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

• Microsoft 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.

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.

Additional query words: vbce

Keywords : kbToolkit kbVBp kbVBp500bug kbWinCE kbGrpVB
Version : WINDOWS:1.0
Platform : WINDOWS
Issue type : kbbug