[RESOLVED] Monitor Brightness

[TT(n)]

I'm glad you got something to work.

I'm still not happy with it not working on all PC's for my own library example, so I'm looking at this API:
DeviceIoControl
With the constant: IOCTL_VIDEO_SET_DISPLAY_BRIGHTNESS
http://msdn.microsoft.com/en-us/libr...04(VS.85).aspx

If you don't mind I'll post it here, if I can make it work.
That way future searchers will find both answers in one spot. Or not. lol

[stin]

Sounds good to me. I ran across somebody suggesting that API, but said it was kinda buggy, or at least messy.

Good luck.

[HanneSThEGreaT]

Whoah ,seems like I missed all the action last night - was late here and I had to go home, and didn't get chance to pop into CG again.

For interest sake, I'll also play a bit with the DeviceIoControl API

Thanks guys for teaching me so much

[TT(n)]

Well this is frustrating to say the least.
Vista/7 has a function SetMonitorBrightness, but I can't find any declarations or anything, so I gave up on that.

DeviceIoControl and CreateFile do so many things, it's hard to wrap a succinct snippet of code around it.

Here is what I have so far, but I can't get a device handle out of CreateFile.
It's almost as if everyone purposely leaves out how to get the correct device/driver name, or path. Like we are supposed to be mind readers.

'Code found http://www.dreamincode.net/forums/blog/126/entry-596-set-the-brightness-of-a-laptop-through-vbnet/
   'Input Output control codes
    Const IOCTL_VIDEO_SET_DISPLAY_BRIGHTNESS As Int32 = 2294940
    Const IOCTL_VIDEO_QUERY_DISPLAY_BRIGHTNESS As Int32 = 2294936
    Const IOCTL_VIDEO_QUERY_SUPPORTED_BRIGHTNESS As Int32 = 2294932
    'desired access param of create file
    Const GENERIC_NONE As Int32 = 0 'This may gain access when GENERIC_READ fails because of access restriction
    Const GENERIC_READ As Int32 = -2147483648
    Const GENERIC_WRITE As Int32 = 1073741824
    Const GENERIC_ALL As Int32 = GENERIC_READ Or GENERIC_WRITE
    'share mode param of create file
    Const FILE_SHARE_ALL As Int32 = 7
    Const FILE_SHARE_READ As Int32 = 1
    Const FILE_SHARE_WRITE As Int32 = 2
    Const FILE_EXCLUSIVE_ACCESS As Int32 = 0 'Blocks others
    'misc
    Const OPEN_EXISTING As Int32 = 3   'creation method
    Const INVALID_HANDLE_VALUE As Int32 = -1 'return of create file
    Const FILE_ATTRIBUTE_NORMAL As Int32 = 128   'Possible file attribute for device?

    Private Structure BRIGHTNESS
        Public ucDisplayPolicy As Byte
        Public ucACBrightness As Byte
        Public ucDCBrightness As Byte
    End Structure

    'Private Declare  Function apiCreateFileLong Lib "kernel32" Alias "CreateFileW" (ByVal lpFileName As String, ByVal dwDesiredAccess As Int32, ByVal dwShareMode As Int32, ByVal lpSecurityAttributes As Int32, ByVal dwCreationDisposition As Int32, ByVal dwFlagsAndAttributes As Int32, ByVal hTemplateFile As Int32) As Int32 'You can use paths longer than MAX_PATH characters by calling the wide (W) version(or Auto) of CreateFile and prepending “\\?\” to the path. The “\\?\” tells the function to turn off path parsing. This lets you use paths that are nearly 32,000 Unicode characters long. You must use fully-qualified paths with this technique. This also works with UNC names. The “\\?\” is ignored as part of the path. For example, “\\?\C:\myworld\private” is seen as “C:\myworld\private”, and “\\?\UNC\tom_1\hotstuff\coolapps” is seen as “\\tom_1\hotstuff\coolapps”.
    Private Declare Function apiCreateFile Lib "kernel32" Alias "CreateFileA" (ByVal lpFileName As String, ByVal dwDesiredAccess As Int32, ByVal dwShareMode As Int32, ByVal lpSecurityAttributes As Int32, ByVal dwCreationDisposition As Int32, ByVal dwFlagsAndAttributes As Int32, ByVal hTemplateFile As Int32) As Int32
    Private Declare Function apiDeviceIoControl Lib "kernel32" Alias "DeviceIoControl" (ByVal hDevice As Int32, ByVal dwIoControlCode As Int32, ByRef lpInBuffer As BRIGHTNESS, ByVal nInBufferSize As Int32, ByVal lpOutBuffer As Int32, ByVal nOutBufferSize As Int32, ByRef lpBytesReturned As Int32, ByVal lpOverlapped As Int32) As Boolean
    Private Declare Function apiCloseHandle Lib "kernel32" Alias "CloseHandle" (ByVal hObject As Int32) As Boolean

