Windows 设置显示亮度代码【msdn】

GetPhysicalMonitorsFromHMONITOR function

Microsoft code：

HMONITOR hMonitor = NULL;
DWORD cPhysicalMonitors;
LPPHYSICAL_MONITOR pPhysicalMonitors = NULL;

// Get the monitor handle.
hMonitor = MonitorFromWindow(hWnd, MONITOR_DEFAULTTOPRIMARY);

// Get the number of physical monitors.
BOOL bSuccess = GetNumberOfPhysicalMonitorsFromHMONITOR(
  hMonitor, 
  &cPhysicalMonitors
   );

if (bSuccess)
{
    // Allocate the array of PHYSICAL_MONITOR structures.
    pPhysicalMonitors = (LPPHYSICAL_MONITOR)malloc(
        cPhysicalMonitors* sizeof(PHYSICAL_MONITOR));

    if (pPhysicalMonitors != NULL)
    {
        // Get the array.
        bSuccess = GetPhysicalMonitorsFromHMONITOR(
            hMonitor, cPhysicalMonitors, pPhysicalMonitors);

       // Use the monitor handles (not shown).

        // Close the monitor handles.
        bSuccess = DestroyPhysicalMonitors(
            cPhysicalMonitors, 
            pPhysicalMonitors);

        // Free the array.
        free(pPhysicalMonitors);
}

you can use GetMonitorBrightness() to obtain detail max/min brightness before to set brightness.

BOOL GetMonitorBrightness(
  __in   HANDLE hMonitor,
  __out  LPDWORD pdwMinimumBrightness,
  __out  LPDWORD pdwCurrentBrightness,
  __out  LPDWORD pdwMaximumBrightness
);

SetMonitorBrightness function