How can I get the HMONITOR handle from the name of the display device?

Question

I want to get a monitor descriptor ( HMONITOR), which can be used with the API for multiple Windows monitors for a specific monitor connected to the system by index. For example, let's say I have three monitors attached to my system and part of my desktop; I want to get a handle for monitoring 3.

I already know how to get the device name for a specific monitor by index by calling a function EnumDisplayDevices. For example:

HMONITOR MonitorFromIndex(int index /* (zero-indexed) */)
{
    DISPLAY_DEVICE dd;
    dd.cb = sizeof(dd);
    if (EnumDisplayDevices(NULL, index, &dd, 0) != FALSE)
    {
       // We found a match; make sure that it part of the desktop.
       if ((dd.StateFlags & DISPLAY_DEVICE_ATTACHED_TO_DESKTOP) == DISPLAY_DEVICE_ATTACHED_TO_DESKTOP)
       {
          // Yup. Now we've got the name of the device:
          std::cout << dd.DeviceName << std::endl;

          // But how do I obtain an HMONITOR for this device?
          // ...
       }
    }
   return NULL;  // indicate failure
}

In the above code, we found the name of the desired device ( dd.DeviceName). I can use this name to create a DC for this monitor by calling CreateDC:

HDC hDC = CreateDC(dd.DeviceName, dd.DeviceName, NULL, NULL);

And I can get information about this monitor by calling EnumDisplaySettings:

DEVMODE dm;
dm.dmSize        = sizeof(dm);
dm.dmDriverExtra = 0;
if (EnumDisplaySettings(dd.DeviceName, ENUM_CURRENT_SETTINGS, &dm) != FALSE)
{
    std::cout << "The monitor supports " << dm.dmBitsPerPel << " bits per pixel." << std::endl;
}

, , . ?

EnumDisplayMonitors, , CreateDC, , , . , EnumDisplayMonitors FALSE ( ):

struct FoundMatch
{
   BOOL     found;
   HMONITOR hMonitor;
};

BOOL CALLBACK MonitorEnumProc(HMONITOR hMonitor, HDC, LPRECT, LPARAM dwData)
{
   FoundMatch* pfm = reinterpret_cast<FoundMatch*>(dwData);
   pfm->found    = TRUE;
   pfm->hMonitor = hMonitor;
   return FALSE;  // stop enumerating
}

// elsewhere, after getting the device name and using it to create a DC
FoundMatch fm;
fm.found    = FALSE;
fm.hMonitor = NULL;
BOOL result = EnumDisplayMonitors(hDC, NULL, MonitorEnumProc, reinterpret_cast<LPARAM>(&fm));

Answer 1

, , , - .

API , , . , dd.DeviceName, EnumDisplayMonitors(), dd.DeviceName MONITORINFOEX.szDevice.

MONITORINFOEX GetMonitorInfo().

- ++ 11:

struct DataBag
{
    HMONITOR hmon;
    TCHAR* devname;
} bag;

bag.hmon = NULL;
bag.devname = &dd.DeviceName;

BOOL bRes = EnumDisplayMonitors(
    NULL, NULL,
    [](HMONITOR hMonitor, HDC hDC, LPRECT rc, LPARAM data) -> BOOL {
        auto& bag = *reinterpret_cast<DataBag*>(data);
        MONITORINFOEX mi;
        mi.cbSize = sizeof(mi);
        if (/* match bag.devname against mi.szDevice */ && GetMonitorInfo(hMonitor, &mi))
        {
            bag.hmon = hMonitor;
            return FALSE;
        }
        return TRUE;
    },
    reinterpret_cast<LPARAM>(&bag));
if (bRes && bag.hmon)
{
    // Monitor found!
}