Get monitor index from its handle (HMONITOR)

Question

I'm interested in getting the monitor index (1-based, to match Windows numbering) given the monitor handle.

Case of use: given a window's rect I want to know the monitor it belongs to. I can get the handle of the monitor using MonitorFromRect:

// RECT rect
const HMONITOR hMonitor = MonitorFromRect(rect, MONITOR_DEFAULTTONEAREST);

How can I get the monitor index from this handle?

PS: not sure if duplicate, but I've been looking around with no luck.

Answer 1

I found this post with the opposite question: finding the handle given the index (0-based in that case).

Based on it I worked this solution:

struct sEnumInfo {
  int iIndex = 0;
  HMONITOR hMonitor = NULL;
};

BOOL CALLBACK GetMonitorByHandle(HMONITOR hMonitor, HDC hdcMonitor, LPRECT lprcMonitor, LPARAM dwData)
{
  auto info = (sEnumInfo*)dwData;
  if (info->hMonitor == hMonitor) return FALSE;
  ++info->iIndex;
  return TRUE;
}

int GetMonitorIndex(HMONITOR hMonitor)
{
  sEnumInfo info;
  info.hMonitor = hMonitor;

  if (EnumDisplayMonitors(NULL, NULL, GetMonitorByHandle, (LPARAM)&info)) return -1;
  return info.iIndex + 1; // 1-based index
}