The information in this article applies to:
- Microsoft Visual FoxPro for Windows, versions 3.0 and 3.0b
SUMMARY
With Visual FoxPro, you can use the PageCount property to add and remove
pages from a pageframe easily.
If, however, you use ADDOBJECT or REMOVEOBJECT to control the number of
pages in the pageframe, you can take advantage of the methods and events of
the page.
MORE INFORMATION
There are advantages to defining a page class and using ADDOBJECT or
REMOVEOBJECT instead of changing the PageCount property. Adding a page by
increasing the page count by 1 won't allow changes to any methods or events
associated with the page. All methods or events are read-only at run time.
Defining a page class allows you to place code inside the methods or events
and arrange a page exactly as needed before a page is added to the
pageframe. The following example demonstrates how this is accomplished.
Step-by-Step Example
- Create a new form.
- Add a pageframe to the form.
- Change the PageCount property of the pageframe to 0.
- Add three new properties to the form: Page1, Page2, and Page3.
- Type the following inside PAGEFRAME1.REFRESH
* The following refresh method will help automate the process
* of adding and removing pages from the pageframe.
*
* Display Page Not Display Page
* THISFORM.Page1 .T. .F.
* THISFORM.Page2 .T. .F.
* THISFORM.Page3 .T. .F.
IF THIS.PAGECOUNT > 0
DIMENSION lcPage(THIS.PAGECOUNT) && Array of names for visible pages
FOR lni=1 to THIS.PAGECOUNT
lcPage(lni)=UPPER(THIS.PAGES(lni).NAME) && Does page exist
ENDFOR
ELSE
DIMENSION lcPage(1)
lcPage(1) = ""
ENDIF
FOR lni = 1 to 3 && Looping stops at 3 because we only have 3
lcx = "Page"+ALLTRIM(STR(lni)) && possible pages to display.
IF THISFORM.&lcx. && IF true display the page
lny=ASCAN(lcPage,UPPER(lcx))
IF lny=0 && If lny=0, then the page does not exist
THISFORM.PAGEFRAME1.ADDOBJECT(lcx,lcx)
ENDIF
ELSE && ELSE (The page should NOT be displayed)
lny=ASCAN(lcPage,UPPER(lcx))
IF lny>0 && If lny>0, remove the page from the page frame
THISFORM.PAGEFRAME1.REMOVEOBJECT(lcx,lcx)
ENDIF
ENDIF
ENDFOR
- Create a program file that contains the following code:
SET PROCEDURE TO <this program>
DO FORM <form name>
* Three classes are defined as Page1, Page2, and Page3
* respectively. These are the pages that will be added
* with ADDOBJECT inside the PAGEFRAME1.REFRESH.
DEFINE CLASS Page1 AS PAGE
ADD OBJECT command1 AS COMMANDBUTTON
PROCEDURE CLICK
WAIT WINDOW "click" NOWAIT
ENDPROC
ENDDEFINE
DEFINE CLASS Page2 AS PAGE
ADD OBJECT command2 AS COMMANDBUTTON
ENDDEFINE
DEFINE CLASS Page3 AS PAGE
ADD OBJECT text1 AS TEXTBOX
ENDDEFINE
- Run the program. You should see a form with an empty pageframe.
- Make page1 and page2 visible by typing the following in the Command
window:
_SCREEN.FORMS(1).PAGE1 = .T.
_SCREEN.FORMS(1).PAGE2 = .T.
_SCREEN.FORMS(1).PAGE3 = .F.
_SCREEN.FORMS(1).REFRESH
- Make page1 and page3 visible by typing the following in the Command
window:
_SCREEN.FORMS(1).PAGE1 = .T.
_SCREEN.FORMS(1).PAGE2 = .F.
_SCREEN.FORMS(1).PAGE3 = .T.
_SCREEN.FORMS(1).REFRESH
|