Printable View
I'm looking for a way to adjust the monitor's temperature. There's a program called f.lux that does this, but it doesn't get dark enough. The program I'm writing will be used on a boat and needs to be dark enough so that it's not blinding while driving at night.
Any thoughts?
Temperature does not control brightness. It will only control blue to yellow hue.
OK, thanks. Then I'll need to look for ways to change brightness, contrast and temp.
Is it possible?
One way to change the brightness is to change the Gamma component to give you a feeling that brightness is reduced. Actually the contrast is reduced. :D
To do this, you'll need the SetDeviceGammaRamp API :
I am attaching a working project ( in VB 2010 ) with :)Code:<DllImport("gdi32.dll")> _
Private Shared Function SetDeviceGammaRamp(ByVal hDC As IntPtr, ByRef lpRamp As RAMP) As Boolean
End Function
Super cool. I'll take a look at this tonight.
I was able to look at it at work, and I think that's going to be part of the solution, but it just doesn't get it dark enough. I think I still need something with the brightness at least.
I'm afraid that is as good as it will get. I'll try to see what else I can come up with, but the SetDeviceGammaRamp API is sufficient 99% of the time...
I'll have to look at in the dark and see what it looks like in practice.
After looking at it in the dark, that may be just what the doctor ordered. Doesn't do much with an all white background, but in conjunction with wise color choices for the background could be just right. Thanks a bunch.
That's great news :) Glad you came right :)
Please remember to mark your thread resolved if you feel you have solved this issue; it is explained here :
http://www.codeguru.com/forum/showthread.php?t=403073
I know this is marked resolved but I was wondering if there is a similar function to get the current gamma settings? I tried getDeviceGammaRamp, but from what I could tell that returns whether or not the devices is able to change the gamma.
Hi Stin :)
Hmm, not sure that there is something, offhand :)
Could you perhaps explain a bit more what you'd like to achieve then we can hopefully, possibly identify a solution
Hannes
The program will allow the user to change their gamma settings and then reset them when they leave. So really I just would like to capture what it's at when they start the program. The one you gave me starts at 14 or 18 which seams to be an arbitrary number.
I see :)
We will have to use GetDeviceGammaRamp at Form load, then with the Form_Closing event set it to what was retrieved at Form load. That will reset it to the value it was before the program was run.
Should I try to incorporate this into my previous example for you?
Sorry, this was very sloppy programming on my side, I should have done that initially :)
If it's not too much trouble that would fantastic. Using APIs isn't my forte, and as I mentioned, I tried using the getDeviceGammaRamp, but couldn't get it to work.
Thank you so much for your help.
It's no problem at all :)
I'll have a look at it over the weekend
Hannes
Hi Stin :)
I am looking for external help on this issue. I know what to use and what should be done, but, for the love of me, I can't manage to get it working. perhaps I'm too stupid :p
Hang in there...
Hannes
I really appreciate your help. It's not urgent, and I could get by with a hard coded number.
This might steer someone in the right direction. Seems that it's been solved before. Looks like C++ though.
http://www.autohotkey.com/forum/topic32034.html
That is not C code.. As far as I can tell it is a script for AutoHotKey
OK, I haven't received any response yt on any of the forums I have posted this question to :(
I did try this :
But it doesn't restore the screen back. either the settings doesn't get stored into my array ( which I think is the most likely explanation ), or the SetDeviceGammaRamp doesn't want to get the right values to apply. I'm feeling out of my league here.... :(Code:Imports System
Imports System.Runtime.InteropServices
Imports System.Windows.Forms
Public Class SetBrightness
Inherits Form
<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, ByVal lpv As Int32) As Int32
End Function
Private WithEvents TrackBar1 As System.Windows.Forms.TrackBar
Private Shared Ramp1(0 To 255, 0 To 2) As Integer
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 Integer)
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), MyRamp)
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(Ramp1(0, 0))
End Sub
Private Sub SetBrightness_Load(ByVal sender As Object, ByVal e As System.EventArgs) Handles Me.Load
GetDeviceGammaRamp(GetDC(IntPtr.Zero), Ramp1(0, 0))
End Sub
End Class
Yikes. If you're out of your league...
I didn't originally realize how popular this question was.
I mean the question of brightness, instead of temp.
Since this is pretty interesting, and possibly useful to me as well, I'll take a look into it.
I've seen alot online about it, and several programs that apparently do it.
Another set of eyes is always welcome.
got it!
I found the vb6 version kickin around in the API-Guide.
Made it work for the desktop with the right Device context.
It will take a few moments to convert this to .NET, so I'll post back.
For giggles, here is the vb6 example.
