src/add-ons/media/plugins/matroska/libebml/EbmlVoid.cpp

   1 /****************************************************************************
   2 ** libebml : parse EBML files, see http://embl.sourceforge.net/
   3 **
   4 ** <file/class description>
   5 **
   6 ** Copyright (C) 2002-2005 Steve Lhomme.  All rights reserved.
   7 **
   8 ** This file is part of libebml.
   9 **
  10 ** This library is free software; you can redistribute it and/or
  11 ** modify it under the terms of the GNU Lesser General Public
  12 ** License as published by the Free Software Foundation; either
  13 ** version 2.1 of the License, or (at your option) any later version.
  14 **
  15 ** This library is distributed in the hope that it will be useful,
  16 ** but WITHOUT ANY WARRANTY; without even the implied warranty of
  17 ** MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE.  See the GNU
  18 ** Lesser General Public License for more details.
  19 **
  20 ** You should have received a copy of the GNU Lesser General Public
  21 ** License along with this library; if not, write to the Free Software
  22 ** Foundation, Inc., 59 Temple Place, Suite 330, Boston, MA  02111-1307  USA
  23 **
  24 ** See http://www.matroska.org/license/lgpl/ for LGPL licensing information.
  25 **
  26 ** Contact license@matroska.org if any conditions of this licensing are
  27 ** not clear to you.
  28 **
  29 **********************************************************************/
  30
  31 /*!
  32         \file
  33         \version \$Id: EbmlVoid.cpp 1232 2005-10-15 15:56:52Z robux4 $
  34         \author Steve Lhomme     <robux4 @ users.sf.net>
  35 */
  36 #include "ebml/EbmlVoid.h"
  37 #include "ebml/EbmlContexts.h"
  38
  39 START_LIBEBML_NAMESPACE
  40
  41 EbmlId EbmlVoid_TheId(0xEC, 1);
  42 const EbmlCallbacks EbmlVoid::ClassInfos(EbmlVoid::Create, EbmlVoid_TheId, "EBMLVoid", EbmlVoid_Context);
  43
  44 EbmlVoid::EbmlVoid()
  45 {
  46         bValueIsSet = true;
  47 }
  48
  49 uint32 EbmlVoid::RenderData(IOCallback & output, bool bForceRender, bool bKeepIntact)
  50 {
  51         // write dummy data by 4KB chunks
  52         static binary DummyBuf[4*1024];
  53
  54         uint64 SizeToWrite = Size;
  55         while (SizeToWrite > 4*1024)
  56         {
  57                 output.writeFully(DummyBuf, 4*1024);
  58                 SizeToWrite -= 4*1024;
  59         }
  60         output.writeFully(DummyBuf, SizeToWrite);
  61         return Size;
  62 }
  63
  64 uint64 EbmlVoid::ReplaceWith(EbmlElement & EltToReplaceWith, IOCallback & output, bool ComeBackAfterward, bool bKeepIntact)
  65 {
  66         EltToReplaceWith.UpdateSize(bKeepIntact);
  67         if (HeadSize() + Size < EltToReplaceWith.GetSize() + EltToReplaceWith.HeadSize()) {
  68                 // the element can't be written here !
  69                 return 0;
  70         }
  71         if (HeadSize() + Size - EltToReplaceWith.GetSize() - EltToReplaceWith.HeadSize() == 1) {
  72                 // there is not enough space to put a filling element
  73                 return 0;
  74         }
  75
  76         uint64 CurrentPosition = output.getFilePointer();
  77
  78         output.setFilePointer(GetElementPosition());
  79         EltToReplaceWith.Render(output, bKeepIntact);
  80
  81         if (HeadSize() + Size - EltToReplaceWith.GetSize() - EltToReplaceWith.HeadSize() > 1) {
  82           // fill the rest with another void element
  83           EbmlVoid aTmp;
  84           aTmp.SetSize(HeadSize() + Size - EltToReplaceWith.GetSize() - EltToReplaceWith.HeadSize() - 1); // 1 is the length of the Void ID
  85           int HeadBefore = aTmp.HeadSize();
  86           aTmp.SetSize(aTmp.GetSize() - CodedSizeLength(aTmp.Size, aTmp.SizeLength, aTmp.bSizeIsFinite));
  87           int HeadAfter = aTmp.HeadSize();
  88           if (HeadBefore != HeadAfter) {
  89                   aTmp.SetSizeLength(CodedSizeLength(aTmp.Size, aTmp.SizeLength, aTmp.bSizeIsFinite) - (HeadAfter - HeadBefore));
  90           }
  91           aTmp.RenderHead(output, false, bKeepIntact); // the rest of the data is not rewritten
  92         }
  93
  94         if (ComeBackAfterward) {
  95                 output.setFilePointer(CurrentPosition);
  96         }
  97
  98         return Size + HeadSize();
  99 }
 100
 101 uint64 EbmlVoid::Overwrite(const EbmlElement & EltToVoid, IOCallback & output, bool ComeBackAfterward, bool bKeepIntact)
 102 {
 103 //      EltToVoid.UpdateSize(bKeepIntact);
 104         if (EltToVoid.GetElementPosition() == 0) {
 105                 // this element has never been written
 106                 return 0;
 107         }
 108         if (EltToVoid.GetSize() + EltToVoid.HeadSize() <2) {
 109                 // the element can't be written here !
 110                 return 0;
 111         }
 112
 113         uint64 CurrentPosition = output.getFilePointer();
 114
 115         output.setFilePointer(EltToVoid.GetElementPosition());
 116
 117         // compute the size of the voided data based on the original one
 118         Size = EltToVoid.GetSize() + EltToVoid.HeadSize() - 1; // 1 for the ID
 119         Size -= CodedSizeLength(Size, SizeLength, bSizeIsFinite);
 120         // make sure we handle even the strange cases
 121         //uint32 A1 = Size + HeadSize();
 122         //uint32 A2 = EltToVoid.GetSize() + EltToVoid.HeadSize();
 123         if (Size + HeadSize() != EltToVoid.GetSize() + EltToVoid.HeadSize()) {
 124                 Size--;
 125                 SetSizeLength(CodedSizeLength(Size, SizeLength, bSizeIsFinite) + 1);
 126         }
 127
 128         if (Size != 0) {
 129                 RenderHead(output, false, bKeepIntact); // the rest of the data is not rewritten
 130         }
 131
 132         if (ComeBackAfterward) {
 133                 output.setFilePointer(CurrentPosition);
 134         }
 135
 136         return EltToVoid.GetSize() + EltToVoid.HeadSize();
 137 }
 138
 139 END_LIBEBML_NAMESPACE