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Q132356: How to Use a Container Object Instead of a Custom Object

Article: Q132356
Product(s): Microsoft FoxPro
Version(s): WINDOWS:3.0
Operating System(s): 
Keyword(s): 
Last Modified: 15-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
=======

This article describes how you can use the container control instead of the
custom control to obtain additional functionality for your custom controls.

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

The container and custom classes are both Visual FoxPro base classes. Both can
contain member objects that are user-defined controls. An object based on the
custom class does not have a visual representation and receives the Init,
Destroy, and Error events.

On another hand, the container class has a visual representation. An object based
on the Container class can receive the following events: Click, DragDrop,
GotFocus, MouseDown, MouseMove, Resize, Destroy, Error, LostFocus, MouseUp, and
UiEnable.

The container class is therefore more versatile than the custom class. If you
plan on performing operations that require a visual representation, such as
moving an object to an area and using the DragDrop event, an object based on the
Container class might be appropriate. If you do not want to represent the
container visually, you can set the Visible property of the container to false
(.F.).

For more information about the Container and Custom classes, search for Container
object and Custom object in the Visual FoxPro Help file.

The following code sample shows how to use an object based on the Container
class. In this code, a form is drawn that contains a container and a command
button. The command button is dragged to the container. To run this code, copy
and paste it into a program (.PRG) file. Once the form is displayed, drag the
command button to the left, and drop it in the container. This functionality
could not be achieved with a custom class.

Code Sample
-----------

  PUBLIC oForm

  oForm=CREATEOBJECT('MYFORM')
  oForm.SHOW

  *:*************************************************************************
  *:
  *: Class:MYFORM  BaseClass: FORM
  *:
  *:*************************************************************************
  DEFINE CLASS MYFORM AS FORM
     ADD OBJECT Container1 AS MYCONTAINER WITH Top=1, Left=1
     ADD OBJECT Command1 AS COMMANDBUTTON WITH Top=1,Width=78, Left=84,;
          DragMode=1
  ENDDEFINE

  *:*************************************************************************
  *:
  *: Class:MYCONTAINER  BaseClass: CONTAINER
  *:
  *:*************************************************************************

  DEFINE CLASS Mycontainer AS CONTAINER
     Dragmode=1
     Width=80

     PROCEDURE DragDrop
        PARAMETERS OSOURCE, XCOORD,YCOORD
        ONAME=OSOURCE.NAME
        nNberofMembers=AMEMBERS(atest,THIS,2)

        IF TYPE('atest')<>"U"  && there are member objects
           nIsObjectThere=ASCAN('atest',ALLTRIM(UPPER(ONAME)))
           IF nIsObjectThere<>0
              ONAME=ALLTRIM(ONAME)+ALLTRIM(STR(nNberofMembers+1))
           ENDIF
        ENDIF
        THIS.ADDOBJECT(ONAME,OSOURCE.CLASS)
        Oref=EVAL('this.'+oname)
        Oref.Top=(nNberofMembers*OSOURCE.HEIGHT)+3
        Oref.Visible=.T.
     ENDPROC
  ENDDEFINE

Additional query words: VFoxWin

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

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