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Archived:How to develop a Geo-scheduler application - Part 1

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== Introduction ==
 
== Introduction ==
 
  
 
Do you want to develop location-based applications?  
 
Do you want to develop location-based applications?  
  
This article is the first in a series approaching all the basics for developing a location-based application for mobile device. The application can be defined as a Geo-Scheduler or a Location scheduler. The simplest rapid mobile application development tool, [[PyS60]], is used to develop the application.
+
This article is the first in a series approaching all the basics for developing a location-based application for mobile devices. The application can be defined as a Geo-Scheduler or a Location scheduler. The simplest rapid mobile application development tool, [[PyS60]], is used to develop the application.
  
The following modules are used to develop this application:
+
The following modules are used when developing this application:
  
 
*appuifw module
 
*appuifw module
Line 28: Line 27:
  
  
The extensions mentioned above can be downloaded from the [[C++ Python Extensions]].
+
The extensions listed above can be downloaded from the [[C++ Python Extensions]].
  
 
== Development tools ==
 
== Development tools ==
Line 52: Line 51:
 
== Basic approach ==
 
== Basic approach ==
  
In this application, localization is done using the network info. The network info can be provided using the location module, ''cellid''. If you are not familiar with retrieving the cellid using Pys60, using the appswitch module, usingthe envy module, read the following articles before proceeding.  
+
In this application, localization is done using the network information. The network information can be provided using the location module, ''cellid''. If you are not familiar with retrieving the cellid using Pys60, using the appswitch module, or using the envy module, read the following articles before you proceed.  
  
 
[[How to switch application in foreground]]
 
[[How to switch application in foreground]]
Line 63: Line 62:
 
==Methods and functions==
 
==Methods and functions==
  
The following methods or functions will be used:
+
The following methods or functions are used:
  
 
===File functions ===
 
===File functions ===
  
1) save_location: Save location information into file
+
1) <tt>save_location</tt>: Save location information into file
  
2) load_location: Read location information into variables
+
2) <tt>load_location</tt>: Read location information into variables
  
3) save_reminder: Save reminder information into a file
+
3) <tt>save_reminder</tt>: Save reminder information into a file
  
4) load_reminder: Read reminder information into variables
+
4) <tt>load_reminder</tt>: Read reminder information into variables
  
5) dictionary_copy: Dictionary copy
+
5) <tt>dictionary_copy</tt>: Dictionary copy
  
6) location_list: Return the location names
+
6) <tt>location_list</tt>: Return the location names
  
  
Line 84: Line 83:
  
  
1) add_location: Add a new location
+
1) <tt>add_location</tt>: Add a new location
  
2) edit_location: Edit a location
+
2) <tt>edit_location</tt>: Edit a location
  
3) add_reminder: Add a new reminder
+
3) <tt>add_reminder</tt>: Add a new reminder
  
4) edit_reminder: Editing screen function
+
4) <tt>edit_reminder</tt>: Editing screen function
  
5) edit_reminder_bylocation: Edit reminder by location function
+
5) <tt>edit_reminder_bylocation</tt>: Edit reminder by location function
  
6) edit_reminder_byreminder: Edit reminder by reminder function
+
6) <tt>edit_reminder_byreminder</tt>: Edit reminder by reminder function
  
  
Line 100: Line 99:
  
  
1) ms_handler: MS option handler
+
1) <tt>ms_handler</tt>: MS option handler
  
2) main: Start program
+
2) <tt>main</tt>: Start program
  
3) tracker: Main tracker function
+
3) <tt>tracker</tt>: Main tracker function
  
4) background_handler: Background handler options
+
4) <tt>background_handler</tt>: Background handler options
  
  
Line 118: Line 117:
  
  
This function adds the location information to the database file.
+
This function adds the location information to the database file. A file handler named <tt>file_handler</tt> is created to handle file operations. A .dat file specified by the variable <tt>file_handler_location</tt> is accessed here. In this example, the  <tt>location.dat</tt> file is in C:, and it is assigned to the <tt>file_handler_location</tt>.
  
A file handler named file_handler is created to handle file operations. A .dat file specified by the variable file_handler_location is accessed here. In this example, the  location.dat file is in C:, and it is assigned to the file_handler_location.
+
'''Note:''' <tt>location.dat</tt> contains locations added by the <tt>save_location()</tt> function.
 
