tabrawbinblock.h

linux下一款GIS程序源码

// tabrawbinblock.h: interface for the TABRawBinBlock class.
//
/*---------------------------------------------------------------------
 *                      class TABRawBinBlock
 *                      读/写二进制块          $zgq
 * This is the base class used for all other data block types... it 
 * contains all the base functions to handle binary data.
 *--------------------------------------------------------------------*/

#ifndef  TABRawBinBlock_H
#define  TABRawBinBlock_H

#include "ugkglobal.h"

class TABRawBinBlock  
{
protected:
    FILE        *m_fp;          /* Associated file handle               */
    TABAccess   m_eAccess;      /* Read/Write access mode               */

	int         m_nBlockType;

    UGKByte       *m_pabyBuf;     /* Buffer to contain the block's data    */
    int         m_nBlockSize;   /* Size of current block (and buffer)    */
    int         m_nSizeUsed;    /* Number of bytes used in buffer        */
    UGKBool       m_bHardBlockSize;/* TRUE=Blocks MUST always be nSize bytes  */
                                 /* FALSE=last block may be less than nSize */
    int         m_nFileOffset;  /* Location of current block in the file */
    int         m_nCurPos;      /* Next byte to read from m_pabyBuf[]    */
    int         m_nFirstBlockPtr;/* Size of file header when different from */
                                 /* block size (used by GotoByteInFile())   */
	                             //第一个块在文件中的位置 有可能并不是从0开始
	int         m_bModified;     /* Used only to detect changes        */
public:
    TABRawBinBlock(TABAccess eAccessMode = TABRead,
                   UGKBool bHardBlockSize = TRUE);
	virtual ~TABRawBinBlock();

	virtual int ReadFromFile(FILE *fpSrc, int nOffset, int nSize = 512);
	virtual int CommitToFile();

    virtual int InitBlockFromData(UGKByte *pabyBuf, int nSize, 
                              UGKBool bMakeCopy = TRUE,
                              FILE *fpSrc = NULL, int nOffset = 0);

	virtual int InitNewBlock(FILE *fpSrc, int nBlockSize, int nFileOffset=0);
	
	int         GetBlockType();
	virtual int GetBlockClass() { return TAB_RAWBIN_BLOCK; };

	UGKInt32      GetStartAddress() {return m_nFileOffset;};
	
	virtual void Dump(FILE *fpOut = NULL);

    int         GotoByteRel(int nOffset);
    int         GotoByteInBlock(int nOffset);
    int         GotoByteInFile(int nOffset);
    void        SetFirstBlockPtr(int nOffset);

    int         GetNumUnusedBytes();
    int         GetFirstUnusedByteOffset();
    int         GetCurAddress();

    virtual int ReadBytes(int numBytes, UGKByte *pabyDstBuf);
    UGKByte       ReadByte();
    UGKInt16      ReadInt16();
    UGKInt32      ReadInt32();
    float       ReadFloat();
    double      ReadDouble();

    virtual int WriteBytes(int nBytesToWrite, UGKByte *pBuf);
    int         WriteByte(UGKByte byValue);
    int         WriteInt16(UGKInt16 n16Value);
    int         WriteInt32(UGKInt32 n32Value);
    int         WriteFloat(float fValue);
    int         WriteDouble(double dValue);
    int         WriteZeros(int nBytesToWrite);
    int         WritePaddedString(int nFieldSize, const char *pszString);

	void        SetModifiedFlag(UGKBool bModified) {m_bModified=bModified;};

	UGKByte *     GetCurDataPtr() { return (m_pabyBuf + m_nCurPos); } ;
};


TABRawBinBlock *TABCreateMAPBlockFromFile(FILE *fpSrc, int nOffset, 
                                          int nSize = 512, 
                                          UGKBool bHardBlockSize = TRUE,
                                          TABAccess eAccessMode = TABRead);

#endif