Introduction

I have always wanted to get or set my system screen resolution with GDI. Now I have found how to do that, and want to share my finding with others

Let's go!...

Step1

First you should find your active display device and its settings:

EnumDisplaySettingsW(NULL,ENUM_CURRENT_SETTINGS,&devMode);
m_PrevMode = devMode;
disDev.cb = sizeof(DISPLAY_DEVICE);
disDev.StateFlags = DISPLAY_DEVICE_ATTACHED_TO_DESKTOP;

Step2

Then you can save found information somewhere to print:

strTemp.Format(_T("Active Display Device settings : \n\nDevice Name : %s\nDevice Resolution : %d × %d\nBits per Pixel: %d bits\nFrequency : %d Hz")
        ,disDev.DeviceString
        ,devMode.dmPelsWidth
        ,devMode.dmPelsHeight
         ,devMode.dmBitsPerPel
         ,devMode.dmDisplayFrequency);
    GetDlgItem(IDC_RESMSG)->SetWindowTextW(strTemp);//print them

Step3

After that you may want to find all available Display mode like this:

  for (unsigned i = 0;EnumDisplaySettingsW(NULL, i, &devMode);i++)
    {
        CStringW strTemp;
        m_Array.Add(devMode);//m_Array is a place to save found Modes
        strTemp.Format(_T("%d × %d, %d bits, %d Hz")          /*save them */
            ,devMode.dmPelsWidth
            ,devMode.dmPelsHeight
            ,devMode.dmBitsPerPel
            ,devMode.dmDisplayFrequency
     );
     ((CListBox*)GetDlgItem(IDC_RESLIST))->AddString(strTemp);//print them

Step4

Finally you can set any found mode you want :

 m_Array.GetAt(iCurSel).dmSize = sizeof(DEVMODE);
        m_Array.GetAt(iCurSel).dmFields = DM_BITSPERPEL|DM_PELSWIDTH|DM_PELSHEIGHT|DM_DISPLAYFREQUENCY;
        result = ChangeDisplaySettingsW(&m_Array.GetAt(iCurSel),CDS_UPDATEREGISTRY);    
        if(DISP_CHANGE_SUCCESSFUL == result)
        {
            if(IDYES == AfxMessageBox(_T("Do you want to keep this setting ?"),MB_YESNO))
                m_PrevMode = m_Array.GetAt(iCurSel);
            else
            {
                if(DISP_CHANGE_SUCCESSFUL != ChangeDisplaySettingsW(&m_PrevMode,CDS_UPDATEREGISTRY))
                    AfxMessageBox(_T("Couldn't restore previous Display Mode"),MB_ICONERROR);
            }
        }
        else
        {
            switch(result)
            {
                case DISP_CHANGE_BADDUALVIEW:
                    strMessage.Format(_T("The settings change was unsuccessful because system is DualView capable."));
                    break;
                case DISP_CHANGE_FAILED:
                    strMessage.Format(_T("The display driver failed the specified graphics mode."));
                    break;
                case DISP_CHANGE_RESTART:
                    strMessage.Format(_T("The computer must be restarted in order for the graphics mode to work."));
                    break;
                case DISP_CHANGE_NOTUPDATED:
                    strMessage.Format(_T("Unable to write settings to the registry."));
                    break;
            }
            AfxMessageBox(strMessage,MB_ICONERROR);
        }
    }
    else
        AfxMessageBox(_T("No Display Setting was selected to Apply"),MB_ICONINFORMATION);

Note that if you find this article having source code instead of explanation,its due to the very busy time that I have this days. Please accept my sorriness!

Points of Interest

Note that this app has a undo feature!

How to get or set screen resolution in GDI