How To Adding or Removing Pages from a PageFrame

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
   						

6. 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
   						

7. Run the program. You should see a form with an empty pageframe.
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
   						

9. 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