+
'''Note:''' location.dat contains locations added by the save_location() function.
+
  
 
<code python>
 
<code python>
Line 130: Line 127:
 
The geo and cellids are populated before running the file functions to NULL.
 
The geo and cellids are populated before running the file functions to NULL.
  
'''Note:''' The geo and cellids must be cleared by using the clear() function so that they do not contain any previously used values.
+
'''Note:''' The geo and cellids must be cleared by using the <tt>clear()</tt> function so that they do not contain any previously used values.
  
The definition for the save_location() function is as follows:
+
The definition for the <tt>save_location()</tt> function is as follows:
  
 
<code python>
 
<code python>
Line 149: Line 146:
 
</code>
 
</code>
  
The function dictionary_copy(cellids) is defined [http://wiki.forum.nokia.com/index.php/How_to_develop_a_Geo-scheduler_application_-_Part_1#dictionary_copy.28dictionary.29 here].
+
The function <tt>dictionary_copy(cellids)</tt> is defined [http://wiki.forum.nokia.com/index.php/How_to_develop_a_Geo-scheduler_application_-_Part_1#dictionary_copy.28dictionary.29 here].
  
  
Line 158: Line 155:
 
This function is responsible for loading the locations into variables. Here the value of the cellid is stored into variables.
 
This function is responsible for loading the locations into variables. Here the value of the cellid is stored into variables.
  
The same file_handler and the fil_handler_location are used to access the location.dat this time to read the location values.
+
The same <tt>file_handler</tt> and the <tt>file_handler_location</tt> are used to access the <tt>location.dat</tt> this time to read the location values.
  
 
<code python> file_handler = file(file_handler_location, "r")</code>
 
<code python> file_handler = file(file_handler_location, "r")</code>
  
  
Using iterations, the location.dat is read for locations/values of cellid. The values are loaded to variable geo[loc].
+
Using iterations, <tt>location.dat</tt> is read for locations/values of cellid. The values are loaded to variable geo[loc].
  
 
geo and cellids variables are populated before calling the load function.
 
geo and cellids variables are populated before calling the load function.
Line 171: Line 168:
  
  
The definition for the load_location() function is as follows:
+
The definition for the <tt>load_location()</tt> function is as follows:
  
 
<code python>
 
<code python>
Line 189: Line 186:
 
== save_reminder() ==
 
== save_reminder() ==
  
The save_reminder() function adds a new reminder to the file.
+
The <tt>save_reminder()</tt> function adds a new reminder to the file.
  
The file_handler_reminder is referenced to the .dat file which used to record reminders.
+
The <tt>file_handler_reminder</tt> is referenced in the .dat file used to record reminders.
  
In the following example, the reminder.dat file is in C:, and it is assigned to the variable file_handler_reminder.
+
In the following example, the <tt>reminder.dat</tt> file is in C:, and it is assigned to the variable <tt>file_handler_reminder</tt>.
  
 
<code python>file_handler_reminder = "c:\\reminder.dat"</code>
 
<code python>file_handler_reminder = "c:\\reminder.dat"</code>
  
dictionary_copy(items) is defined [http://wiki.forum.nokia.com/index.php/How_to_develop_a_Geo-scheduler_application_-_Part_1#dictionary_copy.28dictionary.29 here]. It returns the value of the temporary variable which was initialized as NULL in the scope of the dictionary_copy(dictionary) function.
+
<tt>dictionary_copy(items)</tt> is defined [http://wiki.forum.nokia.com/index.php/How_to_develop_a_Geo-scheduler_application_-_Part_1#dictionary_copy.28dictionary.29 here]. It returns the value of the temporary variable which was initialized as NULL in the scope of the <tt>dictionary_copy(dictionary)</tt> function.
  
The reminder string and the value of the cell are written to the file reminder.dat.
+
The reminder string and the value of the cell are written to the file <tt>reminder.dat</tt>.
  
The definition for the save_reminder() function is as follows:
+
The definition for the <tt>save_reminder()</tt> function is as follows:
  
 
<code python>
 
<code python>
Line 219: Line 216:
 
   
 
   
  
This function reads the reminders in the file_handler_reminder, that is, from the reminder.dat file.
+
This function reads the reminders in the <tt>file_handler_reminder</tt>, that is, from the <tt>reminder.dat</tt> file.
  
file_handler is used to open the reminder.dat to read values.
+
<tt>file_handler</tt> is used to open the <tt>reminder.dat</tt> to read values.
  
