This page was last modified on 7 September 2007, at 10:48.
A 100% Python implemented Listbox base class
From Forum Nokia Wiki
When getting the specifications for my Python framework for S60, it appeared that the listbox wrappers provided by PyS60 did not satisfy the requirements.
I needed for example to have a listbox style with three lines of text items displaying the description of some articles.
Another one was to have the same 3 lines description item but also with a picture thumbnail on the left part of it.
In addition I needed to have a callback called every time the current focused object changed in order to set/dim the menu depending on one condition to another.
The easiest way (not the best performances) was to re-implement the listbox object in Python.
The source below is the base class I'm using for all the listboxes styles. I freshly modified it today since I had a chance to have a N93. Switching the view to portrait or landscape is now handled as well as the recalculation of the elements to be displayed on the canvas.
Contents |
Source
import appuifw, e32
from key_codes import EScancodeUpArrow, EScancodeDownArrow, EScancodeSelect
from graphics import Image
try:
from akntextutils import wrap_text_to_array
except:
import sys
sys.exit("akntextutils module isn't installed!")
## Keyboard handler class.
class Keyboard( object ):
## The constructor
# @param self The object pointer
# @param aOnevent An optional function that can be called on events
def __init__( self, aOnevent=lambda:None ):
## Keboard state dictionnary
self._keyboard_state = { }
## Key down dictionnary
self._downs = { }
## User defined callback function run when an event occures
self._onevent = aOnevent
## Event handler
# @param self The object pointer
# @param aEvent Event detected
def handle_event( self, aEvent ):
if aEvent['type'] == appuifw.EEventKeyDown:
code = aEvent['scancode']
if not self.is_down( code ):
self._downs[code] = self._downs.get( code, 0 ) + 1
self._keyboard_state[code] = 1
elif aEvent['type'] == appuifw.EEventKeyUp:
self._keyboard_state[aEvent['scancode']] = 0
self._onevent( )
## Detects if the given keycode key is down
# @param self The object pointer
# @param aScancode key code
def is_down( self, aScancode ):
return self._keyboard_state.get( aScancode, 0 )
## Returns true if the given keycode key has been pressed
# @param self The object pointer
# @param aScancode Key code
def pressed( self, aScancode ):
if self._downs.get( aScancode, 0 ):
self._downs[aScancode] -= 1
return True
return False
## Base class for creating custom listboxes.
# @todo Find a way to automatically calculate the scroll factor and the line
# spacing with scallable fonts.
class ListBaseClass( object, appuifw.Canvas ):
# private const class variables
## Background color for the list
_iBackgroundColor = 0xffffff
## Current item focus
_iCurrentFocus = 0
## Default text font
_iDefaultFont = 'dense'
## Value used to display the selection rectangle at the right line
_iFactor = 1
## Selection background color
_iFocusBackgroundColor = 0xc3d9ff
## Selection outline color
_iFocusOutlineColor = 0x0000ff
## Line space
_iLineSpace = 13
## Lines color ( here black )
_iLineColor = 0x000000
## Maximum item to be displayed. By default 5 it is recalculated for each
# new view.
_iMaxItem = 5
## When True, elements are drawn
_iReady = False
## Scrollbar outline color
_iScrollbarOutlineColor = 0x000000
## Scrollbar cursor outline color
_iScrollbarCursorOutlineColor = 0x0000ff
## Scrollbar cursor fill color
_iScrollbarCursorFillColor = 0xc3d9ff
## Scroll translation factor in pixel
_iScrollFactor = 25
## Text color
_iTextColor = 0x000000
## Text x origin in pixel
_iXText = 25
## Text y origin in pixel
_iYText = 20
# public methods
############################################################################
## The constructor.
# @param self The object pointer
# @param aUserCallback User defined callback method or function. Return
# current focus id when select key it pressed
# @param aItems List of items to display
# @param aScrollY By defaul True. Display scrollbar or not
# @param aMenuDimmer Send signal to the menu dimmer callback if set.
def __init__( self, aUserCallback, aItems, aMenuDimmer=lambda:None,
aScrollY=True ):
## User defined callback method
self._mUserCallback = aUserCallback
## List of unformated items to be displayed
self._iRawItems = aItems
## List of formated items to be displayed
self._iItems = None
## If True, the scrollbar will be displayed
self._iScrollY = aScrollY
## Send signal to the menu dimmer callback if set
# added on 2007-03-22: missing feature
self._mMenuDimmer = aMenuDimmer
## Current item focus
self._iCurrentFocus = 0
## Keyboard handler instance
self._iKeyboard = Keyboard ( self._eventCallback)
appuifw.Canvas.__init__( self,
self._redrawCallback,
self._iKeyboard.handle_event,
self._resizeCallback)
self._formatData( )
