ref: b5b68e541c7164b5be892b3f56d2d2b2a2f511a2
dir: /common/id3lib/src/tag.cpp/
// $Id: tag.cpp,v 1.1 2002/01/21 08:16:22 menno Exp $
// id3lib: a C++ library for creating and manipulating id3v1/v2 tags
// Copyright 1999, 2000 Scott Thomas Haug
// This library is free software; you can redistribute it and/or modify it
// under the terms of the GNU Library General Public License as published by
// the Free Software Foundation; either version 2 of the License, or (at your
// option) any later version.
//
// 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 Library General Public
// License for more details.
//
// You should have received a copy of the GNU Library 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.
// The id3lib authors encourage improvements and optimisations to be sent to
// the id3lib coordinator. Please see the README file for details on where to
// send such submissions. See the AUTHORS file for a list of people who have
// contributed to id3lib. See the ChangeLog file for a list of changes to
// id3lib. These files are distributed with id3lib at
// http://download.sourceforge.net/id3lib/
#if defined HAVE_CONFIG_H
#include <config.h>
#endif
#if defined HAVE_SYS_PARAM_H
#include <sys/param.h>
#endif
#include "tag.h"
#include "uint28.h"
#include <string.h>
#ifdef MAXPATHLEN
# define ID3_PATH_LENGTH (MAXPATHLEN + 1)
#elif defined (PATH_MAX)
# define ID3_PATH_LENGTH (PATH_MAX + 1)
#else /* !MAXPATHLEN */
# define ID3_PATH_LENGTH (2048 + 1)
#endif /* !MAXPATHLEN && !PATH_MAX */
/** \class ID3_Tag
** \brief The representative class of an id3 tag.
**
** This is the 'container' class for everything else. It is through an
** ID3_Tag that most of the productive stuff happens.
** Let's look at what's
** required to start using ID3v2 tags.
**
** \code
** #include <id3/tag.h>
** \endcode
**
** This simple \c #include does it all. In order to read an
** existing tag, do the following:
**
** \code
** ID3_Tag myTag;
** myTag.Link("something.mp3");
** \endcode
**
** That is all there is to it. Now all you have to do is use the
** Find() method to locate the frames you are interested in
** is the following:
**
** \code
** ID3_Frame *myFrame;
** if (myTag.Find(ID3FID_TITLE) == myFrame)
** {
** char title[1024];
** myFrame->Field(ID3FN_TEXT).Get(title, 1024);
** cout << "Title: " << title << endl;
** }
** \endcode
**
** This code snippet locates the ID3FID_TITLE frame and copies the contents of
** the text field into a buffer and displays the buffer. Not difficult, eh?
**
** When using the ID3_Tag::Link() method, you automatically gain access to any
** ID3v1/1.1, ID3v2, and Lyrics3 v2.0 tags present in the file. The class
** will automaticaly parse and convert any of these foreign tag formats into
** ID3v2 tags. Also, id3lib will correctly parse any correctly formatted
** 'CDM' frames from the unreleased ID3v2 2.01 draft specification.
**
** \author Dirk Mahoney
** \version $Id: tag.cpp,v 1.1 2002/01/21 08:16:22 menno Exp $
** \sa ID3_Frame
** \sa ID3_Field
** \sa ID3_Err
**/
/** Analyses a buffer to determine if we have a valid ID3v2 tag header.
