/src/FreeImage/Source/OpenEXR/IlmImf/ImfIO.h

  1///////////////////////////////////////////////////////////////////////////
  2//
  3// Copyright (c) 2002, Industrial Light & Magic, a division of Lucas
  4// Digital Ltd. LLC
  5// 
  6// All rights reserved.
  7// 
  8// Redistribution and use in source and binary forms, with or without
  9// modification, are permitted provided that the following conditions are
 10// met:
 11// *       Redistributions of source code must retain the above copyright
 12// notice, this list of conditions and the following disclaimer.
 13// *       Redistributions in binary form must reproduce the above
 14// copyright notice, this list of conditions and the following disclaimer
 15// in the documentation and/or other materials provided with the
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 18// its contributors may be used to endorse or promote products derived
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 20// 
 21// THIS SOFTWARE IS PROVIDED BY THE COPYRIGHT HOLDERS AND CONTRIBUTORS
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 24// A PARTICULAR PURPOSE ARE DISCLAIMED. IN NO EVENT SHALL THE COPYRIGHT
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 32//
 33///////////////////////////////////////////////////////////////////////////
 34
 35
 36#ifndef INCLUDED_IMF_IO_H
 37#define INCLUDED_IMF_IO_H
 38
 39//-----------------------------------------------------------------------------
 40//
 41//	Low-level file input and output for OpenEXR.
 42//
 43//-----------------------------------------------------------------------------
 44
 45#include <ImfInt64.h>
 46#include <string>
 47
 48namespace Imf {
 49
 50//-----------------------------------------------------------
 51// class IStream -- an abstract base class for input streams.
 52//-----------------------------------------------------------
 53
 54class IStream
 55{
 56  public:
 57
 58    //-----------
 59    // Destructor
 60    //-----------
 61
 62    virtual ~IStream ();
 63    
 64    
 65    //-------------------------------------------------
 66    // Does this input stream support memory-mapped IO?
 67    //
 68    // Memory-mapped streams can avoid an extra copy;
 69    // memory-mapped read operations return a pointer
 70    // to an internal buffer instead of copying data
 71    // into a buffer supplied by the caller.
 72    //-------------------------------------------------
 73
 74    virtual bool        isMemoryMapped () const;
 75
 76
 77    //------------------------------------------------------
 78    // Read from the stream:
 79    //
 80    // read(c,n) reads n bytes from the stream, and stores
 81    // them in array c.  If the stream contains less than n
 82    // bytes, or if an I/O error occurs, read(c,n) throws
 83    // an exception.  If read(c,n) reads the last byte from
 84    // the file it returns false, otherwise it returns true.
 85    //------------------------------------------------------
 86
 87    virtual bool	read (char c[/*n*/], int n) = 0;
 88    
 89    
 90    //---------------------------------------------------
 91    // Read from a memory-mapped stream:
 92    //
 93    // readMemoryMapped(n) reads n bytes from the stream
 94    // and returns a pointer to the first byte.  The
 95    // returned pointer remains valid until the stream
 96    // is closed.  If there are less than n byte left to
 97    // read in the stream or if the stream is not memory-
 98    // mapped, readMemoryMapped(n) throws an exception.  
 99    //---------------------------------------------------
100
101    virtual char *	readMemoryMapped (int n);
102
103
104    //--------------------------------------------------------
105    // Get the current reading position, in bytes from the
106    // beginning of the file.  If the next call to read() will
107    // read the first byte in the file, tellg() returns 0.
108    //--------------------------------------------------------
109
110    virtual Int64	tellg () = 0;
111
112
113    //-------------------------------------------
114    // Set the current reading position.
115    // After calling seekg(i), tellg() returns i.
116    //-------------------------------------------
117
118    virtual void	seekg (Int64 pos) = 0;
119
120
121    //------------------------------------------------------
122    // Clear error conditions after an operation has failed.
123    //------------------------------------------------------
124
125    virtual void	clear ();
126
127
128    //------------------------------------------------------
129    // Get the name of the file associated with this stream.
130    //------------------------------------------------------
131
132    const char *	fileName () const;
133
134  protected:
135
136    IStream (const char fileName[]);
137
138  private:
139
140    IStream (const IStream &);			// not implemented
141    IStream & operator = (const IStream &);	// not implemented
142
143    std::string		_fileName;
144};
145
146
147//-----------------------------------------------------------
148// class OStream -- an abstract base class for output streams
149//-----------------------------------------------------------
150
151class OStream
152{
153  public:
154
155    //-----------
156    // Destructor
157    //-----------
158
159    virtual ~OStream ();
160  
161
162    //----------------------------------------------------------
163    // Write to the stream:
164    //
165    // write(c,n) takes n bytes from array c, and stores them
166    // in the stream.  If an I/O error occurs, write(c,n) throws
167    // an exception.
168    //----------------------------------------------------------
169
170    virtual void	write (const char c[/*n*/], int n) = 0;
171
172
173    //---------------------------------------------------------
174    // Get the current writing position, in bytes from the
175    // beginning of the file.  If the next call to write() will
176    // start writing at the beginning of the file, tellp()
177    // returns 0.
178    //---------------------------------------------------------
179
180    virtual Int64	tellp () = 0;
181
182
183    //-------------------------------------------
184    // Set the current writing position.
185    // After calling seekp(i), tellp() returns i.
186    //-------------------------------------------
187
188    virtual void	seekp (Int64 pos) = 0;
189
190
191    //------------------------------------------------------
192    // Get the name of the file associated with this stream.
193    //------------------------------------------------------
194
195    const char *	fileName () const;
196
197  protected:
198
199    OStream (const char fileName[]);
200
201  private:
202
203    OStream (const OStream &);			// not implemented
204    OStream & operator = (const OStream &);	// not implemented
205
206    std::string		_fileName;
207};
208
209
210//-----------------------
211// Helper classes for Xdr
212//-----------------------
213
214struct StreamIO
215{
216    static void
217    writeChars (OStream &os, const char c[/*n*/], int n)
218    {
219	os.write (c, n);
220    }
221
222    static bool
223    readChars (IStream &is, char c[/*n*/], int n)
224    {
225	return is.read (c, n);
226    }
227};
228
229
230struct CharPtrIO
231{
232    static void
233    writeChars (char *&op, const char c[/*n*/], int n)
234    {
235	while (n--)
236	    *op++ = *c++;
237    }
238
239    static bool
240    readChars (const char *&ip, char c[/*n*/], int n)
241    {
242	while (n--)
243	    *c++ = *ip++;
244
245	return true;
246    }
247};
248
249
250} // namespace Imf
251
252#endif