Monitor and adjust brightness on laptops with GFA

[webu]

Hi all over the world,

Which operating system routine can we use with GFA to monitor the display brightness of laptops and also adjust it if necessary? Is there anything general or does it depend on the manufacturer?

[(X)]

docs.microsoft.com/en-us/windows/win32/api/highlevelmonitorconfigurationapi/nf-highlevelmonitorconfigurationapi-setmonitorbrightness

[(X)]

This code may work with a few tweaks to convert to GFA...

forums.codeguru.com/showthread.php?498043-RESOLVED-Monitor-Brightness/page5

Public Class Form1
   Private Structure RAMP
       <System.Runtime.InteropServices.MarshalAs(System.Runtime.InteropServices.UnmanagedType.ByValArray, SizeConst:=256)> _
       Public Red As UShort()
       <System.Runtime.InteropServices.MarshalAs(System.Runtime.InteropServices.UnmanagedType.ByValArray, SizeConst:=256)> _
       Public Green As UShort()
       <System.Runtime.InteropServices.MarshalAs(System.Runtime.InteropServices.UnmanagedType.ByValArray, SizeConst:=256)> _
       Public Blue As UShort()
   End Structure
   Private Declare Function apiGetDeviceGammaRamp Lib "gdi32" Alias "GetDeviceGammaRamp" (ByVal hdc As Int32, ByRef lpv As RAMP) As Int32
   Private Declare Function apiSetDeviceGammaRamp Lib "gdi32" Alias "SetDeviceGammaRamp" (ByVal hdc As Int32, ByRef lpv As RAMP) As Int32
   Private Declare Function apiGetWindowDC Lib "user32" Alias "GetWindowDC" (ByVal hwnd As Int32) As Int32
   Private Declare Function apiGetDesktopWindow Lib "user32" Alias "GetDesktopWindow" () As Int32
   Private newRamp As New RAMP()
   Private usrRamp As New RAMP()
   Private IsLoaded As Boolean

   Private Sub Form1_Load(ByVal sender As Object, ByVal e As System.EventArgs) Handles Me.Load
       TrackBar1.Minimum = 1000 : TrackBar1.Maximum = 2000 'Set trackbar to valid range, since if will be half, the lower range is invalid
       TrackBar2.Minimum = 25 : TrackBar2.Maximum = 44
       apiGetDeviceGammaRamp(apiGetWindowDC(apiGetDesktopWindow), usrRamp)
       IsLoaded = True
   End Sub

   Private Sub Form1_FormClosed(ByVal sender As Object, ByVal e As System.Windows.Forms.FormClosedEventArgs) Handles Me.FormClosed
       apiSetDeviceGammaRamp(apiGetWindowDC(apiGetDesktopWindow), usrRamp)
   End Sub

   Private Sub TrackBar1_ValueChanged(ByVal sender As Object, ByVal e As System.EventArgs) Handles TrackBar1.ValueChanged
       If IsLoaded = False Then Exit Sub
       DesktopBrightnessContrast(TrackBar1.Value, 44 - TrackBar2.Value + 3)
       Label2.Text = "Dim 1/" & (TrackBar1.Value / 1000).ToString
   End Sub

   Private Sub TrackBar2_ValueChanged(ByVal sender As Object, ByVal e As System.EventArgs) Handles TrackBar2.ValueChanged
       If IsLoaded = False Then Exit Sub
       DesktopBrightnessContrast(TrackBar1.Value, 44 - TrackBar2.Value + 3)
       Label3.Text = "Contrast " & TrackBar2.Value.ToString
   End Sub

   Private Function DesktopBrightnessContrast(ByVal bLevel As Int32, ByVal gamma As Int32) As Int32
       newRamp.Red = New UShort(255) {} : newRamp.Green = New UShort(255) {} : newRamp.Blue = New UShort(255) {}
       For i As Int32 = 1 To 255   ' gamma is a value between 3 and 44
           newRamp.Red(i) = InlineAssignHelper(newRamp.Green(i), InlineAssignHelper(newRamp.Blue(i), CUShort((Math.Min(65535, Math.Max(0, Math.Pow((i + 1) / 256.0R, gamma * 0.1) * 65535 + 0.5))))))
       Next
       For iCtr As UShort = 0 To 255
           newRamp.Red(iCtr) = CUShort(newRamp.Red(iCtr) / CDbl(bLevel / 1000))
           newRamp.Green(iCtr) = CUShort(newRamp.Green(iCtr) / CDbl(bLevel / 1000))
           newRamp.Blue(iCtr) = CUShort(newRamp.Blue(iCtr) / CDbl(bLevel / 1000))
       Next
       Return apiSetDeviceGammaRamp(apiGetWindowDC(apiGetDesktopWindow), newRamp) ' Now set the value.
   End Function

   Private Function InlineAssignHelper(Of T)(ByRef target As T, ByVal value As T) As T
       target = value : InlineAssignHelper = value
   End Function


End Class