.NET TWAIN image scanner

using System;
using System.Runtime.InteropServices;
using System.Windows.Forms;

namespace TwainLib
{

public class TwProtocol
	{									// TWON_PROTOCOL...
	public const short Major	= 1;
	public const short Minor	= 9;
	}


	[Flags]
internal enum TwDG : short
	{									// DG_.....
	Control			= 0x0001,
	Image			= 0x0002,
	Audio			= 0x0004
	}

internal enum TwDAT : short
	{									// DAT_....
	Null			= 0x0000,
	Capability		= 0x0001,
	Event			= 0x0002,
	Identity		= 0x0003,
	Parent			= 0x0004,
	PendingXfers	= 0x0005,
	SetupMemXfer	= 0x0006,
	SetupFileXfer	= 0x0007,
	Status			= 0x0008,
	UserInterface	= 0x0009,
	XferGroup		= 0x000a,
	TwunkIdentity	= 0x000b,
	CustomDSData	= 0x000c,
	DeviceEvent		= 0x000d,
	FileSystem		= 0x000e,
	PassThru		= 0x000f,

	ImageInfo		= 0x0101,
	ImageLayout		= 0x0102,
	ImageMemXfer	= 0x0103,
	ImageNativeXfer	= 0x0104,
	ImageFileXfer	= 0x0105,
	CieColor		= 0x0106,
	GrayResponse	= 0x0107,
	RGBResponse		= 0x0108,
	JpegCompression	= 0x0109,
	Palette8		= 0x010a,
	ExtImageInfo	= 0x010b,

	SetupFileXfer2	= 0x0301
	}

internal enum TwMSG : short
	{									// MSG_.....
	Null			= 0x0000,
	Get				= 0x0001,
	GetCurrent		= 0x0002,
	GetDefault		= 0x0003,
	GetFirst		= 0x0004,
	GetNext			= 0x0005,
	Set				= 0x0006,
	Reset			= 0x0007,
	QuerySupport	= 0x0008,

	XFerReady		= 0x0101,
	CloseDSReq		= 0x0102,
	CloseDSOK		= 0x0103,
	DeviceEvent		= 0x0104,

	CheckStatus		= 0x0201,

	OpenDSM			= 0x0301,
	CloseDSM		= 0x0302,

	OpenDS			= 0x0401,
	CloseDS			= 0x0402,
	UserSelect		= 0x0403,

	DisableDS		= 0x0501,
	EnableDS		= 0x0502,
	EnableDSUIOnly	= 0x0503,

	ProcessEvent	= 0x0601,

	EndXfer			= 0x0701,
	StopFeeder		= 0x0702,

	ChangeDirectory	= 0x0801,
	CreateDirectory	= 0x0802,
	Delete			= 0x0803,
	FormatMedia		= 0x0804,
	GetClose		= 0x0805,
	GetFirstFile	= 0x0806,
	GetInfo			= 0x0807,
	GetNextFile		= 0x0808,
	Rename			= 0x0809,
	Copy			= 0x080A,
	AutoCaptureDir	= 0x080B,

	PassThru		= 0x0901
	}


internal enum TwRC : short
	{									// TWRC_....
	Success				= 0x0000,
	Failure				= 0x0001,
	CheckStatus			= 0x0002,
	Cancel				= 0x0003,
	DSEvent				= 0x0004,
	NotDSEvent			= 0x0005,
	XferDone			= 0x0006,
	EndOfList			= 0x0007,
	InfoNotSupported	= 0x0008,
	DataNotAvailable	= 0x0009
	}

internal enum TwCC : short
	{									// TWCC_....
	Success				= 0x0000,
	Bummer				= 0x0001,
	LowMemory			= 0x0002,
	NoDS				= 0x0003,
	MaxConnections		= 0x0004,
	OperationError		= 0x0005,
	BadCap				= 0x0006,
	BadProtocol			= 0x0009,
	BadValue			= 0x000a,
	SeqError			= 0x000b,
	BadDest				= 0x000c,
	CapUnsupported		= 0x000d,
	CapBadOperation		= 0x000e,
	CapSeqError			= 0x000f,
	Denied				= 0x0010,
	FileExists			= 0x0011,
	FileNotFound		= 0x0012,
	NotEmpty			= 0x0013,
	PaperJam			= 0x0014,
	PaperDoubleFeed		= 0x0015,
	FileWriteError		= 0x0016,
	CheckDeviceOnline	= 0x0017
	}




internal enum TwOn : short
	{									// TWON_....
	Array			= 0x0003,
	Enum			= 0x0004,
	One				= 0x0005,
	Range			= 0x0006,
	DontCare		= -1
	}