The values of the reminder.dat (description) are loaded into the variable rems (reminders).
+
The values of the </tt>reminder.dat<tt> (description) are loaded into the variable <tt>rems</tt> (reminders).
  
 
<code python>
 
<code python>
Line 229: Line 226:
 
</code>
 
</code>
  
Finally, the definition for load_reminder() is as follows:
+
Finally, the definition for <tt>load_reminder()</tt> is as follows:
  
 
<code python>
 
<code python>
Line 248: Line 245:
 
== dictionary_copy(dictionary) ==
 
== dictionary_copy(dictionary) ==
  
In the save_location and save_reminder, the function returns the value of the temporary variable.
+
In <tt>save_location</tt> and <tt>save_reminder</tt>, the function returns the value of the temporary variable.
  
 
A parameter must be passed to the dictionary function.
 
A parameter must be passed to the dictionary function.
  
For example, in the ave_location() function it is used as follows:
+
For example, in the <tt>ave_location()</tt> function it is used as follows:
  
  
Line 258: Line 255:
 
temporary = dictionary_copy(cellids)</code>
 
temporary = dictionary_copy(cellids)</code>
  
The definition of dictionary_copy() is:
+
The definition of <tt>dictionary_copy()</tt> is:
  
 
<code python>
 
<code python>
Line 271: Line 268:
 
== location_list() ==
 
== location_list() ==
  
location_list(): Return the location names
+
<tt>location_list()</tt>: Return the location names
  
There is no need to pass a parameter to this function. However, the variable cellids can always be passed for its global.
+
There is no need to pass a parameter to this function. However, the variable <tt>cellids</tt> can always be passed for its global. However, the preferred way is to have it without the parameters.
  
However, the preferred way is to have it without the parameters.
+
In the same way as the function <tt>dictionary_copy(dictionary)</tt>, this also returns the temporary variable, but from the items of the <tt>cellids</tt> variable.
  
In the same way as the function dictionary_copy(dictionary), this also returns the temporaty variable, but from the items of the ''cellids'' variable.
+
The definition for the <tt>location_list()</tt> function is:
 
+
The definition for the location_list() function is:
+
  
 
<code python>
 
<code python>
Line 298: Line 293:
 
= Screenshots =
 
= Screenshots =
  
These screenshots demonstrate the menu and how these functions are be used:
+
These screenshots demonstrate the menu and how these functions are be used. The screenshots are relevant only to Part 1.
 
+
(The below screenshots are relevant only to Part 1)
+
  
  

Revision as of 12:50, 14 August 2008

Featured Article

Contents

Introduction

Do you want to develop location-based applications?

This article is the first in a series approaching all the basics for developing a location-based application for mobile devices. The application can be defined as a Geo-Scheduler or a Location scheduler. The simplest rapid mobile application development tool, PyS60, is used to develop the application.

The following modules are used when developing this application:

  • appuifw module
  • audio module
  • e32 module
  • time module
  • os module
  • location module


The extensions listed above can be downloaded from the C++ Python Extensions.

Development tools

1) A text editor

(Preferred editor: Python's IDLE - Integrated DeveLopment Environment)

2) Python for S60

(Preferred version: latest release 1.4.4)

3) Python for S60 script shell

(Preferred version: Latest release 1.4.4)

4) Extensions listed above which are not bundled with PyS60


The PyS60 tools can be downloaded from Sourceforge resources.


Basic approach

In this application, localization is done using the network information. The network information can be provided using the location module, cellid. If you are not familiar with retrieving the cellid using Pys60, using the appswitch module, or using the envy module, read the following articles before you proceed.

How to switch application in foreground

How to use the envy module

How to get info on cell location


Methods and functions

The following methods or functions are used:

File functions

1) save_location: Save location information into file

2) load_location: Read location information into variables

3) save_reminder: Save reminder information into a file

4) load_reminder: Read reminder information into variables

5) dictionary_copy: Dictionary copy

6) location_list: Return the location names


Feature functions

1) add_location: Add a new location

2) edit_location: Edit a location

3) add_reminder: Add a new reminder

4) edit_reminder: Editing screen function

5) edit_reminder_bylocation: Edit reminder by location function

6) edit_reminder_byreminder: Edit reminder by reminder function


Application operations

1) ms_handler: MS option handler

2) main: Start program

3) tracker: Main tracker function

4) background_handler: Background handler options


Part 1

This article - Part 1 - discusses the File functions in detail.


save_location()

This function adds the location information to the database file. A file handler named file_handler is created to handle file operations. A .dat file specified by the variable file_handler_location is accessed here. In this example, the location.dat file is in C:, and it is assigned to the file_handler_location.

