EDIT
Oddly enough, I've worked around this issue, but it's still annoying me. I worked around it by sending too-long writes, with padded zeroes; the code works but sends a few hundred unnecessary bytes. Specifically, I need to send exactly 992-byte packets instead of 7 or 19-byte packets. My question still stands however, why is the Logitech code able to make 7- or 19-byte writes when I cannot.
I'm running into an issue where a specific block of code fails or succeeds apparently depending on the length of the data passed to it. This makes no sense to me; I'm obviously doing something wrong but I can't tell what.
I have three cases where I'm trying to use the following block of code, which writes a byte stream to a USB device (one of two Logitech G-Series keyboards):
Friend Function WriteData(ByVal Keyboard As GSeriesKeyboard, ByVal Data() As Byte) As Integer
Dim BytesWritten As Integer = Data.Length
Dim Success As Boolean = Win32.WriteFile(Keyboard.ExternalIOHandle, Data, Data.Length, BytesWritten, Nothing)
Dim ErrorCode As Integer = GetLastError()
Return ErrorCode
End Function
<DllImport("kernel32.dll", SetlastError:=True)> Friend Shared Function WriteFile( _
ByVal File As SafeFileHandle, _
ByVal Buffer() As Byte, _
ByVal NumberOfBytesToWrite As Integer, _
ByRef NumberOfBytesWritten As Integer, _
ByRef Overlapped As System.Threading.NativeOverlapped) As <MarshalAs(UnmanagedType.Bool)> Boolean
End Function
In the first case, I'm passing a 992-byte stream and the write completes successfully. In the second and third cases, I'm writing either 7 or 19 bytes, and WriteFile generates the errors ERROR_INVALID_USER_BUFFER for 7 bytes, or ERROR_INVALID_PARAMETER for 19 bytes. I've opened the handle for reading and writing, non-overlapped.
When using USBTrace, I can see that the default Logitech program is able to write all three cases without trouble, but my own code can only write the 992-byte case. This behavior is the same whether I compile my code as x86 or x64.
The code I'm using to open the handle is this:
Friend Function OpenInterface(ByVal KeyboardPath As String) As SafeFileHandle
Dim SecurityData As New SECURITY_ATTRIBUTES()
Dim security As New DirectorySecurity()
Dim DescriptorBinary As Byte() = security.GetSecurityDescriptorBinaryForm()
Dim SecurityDescriptorPtr As IntPtr = Marshal.AllocHGlobal(DescriptorBinary.Length)
SecurityData.nLength = Marshal.SizeOf(SecurityData)
Marshal.Copy(DescriptorBinary, 0, SecurityDescriptorPtr, DescriptorBinary.Length)
SecurityData.lpSecurityDescriptor = SecurityDescriptorPtr
Dim Handle As SafeFileHandle = Win32.CreateFile(KeyboardPath, GENERIC_READ Or GENERIC_WRITE, _
FILE_SHARE_READ Or FILE_SHARE_WRITE, SecurityData, _
OPEN_EXISTING, FILE_ATTRIBUTE_NORMAL, 0)
If Handle.IsInvalid Then
Dim ErrorInfo As New ComponentModel.Win32Exception()
Debug.Print("Failed to get device IO handle: " & ErrorInfo.Message)
End If
Return Handle
End Function
Friend Overridable Function BitmapToLcdFormat(ByVal SourceBitmap As Bitmap) As Byte()
'Base class is for the generic B&W 160x43 LCD. Override for G19 if I ever get my hands on one
Dim Data As Byte() = New Byte(991) {}
' USBTrace says 992 bytes
Dim Image(640 * 48) As Byte 'Temp array for image conversion. Adds additional 5 lines of unused pixels to avoid an out-of-bounds error
Dim BitmapData As BitmapData = SourceBitmap.LockBits(New Rectangle(0, 0, 160, 43), ImageLockMode.ReadOnly, PixelFormat.Format32bppArgb)
Marshal.Copy(BitmapData.Scan0, Image, 0, (640 * 43))
Data(0) = &H3 'Set-LCD
Dim output As Integer = 32 'First byte of image data starts at byte 32; 960 bytes of image data
Dim ImageOffset As Integer = 0
For Row As Integer = 0 To 5
For Column As Integer = 0 To (SourceBitmap.Width << 2) - 1 Step 4
Dim r As Integer = _
((Image(ImageOffset + Column + BitmapData.Stride * 0) And &H80) >> 7) Or _
((Image(ImageOffset + Column + BitmapData.Stride * 1) And &H80) >> 6) Or _
((Image(ImageOffset + Column + BitmapData.Stride * 2) And &H80) >> 5) Or _
((Image(ImageOffset + Column + BitmapData.Stride * 3) And &H80) >> 4) Or _
((Image(ImageOffset + Column + BitmapData.Stride * 4) And &H80) >> 3) Or _
((Image(ImageOffset + Column + BitmapData.Stride * 5) And &H80) >> 2) Or _
((Image(ImageOffset + Column + BitmapData.Stride * 6) And &H80) >> 1) Or _
((Image(ImageOffset + Column + BitmapData.Stride * 7) And &H80) >> 0)
Data(output) = CByte(r)
output += 1
Next
ImageOffset += BitmapData.Stride * 8
Next
SourceBitmap.UnlockBits(BitmapData)
Return Data
End Function
The exact code blocks that call WriteData() are the following:
(Logitech G15)
HardwareInterface.WriteData(Me, New Byte() {2, 0, 0, 0, 0, 0, 0})
(Logitech G510)
HardwareInterface.WriteData(Me, New Byte() {1, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0})
(Both; the one that works)
HardwareInterface.WriteData(Me, BitmapToLcdFormat(NewImage)) 'Build 992-byte LCD-format bitmap from source iumage
These specific commands are used to remap the macro ("G") keys on the boards to different character codes, in this case 00 disables the key. Anyone with a G15/G19/G510 keyboard can see this by disabling their Logitech gamepanel software and re-plugging the keyboard. G3 will act like F3 in notepad (find next), but after restarting the gamepanel software it will no longer do so.
