Convert PDF to All with OCR engine in C#


Since version 7.0, SautinSoft.PdfFocus can work with OCR. To perform OCR we'll use free OCR library by Nicomsoft (https://www.nicomsoft.com).
The library is freeware and can be used in commercial application.

You need download Nicomsoft OCR SDK from: free_NSOCR_v70_build885_full.exe



Further install it on your PC or server-side.

Notice: Please make sure, that you have installed this package (Nicomsoft OCR SDK) on your computer. And also, when creating your solution, you must place the file "NSOCR.cs" from C:\Program Files (x86)\Nicomsoft OCR\Samples in the directory of your solution. After copying "NSOCR.cs", there will be no errors with the "using NSOCR_NameSpace;".

How to use SautinSoft.PdfFocus with Optical Character Recognition (OCR).

Полный код

//A C# wrapper class for NSOCR.dll functions (calling NSOCR API via platform invoke)

//******************************************************************************
//                        Nicomsoft OCR DLL interface
//                    Copyright (c) 2010-2016 Nicomsoft
//                 Copyright (c) 2010-2016 Michael Kapustin
//                           www.nsocr.com
//******************************************************************************



using System;
using System.Text;
using System.Runtime.InteropServices;


namespace NSOCR_NameSpace
{
    public class TNSOCR
    {
        //// Error codes
        public const int ERROR_FIRST					= 0x70000000;
        public const int ERROR_FILENOTFOUND 			= 0x70000001;
        public const int ERROR_LOADFILE 				= 0x70000002;
        public const int ERROR_SAVEFILE 				= 0x70000003;
        public const int ERROR_MISSEDIMGLOADER 		    = 0x70000004;
        public const int ERROR_OPTIONNOTFOUND		    = 0x70000005;
        public const int ERROR_NOBLOCKS				    = 0x70000006;
        public const int ERROR_BLOCKNOTFOUND			= 0x70000007;
        public const int ERROR_INVALIDINDEX			    = 0x70000008;
        public const int ERROR_INVALIDPARAMETER		    = 0x70000009;
        public const int ERROR_FAILED				    = 0x7000000A;
        public const int ERROR_INVALIDBLOCKTYPE		    = 0x7000000B;
        public const int ERROR_EMPTYTEXT				= 0x7000000D;
        public const int ERROR_LOADINGDICTIONARY		= 0x7000000E;
        public const int ERROR_LOADCHARBASE			    = 0x7000000F;
        public const int ERROR_NOMEMORY				    = 0x70000010;
        public const int ERROR_CANNOTLOADGS			    = 0x70000011;
        public const int ERROR_CANNOTPROCESSPDF		    = 0x70000012;
        public const int ERROR_NOIMAGE				    = 0x70000013;
        public const int ERROR_MISSEDSTEP		    	= 0x70000014;
        public const int ERROR_OUTOFIMAGE               = 0x70000015;
        public const int ERROR_EXCEPTION                = 0x70000016;
        public const int ERROR_NOTALLOWED               = 0x70000017;
        public const int ERROR_NODEFAULTDEVICE          = 0x70000018;
        public const int ERROR_NOTAPPLICABLE			= 0x70000019;
        public const int ERROR_MISSEDBARCODEDLL         = 0x7000001A;
        public const int ERROR_PENDING                  = 0x7000001B;
        public const int ERROR_OPERATIONCANCELLED       = 0x7000001C;
        public const int ERROR_TOOMANYLANGUAGES         = 0x7000001D;
        public const int ERROR_OPERATIONTIMEOUT         = 0x7000001E;
        public const int ERROR_LOAD_ASIAN_MODULE	= 0x7000001F;	
        public const int ERROR_LOAD_ASIAN_LANG		= 0x70000020;

        public const int ERROR_INVALIDOBJECT			= 0x70010000;
        public const int ERROR_TOOMANYOBJECTS	    	= 0x70010001;
        public const int ERROR_DLLNOTLOADED		    	= 0x70010002;
        public const int ERROR_DEMO                     = 0x70010003;

        ////Block type
        public const int BT_DEFAULT		    = 0;
        public const int BT_OCRTEXT		    = 1; //machine-printed text
        public const int BT_ICRDIGIT        = 2; //handwritten digits 
        public const int BT_CLEAR           = 3;
        public const int BT_PICTURE         = 4;
        public const int BT_ZONING          = 5;
        public const int BT_OCRDIGIT = 6; //machine-printed digits
        public const int BT_BARCODE = 7;
        public const int BT_TABLE = 8;
        public const int BT_MRZ = 9;