** If so, return the total number of bytes (including the header) to
** read so we get all of the tag
**/
size_t ID3_Tag::IsV2Tag(const uchar* const data)
{
lsint tagSize = 0;
if (strncmp(ID3_TagHeader::ID, (char *)data, ID3_TagHeader::ID_SIZE) == 0 &&
data[ID3_TagHeader::MAJOR_OFFSET] < 0xFF &&
data[ID3_TagHeader::MINOR_OFFSET] < 0xFF &&
data[ID3_TagHeader::SIZE_OFFSET + 0] < 0x80 &&
data[ID3_TagHeader::SIZE_OFFSET + 1] < 0x80 &&
data[ID3_TagHeader::SIZE_OFFSET + 2] < 0x80 &&
data[ID3_TagHeader::SIZE_OFFSET + 3] < 0x80)
{
uint28 data_size(&data[ID3_TagHeader::SIZE_OFFSET]);
tagSize = data_size.to_uint32() + ID3_TagHeader::SIZE;
}
return tagSize;
}
int32 ID3_IsTagHeader(const uchar data[ID3_TAGHEADERSIZE])
{
size_t size = ID3_Tag::IsV2Tag(data);
if (!size)
{
return -1;
}
return size - ID3_TagHeader::SIZE;
}
void ID3_RemoveFromList(ID3_Elem *which, ID3_Elem **list)
{
ID3_Elem *cur = *list;
if (cur == which)
{
*list = which->pNext;
delete which;
which = NULL;
}
else
{
while (cur)
{
if (cur->pNext == which)
{
cur->pNext = which->pNext;
delete which;
which = NULL;
break;
}
else
{
cur = cur->pNext;
}
}
}
}
void ID3_ClearList(ID3_Elem *list)
{
ID3_Elem *next = NULL;
for (ID3_Elem *cur = list; cur; cur = next)
{
next = cur->pNext;
delete cur;
}
}
/** Copies a frame to the tag. The frame parameter can thus safely be deleted
** or allowed to go out of scope.
**
** Operator<< supports the addition of a pointer to a frame object, or
** the frame object itself.
**
** \code
** ID3_Frame *pFrame, frame;
** p_frame = &frame;
** myTag << pFrame;
** myTag << frame;
** \endcode
**
** Both these methods copy the given frame to the tag---the tag creates its
** own copy of the frame.
**
** \name operator<<
** \param frame The frame to be added to the tag.
**/
ID3_Tag& operator<<(ID3_Tag& tag, const ID3_Frame& frame)
{
tag.AddFrame(frame);
return tag;
}
ID3_Tag& operator<<(ID3_Tag& tag, const ID3_Frame *frame)
{
tag.AddFrame(frame);
return tag;
}
/** Default constructor; it can accept an optional filename as a parameter.
**
** If this file exists, it will be opened and all id3lib-supported tags will
** be parsed and converted to id3v2 if necessary. After the conversion, the
** file will remain unchanged, and will continue to do so until you use the
** Update() method on the tag (if you choose to Update() at all).
**
** \param name The filename of the mp3 file to link to
**/
ID3_Tag::ID3_Tag(const char *name)
: __frames(NULL),
__file_name(new char[ID3_PATH_LENGTH]),
__file_handle(NULL)
{
this->Clear();
if (name)
{
this->Link(name);
}
}
/** Standard copy constructor.
**
** \param tag What is copied into this tag
**/
ID3_Tag::ID3_Tag(const ID3_Tag &tag)
: __frames(NULL),
__file_name(new char[ID3_PATH_LENGTH]),
__file_handle(NULL)
{
*this = tag;
}
ID3_Tag::~ID3_Tag()
{
this->Clear();
delete [] __file_name;
}
/** Clears the object and disassociates it from any files.
**
** It frees any resources for which the object is responsible, and the
** object is now free to be used again for any new or existing tag.
**/
void ID3_Tag::Clear()
{
this->CloseFile();
if (__frames)
{
ID3_ClearList(__frames);
__frames = NULL;
}
__num_frames = 0;
__cursor = NULL;
__is_padded = true;
__hdr.Clear();
__hdr.SetSpec(ID3V2_LATEST);
__file_size = 0;
__starting_bytes = 0;
__ending_bytes = 0;
__is_file_writable = false;
__tags_to_parse.clear();
__file_tags.clear();
__changed = true;
}
void ID3_Tag::AddFrame(const ID3_Frame& frame)
{
this->AddFrame(&frame);
