blobsize,img.size[1]-blobsize
gravity=0.03
acceleration=0.05



import time
start_time=time.clock()
n_frames=0

labeltext=u'Use arrows to move ball'
textrect=img.measure_text(labeltext, font='normal')[0]
text_img=Image.new((textrect[2]-textrect[0],textrect[3]-textrect[1]))
text_img.clear(0)
text_img.text((-textrect[0],-textrect[1]),labeltext,fill=0xffffff,font='normal')



while running:
    img.clear(0)
    img.blit(text_img, (0,0))
    img.point((location[0]+blobsize/2,location[1]+blobsize/2),
              0x00ff00,width=blobsize)
    handle_redraw(())
    e32.ao_yield()
    speed[0]*=0.999
    speed[1]*=0.999
    speed[1]+=gravity
    location[0]+=speed[0]
    location[1]+=speed[1]
    if location[0]>xs:
        location[0]=xs-(location[0]-xs)
        speed[0]=-0.80*speed[0]
        speed[1]=0.90*speed[1]
    if location[0]<0:
        location[0]=-location[0]
        speed[0]=-0.80*speed[0]
        speed[1]=0.90*speed[1]
    if location[1]>ys:
        location[1]=ys-(location[1]-ys)
        speed[0]=0.90*speed[0]
        speed[1]=-0.80*speed[1]
    if location[1]<0:
        location[1]=-location[1]
        speed[0]=0.90*speed[0]
        speed[1]=-0.80*speed[1]
        
    if keyboard.is_down(EScancodeLeftArrow):  speed[0] -= acceleration
    if keyboard.is_down(EScancodeRightArrow): speed[0] += acceleration
    if keyboard.is_down(EScancodeDownArrow):  speed[1] += acceleration
    if keyboard.is_down(EScancodeUpArrow):    speed[1] -= acceleration
    if keyboard.pressed(EScancodeHash):
        filename=u'e:\\screenshot.png'
        canvas.text((0,32),u'Saving screenshot to:',fill=0xffff00)
        canvas.text((0,48),filename,fill=0xffff00)
        img.save(filename)

    n_frames+=1
end_time=time.clock()
total=end_time-start_time

print "%d frames, %f seconds, %f FPS, %f ms/frame."%(n_frames,total,
                                                     n_frames/total,
                                                     total/n_frames*1000.)