        ////Constants for Img_LoadBmpData function
        public const int BMP_24BIT          = 0x00;
        public const int BMP_8BIT         = 0x01;
        public const int BMP_1BIT           = 0x02;
        public const int BMP_32BIT           = 0x03;
        public const int BMP_BOTTOMTOP      = 0x100;

        ////Constants for Img_GetImgText, Blk_GetText and Svr_AddPage functions
        public const int FMT_EDITCOPY = 0x00;
        public const int FMT_EXACTCOPY	= 0x01;

        //for Img_OCR
        public const int OCRSTEP_FIRST			= 0x00; //first step
        public const int OCRSTEP_PREFILTERS		= 0x10; //filters before binarizing: scaling, invert, rotate etc
        public const int OCRSTEP_BINARIZE		= 0x20; //binarize
        public const int OCRSTEP_POSTFILTERS	= 0x50; //bin garbage filter etc
        public const int OCRSTEP_REMOVELINES    = 0x60; //find and remove lines
        public const int OCRSTEP_ZONING         = 0x70; //analyze page layout
        public const int OCRSTEP_OCR			= 0x80; //ocr itself
        public const int OCRSTEP_LAST			= 0xFF; //last step

        //for Img_OCR, "Flags" parameter
        public const int OCRFLAG_NONE			= 0x00; //default mode (blocking)
        public const int OCRFLAG_THREAD			= 0x01; //non-blocking mode
        public const int OCRFLAG_GETRESULT		= 0x02; //get result for non-blocking mode
        public const int OCRFLAG_GETPROGRESS	= 0x03; //get progress
        public const int OCRFLAG_CANCEL         = 0x04; //cancel ocr

        //for Img_DrawToDC and Img_GetBmpData
        public const int DRAW_NORMAL			= 0x00;
        public const int DRAW_BINARY			= 0x01;
        public const int DRAW_GETBPP            = 0x100;

        //values for Blk_Inversion function
        public const int BLK_INVERSE_GET        = -1;
        public const int BLK_INVERSE_SET0       = 0;
        public const int BLK_INVERSE_SET1       = 1;
        public const int BLK_INVERSE_DETECT     = 0x100;

        //for Blk_Rotation function
        public const int BLK_ROTATE_GET         = -1;
        public const int BLK_ROTATE_NONE        = 0x00;
        public const int BLK_ROTATE_90			= 0x01;
        public const int BLK_ROTATE_180			= 0x02;
        public const int BLK_ROTATE_270			= 0x03;
        public const int BLK_ROTATE_ANGLE       = 0x100000;
        public const int BLK_ROTATE_DETECT      = 0x100;

        //for Blk_Mirror function
        public const int BLK_MIRROR_GET         = -1;
        public const int BLK_MIRROR_NONE        = 0x00;
        public const int BLK_MIRROR_H			= 0x01;
        public const int BLK_MIRROR_V			= 0x02;

        //for Svr_Create function   
        public const int SVR_FORMAT_PDF             = 0x01;
        public const int SVR_FORMAT_RTF             = 0x02;
        public const int SVR_FORMAT_TXT_ASCII       = 0x03;
        public const int SVR_FORMAT_TXT_UNICODE     = 0x04;
        public const int SVR_FORMAT_XML             = 0x05;
        public const int SVR_FORMAT_PDFA            = 0x06;

        //for Scan_Enumerate function
        public const int SCAN_GETDEFAULTDEVICE      = 0x01;
        public const int SCAN_SETDEFAULTDEVICE      = 0x100;

        //for Scan_ScanToImg and Scan_ScanToFile functions
        public const int SCAN_NOUI                  = 0x01;
        public const int SCAN_SOURCEADF             = 0x02;
        public const int SCAN_SOURCEAUTO            = 0x04;
        public const int SCAN_DONTCLOSEDS           = 0x08;
        public const int SCAN_FILE_SEPARATE		    = 0x10;

        //for Blk_GetWordFontStyle function
        public const int FONT_STYLE_UNDERLINED	    = 0x01;
        public const int FONT_STYLE_STRIKED		    = 0x02;
        public const int FONT_STYLE_BOLD			= 0x04;
        public const int FONT_STYLE_ITALIC          = 0x08;

        //for Img_GetProperty function, PropertyID parameter
        public const int IMG_PROP_DPIX			= 0x01;	//original DPI
        public const int IMG_PROP_DPIY = 0x02;
        public const int IMG_PROP_BPP = 0x03; //color depth
        public const int IMG_PROP_WIDTH = 0x04;	//original width
        public const int IMG_PROP_HEIGHT = 0x05;	//original height
        public const int IMG_PROP_INVERTED = 0x06;   //image inversion flag after OCR_STEP_PREFILTERS step
        public const int IMG_PROP_SKEW	= 0x07;	//image skew angle after OCR_STEP_PREFILTERS step, multiplied by 1000
        public const int IMG_PROP_SCALE = 0x08;	//image scale factor after OCR_STEP_PREFILTERS step, multiplied by 1000
        public const int IMG_PROP_PAGEINDEX = 0x09; //image page index

