EPUB export: use real chapter names

Instead of "Seciton N" placeholders, by backporting the relevant
libepubgen commit.

Change-Id: I7073658597205927eeefc4e63ec23bd95cf4f30c
Reviewed-on: https://gerrit.libreoffice.org/41241Reviewed-by: Miklos Vajna <vmiklos@collabora.co.uk>
Tested-by: Jenkins <ci@libreoffice.org>

external/libepubgen/libepubgen-epub3.patch.1

@@ -1192,3 +1192,217 @@ index cb557b2..aba8827 100644
 -- 
 2.12.3
 
+From 576c2472e384ea1a71739b15f42561cd34de5bba Mon Sep 17 00:00:00 2001
+From: Miklos Vajna <vmiklos@collabora.co.uk>
+Date: Wed, 16 Aug 2017 17:52:37 +0200
+Subject: [PATCH] EPUB_SPLIT_METHOD_HEADING: try to use real chapter names, not
+ Section N
+
+What users call "chapter title" is the text of a paragraph with an
+outline level set.
+
+To keep this simple just handle the text after opening such a paragraph,
+but no other paragraph is opened, i.e. assume that in:
+
+<para outline=y>A<para outline=n>B</para>C</para>
+
+only A is interesting, but not B, neither C. (Which could happen with an
+at-character anchored frame inside a heading text e.g.)
+---
+ src/lib/EPUBGenerator.cpp     |  5 +++++
+ src/lib/EPUBGenerator.h       |  2 ++
+ src/lib/EPUBHTMLManager.cpp   | 26 ++++++++++++++++++++++++--
+ src/lib/EPUBHTMLManager.h     |  3 +++
+ src/lib/EPUBPath.cpp          | 11 +++++++++++
+ src/lib/EPUBPath.h            |  4 ++++
+ src/lib/EPUBTextGenerator.cpp |  6 ++++++
+ 7 files changed, 55 insertions(+), 2 deletions(-)
+
+diff --git a/src/lib/EPUBGenerator.cpp b/src/lib/EPUBGenerator.cpp
+index 4bffb8b..4ce2964 100644
+--- a/src/lib/EPUBGenerator.cpp
++++ b/src/lib/EPUBGenerator.cpp
+@@ -106,6 +106,11 @@ const EPUBHTMLGeneratorPtr_t &EPUBGenerator::getHtml() const
+   return m_currentHtml;
+ }
+ 
++EPUBHTMLManager &EPUBGenerator::getHtmlManager()
++{
++  return m_htmlManager;
++}
++
+ const EPUBSplitGuard &EPUBGenerator::getSplitGuard() const
+ {
+   return m_splitGuard;
+diff --git a/src/lib/EPUBGenerator.h b/src/lib/EPUBGenerator.h
+index 1a67a88..f98c80f 100644
+--- a/src/lib/EPUBGenerator.h
++++ b/src/lib/EPUBGenerator.h
+@@ -45,6 +45,8 @@ public:
+ 
+   const EPUBHTMLGeneratorPtr_t &getHtml() const;
+ 
++  EPUBHTMLManager &getHtmlManager();
++
+   const EPUBSplitGuard &getSplitGuard() const;
+   EPUBSplitGuard &getSplitGuard();
+   int getVersion() const;
+diff --git a/src/lib/EPUBHTMLManager.cpp b/src/lib/EPUBHTMLManager.cpp
+index be56cc7..5141f31 100644
+--- a/src/lib/EPUBHTMLManager.cpp
++++ b/src/lib/EPUBHTMLManager.cpp
+@@ -18,6 +18,20 @@
+ namespace libepubgen
+ {
+ 
++namespace
++{
++
++/// Extracts a title string from a path and provides a fallback if it would be empty.
++void getPathTitle(std::ostringstream &label, const EPUBPath &path, std::vector<EPUBPath>::size_type index)
++{
++  if (path.getTitle().empty())
++    label << "Section " << (index + 1);
++  else
++    label << path.getTitle();
++}
++
++}
++
+ EPUBHTMLManager::EPUBHTMLManager(EPUBManifest &manifest)
+   : m_manifest(manifest)
+   , m_paths()
+@@ -78,7 +92,7 @@ void EPUBHTMLManager::writeTocTo(EPUBXMLSink &sink, const EPUBPath &tocPath, int
