From 1857e61a9d46354b4bb719266fa70cab4cc3059f Mon Sep 17 00:00:00 2001
From: Scott Wheeler <wheeler@kde.org>
Date: Tue, 17 May 2005 23:57:23 +0000
Subject: [PATCH] Instead of returning 0 on finding a deprecated frame type,
 create an UnknownFrame and set the flag to discard it on write.

As a special bonus this meant implementing the discard-on-tag-alter
flag.

BUG:100515


git-svn-id: svn://anonsvn.kde.org/home/kde/trunk/kdesupport/taglib@415248 283d02a7-25f6-0310-bc7c-ecb5cbfe19da
---
 mpeg/id3v2/id3v2frame.cpp        |  5 +++++
 mpeg/id3v2/id3v2frame.h          | 21 ++++++++++++++++++++-
 mpeg/id3v2/id3v2framefactory.cpp |  4 ++--
 mpeg/id3v2/id3v2tag.cpp          |  6 ++++--
 4 files changed, 31 insertions(+), 5 deletions(-)

diff --git a/mpeg/id3v2/id3v2frame.cpp b/mpeg/id3v2/id3v2frame.cpp
index 0675483c..f58e3500 100644
--- a/mpeg/id3v2/id3v2frame.cpp
+++ b/mpeg/id3v2/id3v2frame.cpp
@@ -417,6 +417,11 @@ bool Frame::Header::tagAlterPreservation() const
   return d->tagAlterPreservation;
 }
 
+void Frame::Header::setTagAlterPreservation(bool preserve)
+{
+  d->tagAlterPreservation = preserve;
+}
+
 bool Frame::Header::fileAlterPreservation() const
 {
   return d->fileAlterPreservation;
diff --git a/mpeg/id3v2/id3v2frame.h b/mpeg/id3v2/id3v2frame.h
index 392bb71a..88607715 100644
--- a/mpeg/id3v2/id3v2frame.h
+++ b/mpeg/id3v2/id3v2frame.h
@@ -29,6 +29,7 @@ namespace TagLib {
 
   namespace ID3v2 {
 
+    class Tag;
     class FrameFactory;
 
     //! ID3v2 frame implementation
@@ -44,6 +45,7 @@ namespace TagLib {
 
     class Frame
     {
+      friend class Tag;
       friend class FrameFactory;
 
     public:
@@ -295,10 +297,27 @@ namespace TagLib {
       /*!
        * Returns true if the flag for tag alter preservation is set.
        *
-       * \note This flag is currently ignored internally in TagLib.
+       * The semantics are a little backwards from what would seem natural
+       * (setting the preservation flag to throw away the frame), but this
+       * follows the ID3v2 standard.
+       *
+       * \see setTagAlterPreservation()
        */
       bool tagAlterPreservation() const;
 
+      /*!
+       * Sets the flag for preservation of this frame if the tag is set.  If
+       * this is set to true the frame will not be written when the tag is
+       * saved.
+       *
+       * The semantics are a little backwards from what would seem natural
+       * (setting the preservation flag to throw away the frame), but this
+       * follows the ID3v2 standard.
+       *
+       * \see tagAlterPreservation()
+       */
+      void setTagAlterPreservation(bool discard);
+
       /*!
        * Returns true if the flag for file alter preservation is set.
        *
diff --git a/mpeg/id3v2/id3v2framefactory.cpp b/mpeg/id3v2/id3v2framefactory.cpp
index 1d695d08..1755b4d3 100644
--- a/mpeg/id3v2/id3v2framefactory.cpp
+++ b/mpeg/id3v2/id3v2framefactory.cpp
@@ -99,8 +99,8 @@ Frame *FrameFactory::createFrame(const ByteVector &data, uint version) const
   }
 
   if(!updateFrame(header)) {
-    delete header;
-    return 0;
+    header->setTagAlterPreservation(true);
+    return new UnknownFrame(data, header);
   }
 
   // updateFrame() might have updated the frame ID.
diff --git a/mpeg/id3v2/id3v2tag.cpp b/mpeg/id3v2/id3v2tag.cpp
index 3daa1515..1032489f 100644
--- a/mpeg/id3v2/id3v2tag.cpp
+++ b/mpeg/id3v2/id3v2tag.cpp
@@ -343,8 +343,10 @@ ByteVector ID3v2::Tag::render() const
 
   // Loop through the frames rendering them and adding them to the tagData.
 
-  for(FrameList::Iterator it = d->frameList.begin(); it != d->frameList.end(); it++)
-    tagData.append((*it)->render());
+  for(FrameList::Iterator it = d->frameList.begin(); it != d->frameList.end(); it++) {
+    if(!(*it)->header()->tagAlterPreservation())
+      tagData.append((*it)->render());
+  }
 
   // Compute the amount of padding, and append that to tagData.