Code:Option Explicit
Private Ramp1(0 To 255, 0 To 2) As Integer
Private Ramp2(0 To 255, 0 To 2) As Integer
Private Declare Function apiGetDeviceGammaRamp Lib "gdi32" Alias "GetDeviceGammaRamp" (ByVal hdc As Long, ByRef lpv As Any) As Long
Private Declare Function apiSetDeviceGammaRamp Lib "gdi32" Alias "SetDeviceGammaRamp" (ByVal hdc As Long, ByRef lpv As Any) As Long
Private Declare Function apiCopyMemory Lib "kernel32" Alias "RtlMoveMemory" (ByRef Destination As Any, ByRef Source As Any, ByVal Length As Long) As Long
Private Declare Function apiGetWindowDC Lib "user32" Alias "GetWindowDC" (ByVal hwnd As Long) As Long
Private Declare Function apiGetDesktopWindow Lib "user32" Alias "GetDesktopWindow" () As Long
Private Sub Form_Load()
Dim iCtr As Integer
Dim lVal As Long
Call apiGetDeviceGammaRamp(apiGetWindowDC(apiGetDesktopWindow), Ramp1(0, 0))
For iCtr = 0 To 255
lVal = Int2Lng(Ramp1(iCtr, 0))
Ramp2(iCtr, 0) = Lng2Int(Int2Lng(Ramp1(iCtr, 0)) / 2)
Ramp2(iCtr, 1) = Lng2Int(Int2Lng(Ramp1(iCtr, 1)) / 2)
Ramp2(iCtr, 2) = Lng2Int(Int2Lng(Ramp1(iCtr, 2)) / 2)
Next iCtr
Call apiSetDeviceGammaRamp(apiGetWindowDC(apiGetDesktopWindow), Ramp2(0, 0))
End Sub
Private Sub Form_Unload(Cancel As Integer)
Call apiSetDeviceGammaRamp(apiGetWindowDC(apiGetDesktopWindow), Ramp1(0, 0))
End Sub
Public Function Int2Lng(IntVal As Integer) As Long
Call apiCopyMemory(Int2Lng, IntVal, 2)
End Function
Public Function Lng2Int(Value As Long) As Integer
Call apiCopyMemory(Lng2Int, Value, 2)
End Function
Just when I was starting too lose all hope, the Honourable mr TT(n) pops in! :D
Let us hope for the best :)
Hannes
I just found a vb6 project too at CodeProject.com that I was starting to look at!
Sad to say, but VB 6 wins .NET hands down here!! Amzingly surprisingly easy in VB 6 - unbelievable!!
Look at this. Add 2 buttons on a VB 6 form, and a checkbox. If the Checkbox is checked and command1 is clicked it dims. And when the second commandbutton is clicked, it restores everything!
I am flabbergasted! This is one more reason why I'll probably never leave VB 6!
Hannes
Here is a basic .NET example, which works to start from. {XP only, Vista/7 solution shown later in this thread}
Code:Option Strict On
Option Explicit On
Public Class Form1
Private Ramp1(255, 2) As Short
Private Ramp2(255, 2) As Short
Private Declare Function apiGetDeviceGammaRamp Lib "gdi32" Alias "GetDeviceGammaRamp" (ByVal hdc As Int32, ByRef lpv As Short) As Int32
Private Declare Function apiSetDeviceGammaRamp Lib "gdi32" Alias "SetDeviceGammaRamp" (ByVal hdc As Int32, ByRef lpv As Short) As Int32
Private Declare Function apiCopyMemoryIntShrt Lib "kernel32" Alias "RtlMoveMemory" (ByRef Destination As Int32, ByRef Source As Short, ByVal Length As Int32) As Int32
Private Declare Function apiCopyMemoryShrtInt Lib "kernel32" Alias "RtlMoveMemory" (ByRef Destination As Short, ByRef Source As Int32, ByVal Length As Int32) 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 eventSender As System.Object, ByVal eventArgs As System.EventArgs) Handles MyBase.Load
Dim iCtr As Short
Dim lVal As Int32
apiGetDeviceGammaRamp(apiGetWindowDC(apiGetDesktopWindow), Ramp1(0, 0))
For iCtr = 0 To 255
lVal = Shr2Int(Ramp1(iCtr, 0))
Ramp2(iCtr, 0) = Int2Shr(CInt(Shr2Int(Ramp1(iCtr, 0)) / 2))
Ramp2(iCtr, 1) = Int2Shr(CInt(Shr2Int(Ramp1(iCtr, 1)) / 2))
Ramp2(iCtr, 2) = Int2Shr(CInt(Shr2Int(Ramp1(iCtr, 2)) / 2))
Next
apiSetDeviceGammaRamp(apiGetWindowDC(apiGetDesktopWindow), Ramp2(0, 0))
End Sub
Private Sub Form1_FormClosed(ByVal eventSender As System.Object, ByVal eventArgs As System.Windows.Forms.FormClosedEventArgs) Handles Me.FormClosed
apiSetDeviceGammaRamp(apiGetWindowDC(apiGetDesktopWindow), Ramp1(0, 0))
End Sub
Public Function Shr2Int(ByRef shrVal As Short) As Int32
apiCopyMemoryIntShrt(Shr2Int, shrVal, 2)
End Function
Public Function Int2Shr(ByRef Value As Int32) As Short
apiCopyMemoryShrtInt(Int2Shr, Value, 2)
End Function
End Class
Great work TT(n)!
