Thread: How to detect screen resolution and set wallpaper

I've been playing around with C++, and decided on a simple app to change wallpaper depending on screen resolution, since at college(sixth form) some of our computers are 16:9 and others are 4:3.

What I want to know is what Windows API calls do I need to make in order to achieve this? And also what syntax? (e.g. Resolution(width, height)), I've had a look on google and here, but I'm still a little mystified. If there is anything compiler specific, I'm using GCC.

Thanks in advance.

Yes, I found info, and I think I have an idea, and I'm about to try something, which I found on Google and if it doesn't work I will post source code to find out what's wrong, happy?

Ok, several compiling errors, I assume I have something fundamentally wrong in my code, any ideas? I'm not asking to be spoon fed, just a pointer or two.

Code:

#include <iostream>

using namespace std;

int main(void)
{
	int cx = GetSystemMetrics(SM_CXSCREEN);
	/*int cy = GetSystemMetrics(SM_CYSCREEN)*/

	if (cx = 1440)
	{
		SystemParametersInfo(SPI_SETDESKWALLPAPER,TRUE,(LPVOID)"E:\\my_docs\\test.bmp",SPIF_SENDWININICHANGE| SPIF_UPDATEINIFILE);
	}
	else
	{
		SystemParametersInfo(SPI_SETDESKWALLPAPER,TRUE,(LPVOID)"E:\\my_docs\\test2.bmp",SPIF_SENDWININICHANGE| SPIF_UPDATEINIFILE);
	}
}

Compile Errors:
H:\Projects\C++\wallpaper.cpp|6|error: `main' must return `int'|
H:\Projects\C++\wallpaper.cpp||In function `int main(...)':|
H:\Projects\C++\wallpaper.cpp|7|error: `SM_CXSCREEN' was not declared in this scope|
H:\Projects\C++\wallpaper.cpp|7|error: `GetSystemMetrics' was not declared in this scope|
H:\Projects\C++\wallpaper.cpp|12|error: `SPI_SETDESKWALLPAPER' was not declared in this scope|
H:\Projects\C++\wallpaper.cpp|12|error: `TRUE' was not declared in this scope|
H:\Projects\C++\wallpaper.cpp|12|error: `LPVOID' was not declared in this scope|
H:\Projects\C++\wallpaper.cpp|12|error: `SPIF_SENDWININICHANGE' was not declared in this scope|
H:\Projects\C++\wallpaper.cpp|12|error: `SPIF_UPDATEINIFILE' was not declared in this scope|
H:\Projects\C++\wallpaper.cpp|12|error: `SystemParametersInfo' was not declared in this scope|
H:\Projects\C++\wallpaper.cpp|16|error: `SPI_SETDESKWALLPAPER' was not declared in this scope|
H:\Projects\C++\wallpaper.cpp|16|error: `TRUE' was not declared in this scope|
H:\Projects\C++\wallpaper.cpp|16|error: `LPVOID' was not declared in this scope|
H:\Projects\C++\wallpaper.cpp|16|error: `SPIF_SENDWININICHANGE' was not declared in this scope|
H:\Projects\C++\wallpaper.cpp|16|error: `SPIF_UPDATEINIFILE' was not declared in this scope|
H:\Projects\C++\wallpaper.cpp|16|error: `SystemParametersInfo' was not declared in this scope|
||=== Build finished: 15 errors, 0 warnings ===|

It appears that it is trying to read the various declarations as variables, but they're not.

Code:

#pragma comment(lib, "user32.lib")
#include <iostream>
#include <windows.h>
using namespace std;

int main(void)
{
	int cx = GetSystemMetrics(SM_CXSCREEN);
	/*int cy = GetSystemMetrics(SM_CYSCREEN)*/

	if (cx = 1440)
	{
		SystemParametersInfo(SPI_SETDESKWALLPAPER,TRUE,(LPVOID)"E:\\my_docs\\test.bmp",SPIF_SENDWININICHANGE| SPIF_UPDATEINIFILE);
	}
	else
	{
		SystemParametersInfo(SPI_SETDESKWALLPAPER,TRUE,(LPVOID)"E:\\my_docs\\test2.bmp",SPIF_SENDWININICHANGE| SPIF_UPDATEINIFILE);
	}
}

Of course, I hadn't realised I needed Windows specific libraries having not used them before. Thanks. Forgive my complete and utter ignorance, still learning, having come from a mostly VB.NET environment, and I'm a novice there as well. :P

Check the following solutins:
Change screen resolution: C++ Builder Tips and Tricks: How to change screen settings?
Change the desktop background: C++ Builder Tips and Tricks: How to change the desktop background?

I forgot to add this:
C++ Builder Tips and Tricks: How to check current screen resolution? (WinAPI)
C++ Builder Tips and Tricks: How to check current screen resolution? (VCL)

hi! please help! the above code doesn't work (do anything) for me

I've searched on the internets and have tried both

Code:

HKEY hKey;
DWORD dwDisposition;
char szData[50]="c:\\kovtunets2.bmp";

RegCreateKeyEx(HKEY_CURRENT_USER, _T("Control Panel\\Desktop"), 0, NULL, 0, KEY_ALL_ACCESS, NULL, &hKey, &dwDisposition);
RegSetValueEx(hKey, _T("Wallpaper"), 0, REG_SZ, (LPBYTE)szData, sizeof(szData));
RegCloseKey(hKey);

and

Code:

int main()
{
SystemParametersInfo( SPI_SETDESKWALLPAPER, 0, "c:\\kovtunets2.bmp", SPIF_UPDATEINIFILE );
}

each file complies however neither does anything

Originally Posted by yuriythebest

I've searched on the internets

All three of them?