        //for "Blk_SetWordRegEx" function
        public const int REGEX_SET				= 0x00;
        public const int REGEX_CLEAR			= 0x01;
        public const int REGEX_CLEAR_ALL		= 0x02;
        public const int REGEX_DISABLE_DICT     = 0x04;
        public const int REGEX_CHECK            = 0x08;

        //for Svr_SetDocumentInfo function
        public const int INFO_PDF_AUTHOR		= 0x01;
        public const int INFO_PDF_CREATOR		= 0x02;
        public const int INFO_PDF_PRODUCER		= 0x03;
        public const int INFO_PDF_TITLE			= 0x04;
        public const int INFO_PDF_SUBJECT		= 0x05;
        public const int INFO_PDF_KEYWORDS      = 0x06;

        //for Blk_GetBarcodeType function
        public const int BARCODE_TYPE_EAN8      = 0x01;
        public const int BARCODE_TYPE_UPCE		= 0x02;
        public const int BARCODE_TYPE_ISBN10	= 0x03;
        public const int BARCODE_TYPE_UPCA		= 0x04;
        public const int BARCODE_TYPE_EAN13		= 0x05;
        public const int BARCODE_TYPE_ISBN13	= 0x06;
        public const int BARCODE_TYPE_ZBAR_I25	= 0x07;
        public const int BARCODE_TYPE_CODE39	= 0x08;
        public const int BARCODE_TYPE_QRCODE	= 0x09;
        public const int BARCODE_TYPE_CODE128	= 0x0A;

        //for "BarCode/TypesMask" configuration option
        public const int BARCODE_TYPE_MASK_EAN8     = 0x01;
        public const int BARCODE_TYPE_MASK_UPCE		= 0x02;
        public const int BARCODE_TYPE_MASK_ISBN10	= 0x04;
        public const int BARCODE_TYPE_MASK_UPCA		= 0x08;
        public const int BARCODE_TYPE_MASK_EAN13	= 0x10;
        public const int BARCODE_TYPE_MASK_ISBN13	= 0x20;
        public const int BARCODE_TYPE_MASK_ZBAR_I25	= 0x40;
        public const int BARCODE_TYPE_MASK_CODE39	= 0x80;
        public const int BARCODE_TYPE_MASK_QRCODE	= 0x100;
        public const int BARCODE_TYPE_MASK_CODE128	= 0x200;

        //for Img_SaveToFile function
        public const int IMG_FORMAT_BMP			=  0;
        public const int IMG_FORMAT_JPEG		=  2;
        public const int IMG_FORMAT_PNG			= 13;
        public const int IMG_FORMAT_TIFF        	= 18;
        public const int IMG_FORMAT_FLAG_BINARIZED	= 0x100;
////////////////////////////////////////////////////////////////////

        //use appropriate path, otherwise you will get "BadImageFormatException"
        //for x86
        public const string LIBNAME = @"..\..\OCR Lib\Bin\NSOCR.dll"; //IMPORTANT: CORRECT PATH TO X86 NSOCR.DLL
        //for x64
        //public const string LIBNAME = @"..\..\OCR Lib\Bin64\NSOCR.dll"; //IMPORTANT: CORRECT PATH TO X64 NSOCR.DLL



        [DllImport(LIBNAME)]
        public static extern int Engine_Initialize();

        [DllImport(LIBNAME)]
        public static extern int Engine_InitializeAdvanced(out int CfgObj, out int OcrObj, out int ImgObj);

        [DllImport(LIBNAME)]
        public static extern int Engine_Uninitialize();

        [DllImport(LIBNAME)]
        public static extern int Engine_SetDataDirectory([MarshalAs(UnmanagedType.LPWStr)] string DirectoryPath);

        [DllImport(LIBNAME)]
        public static extern int Engine_GetVersion([MarshalAs(UnmanagedType.LPWStr)] StringBuilder OptionValue);

        [DllImport(LIBNAME)]
        public static extern int Engine_SetLicenseKey([MarshalAs(UnmanagedType.LPWStr)] string LicenseKey);
////////

        [DllImport(LIBNAME)]
        public static extern int Cfg_Create(out int CfgObj);

        [DllImport(LIBNAME)]
        public static extern int Cfg_Destroy(int CfgObj);

        [DllImport(LIBNAME)]
        public static extern int Cfg_LoadOptions(int CfgObj, [MarshalAs(UnmanagedType.LPWStr)] string FileName);