I do get a red squiggly at this line though :
And it tells me that it cannot convert Short to Type RAMPCode:apiSetDeviceGammaRamp(apiGetWindowDC(apiGetDesktopWindow), Ramp1(0, 0))
Coincidentally, That is the error I have been battling with the whole time, before I got to the code I had in post # 21
Try it now with the CopyMem API declared with short int, and the other int short. It works either way, but now its compatible with option strict and explicit.
I don't get a squiggly line, though when I step through and get to that line, the program stops.
Thanx for all your work!
No errors now, but it doesn't restore the brightness - I think my PC is just trying to be spiteful LOL!
I am attaching the sample here ( this is the sample for stin ), and as you'll see, it doesn't retore the brighness levels :(
So, it's basically at the same point as what I was with post #21
This thing is driving me nuts!
I am using VB 2010 can that be the problem then?? :confused: :eek:
That did it. I ran it, but didn't see a change in brightness.
Now come this questions, so I can understand how this is working.
Is RAMP1 set to the current gamma when the form loads?
RAMP2 is then supposed to be a change from RAMP1 (darker)?
Stepping though I see that lVal is always 0, so it RAMP2's values will always be 0
Hey Hannes, are you doing that in the closing event of the form?
If so, then try to e.cancel=true, if e.windowsshutdown is not true.
Then also environment.exit(0) after to manually exit the cancelled exit.
If the api are declared the same I think it will work, unless you do have a stubborn monitor ofcourse. lol:)
I am using 2005. In my opinion the best version yet.
This example works on all three machines here, one of them a laptop.
Try it in a new project maybe.
It could be a permissions issue, escpecially if using Shared.
Also try it running as admin, well ofcourse.
Ramp1 isn't getting any values, all 0s
Using VS 2008, btw.
Ramp1(0,0) is supposed to store the current gamma settingsQuote:
Originally Posted by stin
Ramp2 is supposed to be the changed value
My Ramp1 is also all 0's ( even with my previous example ), so I still think the whole problem is that the initial call to GetDeviceGammaRamp doesn't somehow succeed in storing the actual values inside Ramp1.
Initially I did use the Closing event, but changed over to Closed.Quote:
Originally Posted by TT(n)
I really do think my monitor is as stubborn as me, afterall, I feel like I'm the monitor's dad LOL! simple thing :D
Okay well make sure you got drivers that support it first, I guess.
I just tested this on Windows 7 and promtly crashed each time on
GetDeviceGammaRamp API.
MSDN list both API with this:
Quote:
Direct color display modes do not use color lookup tables and are usually 16, 24, or 32 bit. Not all direct color video boards support loadable gamma ramps. GetDeviceGammaRamp succeeds only for devices with drivers that support downloadable gamma ramps in hardware
Crazy stuff. Both machines that I've test this on have been 64-bit (one win 7 the other Vista), and neither work. I'll have to test this out later on my 32-bit vista.
Hold on a minute, that's weird, well not really... but Windows 7 does run the vb6 example perfectly.
So perhaps the solution is to use vb6, if it works well without driver support on your machine. That is a possibility.
If you do want to try the vb6 execute, I could send it to you, or Hannes can compile it as well and test it.
This is such a minor detail that rewritting in 6 just so I can grab the inital ramp just doesn't seem like it makes much sense. Using a value of 14 as the 'default' looks like it works just fine. The target audience of the program is tech savvy enough that they would notice a difference if it should be 14, 12 or 18 even.
I bet the behavior vairies on different machines due to driver/component performance. If it does work on others, then you may want to write the code so that it tries, and upon failure set a default.
EDIT:
Or confirm the VB6 example works without driver support, and if so, then compile the executable.
Then automate it with your existing vb.net program, if you've already written alot of other stuff and don't wan to abandon it.
I agree. I think I'll call this one resolved for good.
Thank you all for you help with this.
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
Sounds good to me. I ran across somebody suggesting that API, but said it was kinda buggy, or at least messy.
Good luck.
Whoah ,seems like I missed all the action last night :D - 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 :) :thumb:
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:'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
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 :
It should have been declared as a Boolean, like this :Code:<DllImport("gdi32.dll")> _
Private Shared Function GetDeviceGammaRamp(ByVal hdc As Int32, ByVal lpv As Int32) As Int32
End Function
So, my initial thoughts were correct, the GetDeviceGammaRamp never got the correct values!Code:<DllImport("gdi32.dll")> _
Private Shared Function GetDeviceGammaRamp(ByVal hdc As Int32, ByRef lpv As RAMP) As Boolean
End Function
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 :) :blush:
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 :D WHOO HOO!!!!!!!