Changing Windows XP wallpaper

[BrammekeDotNet]

Hi,

I'm trying to programatically (VB .NET 2003) change the wallpaper on my
Windows XP machine. I can see the desktop refreshing, but the wallpaper
itself never changes. I also can't make it blank by sending a
null-string (not illustrated here).

This is the code I wrote:


---
Declare Function SystemParametersInfo Lib "user32.dll" Alias
"SystemParametersInfoA" (ByVal uiAction As Long, ByVal uiParam As Long,
ByVal pvParam As Object, ByVal fWinIni As Long) As Boolean

---

Const SPI_SETDESKWALLPAPER = &H14
Const SPI_SETDESKPATTERN = &H15

Const SPIF_UPDATEINIFILE = &H1
Const SPIF_SENDWININICHANGE = &H2
Const SPIF_SENDCHANGE = SPIF_SENDWININICHANGE

SystemParametersInfo(SPI_SETDESKWALLPAPER, 0, filename,
SPIF_UPDATEINIFILE Or SPIF_SENDCHANGE)
---


Could someone give me a clue here? :/

Thanks!
Bram

 

[Herfried K. Wagner [MVP]]

Declare Function SystemParametersInfo Lib "user32.dll" Alias
"SystemParametersInfoA" (ByVal uiAction As Long, ByVal uiParam As Long,
ByVal pvParam As Object, ByVal fWinIni As Long) As Boolean

\\\
Public Declare Function SystemParametersInfo _
Lib "user32.dll" _
Aloas "SystemParametersInfoA" _
( _
ByVal uiAction As UInt32, _
ByVal uiParam As UInt32, _
ByVal pvParam As IntPtr, _
ByCal fWinIni As UInt32 _
) As Boolean
///

 

[BrammekeDotNet]

Looks very much like my code, except for the type declarations.

Error message on pvParam: "Value of type 'String' cannot be converted
to 'System.IntPtr'." How do I send a pointer which points to my string?

 

[BrammekeDotNet]

For the collective archive we call "the Internet", this fixed the
problem:

Declare Function SystemParametersInfo Lib "user32.dll" Alias
"SystemParametersInfoA" (ByVal uiAction As Integer, ByVal uiParam As
Integer, ByVal pvParam As String, ByVal fWinIni As Integer) As Integer
Mind the type of pvParam...