internal enum TwType : short
	{									// TWTY_....
	Int8			= 0x0000,
	Int16			= 0x0001,
	Int32			= 0x0002,
	UInt8			= 0x0003,
	UInt16			= 0x0004,
	UInt32			= 0x0005,
	Bool			= 0x0006,
	Fix32			= 0x0007,
	Frame			= 0x0008,
	Str32			= 0x0009,
	Str64			= 0x000a,
	Str128			= 0x000b,
	Str255			= 0x000c,
	Str1024			= 0x000d,
	Str512			= 0x000e
	}


internal enum TwCap : short
	{
	XferCount		= 0x0001,			// CAP_XFERCOUNT
	ICompression	= 0x0100,			// ICAP_...
	IPixelType		= 0x0101,
	IUnits			= 0x0102,
	IXferMech		= 0x0103
	}










// ------------------- STRUCTS --------------------------------------------

	[StructLayout(LayoutKind.Sequential, Pack=2, CharSet=CharSet.Ansi)]
internal class TwIdentity
	{									// TW_IDENTITY
	public IntPtr		Id;
	public TwVersion	Version;
	public short		ProtocolMajor;
	public short		ProtocolMinor;
	public int			SupportedGroups;
		[MarshalAs(UnmanagedType.ByValTStr, SizeConst=34)]
	public string		Manufacturer;
		[MarshalAs(UnmanagedType.ByValTStr, SizeConst=34)]
	public string		ProductFamily;
		[MarshalAs(UnmanagedType.ByValTStr, SizeConst=34)]
	public string		ProductName;
	}

	[StructLayout(LayoutKind.Sequential, Pack=2, CharSet=CharSet.Ansi)]
internal struct TwVersion
	{									// TW_VERSION
	public short		MajorNum;
	public short		MinorNum;
	public short		Language;
	public short		Country;
		[MarshalAs(UnmanagedType.ByValTStr, SizeConst=34)]
	public string		Info;
	}

	[StructLayout(LayoutKind.Sequential, Pack=2)]
internal class TwUserInterface
	{									// TW_USERINTERFACE
	public short		ShowUI;				// bool is strictly 32 bit, so use short
	public short		ModalUI;
	public IntPtr		ParentHand;
	}

	[StructLayout(LayoutKind.Sequential, Pack=2)]
internal class TwStatus
	{									// TW_STATUS
	public short		ConditionCode;		// TwCC
	public short		Reserved;
	}

	[StructLayout(LayoutKind.Sequential, Pack=2)]
internal struct TwEvent
	{									// TW_EVENT
	public IntPtr		EventPtr;
	public short		Message;
	}


	[StructLayout(LayoutKind.Sequential, Pack=2)]
internal class TwImageInfo
	{									// TW_IMAGEINFO
	public int			XResolution;
	public int			YResolution;
	public int			ImageWidth;
	public int			ImageLength;
	public short		SamplesPerPixel;
	[MarshalAs( UnmanagedType.ByValArray, SizeConst=8)] 
	 public short[]		BitsPerSample;
	public short		BitsPerPixel;
	public short		Planar;
	public short		PixelType;
	public short		Compression;
	}

	[StructLayout(LayoutKind.Sequential, Pack=2)]
internal class TwPendingXfers
	{									// TW_PENDINGXFERS
	public short		Count;
	public int			EOJ;
	}






	[StructLayout(LayoutKind.Sequential, Pack=2)]
internal struct TwFix32
	{												// TW_FIX32
	public short		Whole;
	public ushort		Frac;
	
	public float ToFloat()
		{
		return (float) Whole + ( (float)Frac /65536.0f );
		}
	public void FromFloat( float f )
		{
		int i = (int)((f * 65536.0f) + 0.5f);
		Whole = (short) (i >> 16);
		Frac = (ushort) (i & 0x0000ffff);
		}
	}







	[StructLayout(LayoutKind.Sequential, Pack=2)]
internal class TwCapability
	{									// TW_CAPABILITY
	public TwCapability( TwCap cap )
		{
		Cap = (short) cap;
		ConType = -1;
		}
	public TwCapability( TwCap cap, short sval )
		{
		Cap = (short) cap;
		ConType = (short) TwOn.One;
		Handle = Twain.GlobalAlloc( 0x42, 6 );
		IntPtr pv = Twain.GlobalLock( Handle );
		Marshal.WriteInt16( pv, 0, (short) TwType.Int16 );
		Marshal.WriteInt32( pv, 2, (int) sval );
		Twain.GlobalUnlock( Handle );
		}
	~TwCapability()
		{
		if( Handle != IntPtr.Zero )
			Twain.GlobalFree( Handle );
		}
	public short		Cap;
	public short		ConType;
	public IntPtr		Handle;
	}








} // namespace TwainLib