    Private Sub Button1_Click(ByVal sender As System.Object, ByVal e As System.EventArgs) Handles Button1.Click
        Dim ret As Int32
        ret = SetBrightness(75) ' Call the function.
        If ret = 0 Then
            MessageBox.Show("device operation failed or is busy pending...")
        ElseIf ret = INVALID_HANDLE_VALUE Then
            MessageBox.Show("invalid handle")
        ElseIf ret = -2 Then
            MessageBox.Show("device path does not exist")
        Else
            MessageBox.Show("success!")
            'TODO-Get brightness
        End If
    End Sub

    Private Function SetBrightness(ByRef bLvl As Int32) As Int32
        Dim hDev, results, cbSize As Int32, b As New BRIGHTNESS
        b.ucDCBrightness = bLvl ' The brightness on DC Power 
        b.ucACBrightness = bLvl ' The Brightness on AC Power 
        hDev = apiCreateFile("\\.\LCD", GENERIC_READ, FILE_SHARE_ALL, 0, OPEN_EXISTING, 0, 0) ' Get the display 
        If hDev = INVALID_HANDLE_VALUE Then Return -1
        If hDev = 0 Then Return -2 'Since this is an invalid device handle too
        cbSize = System.Runtime.InteropServices.Marshal.SizeOf(b)
        SetBrightness = apiDeviceIoControl(hDev, IOCTL_VIDEO_SET_DISPLAY_BRIGHTNESS, b, cbSize, 0, 0, results, 0) ' Set the brightness. 
        apiCloseHandle(hDev) ' Close the handle. 
    End Function

[HanneSThEGreaT]

Yep, documentation sucks!! I sympathise! I've been having the same problem!

Guess what, I got it working, OK, not me, a genius called Lingzhi Sun, over at MSDN forums! The whole problem was with the GetDeviceGammaRamp API, so freaking small!!

I had it declared as :

  <DllImport("gdi32.dll")> _
  Private Shared Function GetDeviceGammaRamp(ByVal hdc As Int32, ByVal lpv As Int32) As Int32
  End Function

It should have been declared as a Boolean, like this :

  <DllImport("gdi32.dll")> _
    Private Shared Function GetDeviceGammaRamp(ByVal hdc As Int32, ByRef lpv As RAMP) As Boolean
    End Function

So, my initial thoughts were correct, the GetDeviceGammaRamp never got the correct values!

He got the corect declaration for GetDeviceGammaRamp here :

http://www.pinvoke.net/default.aspx/...GammaRamp.html

There were some small errors as wel, but you could have a look at this thread, which explains all :

http://social.msdn.microsoft.com/For...9-df703a07d5c8

stin, this is your project - you will see that it does reset the brightness to what it was originally

And, stin, sorry for taking so long with this, and not helping properly

TT(n), thanks for all your input as well, I know your'e a genius, and much more clever than me, when you started to struggle, I lost all hope LOL!

I'm attaching your project here stin WHOO HOO!!!!!!!

[stin]

You guys are AMAZING. It's why this forum is my goto for help. I feel bad that I'm not able to contribute much, but I do try.

Thanks again!

[stin]

Well, I tried opening your solution, but it open as a blank solution in VS 2008. I've been able to get them open before. Any thoughts?

[HanneSThEGreaT]

You guys are AMAZING. It's why this forum is my goto for help. I feel bad that I'm not able to contribute much, but I do try.

Thanks again!

You're also amazing with all your effort you put in, if I had an employee such as you working for me, you'd have received a raise because of this porject

Helping others comes with time, heck, it took me 4 years to actually start trying to help other members here, I guess I was a bit too scared, or insecure. You'll be amazed what you can learn by helping others, and reading other people's questions. I have learnt a great deal with this thread, so I am happy and grateful to everyone that has contributed

Well, I tried opening your solution, but it open as a blank solution in VS 2008. I've been able to get them open before. Any thoughts?

Strange....

I am attaching a new zip here again. And I'm adding the full code now with this post as well ( to cover both bases )

Imports System.Runtime.InteropServices



Public Class Form1



    <StructLayout(LayoutKind.Sequential, CharSet:=CharSet.Ansi)> _
    Private Structure RAMP



        <MarshalAs(UnmanagedType.ByValArray, SizeConst:=256)> _
        Public Red As UInt16()



        <MarshalAs(UnmanagedType.ByValArray, SizeConst:=256)> _
        Public Green As UInt16()



        <MarshalAs(UnmanagedType.ByValArray, SizeConst:=256)> _
        Public Blue As UInt16()



    End Structure



    <DllImport("gdi32.dll")> _
    Private Shared Function SetDeviceGammaRamp(ByVal hDC As IntPtr, ByRef lpRamp As RAMP) As Boolean