        [DllImport(LIBNAME)]
        public static extern int Cfg_SaveOptions(int CfgObj, [MarshalAs(UnmanagedType.LPWStr)] string FileName);

        [DllImport(LIBNAME)]
        public static extern int Cfg_LoadOptionsFromString(int CfgObj, [MarshalAs(UnmanagedType.LPWStr)] string XMLString);

        [DllImport(LIBNAME)]
        public static extern int Cfg_SaveOptionsToString(int CfgObj, [MarshalAs(UnmanagedType.LPWStr)] StringBuilder XMLString, int MaxLen);

        [DllImport(LIBNAME)]
        public static extern int Cfg_GetOption(int CfgObj, int BlockType, [MarshalAs(UnmanagedType.LPWStr)] string OptionPath, [MarshalAs(UnmanagedType.LPWStr)] StringBuilder OptionValue, int MaxLen);

        [DllImport(LIBNAME)]
        public static extern int Cfg_SetOption(int CfgObj, int BlockType, [MarshalAs(UnmanagedType.LPWStr)] string OptionPath, [MarshalAs(UnmanagedType.LPWStr)] string OptionValue);

        [DllImport(LIBNAME)]
        public static extern int Cfg_DeleteOption(int CfgObj, int BlockType, [MarshalAs(UnmanagedType.LPWStr)] string OptionPath);

////////

        [DllImport(LIBNAME)]
        public static extern int Ocr_Create(int CfgObj, out int OcrObj);

        [DllImport(LIBNAME)]
        public static extern int Ocr_Destroy(int OcrObj);

        [DllImport(LIBNAME)]
        public static extern int Ocr_Destroy(int ImgObj, int SvrObj, int PageIndexStart, int PageIndexEnd, int OcrObjCnt, int Flags);

        [DllImport(LIBNAME)]
        public static extern int Ocr_ProcessPages(int ImgObj, int SvrObj, int PageIndexStart, int PageIndexEnd, int OcrObjCnt, int Flags);
////////

        [DllImport(LIBNAME)]
        public static extern int Img_Create(int OcrObj, out int ImgObj);

        [DllImport(LIBNAME)]
        public static extern int Img_Destroy(int ImgObj);

        [DllImport(LIBNAME)]
        public static extern int Img_LoadFile(int ImgObj, [MarshalAs(UnmanagedType.LPWStr)] string FileName);

        [DllImport(LIBNAME)]
        public static extern int Img_LoadFromMemory(int ImgObj, IntPtr Bytes, int DataSize);

        [DllImport(LIBNAME)]
        public static extern int Img_LoadBmpData(int ImgObj, IntPtr Bytes, int Width, int Height, int Flags, int Stride);

        [DllImport(LIBNAME)]
        public static extern int Img_Unload(int ImgObj);

        [DllImport(LIBNAME)]
        public static extern int Img_GetPageCount(int ImgObj);

        [DllImport(LIBNAME)]
        public static extern int Img_SetPage(int ImgObj, int PageIndex);

        [DllImport(LIBNAME)]
        public static extern int Img_GetSize(int ImgObj, out int Width, out int Height);

        [DllImport(LIBNAME)]
        public static extern int Img_DrawToDC(int ImgObj, int HandleDC, int X, int Y, ref int Width, ref int Height, int Flags);

        [DllImport(LIBNAME)]
        public static extern int Img_DeleteAllBlocks(int ImgObj);

        [DllImport(LIBNAME)]
        public static extern int Img_AddBlock(int ImgObj, int Xpos, int Ypos, int Width, int Height, out int BlkObj);

        [DllImport(LIBNAME)]
        public static extern int Img_DeleteBlock(int ImgObj, int BlkObj);

        [DllImport(LIBNAME)]
        public static extern int Img_GetBlockCnt(int ImgObj);

        [DllImport(LIBNAME)]
        public static extern int Img_GetBlock(int ImgObj, int BlockIndex, out int BlkObj);

        [DllImport(LIBNAME)]
        public static extern int Img_GetImgText(int ImgObj, [MarshalAs(UnmanagedType.LPWStr)] StringBuilder TextStr, int MaxLen, int Flags);

        [DllImport(LIBNAME)]
        public static extern int Img_GetBmpData(int ImgObj, IntPtr Bits, ref int Width, ref int Height, int Flags);

        [DllImport(LIBNAME)]
        public static extern int Img_OCR(int ImgObj, int FirstStep, int LastStep, int Flags);

        [DllImport(LIBNAME)]
        public static extern int Img_SaveBlocks(int ImgObj, [MarshalAs(UnmanagedType.LPWStr)] string FileName);
	
