Microsoft KB Archive/257645

Knowledge Base

FIX: Setting Windowless Control to Transparent Prevents Animation

Article ID: 257645

Article Last Modified on 8/7/2007

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APPLIES TO

• Microsoft Visual Basic 6.0 Professional Edition
• Microsoft Visual Basic 6.0 Enterprise Edition

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This article was previously published under Q257645

SYMPTOMS

When you set the BackStyle property of a windowless control to Transparent, animation effects for that control are prevented from taking place. The effects are drawn, but they are not animated.

CAUSE

This behavior is due to the way Visual Basic draws controls.

STATUS

Microsoft has confirmed that this is a bug in the Microsoft products that are listed at the beginning of this article. This bug was corrected in the latest service pack for Visual Studio 6.0.

For additional information about Visual Studio service packs, click the following article numbers to view the articles in the Microsoft Knowledge Base:

194022 INFO: Visual Studio 6.0 Service Packs, What, Where, Why

194295 HOWTO: Tell That a Visual Studio Service Pack Is Installed

To download the latest Visual Studio service pack, visit the following Microsoft Web site:

http://msdn2.microsoft.com/en-us/vstudio/Aa718353.aspx

MORE INFORMATION

Steps to Reproduce Behavior

1. Create a new ActiveX Control project in Visual Basic. UserControl1 is created by default.
2. Change the Height and Width property of UserControl1 to 1680.
3. Change the Windowless property of UserControl1 to True.

4. Add the following code to UserControl1:

   Option Explicit
   
   Private x As Long
   Private y As Long
   
   Public Property Get BackStyle() As Integer
       BackStyle = UserControl.BackStyle
   End Property
   
   Public Property Let BackStyle(ByVal New_BackStyle As Integer)
       UserControl.BackStyle() = New_BackStyle
       PropertyChanged "BackStyle"
   End Property
   
   Public Property Get BackColor() As OLE_COLOR
       BackColor = UserControl.BackColor
   End Property
   
   Public Property Let BackColor(ByVal New_BackColor As OLE_COLOR)
       UserControl.BackColor() = New_BackColor
       PropertyChanged "BackColor"
   End Property
   
   Private Sub UserControl_Initialize()
       x = Width
       y = x
   End Sub
   
   Private Sub UserControl_Paint()
       If Ambient.UserMode = False Then Exit Sub
       Randomize
       Dim i As Integer
       Dim j As Integer
       For j = 1 To 40
           For i = 1 To 30000
               If i Mod 10000 = 0 Then
                   Circle (x * Rnd, y * Rnd), 50
               End If
           Next
       Next
   End Sub
   
   ' Load property values from storage
   Private Sub UserControl_ReadProperties(PropBag As PropertyBag)
   
       UserControl.BackStyle = PropBag.ReadProperty("BackStyle", 1)
       UserControl.BackColor = PropBag.ReadProperty("BackColor", &H8000000F)
   End Sub
   
   ' Write property values to storage
   Private Sub UserControl_WriteProperties(PropBag As PropertyBag)
   
       Call PropBag.WriteProperty("BackStyle", UserControl.BackStyle, 1)
       Call PropBag.WriteProperty("BackColor", UserControl.BackColor, &H8000000F)
   End Sub
                       

5. From the File menu, select Add Project. Choose Standard EXE and click Open. Form1 is created by default.
6. Close the (designer) window for UserControl1.
7. Add two instances of UserControl1 to Form1. They are named UserControl11 and UserControl12.
8. Change the BackColor property of both UserControls to something other than grey.
9. In the Project Explorer, change the startup project by right-clicking on Project2. Select Set as Startup.
10. Press the F5 key to run the project. Note that you can see circles being drawn on the controls (animation.)
11. Stop the project and change the BackStyle property of UserControl12 to 0 (Transparent.)
12. Press F5 to run, and note that you do not see the circle animation on UserControl11. The form becomes transparent while animating, but you only see the circles on the control after the animation has taken place.

REFERENCES

For additional information on Windowless controls, click the article number below to view the article in the Microsoft Knowledge Base:

184645 HOWTO: Create Lightweight Controls with Visual Basic 6.0

Additional query words: sp4

Keywords: kbbug kbctrlcreate kbfix kbvs600sp4fix kbvs600sp5fix KB257645

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