    End Function



    <DllImport("user32.dll")> _
    Private Shared Function GetDC(ByVal hWnd As IntPtr) As IntPtr

    End Function



    <DllImport("gdi32.dll")> _
    Private Shared Function GetDeviceGammaRamp(ByVal hdc As Int32, ByRef lpv As RAMP) As Boolean

    End Function



    Private WithEvents TrackBar1 As System.Windows.Forms.TrackBar

    'Private Shared Ramp1(0 To 255, 0 To 2) As RAMP



    Private Shared s_ramp As New RAMP()



    Private Shared MyRamp As New RAMP()



    Private Shared Sub SetGamma(ByVal gamma As Integer)



        s_ramp.Red = New UShort(255) {}



        s_ramp.Green = New UShort(255) {}



        s_ramp.Blue = New UShort(255) {}



        For i As Integer = 1 To 255

            ' gamma is a value between 3 and 44 

            s_ramp.Red(i) = InlineAssignHelper(s_ramp.Green(i), InlineAssignHelper(s_ramp.Blue(i), CUShort((Math.Min(65535, Math.Max(0, Math.Pow((i + 1) / 256.0R, gamma * 0.1) * 65535 + 0.5))))))

        Next



        ' Now set the value. 

        SetDeviceGammaRamp(GetDC(IntPtr.Zero), s_ramp)

    End Sub



    Private Shared Sub RestoreGamma(ByVal gamma As RAMP)

        'MyRamp.Red = New UShort(255) {}



        'MyRamp.Green = New UShort(255) {}



        'MyRamp.Blue = New UShort(255) {}



        'For x = 0 To 255

        '    'MyRamp.Red(x) = Ramp1(x, 0)

        '    'MyRamp.Green(x) = Ramp1(x, 1)

        '    'MyRamp.Blue(x) = Ramp1(x, 2)

        'Next

        SetDeviceGammaRamp(GetDC(IntPtr.Zero), gamma)

    End Sub



    Private Shared Function InlineAssignHelper(Of T)(ByRef target As T, ByVal value As T) As T

        target = value

        Return value

    End Function





    Private Sub TrackBar1_Scroll(ByVal sender As System.Object, ByVal e As System.EventArgs) Handles TrackBar1.Scroll

        SetGamma(TrackBar1.Value)

    End Sub



    Private Sub SetBrightness_FormClosing(ByVal sender As Object, ByVal e As System.Windows.Forms.FormClosingEventArgs) Handles Me.FormClosing

        RestoreGamma(MyRamp)

    End Sub



    Private Sub SetBrightness_Load(ByVal sender As Object, ByVal e As System.EventArgs) Handles Me.Load

        GetDeviceGammaRamp(GetDC(IntPtr.Zero), MyRamp)

    End Sub

End Class

Have a great night and weekend, and I'm looking forward to your next "complicated question"

PS: I'll pop in later tonight again to see if you have managed to open the zip

Hannes

[stin]

The zips project still didn't work for me, but copying the code did. Looks like it works! Thank you a lot!

[HanneSThEGreaT]

Cool

Just shout if you get any more issues

Hannes

[TT(n)]

I don't think the Boolean type matters.
I did mention that my declaration works, which was ByRef.
ByVal would be if you were using a memory API, or were omitting the optional functionality of the parameter.(this can make other parameters work sometimes)
In your example you pass the structure, which I should have caught and mentioned though.

[TT(n)]

One quick issue with the slider example.
Awesome work BTW!, I would have not figured out the InlineAssignHelper part. No, you're a genius, ... no you are, ... no YOU are.

BUG:
Trackbar can change before the load event is finished, thus locking in the wrong original ramp, which is nicely returned ofcourse, but to the wrong gamma.

Solution, put in a boolen.

Private IsLoaded As Boolean = False

In the load event switch it on.

Private Sub Form1_Load(ByVal sender As Object, ByVal e As System.EventArgs) Handles Me.Load
GetDeviceGammaRamp(GetDC(IntPtr.Zero), usrRamp)
IsLoaded = True
End Sub

In the trackbar scroll or valuechanged event put this:

    Private Sub TrackBar2_ValueChanged(ByVal sender As Object, ByVal e As System.EventArgs) Handles TrackBar2.ValueChanged
        If IsLoaded = False Then Exit Sub
        SetGamma(TrackBar2.Value)
    End Sub

EDIT: Oh yeah, I noticed that it doesn't matter what device context you pass.
Any works so far, although I prefer to use GetWindowDC(GetDeskTopWindow) which is at least supposed to be the whole desktop window.

[TT(n)]

{BATTERY LOW SOLUTION XP/Vista/7} {VB6}
Full slider dimmer solution shown later in this thread.