        [DllImport(LIBNAME)]
        public static extern int Img_LoadBlocks(int ImgObj, [MarshalAs(UnmanagedType.LPWStr)] string FileName);
	
        [DllImport(LIBNAME)]
        public static extern int Img_GetSkewAngle(int ImgObj);

        [DllImport(LIBNAME)]
        public static extern int Img_GetPixLineCnt(int ImgObj);

        [DllImport(LIBNAME)]
        public static extern int Img_GetPixLine(int ImgObj, int LineInd, out int X1pos, out int Y1pos, out int X2pos, out int Y2pos, out int Width);

        [DllImport(LIBNAME)]
        public static extern int Img_GetScaleFactor(int ImgObj);

        [DllImport(LIBNAME)]
        public static extern int Img_CalcPointPosition(int ImgObj, ref int Xpos, ref int Ypos, int Mode);

        [DllImport(LIBNAME)]
        public static extern int Img_CopyCurrentPage(int ImgObjSrc, int ImgObjDst, int Flags);

        [DllImport(LIBNAME)]
        public static extern int Img_GetProperty(int ImgObj, int PropertyID);

        [DllImport(LIBNAME)]
        public static extern int Img_SaveToFile(int ImgObj, [MarshalAs(UnmanagedType.LPWStr)] string FileName, int Format, int Flags);

        [DllImport(LIBNAME)]
        public static extern int Img_SaveToMemory(int ImgObj, IntPtr Bytes, int BufferSize, int Format, int Flags);
////////

        [DllImport(LIBNAME)]
        public static extern int Blk_GetType(int BlkObj);

        [DllImport(LIBNAME)]
        public static extern int Blk_SetType(int BlkObj, int BlockType);

        [DllImport(LIBNAME)]
        public static extern int Blk_GetRect(int BlkObj, out int Xpos, out int Ypos, out int Width, out int Height);

        [DllImport(LIBNAME)]
        public static extern int Blk_GetText(int BlkObj, [MarshalAs(UnmanagedType.LPWStr)] StringBuilder TextStr, int MaxLen, int Flags);

        [DllImport(LIBNAME)]
        public static extern int Blk_GetLineCnt(int BlkObj);

        [DllImport(LIBNAME)]
        public static extern int Blk_GetLineText(int BlkObj, int LineIndex, [MarshalAs(UnmanagedType.LPWStr)] StringBuilder TextStr, int MaxLen);

        [DllImport(LIBNAME)]
        public static extern int Blk_GetWordCnt(int BlkObj, int LineIndex);

        [DllImport(LIBNAME)]
        public static extern int Blk_GetWordText(int BlkObj, int LineIndex, int WordIndex, [MarshalAs(UnmanagedType.LPWStr)] StringBuilder TextStr, int MaxLen);

        [DllImport(LIBNAME)]
        public static extern int Blk_SetWordText(int BlkObj, int LineIndex, int WordIndex, [MarshalAs(UnmanagedType.LPWStr)] string TextStr);

        [DllImport(LIBNAME)]
        public static extern int Blk_GetCharCnt(int BlkObj, int LineIndex, int WordIndex);

        [DllImport(LIBNAME)]
        public static extern int Blk_GetCharRect(int BlkObj, int LineIndex, int WordIndex, int CharIndex, out int Xpos, out int Ypos, out int Width, out int Height);

        [DllImport(LIBNAME)]
        public static extern int Blk_GetCharText(int BlkObj, int LineIndex, int WordIndex, int CharIndex, int ResultIndex, [MarshalAs(UnmanagedType.LPWStr)] StringBuilder TextStr, int MaxLen);

        [DllImport(LIBNAME)]
        public static extern int Blk_GetCharQual(int BlkObj, int LineIndex, int WordIndex, int CharIndex, int ResultIndex);

        [DllImport(LIBNAME)]
        public static extern int Blk_GetTextRect(int BlkObj, int LineIndex, int WordIndex, out int Xpos, out int Ypos, out int Width, out int Height);

        [DllImport(LIBNAME)]
        public static extern int Blk_Inversion(int BlkObj, int Inversion);

        [DllImport(LIBNAME)]
        public static extern int Blk_Rotation(int BlkObj, int Rotation);

        [DllImport(LIBNAME)]
        public static extern int Blk_Mirror(int BlkObj, int Mirror);

        [DllImport(LIBNAME)]
        public static extern int Blk_IsWordInDictionary(int BlkObj, int LineIndex, int WordIndex);

        [DllImport(LIBNAME)]
        public static extern int Blk_SetRect(int BlkObj, int Xpos, int Ypos, int Width, int Height);

        [DllImport(LIBNAME)]
        public static extern int Blk_GetWordQual(int BlkObj, int LineIndex, int WordIndex);

