Archived:A color picker in PySymbian
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The article is believed to be still valid for the original topic scope.
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When you want to let the user choose a color for a GUI element you need to display colors without annoying the user with technical details about RGB values! This example shows you a way to do it.
Remark : this code is using the easy keyboard handling method.
# Usual code as always
import e32
from appuifw import *
from key_codes import *
class Keyboard(object):
def __init__(self):
self.state = {} # is this key pressing ?
self.buffer= {} # is it waiting to be processed ?
def handle_event(self, event): # for event_callback
code = event['scancode']
if event['type'] == EEventKeyDown:
self.buffer[code]= 1 # put into queue
self.state[code] = 1
elif event['type'] == EEventKeyUp:
self.state[code] = 0
def pressing(self, code): # just check
return self.state.get(code,0)
def pressed(self, code): # check and process the event
if self.buffer.get(code,0):
self.buffer[code] = 0 # take out of queue
return 1
return 0
key = Keyboard()
app.body = canvas = Canvas(event_callback=key.handle_event)
def quit():
global running
running = 0
app.exit_key_handler = quit
running = 1
ff00 = range(0xff, -1, -0x33)
pal = [(r,g,b) for r in ff00 for g in ff00 for b in ff00] # web-safe 216 colors
map_j = range(0,12,2)+range(11,0,-2) # make better grouping
for j in range(12):
for i in range(18):
k = 18*map_j[j] + i
canvas.rectangle([(9*i+1, 9*j+1), (9*i+9, 9*j+9)], None, pal[k])
def clear_box(color=0xffffff):
global x,y
canvas.rectangle([(9*x, 9*y), (9*x+10, 9*y+10)], color) # cursor
x, y = 0, 0
black_white = 0
while running:
if key.pressed(EScancodeLeftArrow):
clear_box()
if x > 0: x -= 1
if key.pressed(EScancodeRightArrow):
clear_box()
if x < 17: x += 1
if key.pressed(EScancodeUpArrow):
clear_box()
if y > 0: y -= 1
if key.pressed(EScancodeDownArrow):
clear_box()
if y < 11: y += 1
if key.pressed(EScancodeSelect):
color = pal[18*map_j[y] + x]
canvas.rectangle([(1,109), (17*9+9,130)], None, color) # show color
black_white ^= 0xffffff # toggle
clear_box(black_white)
e32.ao_sleep(0.2)
Hi Girish,
Its perfectly OK to have references/citations listed if you have used them in your article. These references are helpful to the readers and increase the possibility of discovering more related information for them. In short, they add more value to your articles.
--croozeus 07:46, 4 April 2011 (UTC)
Hi Pankaj,
I am not original author of this article. I have just edited to make more readable to users.
Hi Girish,
I can now see that you are not the original author of this article. Sorry for the nitpick
--croozeus 17:14, 4 April 2011 (UTC)