Note: location.dat contains locations added by the save_location() function.

file_handler_location = "c:\\location.dat"

The geo and cellids are populated before running the file functions to NULL.

Note: The geo and cellids must be cleared by using the clear() function so that they do not contain any previously used values.

The definition for the save_location() function is as follows:

def save_location():
file_handler = file(file_handler_location, "w")
temporary = dictionary_copy(cellids)
 
cellids.clear()
geo.clear()
 
for cell, loc in temporary.items():
file_handler.write(str(cell) + ':' + str(loc) + '\n')
cellids[cell] = loc
geo[loc] = cell
file_handler.close()

The function dictionary_copy(cellids) is defined here.


load_location()

This function is responsible for loading the locations into variables. Here the value of the cellid is stored into variables.

The same file_handler and the file_handler_location are used to access the location.dat this time to read the location values.

 file_handler = file(file_handler_location, "r")


Using iterations, location.dat is read for locations/values of cellid. The values are loaded to variable geo[loc].

geo and cellids variables are populated before calling the load function.

 cellids = {}
 geo = {}


The definition for the load_location() function is as follows:

def load_location():
file_handler = file(file_handler_location, "r")
for line in file_handler:
cell, loc = line.split(":")
cell = cell.strip()
loc = loc.strip()
cellids[cell] = loc
geo[loc] = cell
file_handler.close()


save_reminder()

The save_reminder() function adds a new reminder to the file.

The file_handler_reminder is referenced in the .dat file used to record reminders.

In the following example, the reminder.dat file is in C:, and it is assigned to the variable file_handler_reminder.

file_handler_reminder = "c:\\reminder.dat"

dictionary_copy(items) is defined here. It returns the value of the temporary variable which was initialized as NULL in the scope of the dictionary_copy(dictionary) function.

The reminder string and the value of the cell are written to the file reminder.dat.

The definition for the save_reminder() function is as follows:

def save_reminder():
file_handler = file(file_handler_reminder, "w")
i = 0
temporary = dictionary_copy(rems)
rems.clear()
for key, value in temporary.items():
file_handler.write(str(i) + ':' + str(value['cell']) + ':' + str(value['date']) + ':' + value['desc'] + '\n')
rems[str(i)] = {'cell':value['cell'], 'date':value['date'], 'desc':value['desc']}
i += 1
file_handler.close()


load_reminder()

This function reads the reminders in the file_handler_reminder, that is, from the reminder.dat file.

file_handler is used to open the reminder.dat to read values.

The values of the </tt>reminder.dat (description) are loaded into the variable <tt>rems (reminders).

rems[id] = {'cell':cell, 'date':str(date), 'desc':desc}

Finally, the definition for load_reminder() is as follows:

def load_reminder():
temporary = {}
file_handler = file(file_handler_reminder, "r")
for line in file_handler:
id, cell, date, desc = line.split(":")
id = id.strip()
cell = cell.strip()
date = date.strip()
desc = desc.strip()
rems[id] = {'cell':cell, 'date':str(date), 'desc':desc}
file_handler.close()


dictionary_copy(dictionary)

In save_location and save_reminder, the function returns the value of the temporary variable.

A parameter must be passed to the dictionary function.

For example, in the ave_location() function it is used as follows:


temporary = dictionary_copy(cellids)

The definition of dictionary_copy() is:

def dictionary_copy(dictionary):
temporary = {}
for key, value in dictionary.items():
temporary[key] = value
return temporary


location_list()

location_list(): Return the location names

There is no need to pass a parameter to this function. However, the variable cellids can always be passed for its global. However, the preferred way is to have it without the parameters.

In the same way as the function dictionary_copy(dictionary), this also returns the temporary variable, but from the items of the cellids variable.

The definition for the location_list() function is:

def location_list():
temporary = []
for cell, loc in cellids.items():
temporary.append(unicode(loc))
return temporary


That finishes the file functions (Part 1) for the Geo-scheduler.

These functions are called when the user selects an action from a custom menu.


Screenshots

These screenshots demonstrate the menu and how these functions are be used. The screenshots are relevant only to Part 1.


Screenshot0016.jpg Screenshot0017.jpg

Screenshot0021.jpg Screenshot0022.jpg


See also

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