how to change active desktop wallpaper in c++ - c++

Question

hi i want to write a little program to change the wallpaper in windows 7
i wanted to use the following code:
#include "windows.h"
#include "wininet.h"
#include "shlobj.h"
#include "wchar.h"
#include <iostream>
void SetWallpaper(LPCWSTR file){
CoInitializeEx(0,COINIT_APARTMENTTHREADED);
IActiveDesktop* desktop;
HRESULT status = CoCreateInstance(CLSID_ActiveDesktop,NULL,CLSCTX_INPROC_SERVER,IID_IActiveDesktop,(void**)&desktop);
WALLPAPEROPT wOption;
ZeroMemory(&wOption, sizeof(WALLPAPEROPT));
wOption.dwSize=sizeof(WALLPAPEROPT);
wOption.dwStyle = WPSTYLE_CENTER;
status = desktop->SetWallpaper(file,0);
wcout << status << endl;
status = desktop->SetWallpaperOptions(&wOption,0);
wcout << status << endl;
status = desktop->ApplyChanges(AD_APPLY_ALL);
wcout << status << endl;
desktop->Release();
CoUninitialize();
}
int wmain(int argc, wchar* argv[]){
if(argc<=1){
wcout << "use: " << argv[0] <<" path_to_pic.bmp" <<endl;
}else{
wchar_t* file = argv[1];
SetWallpaper(file);
}
getchar();
return 0;
}
but this code does not change the wallpaper, it only gives me the hresult error-code 80070002 after calling ApplyChanges.
what am i doing wrong please help

Answer 1

Please change your main entry function from
int main(int argc, char* argv[])
to
int wmain(int argc, wchar_t* argv[] )
No casting is necessary like wchar_t* file = (wchar_t*)argv[1]; and it will just work as your wmain arguments are already in wchar_t*
I was able to use your code and my modification and change my computer wall paper

Answer 2

Here's a promising-looking piece of code
http://answers.google.com/answers/threadview/id/512662.html
though I haven't tested it myself:
#include <windows.h>
#include <stdio.h>
const SPI_GETDESKWALLPAPER=115;
void printusage(char *program)
{
fprintf(stderr, "Usage: %s background-file.bmp\n", program);
fprintf(stderr, " Changes desktop background to background-file\n");
return;
}
int main(int argc, char *argp[])
{
DWORD dResult;
BOOL result;
char oldWallPaper[255];
if (argc != 2) {
printusage(argp[0]);
return 1;
}
result = SystemParametersInfo(
SPI_GETDESKWALLPAPER,
sizeof(oldWallPaper)-1,
oldWallPaper,
0);
fprintf(stderr, "Current desktop background is %s\n", oldWallPaper);
result = SystemParametersInfo(
SPI_SETDESKWALLPAPER,
0,
argp[1],
0);
if (!result) {
dResult = GetLastError();
fprintf(stderr, "Attempt to set new desktop background failed; code
%d\n", dResult);
fprintf(stderr, "Will restore prior setting (%s)\n", oldWallPaper);
result = SystemParametersInfo(
SPI_SETDESKWALLPAPER,
0,
oldWallPaper,
0);
return 2;
}
fprintf(stderr, "Desktop background changed to %s\n", argp[1]);
return 0;
}

Answer 3

Code to change your wallpaper with two (or multiple , add more conditions) images ..
#include <windows.h>
int main()
{
int i;
for(i=0;;i++)
{
Sleep(1600);
if(i%2==0)
{
const wchar_t *filenm = L"C:\\Pictures\\image1.jpg"; //ADDRESS of first image
bool isWallSet=SystemParametersInfoW(SPI_SETDESKWALLPAPER, 0,(void*)filenm,SPIF_UPDATEINIFILE);
}
else
{
const wchar_t *filenm = L"C:\\Pictures\\image2.jpg"; //ADDRESS of second image
bool isWallSet=SystemParametersInfoW(SPI_SETDESKWALLPAPER, 0,(void*)filenm,SPIF_UPDATEINIFILE);
}
}
return 0;
}