}
/** Attaches a frame to the tag; the tag doesn't take responsibility for
** releasing the frame's memory when tag goes out of scope.
**
** Optionally, operator<< can also be used to attach a frame to a tag. To
** use, simply supply its parameter a pointer to the ID3_Frame object you wish
** to attach.
**
** \code
** ID3_Frame myFrame;
** myTag.AddFrame(&myFrame);
** \endcode
**
** As stated, this method attaches the frames to the tag---the tag does
** not create its own copy of the frame. Frames created by an application
** must exist until the frame is removed or the tag is finished with it.
**
** \param pFrame A pointer to the frame that is being added to the tag.
** \sa ID3_Frame
**/
void ID3_Tag::AddFrame(const ID3_Frame *frame)
{
if (frame)
{
ID3_Frame* new_frame = new ID3_Frame(*frame);
this->AttachFrame(new_frame);
}
}
/** Attaches a frame to the tag; the tag takes responsibility for
** releasing the frame's memory when tag goes out of scope.
**
** This method accepts responsibility for the attached frame's memory, and
** will delete the frame and its contents when the tag goes out of scope or is
** deleted. Therefore, be sure the frame isn't "Attached" to other tags.
**
** \code
** ID3_Frame *frame = new ID3_Frame;
** myTag.AttachFrame(frame);
** \endcode
**
** \param frame A pointer to the frame that is being added to the tag.
**/
void ID3_Tag::AttachFrame(ID3_Frame *frame)
{
ID3_Elem *elem;
if (NULL == frame)
{
ID3_THROW(ID3E_NoData);
}
elem = new ID3_Elem;
if (NULL == elem)
{
ID3_THROW(ID3E_NoMemory);
}
elem->pNext = __frames;
elem->pFrame = frame;
__frames = elem;
__num_frames++;
__cursor = NULL;
__changed = true;
}
/** Copies an array of frames to the tag.
**
** This method copies each frame in an array to the tag. As in
** AddFrame, the tag adds a copy of the frame, and it assumes responsiblity
** for freeing the frames' memory when the tag goes out of scope.
**
** \code
** ID3_Frame myFrames[10];
** myTag.AddFrames(myFrames, 10);
** \endcode
**
** \sa ID3_Frame
** \sa ID3_Frame#AddFrame
** \param pNewFrames A pointer to an array of frames to be added to the tag.
** \param nFrames The number of frames in the array pNewFrames.
**/
void ID3_Tag::AddFrames(const ID3_Frame *frames, size_t numFrames)
{
for (index_t i = numFrames - 1; i >= 0; i--)
{
AddFrame(frames[i]);
}
}
/** Removes a frame from the tag.
**
** If you already own the frame object in question, then you should already
** have a pointer to the frame you want to delete. If not, or if you wish to
** delete a pre-existing frame (from a tag you have parsed, for example), the
** use one of the Find methods to obtain a frame pointer to pass to this
** method.
**
** \code
** ID3_Frame *someFrame;
** if (someFrame = myTag.Find(ID3FID_TITLE))
** {
** myTag.RemoveFrame(someFrame);
** }
** \endcode
**
** \sa ID3_Tag#Find
** \param pOldFrame A pointer to the frame that is to be removed from the
** tag
**/
ID3_Frame* ID3_Tag::RemoveFrame(const ID3_Frame *frame)
{
ID3_Frame *the_frame = NULL;
ID3_Elem *elem = Find(frame);
if (NULL != elem)
{
the_frame = elem->pFrame;
//assert(the_frame == frame);
elem->pFrame = NULL;
ID3_RemoveFromList(elem, &__frames);
--__num_frames;
}
return the_frame;