self._iReady = True
## Returns the current focus number.
# @param self The object pointer
def current( self ):
return self._iCurrentFocus
## Sets new content for the list class object.
# @param self The object pointer
# @param aItems set a new list to the listbox object
def set( self, aItems ):
self._iItems = aItems
self._formatData( )
self._redrawCallback( )
# Shows the list on the application body.
# @param self reference
def show( self ):
appuifw.app.body = self
self._redrawCallback()
# private methods
###########################################################################
## Calculate the focus factor (_iFactor) depending on the set
# self._iScrollFactor. It shouldn't need to be overwridden.
# @param self The object pointer
def _calculateFocus( self ):
if self._iCurrentFocus == 0:
## Value used to start displaying the items
self._iScroll = 0
## Value used to display the selection rectangle at the right line
self._iFactor = 0
# last item with bottom caption when selecting up
elif self._iCurrentFocus == len( self._iItems ) - 1 and \
self._iScroll == 0:
if len( self._iItems ) < self._iMaxItem:
self._iFactor = ( len( self._iItems ) - 1 ) * \
self._iScrollFactor
else:
self._iScroll = self._iCurrentFocus - ( self._iMaxItem - 1 )
self._iFactor = ( self._iMaxItem - 1 ) * self._iScrollFactor
# no scroll made and 0 <= focus < max item
elif self._iCurrentFocus < self._iMaxItem and self._iScroll == 0:
self._iScroll = 0
self._iFactor = self._iCurrentFocus * self._iScrollFactor
# first scroll down caption down
elif self._iCurrentFocus == self._iMaxItem and self._iScroll == 0:
self._iFactor = ( self._iMaxItem - 1 ) * self._iScrollFactor
self._iScroll += 1
# increment scroll
elif self._iScroll != 0 and \
( self._iCurrentFocus - self._iMaxItem ) == self._iScroll:
self._iFactor = ( self._iMaxItem - 1 ) * self._iScrollFactor
self._iScroll += 1
elif self._iCurrentFocus >= self._iMaxItem and self._iScroll != 0:
if ( self._iCurrentFocus - ( self._iMaxItem - 1 ) ) == 0:
self._iScroll -= 1
self._iFactor = 0
else:
self._iFactor = ( self._iCurrentFocus - self._iScroll ) * \
self._iScrollFactor
if self._iFactor < 0:
self._iFactor = 0
self._iScroll -= 1
elif self._iCurrentFocus < self._iMaxItem and self._iScroll != 0:
if self._iCurrentFocus == ( self._iScroll - 1 ):
self._iScroll -= 1
self._iFactor = 0
elif self._iCurrentFocus == self._iScroll:
self._iFactor = 0
else:
self._iFactor = ( self._iCurrentFocus - self._iScroll ) * \
self._iScrollFactor
## Key down, scrolls down. Shouldn't need to be overridden.
# @param self The object pointer
def _down( self ):
self._iCurrentFocus += 1
if self._iCurrentFocus == len( self._iItems ):
self._iCurrentFocus = 0
# send signal to menu dimmer
if self._mMenuDimmer:
self._mMenuDimmer( )
self._redrawCallback( )
## Draw the focus; here a rectangle caption. Overwrite it for your need.
# @param self The object pointer
def _drawFocus( self ):
self.rectangle( ( 1, 5 + self._iFactor, ( self.size[0] - 4 ), 25 + \
self._iFactor ),
outline=self._iFocusOutlineColor,
fill=self._iFocusBackgroundColor )
## Method for redrawing elements on the screen. Overwrite it for your need
# @param self The object pointer
def _drawItems( self ):
self.clear( self._iBackgroundColor )
if self._iReady:
yText = self._iYText
# vertical left side line
self.line( ( 20, 0, 20, self.size[1] ), outline=self._iLineColor)
# horizontal bottom line
self.line( ( 20, self.size[1]-1, self.size[0], self.size[1]-1 ), \
outline=self._iLineColor)
self._drawFocus( )
for item in self._iItems[self._iScroll : self._iScroll + \
self._iMaxItem]:
self.text( ( self._iXText, yText ), item,
font = self._iDefaultFont )
