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can you change the background?

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Is it possible, using win32, to change the desktop background to a different image? I'm trying to make a simple desktop changing program, and havn't been able to find a command that can do this. I'm wondering if there even is one (it seems like something rather complicated, so i wouldn't be surprised) Thanks^^ Meow.

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i've tried both functions, and with both i get errors that I'm unsure how to fix...

With SystemParametersInfo() The only error i get is with the value that i designate the image to be set as the wallpaper. this is how I have the function called:

SystemParametersInfo(SPI_SETDESKWALLPAPER, 0, "C:\\mountain.bmp", SPIF_UPDATEINIFILE);


Now, with the IActiveDesktop::SetWallpaper() I get a whole slew of errors. My guess is there's a header I need to include?

Again, thanks for any help^^

Mreow.

Edit: I figured out the compiling error, i had to point to the adress of a string, not include a direct string. Now, however, my issue is that the background jsut gets set to black... I'm 100% possitive the file exists...

here is what i have now:

string BackImage = "C:\\Main\\Desktop\\GiftsUngiven.jpg";
SystemParametersInfo(SPI_SETDESKWALLPAPER, 0, &BackImage, SPIF_UPDATEINIFILE);

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This is totally from the hip, but if this is the win32 api, you'll probably want a pointer to a C-String rather than an std::string.

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According to MSDN, SPI_SETDESKWALLPAPER expects a null terminated string [char*], not an actual string. Try BackImage.c_str() instead of &BackImage.

CM

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changing &BackImage to BackImage.c_str() pops the same error as leaving it alone...


string BackImage = "C:\\Main\\Desktop\\GiftsUngiven.jpg";
SystemParametersInfo(SPI_SETDESKWALLPAPER, 0, BackImage.c_str(), SPIF_UPDATEINIFILE);


I'm looking into CStings aswell.

Mreow.

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Quote:
Original post by KuroKitten
changing &BackImage to BackImage.c_str() pops the same error as leaving it alone...

What is that error?

CM

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You might have to cast your char* to a void* because that is what it expects.
so...

string BackImage = "C:\\Main\\Desktop\\GiftsUngiven.jpg";
SystemParametersInfo(SPI_SETDESKWALLPAPER, 0, (void*)BackImage.c_str(), SPIF_UPDATEINIFILE);

also, I think your image has to be a BMP, unless you have Active Desktop enabled. A jpg might result in a blank background being used.

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With SystemParametersInfo () function:

int WINAPI WinMain (HINSTANCE hInstance, HINSTANCE hPrevInstance, LPSTR lpCmdLine, int iShowCmd)
{
SystemParametersInfo(SPI_SETDESKWALLPAPER, 0, "/*Full Path: C:\\A.bmp*/", SPIF_UPDATEINIFILE);

return 0 ;
}




I bypassed error checking and <Windows.h> header, but this little program functions perfectly on VC 2003 with warning level 4. Note that all images that are not bitmap will be converted to a temporary bitmap when you select a wallpaper in Display Properties. So when calling this function, a bitmap should be passed (this stuff is not documented in MSDN - from my experiences, oh well).

With IActiveDesktop::SetWallpaper method:

#include <Windows.h>
#include <WinInet.h> //This header must be included for IActiveDesktop to be declared in <ShlObj.h>
#include <ShlObj.h> //IActiveDesktop is declared when _WININET_ is defined

int WINAPI WinMain (HINSTANCE hInstance, HINSTANCE hPrevInstance, LPSTR lpCmdLine, int iShowCmd)
{
CoInitialize (NULL) ;

HRESULT hr;
IActiveDesktop *pActiveDesktop;

//Create an instance of the Active Desktop
hr = CoCreateInstance(CLSID_ActiveDesktop, NULL, CLSCTX_INPROC_SERVER,
IID_IActiveDesktop, (void**)&pActiveDesktop);

//Insert code to call the IActiveDesktop methods
pActiveDesktop -> SetWallpaper ("/*Full Path: C:\\A.JPG*/", 0) ;

// Call the Release method
pActiveDesktop->Release();

CoUninitialize () ;

return 0 ;
}




I bypassed error checking, this function will work with other file types other than bitmap, but Active Desktop must be actived (one often used feature in Win9x when user select JPEG images, sort of).

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Whoa, thanks^^ I got the SystemParametersInfo() to work, however SetWallpaper() still throughs out a bunch of errors. It may be my compiler as far as that one is concerned.

Perhaps when i'm finished i can include the whole source code^^

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