From a8dce14514b10eaaa398f11a85dc82cc1ed7505e Mon Sep 17 00:00:00 2001
From: Martchus <martchus@gmx.net>
Date: Wed, 16 Nov 2016 19:31:09 +0100
Subject: [PATCH] Allow checking index position

Only implemented for MP4 so far
---
 abstractcontainer.cpp          | 10 ++++++++++
 abstractcontainer.h            |  1 +
 matroska/matroskacontainer.cpp |  5 +++++
 matroska/matroskacontainer.h   |  1 +
 mp4/mp4container.cpp           | 16 ++++++++++++++--
 mp4/mp4container.h             |  1 +
 6 files changed, 32 insertions(+), 2 deletions(-)

diff --git a/abstractcontainer.cpp b/abstractcontainer.cpp
index 6a19856..97e0429 100644
--- a/abstractcontainer.cpp
+++ b/abstractcontainer.cpp
@@ -171,6 +171,16 @@ bool AbstractContainer::supportsTrackModifications() const
     return false;
 }
 
+/*!
+ * \brief Determines the position of the index.
+ * \returns Returns ElementPosition::BeforeData or ElementPosition::AfterData if the position could
+ *          be determined; otherwise returns ElementPosition::Keep.
+ */
+ElementPosition AbstractContainer::determineIndexPosition() const
+{
+    return ElementPosition::Keep;
+}
+
 /*!
  * \brief Internally called to parse the header.
  *
diff --git a/abstractcontainer.h b/abstractcontainer.h
index 2f1be11..fa26751 100644
--- a/abstractcontainer.h
+++ b/abstractcontainer.h
@@ -67,6 +67,7 @@ public:
     virtual bool removeTrack(AbstractTrack *track);
     virtual void removeAllTracks();
     virtual bool supportsTrackModifications() const;
+    virtual ElementPosition determineIndexPosition() const;
 
     virtual AbstractChapter *chapter(std::size_t index);
     virtual std::size_t chapterCount() const;
diff --git a/matroska/matroskacontainer.cpp b/matroska/matroskacontainer.cpp
index f646e1d..458a99b 100644
--- a/matroska/matroskacontainer.cpp
+++ b/matroska/matroskacontainer.cpp
@@ -337,6 +337,11 @@ ElementPosition MatroskaContainer::determineTagPosition() const
     return ElementPosition::Keep; // TODO
 }
 
+ElementPosition MatroskaContainer::determineIndexPosition() const
+{
+    return ElementPosition::Keep; // TODO
+}
+
 void MatroskaContainer::internalParseHeader()
 {
     static const string context("parsing header of Matroska container");
diff --git a/matroska/matroskacontainer.h b/matroska/matroskacontainer.h
index 11e1985..0766f52 100644
--- a/matroska/matroskacontainer.h
+++ b/matroska/matroskacontainer.h
@@ -42,6 +42,7 @@ public:
     MatroskaAttachment *attachment(std::size_t index);
     std::size_t attachmentCount() const;
     ElementPosition determineTagPosition() const;
+    ElementPosition determineIndexPosition() const;
 
     virtual bool supportsTitle() const;
     virtual std::size_t segmentCount() const;
diff --git a/mp4/mp4container.cpp b/mp4/mp4container.cpp
index 80317ed..32e7cd8 100644
--- a/mp4/mp4container.cpp
+++ b/mp4/mp4container.cpp
@@ -48,8 +48,8 @@ void Mp4Container::reset()
 ElementPosition Mp4Container::determineTagPosition() const
 {
     if(m_firstElement) {
-        Mp4Atom *mediaDataAtom = m_firstElement->siblingById(Mp4AtomIds::MediaData);
-        Mp4Atom *userDataAtom = m_firstElement->subelementByPath({Mp4AtomIds::Movie, Mp4AtomIds::UserData});
+        const Mp4Atom *mediaDataAtom = m_firstElement->siblingById(Mp4AtomIds::MediaData);
+        const Mp4Atom *userDataAtom = m_firstElement->subelementByPath({Mp4AtomIds::Movie, Mp4AtomIds::UserData});
         if(mediaDataAtom && userDataAtom) {
             return userDataAtom->startOffset() < mediaDataAtom->startOffset() ? ElementPosition::BeforeData : ElementPosition::AfterData;
         }
@@ -57,6 +57,18 @@ ElementPosition Mp4Container::determineTagPosition() const
     return ElementPosition::Keep;
 }
 
+ElementPosition Mp4Container::determineIndexPosition() const
+{
+    if(m_firstElement) {
+        const Mp4Atom *mediaDataAtom = m_firstElement->siblingById(Mp4AtomIds::MediaData);
+        const Mp4Atom *movieAtom = m_firstElement->siblingById(Mp4AtomIds::Movie);
+        if(mediaDataAtom && movieAtom) {
+            return movieAtom->startOffset() < mediaDataAtom->startOffset() ? ElementPosition::BeforeData : ElementPosition::AfterData;
+        }
+    }
+    return ElementPosition::Keep;
+}
+
 void Mp4Container::internalParseHeader()
 {
     //const string context("parsing header of MP4 container"); will be used when generating notifications
diff --git a/mp4/mp4container.h b/mp4/mp4container.h
index 9240faf..fa0f8f4 100644
--- a/mp4/mp4container.h
+++ b/mp4/mp4container.h
@@ -26,6 +26,7 @@ public:
     bool isFragmented() const;
     void reset();
     ElementPosition determineTagPosition() const;
+    ElementPosition determineIndexPosition() const;
 
 protected:
     void internalParseHeader();