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Q259891: VFP 6.0 Sample: Using the DateTimePicker’s CallBack Field

Article: Q259891
Product(s): Microsoft FoxPro
Version(s): WINDOWS:6.0
Operating System(s): 
Keyword(s): kbfile kbSample kbActiveX kbCtrl kbvfp600 kbGrpDSFox kbDSupport
Last Modified: 10-NOV-2000

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The information in this article applies to:

- Microsoft Visual FoxPro for Windows, version 6.0 
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SUMMARY
=======

Dtpcallb.exe is a sample that provides an example of how to use the CallBack
field feature in the CustomFormat property of the DateTimePicker control.

MORE INFORMATION
================

The following file is available for download from the Microsoft Download
Center:

  Dtpcallb.exe
  (http://download.microsoft.com/download/vfox60/sample1/6/win98/en-us/Dtpcallb.exe)

Release Date: May-24-2000

For additional information about how to download Microsoft Support files, click
the following article number to view the article in the Microsoft Knowledge
Base:

  Q119591 How to Obtain Microsoft Support Files from Online Services

Microsoft scanned this file for viruses. Microsoft used the most current
virus-detection software that was available on the date that the file was
posted. The file is stored on secure servers that prevent any unauthorized
changes to the file.

The Dtpcallb.exe file contains the following files:

+-----------------------+
| File name    | Size   | 
+-----------------------+
| Dtpcallb.scx | 2,232  | 
+-----------------------+
| Dtpcallb.sct | 20,769 | 
+-----------------------+
| ReadMe.txt   | 3,383  | 
+-----------------------+

About the DateTimePicker's CallBack Fields
------------------------------------------

The DateTimePicker control allows you to specify the format used to display the
date or time using the CustomFormat property. By using string fragments to
specify the format fields, you can format the datetime display to suit your
needs. One of these format fields is a CallBack field, which allows you to
customize the output displayed in the control's display area. To declare a
CallBack field, you must include one or more "X" characters (ASCII Code 88)
anywhere in the body of the format string. CallBack fields are displayed in
left-to-right order.

The DateTimePicker control had three events that are used specifically for
CallBack fields: FormatSize, Format, and CallBackKeyDown. For each of these
events, the CallBack field value is passed to the method so that you may code
the appropriate responses for each CallBack field in the CustomFormat property.

The FormatSize event is triggered by the control to determine the size required
for each CallBack field. This event only fires once for each CallBack field in
the CustomFormat property. The size returned by this event is used to allocate
space in the control's display area for the largest value that is returned by
the Format event.

The Format event is triggered by the control each time it is refreshed, and is
fired for each CallBack field in the CustomFormat property. The character string
value returned by this event is displayed in the control's display area in place
of the string fragment used to define the CallBack field.

The CallBackKeyDown event is triggered when a KeyDown event occurs while a
CallBack field is selected in the control. Just like the up/down spinner buttons
on the control, the UP ARROW or DOWN ARROW keys on the keyboard allow you to
"spin" through the valid date/time values in the control while that field in the
control is selected. Because the up/down spinner buttons do not work with a
CallBack field, you may want to simulate the actions that occur using the UP
ARROW or DOWN ARROW keys from the keyboard by using the CallBackKeyDown event.

PLEASE NOTE: This simulation does not enable the spinner buttons to work with the
CallBack field or fields.

The CustomFormat string used in the following sample:

  MM->(XXXX) dd->(XX) yyy

displays a date in the DateTimePicker with the following components:

- a two-digit month, followed by ->

- the first CallBack field, which contains the month's name within parentheses

- a two-digit day, followed by ->

- the second CallBack field, which contains the day of the week name within
  parentheses

- a four-digit year

About This Example
------------------

This example demonstrates the ability to change the language used in the
DateTimePicker control using CallBack fields. While running the form, you may
choose a language (English, French, German, or Spanish) from a combo box. The
DateTimePicker displays the month, day, and year. For the month and day, the
control displays the appropriate month and day of week names in the selected
language. The user may use the spinner buttons to spin through the values for
the month, day, and year. The user may also use the UP ARROW and DOWN ARROW keys
from the keyboard to "spin" through the values for the month, month name, day,
day of week, or year. A text box on the form displays the current contents of
the Value property of the DateTimePicker control.

REFERENCES
==========

For more information about the DateTimePicker control, please see that topic in
the Windows Controls Help file, CMCTL298.CHM, usually located where you have
installed your MSDN Library.

For additional information on the DateTimePicker control, click the article
number below to view the article in the Microsoft Knowledge Base:

  Q259646 SAMPLE: DTPICKER.EXE How to Use the DateTimePicker Control

Additional query words: Dtpcallb

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Keywords          : kbfile kbSample kbActiveX kbCtrl kbvfp600 kbGrpDSFox kbDSupport 
Technology        : kbVFPsearch kbAudDeveloper kbVFP600
Version           : WINDOWS:6.0

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