Q240944: BUG: ListView’s Left/Top Properties Return Unexpected Values

Article: Q240944
Product(s): Microsoft Visual Basic for Windows
Version(s): 6.0
Operating System(s): 
Keyword(s): kbsample kbCmnCtrls kbCtrl kbListView kbVBp kbVBp600bug kbGrpDSVB kbDSupport
Last Modified: 23-MAR-2001

-------------------------------------------------------------------------------
The information in this article applies to:

- Microsoft Visual Basic Learning Edition for Windows, version 6.0 
- Microsoft Visual Basic Professional Edition for Windows, version 6.0 
- Microsoft Visual Basic Enterprise Edition for Windows, version 6.0 
-------------------------------------------------------------------------------

SYMPTOMS
========

When the Left or Top property of the ListView control is assigned a negative
value, the result is a value greater by 1 pixel. Positive values return the
expected result.

RESOLUTION
==========

Step-by-Step Workaround
-----------------------

1. Start a new Standard EXE project in Visual Basic. Form1 is created by
  default.

2. On the Project menu, click to select Components, check Microsoft Windows
  Common Controls 6.0, and then click OK.

3. Draw a ListView control on Form1. On the Properties window, set View = 0 -
  lvwSmallIcon.

4. Add the following code to the General Declarations section of Form1:

  Option Explicit

  Dim itm As ListItem

  Private Sub Form_Click()
      Dim sngLeft As Single
      Dim sngTop As Single
      
      Me.ScaleMode = vbPixels
      sngLeft = -2
      sngTop = -2
      Set itm = ListView1.ListItems.Add(Text:="item")

      ' Inaccurate
      itm.Left = sngLeft
      itm.Top = sngTop
      MsgBox "Left = " & itm.Left & " Top = " & itm.Top

      ' More accurate
      LocateListItems itm, sngLeft, sngTop
      MsgBox "Left = " & itm.Left & " Top = " & itm.Top
  End Sub

  Private Sub LocateListItems(item As ListItem, x As Single, y As Single)
      Select Case x
          Case Is < -1.5
              x = x - 1
          Case Is < 0
              x = x - 1.1
          Case Else
      End Select
      item.Left = x
      Debug.Print "Item.Left = "; item.Left    
      
      Select Case y
          Case Is < -1.5
              y = y - 1
          Case Is < 0
              y = y - 1.1
          Case Else
      End Select
      item.Top = y
      Debug.Print "Item.Top = "; item.Top    
  End Sub

5. Run the project by pressing the F5 key, and note the results in the Immediate
  window. Without correction, the inaccurate result is displayed. After a call
  to the correcting function, the more accurate result is displayed.

STATUS
======

Microsoft has confirmed this to be a bug in the Microsoft products listed at the
beginning of this article.

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

Because these properties are for positions that are stored as real numbers, they
are usually not whole numbers. However, for any negative value that is assigned,
the result is always 1 pixel greater than the assigned value.

Steps to Reproduce Behavior
---------------------------

1. Start a new Standard EXE project in Visual Basic. Form1 is created by
  default.

2. On the Project menu, click to select Components, check Microsoft Windows
  Common Controls 6.0, and then click OK.

3. Draw a ListView control on Form1. On the Properties window, set View =
  lvwSmallIcon.

4. Add the following code to the General Declarations section of Form1:

  Private Sub Form_Click()
      ListView1.ListItems(1).Left = -5
      Debug.Print "Left = "; ListView1.ListItems(1).Left
      ListView1.ListItems(1).Top = -5
      Debug.Print "Top = "; ListView1.ListItems(1).Top
  End Sub

  Private Sub Form_Load()
     Me.ScaleMode = vbPixels
     Call ListView1.ListItems.Add(Text:="item")
  End Sub

5. Run the project by pressing F5, click on the form, and note that this
  produces the following output in the Immediate window:

Left = -3.968504
Top = -3.968504

6. Note that the result is 1 pixel greater than the assigned value.

Additional query words:

======================================================================
Keywords          : kbsample kbCmnCtrls kbCtrl kbListView kbVBp kbVBp600bug kbGrpDSVB kbDSupport 
Technology        : kbVBSearch kbAudDeveloper kbZNotKeyword6 kbZNotKeyword2 kbVB600Search kbVBA600 kbVB600
Version           : :6.0
Issue type        : kbbug
Solution Type     : kbpending

=============================================================================

THE INFORMATION PROVIDED IN THE MICROSOFT KNOWLEDGE BASE IS PROVIDED "AS IS" WITHOUT WARRANTY OF ANY KIND. MICROSOFT DISCLAIMS ALL WARRANTIES, EITHER EXPRESS OR IMPLIED, INCLUDING THE WARRANTIES OF MERCHANTABILITY AND FITNESS FOR A PARTICULAR PURPOSE. IN NO EVENT SHALL MICROSOFT CORPORATION OR ITS SUPPLIERS BE LIABLE FOR ANY DAMAGES WHATSOEVER INCLUDING DIRECT, INDIRECT, INCIDENTAL, CONSEQUENTIAL, LOSS OF BUSINESS PROFITS OR SPECIAL DAMAGES, EVEN IF MICROSOFT CORPORATION OR ITS SUPPLIERS HAVE BEEN ADVISED OF THE POSSIBILITY OF SUCH DAMAGES. SOME STATES DO NOT ALLOW THE EXCLUSION OR LIMITATION OF LIABILITY FOR CONSEQUENTIAL OR INCIDENTAL DAMAGES SO THE FOREGOING LIMITATION MAY NOT APPLY.

Copyright Microsoft Corporation 1986-2002.