Q123967: Code Example Shows How to Manage Navigation Buttons
Article: Q123967
Product(s): Microsoft FoxPro
Version(s): MACINTOSH:2.5b,2.5c,2.6,2.6a; MS-DOS:2.0,2.5,2.5a,2.5b,2.6,2.6a; WINDOWS:2.5,2.5a,2.5b,
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
- Microsoft FoxPro for Windows, versions 2.5, 2.5a, 2.5b, 2.6, 2.6a
- Microsoft FoxPro for MS-DOS, versions 2.0, 2.5, 2.5a, 2.5b, 2.6, 2.6a
- Microsoft FoxPro for Macintosh, versions 2.5b, 2.5c, 2.6, 2.6a
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SUMMARY
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When creating a screen, most developers need to add navigation buttons to move
through the database. You can easily put a push button on a screen to go forward
one record, but you also need to control button behavior when reaching the
beginning or the end of a database.
For example, if the user is navigating through a table and reaches the end of
that table, you might want to have the Next and Bottom buttons disabled.
Likewise, when the user reaches the top of the table, you might want to have the
Top and Prior buttons disabled. This article shows by example how to do this.
MORE INFORMATION
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The code sample in this article moves the pointer before or after the next or
prior record you really want to display, thus allowing you to test for BOF() and
EOF() conditions and have your program respond accordingly by disabling or
enabling the appropriate buttons.
Code Sample
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NOTE: While this code can serve as a solid base for use in your own work, it is
by no means necessarily the only or best way of handling buttons. In its present
form, the code does not check the status of a record to see if it is deleted. If
deleted is OFF (the default), this code has the potential to misbehave, so you
need to check for and handle deleted records and other types of exceptions.
You might want to add code to the "On Screen Entry" or "When" clause code
snippet, because "Top" and "Prior" are not valid at the beginning of a database.
You may need to add this code:
&& Disable Top and Prior buttons on startup.
SHOW GET Buttnvar,1 DISABLE && Disable "Top"
SHOW GET Buttnvar,2 DISABLE && Disable "Prior"
Place the following code in the VALID clause of your button array, and change the
name of the "Buttnvar" variable to the name of the variable you are actually
using:
DO CASE
CASE Buttnvar = 1 && 'TOP' button
GO TOP
SCATTER MEMVAR
SHOW GET Buttnvar,1 DISABLE && Disable "Top"
SHOW GET Buttnvar,2 DISABLE && Disable "Prior"
IF (RECCOUNT() > 1)
SHOW GET Buttnvar,3 ENABLE && Enable "Next"
SHOW GET Buttnvar,4 ENABLE && Enable "Bottom"
ELSE
SHOW GET Buttnvar,3 DISABLE && Disable "Next"
SHOW GET Buttnvar,4 DISABLE && Disable "Bottom"
ENDIF
SHOW GETS
WAIT WINDOW "At first record" TIMEOUT 1
_CUROBJ = OBJNUM(Buttnvar)+3 && Transfer focus to "Next" button
CASE Buttnvar = 2 && 'PRIOR' button
SKIP - 1
IF NOT BOF()
SCATTER MEMVAR
ELSE
WAIT WINDOW "At first record" TIMEOUT 1
SHOW GET Buttnvar,1 DISABLE && Disable "Top"
SHOW GET Buttnvar,2 DISABLE && Disable "Prior"
ENDIF
IF (RECCOUNT() > 1)
SHOW GET Buttnvar,3 ENABLE && Enable "Next"
SHOW GET Buttnvar,4 ENABLE && Enable "Bottom"
ELSE
SHOW GET Buttnvar,3 DISABLE && Disable "Next"
SHOW GET Buttnvar,4 DISABLE && Disable "Bottom"
ENDIF
SHOW GETS
CASE Buttnvar = 3 && 'NEXT' button
IF NOT EOF()
SKIP 1
ENDIF
IF EOF()
SKIP - 1
WAIT WINDOW "At last record" TIMEOUT 1
SHOW GET Buttnvar,3 DISABLE && Disable "Next"
SHOW GET Buttnvar,4 DISABLE && Disable "Bottom"
ELSE
SHOW GET Buttnvar,1 ENABLE && Enable "Top"
SHOW GET Buttnvar,2 ENABLE && Enable "Prior"
SCATTER MEMVAR
ENDIF
SHOW GETS
CASE Buttnvar = 4 && 'BOTTOM' button
GO BOTTOM
SCATTER MEMVAR
SHOW GET Buttnvar,3 DISABLE && Disable "Next"
SHOW GET Buttnvar,4 DISABLE && Disable "Bottom"
IF (RECCOUNT() > 1)
SHOW GET Buttnvar,1 ENABLE && Enable "Top"
SHOW GET Buttnvar,2 ENABLE && Enable "Prior"
ELSE
SHOW GET Buttnvar,1 DISABLE && Disable "Top"
SHOW GET Buttnvar,2 DISABLE && Disable "Prior"
ENDIF
_CUROBJ = OBJNUM(Buttnvar)+1 && Transfer focus to "Prior" button
SHOW GETS
WAIT WINDOW "At last record" TIMEOUT 1
CASE Buttnvar = 5 && 'QUIT' button
CLEAR READ
ENDCASE
You could place the "Show Gets" command at the end of the CASE statement.
However, sometimes it provides a snappier response when placed at the end of a
given instruction.
Additional query words: VFoxWin FoxWin FoxMac FoxDos
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Keywords : kbcode
Technology : kbHWMAC kbOSMAC kbVFPsearch kbAudDeveloper kbFoxproSearch kbZNotKeyword3 kbFoxPro250bMac kbFoxPro260aMac kbFoxPro250cMac kbFoxPro200DOS kbFoxPro250DOS kbFoxPro250aDOS kbFoxPro250bDOS kbFoxPro260DOS kbFoxPro260aDOS kbFoxPro260 kbFoxPro250 kbFoxPro250a kbFoxPro250b kbFoxPro260a kbVFP300
Version : MACINTOSH:2.5b,2.5c,2.6,2.6a; MS-DOS:2.0,2.5,2.5a,2.5b,2.6,2.6a; WINDOWS:2.5,2.5a,2.5b,2.6,2.6a,3.0
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