I brought in the structure in to my example, so that it would work on Vista/7. Great it works!

I did however notice a difference in the look between the two dimmings.
Here is an updated example, that toggle dims, without a slider.
It looks more like a laptop on battery power(the whites are dimmer!), but without the ability to adjust. {To come later}

    Private usrRamp As New RAMP

    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 Sub Form1_Load(ByVal sender As System.Object, ByVal e As System.EventArgs) Handles MyBase.Load
        apiGetDeviceGammaRamp(apiGetWindowDC(apiGetDesktopWindow), usrRamp)
    End Sub
    Private Sub Form1_FormClosed(ByVal eventSender As System.Object, ByVal eventArgs As System.Windows.Forms.FormClosedEventArgs) Handles Me.FormClosed
        apiSetDeviceGammaRamp(apiGetWindowDC(apiGetDesktopWindow), usrRamp)
    End Sub

    Private Sub Button1_Click(ByVal sender As System.Object, ByVal e As System.EventArgs) Handles Button1.Click
        HalfBright()
    End Sub
    Private Function HalfBright() As Int32
        Dim rmp As New RAMP
        apiGetDeviceGammaRamp(apiGetWindowDC(apiGetDesktopWindow), rmp)
        For iCtr As UShort = 0 To 255
            rmp.Red(iCtr) = CUShort(rmp.Red(iCtr) / 2)
            rmp.Green(iCtr) = CUShort(rmp.Green(iCtr) / 2)
            rmp.Blue(iCtr) = CUShort(rmp.Blue(iCtr) / 2)
        Next
        Return apiSetDeviceGammaRamp(apiGetWindowDC(apiGetDesktopWindow), rmp)
    End Function

[HanneSThEGreaT]

I don't think the Boolean type matters.
I did mention that my declaration works, which was ByRef.
ByVal would be if you were using a memory API, or were omitting the optional functionality of the parameter.(this can make other parameters work sometimes)

Yeah, that till bothers me - it will probably keep on bothering me until I'm 60! Perhaps the whole problem was how I stored the retur value of GetDeviceGammaRamp. There is a change in one of the parameters' type as well, so that is more likely to have been the issue. I'm to scared to change it to any other datattype though! LOL! Maybe I should quickly have a look and see what effect it will have

BUG:
Trackbar can change before the load event is finished, thus locking in the wrong original ramp, which is nicely returned ofcourse, but to the wrong gamma.

Solution, put in a boolen.

Never realised that, guess I had tunnel vision

Okay, just when you thought this thread was safe. lol

So I brought in the structure in to my example, so that it would work on Vista/7. Great it works! both examples do.
I did however notice a difference in the look between the two dimmings.
Here is an updated example, that toggle dims, without a slider.
It looks more like a laptop on battery power(the whites are dimmer!), but without the ability to adjust.

    Private usrRamp As New RAMP

    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 Sub Form1_Load(ByVal sender As System.Object, ByVal e As System.EventArgs) Handles MyBase.Load
        apiGetDeviceGammaRamp(apiGetWindowDC(apiGetDesktopWindow), usrRamp)
    End Sub
    Private Sub Form1_FormClosed(ByVal eventSender As System.Object, ByVal eventArgs As System.Windows.Forms.FormClosedEventArgs) Handles Me.FormClosed
        apiSetDeviceGammaRamp(apiGetWindowDC(apiGetDesktopWindow), usrRamp)
    End Sub

    Private Sub Button1_Click(ByVal sender As System.Object, ByVal e As System.EventArgs) Handles Button1.Click
        HalfBright()
    End Sub
    Private Function HalfBright() As Int32
        Dim rmp As New RAMP
        apiGetDeviceGammaRamp(apiGetWindowDC(apiGetDesktopWindow), rmp)
        For iCtr As UShort = 0 To 255
            rmp.Red(iCtr) = CUShort(rmp.Red(iCtr) / 2)
            rmp.Green(iCtr) = CUShort(rmp.Green(iCtr) / 2)
            rmp.Blue(iCtr) = CUShort(rmp.Blue(iCtr) / 2)
        Next
        Return apiSetDeviceGammaRamp(apiGetWindowDC(apiGetDesktopWindow), rmp)
    End Function

Good work!

[HanneSThEGreaT]

Aha! I think the real problem(s) were :
1) As TT(n) pointed out, the second parameter of GetDeviceGammaRamp was supposed to be ByRef and not ByVal
2) The data type of the second parameter shouldn't have been Int32 but RAMP instead. - How could I miss that????

If I do this :

    <DllImport("gdi32.dll")> _
    Private Shared Function GetDeviceGammaRamp(ByVal hdc As Int32, ByRef lpv As RAMP) As Int32
    End Function

I modified my original code.

It also works. TT(n) do you think my observations are correct? Do you agree?

Hannes