        [DllImport(LIBNAME)]
        public static extern int Blk_GetWordFontColor(int BlkObj, int LineIndex, int WordIndex);

        [DllImport(LIBNAME)]
        public static extern int Blk_GetWordFontSize(int BlkObj, int LineIndex, int WordIndex);

        [DllImport(LIBNAME)]
        public static extern int Blk_GetWordFontStyle(int BlkObj, int LineIndex, int WordIndex);

        [DllImport(LIBNAME)]
        public static extern int Blk_GetBackgroundColor(int BlkObj);

        [DllImport(LIBNAME)]
        public static extern int Blk_SetWordRegEx(int BlkObj, int LineIndex, int WordIndex, [MarshalAs(UnmanagedType.LPWStr)] string RegEx, int Flags);

        [DllImport(LIBNAME)]
        public static extern int Blk_GetBarcodeCnt(int BlkObj);

        [DllImport(LIBNAME)]
        public static extern int Blk_GetBarcodeText(int BlkObj, int BarcodeInd, [MarshalAs(UnmanagedType.LPWStr)] StringBuilder TextStr, int MaxLen);

        [DllImport(LIBNAME)]
        public static extern int Blk_GetBarcodeRect(int BlkObj, int BarcodeInd, out int Xpos, out int Ypos, out int Width, out int Height);

        [DllImport(LIBNAME)]
        public static extern int Blk_GetBarcodeType(int BlkObj, int BarcodeInd);

        ////////

        [DllImport(LIBNAME)]
        public static extern int Svr_Create(int CfgObj, int Format, out int SvrObj);

        [DllImport(LIBNAME)]
        public static extern int Svr_Destroy(int SvrObj);

        [DllImport(LIBNAME)]
        public static extern int Svr_NewDocument(int SvrObj);

        [DllImport(LIBNAME)]
        public static extern int Svr_AddPage(int SvrObj, int ImgObj, int Flags);

        [DllImport(LIBNAME)]
        public static extern int Svr_SaveToFile(int SvrObj, [MarshalAs(UnmanagedType.LPWStr)] string FileName);

        [DllImport(LIBNAME)]
        public static extern int Svr_SaveToMemory(int SvrObj, IntPtr Bytes, int BufferSize);

        [DllImport(LIBNAME)]
        public static extern int Svr_GetText(int SvrObj, int PageIndex, [MarshalAs(UnmanagedType.LPWStr)] StringBuilder TextStr, int MaxLen);

        [DllImport(LIBNAME)]
        public static extern int Svr_SetDocumentInfo(int SvrObj, int InfoID, [MarshalAs(UnmanagedType.LPWStr)] string InfoStr);

        ////////

        [DllImport(LIBNAME)]
        public static extern int Scan_Create(int CfgObj, out int ScanObj);

        [DllImport(LIBNAME)]
        public static extern int Scan_Destroy(int ScanObj);

        [DllImport(LIBNAME)]
        public static extern int Scan_Enumerate(int ScanObj, [MarshalAs(UnmanagedType.LPWStr)] StringBuilder ScannerNames, int MaxLen, int Flags);

        [DllImport(LIBNAME)]
        public static extern int Scan_ScanToImg(int ScanObj, int ImgObj, int ScannerIndex, int Flags);

        [DllImport(LIBNAME)]
        public static extern int Scan_ScanToFile(int ScanObj, [MarshalAs(UnmanagedType.LPWStr)] string FileName, int ScannerIndex, int Flags);
    }
}

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'A VB.NET wrapper class for NSOCR

'******************************************************************************
'                        Nicomsoft OCR DLL interface
'                    Copyright (c) 2010-2016 Nicomsoft
'                 Copyright (c) 2010-2016 Michael Kapustin
'                           www.nsocr.com
'******************************************************************************