yText += 25
## Method for drawing the scrollbar. Overwrite it for your need.
# @param self The object pointer
def _drawScrollbar( self ):
if self._iScrollY and len( self._iItems ) > self._iMaxItem:
height = float ( ( self.size[1] - 1 ) / ( len( self._iItems ) ) )
y = float( ( self._iCurrentFocus * height ) + 1 )
self.line( ( self.size[0] - 2, 0, self.size[0] - 2, self.size[1]),
outline=self._iScrollbarOutlineColor)
self.rectangle( ( self.size[0] - 3, y, ( self.size[0] ), y + \
height),
outline=self._iScrollbarCursorOutlineColor,
fill=self._iScrollbarCursorFillColor)
## Envent callback method ( does not support repeat when long press ).
# Shouldn't need to be overwrited except if you want to add a binding
# method for keyboard.
# @param self The object pointer
# @param aEvent Event code
def _eventCallback( self ):
if self._iKeyboard.pressed( EScancodeUpArrow ):
self._up( )
elif self._iKeyboard.pressed( EScancodeDownArrow ):
self._down( )
elif self._iKeyboard.pressed( EScancodeSelect ):
if self._mUserCallback != None:
self._mUserCallback( self.current( ) )
## Format data to the appropriate form you want. Might need to be
# overridden.
# @param self The object pointer
def _formatData( self ):
tempList = []
for item in self._iRawItems:
lines = wrap_text_to_array( item, self._iDefaultFont,
self.size[0] - self._iXText - 5 )
# here I want to keep only the first line if oversized line
if len(lines) > 1:
tempList.append( lines[0] + u'...' )
else:
tempList.append( lines[0] )
self._iItems = tempList
## Redraw callback method. Shouldn't need to be overwrited.
# @param self The object pointer
# @param aRect Attribute value sent by the Canvas object
def _redrawCallback( self, aRect=None ):
self._calculateFocus( )
self._drawItems( )
self._drawScrollbar( )
## Key up, scrolls up. Shouldn't need to be overwrited.
# @param self The object pointer
def _up( self ):
self._iCurrentFocus -= 1
# it means we want the last item of the list
if self._iCurrentFocus == -1:
self._iCurrentFocus = len( self._iItems ) - 1
# send signal to menu dimmer
if self._mMenuDimmer:
self._mMenuDimmer( )
self._redrawCallback( )
## Recalculate how many items can be displayed on the screen.
# @param self The object pointer.
# @param aClientRect two-element tuple that contains the new clientRect
# width and height sent by the canvas object.
def _resizeCallback( self, aClientRect=None ):
try:
oldValue = self._iMaxItem
self._formatData()
self._iMaxItem = int(self.size[1]/self._iScrollFactor)
# if the scrren is switched from portrait to landscape and, the item
# the current item may become focused but invisible. A scroll
# adjustement is needed
self._iScroll += oldValue - self._iMaxItem
if self._iScroll < 0 :
self._iScroll = 0
except:
pass
Usage
SCRIPT_LOCK = e32.Ao_lock( )
def mainCallback( aId ):
print aId
def menuDimmerCallback():
if lb :
appuifw.app.menu = [(u'item %s menu'%str(lb.current()+1), lambda:None)]
def __exit__( ):
SCRIPT_LOCK.signal( )
appuifw.app.exit_key_handler = __exit__
appuifw.app.title= u'ListBaseClass'
llist = [u'item1 item1 item1 item1 item1 item1 item1', u'item2', u'item3',
u'item4', u'item5', u'item6', u'item7', u'item8', u'item9',
u'item10',u'item11', u'item12', u'item13',u'item14', u'item15',
u'item16', u'item17' ]
lb = ListBaseClass( mainCallback, llist, menuDimmerCallback )
lb.show( )
menuDimmerCallback()
SCRIPT_LOCK.wait( )
Screenshots
 Python Listbox Portrait: the first line is too long to be displayed completely; marquees are added (small issue with wrap_text_to_array: the line should be displayed completely...) |
 Python Listbox Landscape: the first line is displayed completely |
 Python Listbox Menu Dimmer: in this screenshot pay attention to "item 5 menu" updated during the navigation |
Remarks
You can easily create new listbox style with this base class by inheriting this base class and overwriting a few methods. I could post some examples later on.
You can see other styles I made on my thesis client, maybe it could give you some ideas.
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