How To Make Move or Resize Call Form's THIS_ACCESS Method (190539)


The information in this article applies to:

  • Microsoft Visual FoxPro for Windows 6.0
This article was previously published under Q190539

SUMMARY

Visual FoxPro 6.0 gives you the ability to attach events to properties. This is accomplished using Access and Assign methods. These events will fire when a property value is queried (that is, accessed) or set to a value (that is, assigned). The THIS_ACCESS method is a special case that is fired whenever any property of an object is queried or set. Normally, this method will be fired only when properties are programmatically set or queried. This article describes how to ensure the THIS_ACCESS method is called even if a property is implicitly changed. An example of when you may want to do this would be when a form is moved the form's Top property is changed.

MORE INFORMATION

This example demonstrates how THIS_ACCESS is not called by properties that are implicitly changed.
  1. Run the following code from a program (.prg) file: 
          PUBLIC oform1

      oform1=NEWOBJECT("form1")
      oform1.SHOW
      RETURN

      DEFINE CLASS form1 AS FORM

         DOCREATE = .T.
         CAPTION = "Form1"
         NAME = "Form1"

         PROCEDURE this_access
            LPARAMETERS cMemberName
            ? cMemberName, TTOC(DATETIME())
            RETURN THIS
         ENDPROC

     ENDDEFINE
  2. Resize or move the form with the mouse. Note that no output is echoed to the form.
This example shows how to make THIS_ACCESS be called when moving or resizing a form by adding code to the form's Moved and Resize methods.
  1. Run the following code from a program (.prg) file. Note the code added to the Moved and Resize methods. 
          PUBLIC oform1

      oform1=NEWOBJECT("form1")
      oform1.SHOW
      RETURN

      DEFINE CLASS form1 AS FORM

         AUTOCENTER = .T.
         CAPTION = "Form1"
         NAME = "Form1"

         PROCEDURE this_access
            LPARAMETERS cMemberName
            ? cMemberName, TTOC(DATETIME())
            RETURN THIS
         ENDPROC

         PROC MOVED
            = THIS.TOP
            = THIS.LEFT
            ?
         ENDPROC

         PROC RESIZE
            = THIS.WIDTH
            = THIS.HEIGHT
            ?
         ENDPROC

      ENDDEFINE
  2. Resize or move the form with the mouse. Note that the properties that are queried get echoed to the form.

REFERENCES

Visual FoxPro Help file, "Access and Assign Methods" topic.
Modification Type:MinorLast Reviewed:7/1/2004
Keywords:kbhowto KB190539
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