}
/** Indicates whether the tag has been altered since the last parse, render,
** or update.
**
** If you have a tag linked to a file, you do not need this method since the
** Update() method will check for changes before writing the tag.
**
** This method is primarily intended as a status indicator for applications
** and for applications that use the Parse() and Render() methods.
**
** Setting a field, changed the ID of an attached frame, setting or grouping
** or encryption IDs, and clearing a frame or field all constitute a change
** to the tag, as do calls to the SetUnsync(), SetExtendedHeader(), and
** SetPadding() methods.
**
** \code
** if (myTag.HasChanged())
** {
** // render and output the tag
** }
** \endcode
**
** \return Whether or not the tag has been altered.
**/
bool ID3_Tag::HasChanged() const
{
bool changed = __changed;
if (! changed)
{
ID3_Elem *cur = __frames;
while (cur)
{
if (cur->pFrame)
{
changed = cur->pFrame->HasChanged();
}
if (changed)
{
break;
}
else
{
cur = cur->pNext;
}
}
}
return changed;
}
bool ID3_Tag::SetSpec(ID3_V2Spec spec)
{
bool changed = __hdr.SetSpec(spec);
__changed = __changed || changed;
return changed;
}
ID3_V2Spec ID3_Tag::GetSpec() const
{
return __hdr.GetSpec();
}
/** Turns unsynchronization on or off, dependant on the value of the boolean
** parameter.
**
** If you call this method with 'false' as the parameter, the
** binary tag will not be unsync'ed, regardless of whether the tag should
** be. This option is useful when the file is only going to be used by
** ID3v2-compliant software. See the id3v2 standard document for futher
** details on unsync.
**
** Be default, tags are created without unsync.
**
** \code
** myTag.SetUnsync(false);
** \endcode
**
** \param bSync Whether the tag should be unsynchronized
**/
bool ID3_Tag::SetUnsync(bool b)
{
bool changed = __hdr.SetUnsync(b);
__changed = changed || __changed;
return changed;
}
/** Turns extended header rendering on or off, dependant on the value of the
** boolean parameter.
**
** This option is currently ignored as id3lib doesn't yet create extended
** headers. This option only applies when rendering tags for id3v2 versions
** that support extended headers.
**
** By default, id3lib will generate extended headers for all tags in which
** extended headers are supported.
**
** \code
** myTag.SetExtendedHeader(true);
** \endcode
**
** \param bExt Whether to render an extended header
**/
bool ID3_Tag::SetExtendedHeader(bool ext)
{
bool changed = __hdr.SetExtended(ext);
__changed = changed || __changed;
return changed;
}
/** Turns padding on or off, dependant on the value of the boolean
** parameter.
**
** When using id3v2 tags in association with files, id3lib can optionally
** add padding to the tags to ensure minmal file write times when updating
** the tag in the future.
**
** When the padding option is switched on, id3lib automatically creates
** padding according to the 'ID3v2 Programming Guidelines'. Specifically,
** enough padding will be added to round out the entire file (song plus
** tag) to an even multiple of 2K. Padding will only be created when the
** tag is attached to a file and that file is not empty (aside from a
** pre-existing tag).
**
** id3lib's addition to the guidelines for padding, is that if frames are
** removed from a pre-existing tag (or the tag simply shrinks because of
** other reasons), the new tag will continue to stay the same size as the
** old tag (with padding making the difference of course) until such time as
** the padding is greater than 4K. When this happens, the padding will be
** reduced and the new tag will be smaller than the old.
**
** By default, padding is switched on.
**
** \code
** myTag.SetPadding(false);
** \endcode
**
** \param bPad Whether or not render the tag with padding.
**/
bool ID3_Tag::SetPadding(bool pad)
{
bool changed = (__is_padded != pad);
__changed = changed || __changed;
if (changed)
{
__is_padded = pad;
}
return changed;
}
ID3_Tag &
ID3_Tag::operator=( const ID3_Tag &rTag )
{
if (this != &rTag)
{
Clear();
size_t nFrames = rTag.NumFrames();
for (size_t nIndex = 0; nIndex < nFrames; nIndex++)
{
ID3_Frame *frame = new ID3_Frame;
// Copy the frames in reverse order so that they appear in the same order
// as the original tag when rendered.
*frame = *(rTag[nFrames - nIndex - 1]);
AttachFrame(frame);
}
}
return *this;
}