Dynamic Filter and Sort Dialog Styles

Provide the users with an opportunity to select the filter and sort dialog window styles.

What

• n_cst_appmanager: PFC extension application manager service.
• n_cst_style_preferences: New service for saving and restoring a user’s style preferences for the PFC filter and sort services.
• w_r_set_style_preferences: New response window allowing the user to test, select, and save different styles for the PFC filter and sort services (see Figure 1 below).

Figure 1: Set Style Preferences window

Why

• Provide the users with an opportunity to test, and select, the style they feel most comfortable using when filtering or sorting data.
• Enforce standard filter and sort styles throughout the entire application by encapsulating behavior at the application level.
• Increase the application’s ability to adapt to changing requirements.
  • The implementation of the style preferences service will accommodate the various degrees of computer literacy throughout the user community.  As users become more comfortable with the user interface, and Windows in general, they can increase the level of interface complexity at their own pace.
  • If a filter or sort style is added or changed during development/maintenance, all DataWindows can quickly take advantage of the new style(s); otherwise, a new requirement will cause an enormous amount of work (depending on the number of objects using the services).

How
Using the objects in the attached zip file, simply follow the steps listed below to implement the style preferences service into your application:

1.    Copy the n_cst_style_preferences object into one of your application .PBLs.

2.    Copy the w_r_set_style_preferences object into one of your application .PBLs.

3.    If you have not implemented any changes in n_cst_appmanager in the extension layer, copy the attached n_cst_appmanager object into PFEAPSRV.PBL and skip to step 4; otherwise, follow the steps below to integrate the style preferences service into your existing n_cst_appmanager object:

        3.1.    Declare a public instance variable of type n_cst_style_preferences in n_cst_appmanager:
 

 
        3.2.    Create a function in n_cst_appmanager named of_SetStylePreferences to create/destroy the style preferences service.  (You can model the function after the of_SetError function in pfc_n_cst_appmanager, replacing inv_Error with inv_StylePreferences and n_cst_error with n_cst_style_preferences.)

        3.3.    Create the style preferences service in the pfc_open event of n_cst_appmanager:
 

 
        3.4.    Destroy the style preferences service in the destructor event of n_cst_appmanager:
 

 
       3.5.    Specify the .INI file, containing the current style preferences, in the pfc_open event of n_cst_appmanager:
 

 
       3.6.    Restore the current style preferences from the .INI file in the pfc_open event of n_cst_appmanager:
 

 
4.    Create a grid DataWindow object referencing a table in your database and assign it to the DataWindow control in w_r_set_style_preferences.   (The current DataWindow object, d_employees, is referencing the EMPLOYEE table from the Powersoft Demo DB.)

5.    Create an .INI file named STYLES.INI in your Windows directory/folder with the following section:
 

 
6.    To use the style preferences defined by the user, simply use the appropriate get function as the argument for the of_SetStyle function in each service.  For example, place the following script in the constructor event of your DataWindow (inherited from u_dw):
 

 
7.    Add a menu item providing the user access to the Set Style Preferences window.  Place the following script in the clicked event of the new menu item to evoke the window (or use of_SendMessage):
 

Where
The following objects/files are available in the attached zip file:

• PFCGUIDE.DOC (MS Word 95 document describing the style preferences service)
• PFCGUIDE.PBL
  • d_employees
  • n_cst_appmanager
  • n_cst_style_preferences
  • w_r_set_style_preferences
• STYLES.INI

Other Tips and Ideas…

• Even if you don’t want to give users the power to change styles, you can still enforce user interface standards by using the style preferences service.
• If all DataWindows are using the filter and/or sort service(s), the instantiation and initialization of each service may be implemented in the ancestor DataWindow control (i.e., u_dw).
• Enhance the style preferences service to allow the user to select the column source name for the filter and sort services (e.g., database column names instead of column headers).
• Enhance the style preferences service to use the registry.
• The .INI file containing the style preferences can be the application .INI file or a separate .INI file.
• Any style that could vary based on a user’s preference can be added to the style preferences service.

The concepts described in this document may be applied to any function where the arguments are static values (e.g., 0, 1, 2, ‘Scale’, ‘ScaleToRight’, etc.).  You can dramatically increase the flexibility and consistency of your applications by using this approach for other preference-related features.   Naturally, the implementation would depend on the users’ expectations; if one of those expectations is to use a standard window for each service, this approach will easily satisfy that requirement.  Best of all, if the requirement ever changes (or should I say as the requirement changes), code modifications will be minimal since the implementation is centralized.

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Last Revised: February 15, 2004 03:58 AM.