taglib/toolkit/tfile.h
Scott Wheeler 784f71409b Add a warning note to File::save()
git-svn-id: svn://anonsvn.kde.org/home/kde/trunk/kdesupport/taglib@573841 283d02a7-25f6-0310-bc7c-ecb5cbfe19da
2006-08-17 10:31:52 +00:00

247 lines
7.9 KiB
C++

/***************************************************************************
copyright : (C) 2002, 2003 by Scott Wheeler
email : wheeler@kde.org
***************************************************************************/
/***************************************************************************
* This library is free software; you can redistribute it and/or modify *
* it under the terms of the GNU Lesser General Public License version *
* 2.1 as published by the Free Software Foundation. *
* *
* This library is distributed in the hope that it will be useful, but *
* WITHOUT ANY WARRANTY; without even the implied warranty of *
* MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE. See the GNU *
* Lesser General Public License for more details. *
* *
* You should have received a copy of the GNU Lesser General Public *
* License along with this library; if not, write to the Free Software *
* Foundation, Inc., 59 Temple Place, Suite 330, Boston, MA 02111-1307 *
* USA *
***************************************************************************/
#ifndef TAGLIB_FILE_H
#define TAGLIB_FILE_H
#include "taglib.h"
#include "tbytevector.h"
namespace TagLib {
class String;
class Tag;
class AudioProperties;
//! A file class with some useful methods for tag manipulation
/*!
* This class is a basic file class with some methods that are particularly
* useful for tag editors. It has methods to take advantage of
* ByteVector and a binary search method for finding patterns in a file.
*/
class File
{
public:
/*!
* Position in the file used for seeking.
*/
enum Position {
//! Seek from the beginning of the file.
Beginning,
//! Seek from the current position in the file.
Current,
//! Seek from the end of the file.
End
};
/*!
* Destroys this File instance.
*/
virtual ~File();
/*!
* Returns the file name in the local file system encoding.
*/
const char *name() const;
/*!
* Returns a pointer to this file's tag. This should be reimplemented in
* the concrete subclasses.
*/
virtual Tag *tag() const = 0;
/*!
* Returns a pointer to this file's audio properties. This should be
* reimplemented in the concrete subclasses. If no audio properties were
* read then this will return a null pointer.
*/
virtual AudioProperties *audioProperties() const = 0;
/*!
* Save the file and its associated tags. This should be reimplemented in
* the concrete subclasses. Returns true if the save succeeds.
*
* \warning On UNIX multiple processes are able to write to the same file at
* the same time. This can result in serious file corruption. If you are
* developing a program that makes use of TagLib from multiple processes you
* must insure that you are only doing writes to a particular file from one
* of them.
*/
virtual bool save() = 0;
/*!
* Reads a block of size \a length at the current get pointer.
*/
ByteVector readBlock(ulong length);
/*!
* Attempts to write the block \a data at the current get pointer. If the
* file is currently only opened read only -- i.e. readOnly() returns true --
* this attempts to reopen the file in read/write mode.
*
* \note This should be used instead of using the streaming output operator
* for a ByteVector. And even this function is significantly slower than
* doing output with a char[].
*/
void writeBlock(const ByteVector &data);
/*!
* Returns the offset in the file that \a pattern occurs at or -1 if it can
* not be found. If \a before is set, the search will only continue until the
* pattern \a before is found. This is useful for tagging purposes to search
* for a tag before the synch frame.
*
* Searching starts at \a fromOffset, which defaults to the beginning of the
* file.
*
* \note This has the practial limitation that \a pattern can not be longer
* than the buffer size used by readBlock(). Currently this is 1024 bytes.
*/
long find(const ByteVector &pattern,
long fromOffset = 0,
const ByteVector &before = ByteVector::null);
/*!
* Returns the offset in the file that \a pattern occurs at or -1 if it can
* not be found. If \a before is set, the search will only continue until the
* pattern \a before is found. This is useful for tagging purposes to search
* for a tag before the synch frame.
*
* Searching starts at \a fromOffset and proceeds from the that point to the
* beginning of the file and defaults to the end of the file.
*
* \note This has the practial limitation that \a pattern can not be longer
* than the buffer size used by readBlock(). Currently this is 1024 bytes.
*/
long rfind(const ByteVector &pattern,
long fromOffset = 0,
const ByteVector &before = ByteVector::null);
/*!
* Insert \a data at position \a start in the file overwriting \a replace
* bytes of the original content.
*
* \note This method is slow since it requires rewriting all of the file
* after the insertion point.
*/
void insert(const ByteVector &data, ulong start = 0, ulong replace = 0);
/*!
* Removes a block of the file starting a \a start and continuing for
* \a length bytes.
*
* \note This method is slow since it involves rewriting all of the file
* after the removed portion.
*/
void removeBlock(ulong start = 0, ulong length = 0);
/*!
* Returns true if the file is read only (or if the file can not be opened).
*/
bool readOnly() const;
/*!
* Since the file can currently only be opened as an argument to the
* constructor (sort-of by design), this returns if that open succeeded.
*/
bool isOpen() const;
/*!
* Returns true if the file is open and readble and valid information for
* the Tag and / or AudioProperties was found.
*/
bool isValid() const;
/*!
* Move the I/O pointer to \a offset in the file from position \a p. This
* defaults to seeking from the beginning of the file.
*
* \see Position
*/
void seek(long offset, Position p = Beginning);
/*!
* Reset the end-of-file and error flags on the file.
*/
void clear();
/*!
* Returns the current offset withing the file.
*/
long tell() const;
/*!
* Returns the length of the file.
*/
long length();
/*!
* Returns true if \a file can be opened for reading. If the file does not
* exist, this will return false.
*/
static bool isReadable(const char *file);
/*!
* Returns true if \a file can be opened for writing.
*/
static bool isWritable(const char *name);
protected:
/*!
* Construct a File object and opens the \a file. \a file should be a
* be a C-string in the local file system encoding.
*
* \note Constructor is protected since this class should only be
* instantiated through subclasses.
*/
File(const char *file);
/*!
* Marks the file as valid or invalid.
*
* \see isValid()
*/
void setValid(bool valid);
/*!
* Truncates the file to a \a length.
*/
void truncate(long length);
/*!
* Returns the buffer size that is used for internal buffering.
*/
static uint bufferSize();
private:
File(const File &);
File &operator=(const File &);
class FilePrivate;
FilePrivate *d;
};
}
#endif