Public Class TNSOCR

    'error codes
    Public Const ERROR_FIRST = &H70000000
    Public Const ERROR_FILENOTFOUND = &H70000001
    Public Const ERROR_LOADFILE = &H70000002
    Public Const ERROR_SAVEFILE = &H70000003
    Public Const ERROR_MISSEDIMGLOADER = &H70000004
    Public Const ERROR_OPTIONNOTFOUND = &H70000005
    Public Const ERROR_NOBLOCKS = &H70000006
    Public Const ERROR_BLOCKNOTFOUND = &H70000007
    Public Const ERROR_INVALIDINDEX = &H70000008
    Public Const ERROR_INVALIDPARAMETER = &H70000009
    Public Const ERROR_FAILED = &H7000000A
    Public Const ERROR_INVALIDBLOCKTYPE = &H7000000B
    Public Const ERROR_EMPTYTEXT = &H7000000D
    Public Const ERROR_LOADINGDICTIONARY = &H7000000E
    Public Const ERROR_LOADCHARBASE = &H7000000F
    Public Const ERROR_NOMEMORY = &H70000010
    Public Const ERROR_CANNOTLOADGS = &H70000011
    Public Const ERROR_CANNOTPROCESSPDF = &H70000012
    Public Const ERROR_NOIMAGE = &H70000013
    Public Const ERROR_MISSEDSTEP = &H70000014
    Public Const ERROR_OUTOFIMAGE = &H70000015
    Public Const ERROR_EXCEPTION = &H70000016
    Public Const ERROR_NOTALLOWED = &H70000017
    Public Const ERROR_NODEFAULTDEVICE = &H70000018
    Public Const ERROR_NOTAPPLICABLE = &H70000019
    Public Const ERROR_MISSEDBARCODEDLL = &H7000001A
    Public Const ERROR_PENDING = &H7000001B
    Public Const ERROR_OPERATIONCANCELLED = &H7000001C
    Public Const ERROR_TOOMANYLANGUAGES = &H7000001D
    Public Const ERROR_OPERATIONTIMEOUT = &H7000001E
    Public Const ERROR_LOAD_ASIAN_MODULE= &H7000001F	
    Public Const ERROR_LOAD_ASIAN_LANG	= &H70000020
    Public Const ERROR_INVALIDOBJECT = &H70010000
    Public Const ERROR_TOOMANYOBJECTS = &H70010001
    Public Const ERROR_DLLNOTLOADED = &H70010002
    Public Const ERROR_DEMO = &H70010003

    'block types
    Public Const BT_DEFAULT = 0
    Public Const BT_OCRTEXT = 1
    Public Const BT_ICRDIGIT = 2
    Public Const BT_CLEAR = 3
    Public Const BT_PICTURE = 4
    Public Const BT_ZONING = 5
    Public Const BT_OCRDIGIT = 6
    Public Const BT_BARCODE = 7
    Public Const BT_TABLE = 8
    Public Const BT_MRZ = 9

    'Constants for Img_LoadBmpData function
    Public Const BMP_24BIT = &H0
    Public Const BMP_8BIT = &H1
    Public Const BMP_1BIT = &H2
    Public Const BMP_32BIT = &H3
    Public Const BMP_BOTTOMTOP = &H100

    'Constants for Img_GetImgText, Blk_GetText and Svr_AddPage functions
    Public Const FMT_EDITCOPY = &H0
    Public Const FMT_EXACTCOPY = &H1

    'for Img_OCR
    Public Const OCRSTEP_FIRST = &H0 'first step
    Public Const OCRSTEP_PREFILTERS = &H10 'filters before binarizing: scaling, invert, rotate etc
    Public Const OCRSTEP_BINARIZE = &H20 'binarize
    Public Const OCRSTEP_POSTFILTERS = &H50 'bin garbage filter etc
    Public Const OCRSTEP_REMOVELINES = &H60 'find and remove lines
    Public Const OCRSTEP_ZONING = &H70 'analyze page layout
    Public Const OCRSTEP_OCR = &H80 'ocr itself
    Public Const OCRSTEP_LAST = &HFF 'last step

    'for Img_OCR, "Flags" parameter
    Public Const OCRFLAG_NONE = &H0 'default mode (blocking)
    Public Const OCRFLAG_THREAD = &H1 'non-blocking mode
    Public Const OCRFLAG_GETRESULT = &H2 'get result for non-blocking mode
    Public Const OCRFLAG_GETPROGRESS = &H3 'get progress
    Public Const OCRFLAG_CANCEL = &H4 'cancel ocr

    'for Img_DrawToDC and Img_GetBmpData
    Public Const DRAW_NORMAL = &H0
    Public Const DRAW_BINARY = &H1
    Public Const DRAW_GETBPP = &H100

    'values for Blk_Inversion function
    Public Const BLK_INVERSE_GET = -1
    Public Const BLK_INVERSE_SET0 = 0
    Public Const BLK_INVERSE_SET1 = 1
    Public Const BLK_INVERSE_DETECT = &H100

    'for Blk_Rotation function
    Public Const BLK_ROTATE_GET = -1
    Public Const BLK_ROTATE_NONE = 0
    Public Const BLK_ROTATE_90 = &H1
    Public Const BLK_ROTATE_180 = &H2
    Public Const BLK_ROTATE_270 = &H3
    Public Const BLK_ROTATE_ANGLE = &H100000
    Public Const BLK_ROTATE_DETECT = &H100

    'for Blk_Mirror function
    Public Const BLK_MIRROR_GET = -1
    Public Const BLK_MIRROR_H = &H1
    Public Const BLK_MIRROR_V = &H2

