Q138920: How to Enable One Check Box While Disabling the Others

Article: Q138920
Product(s): Microsoft FoxPro
Version(s): WINDOWS:3.0
Operating System(s): 
Keyword(s): kbcode
Last Modified: 11-FEB-2000

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The information in this article applies to:

- Microsoft Visual FoxPro for Windows, version 3.0 
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SUMMARY
=======

Multiple check boxes are often necessary to gather required input. Frequently,
it is desirable to disable the unselected check boxes after the first check box
is selected. The example in this article illustrates how to disable the
unselected check boxes in a form.

Although option (also known as radio) buttons are generally the preferred of
allowing users to make only once choice among a group of choices, this article
provides an alternative method of doing so using check boxes.

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

The form created by the following example contains three check boxes. When a
check box is selected, its Value property is set to 1. After checking the Value
property in the Click event of each individual check box, the Enabled properties
of the remaining check boxes are changed to false (.F.). Changing these
properties disables the check boxes.

Step-by-Step Example
--------------------

1. Create a new form, and name it Test.scx.

2. Place three check boxes on the form by using the Form Builder.

3. In the Refresh event of the form, place the following code:

     IF ThisForm.Check1.Enabled=.t. and ThisForm.Check1.Value=1
         ThisForm.Check2.Enabled=.f.
         ThisForm.Check3.Enabled=.f.
     ENDIF

     IF ThisForm.Check2.Enabled=.t. and ThisForm.Check2.Value=1
          ThisForm.Check1.Enabled=.f.
          ThisForm.Check3.Enabled=.f.
     ENDIF

     IF ThisForm.Check3.Enabled=.t. and ThisForm.Check3.Value=1
          ThisForm.Check1.Enabled=.f.
          ThisForm.Check2.Enabled=.f.
     ENDIF

     IF ThisForm.Check1.Enabled=.t. and ThisForm.Check1.Value=0
         ThisForm.Check2.Enabled=.t.
         ThisForm.Check3.Enabled=.t.
     ENDIF

     IF ThisForm.Check2.Enabled=.t. and ThisForm.Check2.Value=0
         ThisForm.Check1.Enabled=.t.
         ThisForm.Check3.Enabled=.t.
     ENDIF

     IF ThisForm.Check3.Enabled=.t. and ThisForm.Check3.Value=0
         ThisForm.Check1.Enabled=.t.
         ThisForm.Check2.Enabled=.t.
     ENDIF

4. In the InteractiveChange event of each check box, add the following line of
  code:

     ThisForm.Refresh

5. If you want the disabled check boxes to appear in a different color, set the
  DisabledBackColor property for each box. The box will automatically change
  color when disabled.

6. Save and run the form.

7. Click any check box to select it, and the remaining check boxes are disabled.
  Click the check box a second time to clear it, and the other check boxes are
  reenabled.

Additional Notes
----------------

- Changing the BackColor property to gray emulates a disabled check box in
  FoxPro 2.x for Windows.

- Typing "Help Backcolor" (without the quotation marks) in the Command window
  provides a list of colors and their corresponding numbers.

REFERENCES
==========

For more information about Disabling check boxes in FoxPro 2.x, please see the
following article in the Microsoft Knowledge Base:

  Q111918 How to Enable One Check Box While Disabling the Others

Additional query words: VFoxWin

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Keywords          : kbcode 
Technology        : kbVFPsearch kbAudDeveloper kbVFP300
Version           : WINDOWS:3.0

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