Categories: S60 | Python | How To | Code Examples | UI

This page was last modified 16:22, 24 March 2008.

From Forum Nokia Wiki

Method 1

Nokia offers a keyboard class in the code examples but often it's too complex to handle. Here's a more convenient and easy way to handle keypress. Add this class Keyboard.

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

Now you can check the keyboard status with key.pressing and key.pressed:

from appuifw import *
 
key = Keyboard()
app.body = canvas = Canvas(event_callback=key.handle_event)
 
print key.state   # just pressed up arrow {17: 0}
print key.buffer  # {17: 1}
print key.pressing(EScancodeUpArrow)  # it's not pressing = 0
print key.pressed(EScancodeUpArrow)   # yes, it's pressed = 1
print key.pressed(EScancodeUpArrow)   # no, you've just processed it = 0

Remarks : Don't put it in another module because it doesn't work ! Put it directly in your main code !

Method 2

An alternate, but very similar method is to define the class like this:

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()

and to create a loop that checks for keypresses:

import e32, appuifw
 
canvas=appuifw.Canvas(event_callback=keyboard.handle_event, redraw_callback=None)
appuifw.app.body=canvas
 
running=1
while(running==1):
    if(keyboard.pressed(EScancodeRightArrow)):  #If the specified key is pressed
         print "Right arrow key was pressed"
    if(keyboard.pressed(EScancodeRightSoftkey)):
         running=0                                #Break the loop
    e32.ao_yield()