    'for Svr_Create function   
    Public Const SVR_FORMAT_PDF = &H1
    Public Const SVR_FORMAT_RTF = &H2
    Public Const SVR_FORMAT_TXT_ASCII = &H3
    Public Const SVR_FORMAT_TXT_UNICODE = &H4
    Public Const SVR_FORMAT_XML = &H5
    Public Const SVR_FORMAT_PDFA = &H6

    'for Scan_Enumerate function
    Public Const SCAN_GETDEFAULTDEVICE = &H1
    Public Const SCAN_SETDEFAULTDEVICE = &H100

    'for Scan_ScanToImg and Scan_ScanToFile functions
    Public Const SCAN_NOUI = &H1
    Public Const SCAN_SOURCEADF = &H2
    Public Const SCAN_SOURCEAUTO = &H4
    Public Const SCAN_DONTCLOSEDS = &H8
    Public Const SCAN_FILE_SEPARATE = &H10

    'for Blk_GetWordFontStyle function
    Public Const FONT_STYLE_UNDERLINED = &H1
    Public Const FONT_STYLE_STRIKED = &H2
    Public Const FONT_STYLE_BOLD = &H4
    Public Const FONT_STYLE_ITALIC = &H8

    'for Img_GetProperty function, PropertyID parameter
    Public Const IMG_PROP_DPIX = &H1   'original DPI
    Public Const IMG_PROP_DPIY = &H2
    Public Const IMG_PROP_BPP = &H3   'color depth
    Public Const IMG_PROP_WIDTH = &H4   'original width
    Public Const IMG_PROP_HEIGHT = &H5   'original height
    Public Const IMG_PROP_INVERTED = &H6    'image was inverted
    Public Const IMG_PROP_SKEW = &H7   'image skew angle after OCR_STEP_PREFILTERS step, multiplied by 1000
    Public Const IMG_PROP_SCALE = &H8   'image scale factor after OCR_STEP_PREFILTERS step, multiplied by 1000
    Public Const IMG_PROP_PAGEINDEX = &H9 'image page index

    'for "Blk_SetWordRegEx" function
    Public Const REGEX_SET = &H0
    Public Const REGEX_CLEAR = &H1
    Public Const REGEX_CLEAR_ALL = &H2
    Public Const REGEX_DISABLE_DICT = &H4
    Public Const REGEX_CHECK = &H8

    'for Svr_SetDocumentInfo function
    Public Const INFO_PDF_AUTHOR = &H1
    Public Const INFO_PDF_CREATOR = &H2
    Public Const INFO_PDF_PRODUCER = &H3
    Public Const INFO_PDF_TITLE = &H4
    Public Const INFO_PDF_SUBJECT = &H5
    Public Const INFO_PDF_KEYWORDS = &H6

    'for Blk_GetBarcodeType function
    Public Const BARCODE_TYPE_EAN8 = &H1
    Public Const BARCODE_TYPE_UPCE = &H2
    Public Const BARCODE_TYPE_ISBN10 = &H3
    Public Const BARCODE_TYPE_UPCA = &H4
    Public Const BARCODE_TYPE_EAN13 = &H5
    Public Const BARCODE_TYPE_ISBN13 = &H6
    Public Const BARCODE_TYPE_ZBAR_I25 = &H7
    Public Const BARCODE_TYPE_CODE39 = &H8
    Public Const BARCODE_TYPE_QRCODE = &H9
    Public Const BARCODE_TYPE_CODE128 = &HA

    'for "BarCode/TypesMask" configuration option
    Public Const BARCODE_TYPE_MASK_EAN8 = &H1
    Public Const BARCODE_TYPE_MASK_UPCE = &H2
    Public Const BARCODE_TYPE_MASK_ISBN10 = &H4
    Public Const BARCODE_TYPE_MASK_UPCA = &H8
    Public Const BARCODE_TYPE_MASK_EAN13 = &H10
    Public Const BARCODE_TYPE_MASK_ISBN13 = &H20
    Public Const BARCODE_TYPE_MASK_ZBAR_I25 = &H40
    Public Const BARCODE_TYPE_MASK_CODE39 = &H80
    Public Const BARCODE_TYPE_MASK_QRCODE = &H100
    Public Const BARCODE_TYPE_MASK_CODE128 = &H200

    'for Img_SaveToFile function
    Public Const IMG_FORMAT_BMP = 0
    Public Const IMG_FORMAT_JPEG = 2
    Public Const IMG_FORMAT_PNG = 13
    Public Const IMG_FORMAT_TIFF = 18
    Public Const IMG_FORMAT_FLAG_BINARIZED = &H100
End Class

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