Function EnumMonitorProc

source/script2.cpp:3268–3296

BOOL CALLBACK EnumMonitorProc(HMONITOR hMonitor, HDC hdcMonitor, LPRECT lprcMonitor, LPARAM lParam)
{
	MonitorInfoPackage &mip = *(MonitorInfoPackage *)lParam;  // For performance and convenience.
	if (mip.monitor_number_to_find == COUNT_ALL_MONITORS)
	{
		++mip.count;
		return TRUE;  // Enumerate all monitors so that they can be counted.
	}
	if (!GetMonitorInfo(hMonitor, &mip.monitor_info_ex)) // Failed.  Probably very rare.
		return FALSE; // Due to the complexity of needing to stop at the correct monitor number, do not continue.
		// In the unlikely event that the above fails when the caller wanted us to find the primary
		// monitor, the caller will think the primary is the previously found monitor (if any).
		// This is just documented here as a known limitation since this combination of circumstances
		// is probably impossible.
	++mip.count; // So that caller can detect failure, increment only now that failure conditions have been checked.
	if (mip.monitor_number_to_find) // Caller gave a specific monitor number, so don't search for the primary monitor.
	{
		if (mip.count == mip.monitor_number_to_find) // Since the desired monitor has been found, must not continue.
			return FALSE;
	}
	else // Caller wants the primary monitor found.
		// MSDN docs are unclear that MONITORINFOF_PRIMARY is a bitwise value, but the name "dwFlags" implies so:
		if (mip.monitor_info_ex.dwFlags & MONITORINFOF_PRIMARY)
			return FALSE;  // Primary has been found and "count" contains its number. Must not continue the enumeration.
			// Above assumes that it is impossible to not have a primary monitor in a system that has at least
			// one monitor.  MSDN certainly implies this through multiple references to the primary monitor.
	// Otherwise, continue the enumeration:
	return TRUE;
}