BUG: Setting Text/Caption Property Leaks Memory on Windows CE

ID: Q198090

The information in this article applies to:

Windows CE Toolkit for Visual Basic 5.0, version 1.0

SYMPTOMS

The amount of available program memory decreases when repeatedly setting text or caption properties of intrinsic controls.

RESOLUTION

There are a couple of potential workarounds for this behavior. Most straightforward is to minimize the frequency of changing text or caption properties of controls.

Secondly, painting the desired text directly onto the form or control as opposed to setting the text or caption property also works around this behavior. For example:

1. Create a new Windows CE Project in Visual Basic. Form1 is created by

   default.

2. In the Project Properties dialog box, make sure that "Run on Target" is

   set to Remote Device.

3. Place a command button on Form1.

4. Add the following code into the code module for Form1:

      Option Explicit

      Dim NewLabelCaption

      Private Sub Form_Load()
         ScaleMode = vbPixels
         Command1.Caption = "Update"
      End Sub

      Private Sub Command1_Click()
         NewLabelCaption = FormatDateTime(Now)
         DrawLabels
      End Sub

      Public Sub DrawLabels()
         Cls
         ' Label1
         CurrentX = 10
         CurrentY = 25
         Print NewLabelCaption
         ' Label2
         CurrentX = 10
         CurrentY = 50
         Print NewLabelCaption
         ' Label3
         CurrentX = 10
         CurrentY = 75
         Print NewLabelCaption
      End Sub

5. Run the project.

6. On the H/PC device, go to the Control Panel and launch the System

   applet. Select the Memory tab.

7. In the Visual Basic CE project, click the command button repeatedly.

Notice that the Program Memory "In Use" does not increase each time the command button is clicked.

STATUS

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

MORE INFORMATION

This problem exists for all controls that have a Text or Caption property. The amount of memory leaked is the same as the size of the string assigned to the property.

Steps to Reproduce Behavior

1. Create a new Windows CE Project in Visual Basic. Form1 is created by

   default.

2. In the Project Properties dialog box, make sure that "Run on Target" is

   set to Remote Device.

3. Place a command utton and a label on Form1.

4. Add the following code into the code module for Form1:

      Option Explicit
      Dim MyString

      Private Sub Command1_Click()
         Label1.Caption = MyString
      End Sub

      Private Sub Form_Load()
         Dim lLoop
         'Load the string with 10k of data
         For lLoop = 0 To 10000
            MyString = MyString & "x"
         Next
      End Sub

5. Run the project.

6. On the H/PC device, go to the Control Panel and launch the System

   applet. Select the Memory tab.

7. In the Visual Basic CE project, click the command button repeatedly.

Notice that the Program Memory "In Use" increases each time the command button is clicked.

Additional query words: vbce

Keywords          : kbToolkit kbVBp kbVBp500bug kbWinCE 
Version           : WINDOWS:1.0
Platform          : WINDOWS
Issue type        : kbbug
Solution Type     : kbpending

Last Reviewed: December 31, 1998