Archived:How to develop brick-breaker game in PySymbian - Part 1
The article is believed to be still valid for the original topic scope.
Brick-Breaker is a simple arcade game where the player moves a paddle on the screen and bounces a ball towards bricks at the top of the screen. When the ball hits a brick it breaks and the ball bounces back - the objective of the game is to destroy all the bricks. This is the first article explaining the PySymbian implementation of Brick-Breaker - it covers the different slider functions in detail.
02 Aug
2009
Contents |
Development tools
- Text editor - notepad is sufficient.
- PySymbian - preferred version: PySymbian 1.4.5 stable release
- PySymbian script shell - preferred version: PySymbian 1.4.5 stable release
The PySymbian tools can be downloaded from Sourceforge resources.
The following modules are used when developing this application:
- appuifw module
- sysinfo module
- graphics module
- e32 module
- key_codes module
- random module
- math module
- time module
Functions
The following functions are used in Brick Breaker game.
- draw_screen: draw black screen in canvas.
- draw_slider: draw slider.
- leftkey: control the slider by left key.
- rightkey: control the slider by right key.
- draw_bricks: draw number of bricks.
- erase_bricks: erase bricks.
Initializing slider parameter
Before discussing, any functions in detail - let us define some of the slider parameters.
#SLIDER PARAMETERS#####
SliderX1=120
SliderY1=305
SliderX2=160
SliderY2=315
SliderSpeed=22
SliderColor=RED
import sysinfo
TotalScreenWidth=sysinfo.display_pixels()[1]
draw_screen()
By using this function, We create a black screen in canvas. The definition of the draw_screen() is as follows:
#defining draw function
def draw_screen():
#Set the screen to full
appuifw.app.screen = 'full'
#Global variable for application UI
global canvas
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)
draw_slider()
By using this function, we create a slider in canvas using keyboard shortcuts. The definition of the draw_screen() is as follows:
#defining slider function
def draw_slider():
global canvas
#Keyboard shortcuts
canvas.bind(key_codes.EKeyLeftArrow,lambda: leftkey())
canvas.bind(key_codes.EKeyRightArrow,lambda: rightkey())
appuifw.app.body = canvas
appuifw.app.exit_key_handler = quit
#draw the rectangle
img.rectangle((SliderX1,SliderY1,SliderX2,SliderY2),fill=SliderColor)
handle_redraw(None)
leftkey()
The leftkey() is called from the draw_slider() function. By using this function, we can move the slider to left side by pressing left key. Thus, the code of leftkey() function is as follows:
#defining leftkey function
def leftkey():
if (SliderX1>0):
#draw the rectangle
img.rectangle((SliderX1, SliderY1, SliderX2, SliderY2),fill=BLACK)
#globally define variables
global img, canvas,SliderX1, SliderY1, SliderX2, SliderY2
#defining the slider coordinate X1 and X2
SliderX1=SliderX1-SliderSpeed
SliderX2=SliderX2-SliderSpeed
img.rectangle((SliderX1, SliderY1, SliderX2, SliderY2),fill=SliderColor)
#appuifw.note(u"Left arrow was pressed")
handle_redraw(None)
rightkey()
The rightkey() is called from the draw_slider() function. By using this function, we can move the slider to right side by pressing right key. Thus the code of rightkey() function is as follows:
#defining right key function
def rightkey():
if (SliderX2<TotalScreenWidth):
#if (SliderX2<sysinfo.display_pixels()[1]):
#draw rectangle
img.rectangle((SliderX1, SliderY1, SliderX2, SliderY2),fill=BLACK)
#globally define variables
global img, canvas,SliderX1, SliderY1, SliderX2, SliderY2
#defining the slider coordinate X1 and X2
SliderX1=SliderX1+SliderSpeed
SliderX2=SliderX2+SliderSpeed
img.rectangle((SliderX1, SliderY1, SliderX2, SliderY2),fill=SliderColor)
#appuifw.note(u"Left arrow was pressed")
handle_redraw(None)
That finishes the slider functions (Part 1) for the Brick-Breaker Game.
The next article in the series : Part 2 for brick-Breaker, would cover Brick functions for this game.
Screenshots
These screenshots demonstrate the Slider and its movable position on canvas. The screenshots are relevant only to Part 1.
