HOWTO: Adding or Removing Pages from a PageFrame

ID: Q141529

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

1. Create a new form.

2. Add a pageframe to the form.

3. Change the PageCount property of the pageframe to 0.

4. Add three new properties to the form: Page1, Page2, and Page3.

5. 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

   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

8. 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

   window:

   _SCREEN.FORMS(1).PAGE1 = .T.
   _SCREEN.FORMS(1).PAGE2 = .F.
   _SCREEN.FORMS(1).PAGE3 = .T.
   _SCREEN.FORMS(1).REFRESH

Keywords          : kbcode kbVFp FxprgGeneral 
Version           : 3.0 3.0b
Platform          : WINDOWS
Issue type        : kbhowto