How to query GetMonitorBrightness from C#

Question

How does GetMonitorBrightness http://msdn.microsoft.com/en-us/library/ms775205.aspx work? Can someone give me an actual working implementation calling this code in C#?

I'm trying to retrieve the allowed brightness levels my laptop supports.

I have the following working code that sets the brightness from 1 to ~150. But I'm looking for the allowed input values (min max values).

    static void SetBrightness(byte targetBrightness)
    {
        ManagementScope scope = new ManagementScope("root\\WMI");
        SelectQuery query = new SelectQuery("WmiMonitorBrightnessMethods");
        using (ManagementObjectSearcher searcher = new ManagementObjectSearcher(scope, query))
        {
            using (ManagementObjectCollection objectCollection = searcher.Get())
            {
                foreach (ManagementObject mObj in objectCollection)
                {
                    mObj.InvokeMethod("WmiSetBrightness",
                        new Object[] { UInt32.MaxValue, targetBrightness });
                    break;
                }
            }
        }
    }

Answer 1

While using Interop should be possible this function is also available through WMI. Changing my original code a bit resulted in the following code that should work:

 ManagementScope scope;
 SelectQuery query;

 scope = new ManagementScope("root\\WMI");
 query = new SelectQuery("SELECT * FROM WmiMonitorBrightness");

 using (ManagementObjectSearcher searcher = new ManagementObjectSearcher(scope, query))
 {
    using (ManagementObjectCollection objectCollection = searcher.Get())
    {
      foreach (ManagementObject mObj in objectCollection)
      {
        Console.WriteLine(mObj.ClassPath);
        foreach (var item in mObj.Properties)
        {
          Console.WriteLine(item.Name + " " +item.Value.ToString());
          if(item.Name =="CurrentBrightness")
            //Do something with CurrentBrightness
        }
      }
    }
  }

Now I'm really curious how to handle 'special' cases like non laptop Screen's and if they implement any way to influence brightness.

Answer 2

The function has an output of the minimum and maximum values:

LPDWORD pdwMinimumBrightness=NULL;
LPDWORD pdwMaximumBrightness=NULL;
HANDLE pmh = pPhysicalMonitors[0].hPhysicalMonitor;
GetMonitorBrightness(pmh, pdwMinimumBrightness, pdwMaximumBrightness);

This is assuming that you want the values for the first monitor.