+       anchorAttrs.insert("href", m_paths[i].relativeTo(tocPath).str().c_str());
+       sink.openElement("a", anchorAttrs);
+       std::ostringstream label;
+-      label << "Section " << (i + 1);
++      getPathTitle(label, m_paths[i], i);
+       sink.insertCharacters(label.str().c_str());
+       sink.closeElement("a");
+       sink.closeElement("li");
+@@ -101,7 +115,7 @@ void EPUBHTMLManager::writeTocTo(EPUBXMLSink &sink, const EPUBPath &tocPath, int
+     sink.openElement("navLabel");
+     sink.openElement("text");
+     std::ostringstream label;
+-    label << "Section " << (i + 1);
++    getPathTitle(label, m_paths[i], i);
+     sink.insertCharacters(label.str().c_str());
+     sink.closeElement("text");
+     sink.closeElement("navLabel");
+@@ -112,6 +126,14 @@ void EPUBHTMLManager::writeTocTo(EPUBXMLSink &sink, const EPUBPath &tocPath, int
+   }
+ }
+ 
++void EPUBHTMLManager::insertHeadingText(const std::string &text)
++{
++  if (m_paths.empty())
++    return;
++
++  m_paths.back().appendTitle(text);
++}
++
+ }
+ 
+ /* vim:set shiftwidth=2 softtabstop=2 expandtab: */
+diff --git a/src/lib/EPUBHTMLManager.h b/src/lib/EPUBHTMLManager.h
+index 2ec7bb7..6b480c4 100644
+--- a/src/lib/EPUBHTMLManager.h
++++ b/src/lib/EPUBHTMLManager.h
+@@ -48,6 +48,9 @@ public:
+   void writeSpineTo(EPUBXMLSink &sink);
+   void writeTocTo(EPUBXMLSink &sink, const EPUBPath &tocPath, int version);
+ 
++  /// Appends text to the title of the current heading.
++  void insertHeadingText(const std::string &text);
++
+ private:
+   EPUBManifest &m_manifest;
+   std::vector<EPUBPath> m_paths;
+diff --git a/src/lib/EPUBPath.cpp b/src/lib/EPUBPath.cpp
+index 9def6f6..e1c05ed 100644
+--- a/src/lib/EPUBPath.cpp
++++ b/src/lib/EPUBPath.cpp
+@@ -53,6 +53,7 @@ EPUBPath::Relative::Relative(const std::vector<std::string> &components)
+ 
+ EPUBPath::EPUBPath(const std::string &path)
+   : m_components()
++  , m_title()
+ {
+   const std::string trimmed(algorithm::trim_left_copy_if(path, algorithm::is_any_of("/")));
+   algorithm::split(m_components, trimmed, algorithm::is_any_of("/"), algorithm::token_compress_on);
+@@ -110,6 +111,16 @@ const EPUBPath::Relative EPUBPath::relativeTo(const EPUBPath &base) const
+   return Relative(components);
+ }
+ 
++void EPUBPath::appendTitle(const std::string &title)
++{
++  m_title += title;
++}
++
++std::string EPUBPath::getTitle() const
++{
++  return m_title;
++}
++
+ bool operator==(const EPUBPath &left, const EPUBPath &right)
+ {
+   return left.m_components == right.m_components;
+diff --git a/src/lib/EPUBPath.h b/src/lib/EPUBPath.h
+index 18bf058..12b8f25 100644
+--- a/src/lib/EPUBPath.h
++++ b/src/lib/EPUBPath.h
+@@ -48,8 +48,12 @@ public:
+ 
+   const Relative relativeTo(const EPUBPath &base) const;
+ 
++  void appendTitle(const std::string &title);
++  std::string getTitle() const;
++
+ private:
+   std::vector<std::string> m_components;
++  std::string m_title;
+ };
+ 
+ bool operator==(const EPUBPath &left, const EPUBPath &right);
+diff --git a/src/lib/EPUBTextGenerator.cpp b/src/lib/EPUBTextGenerator.cpp
+index aba8827..b1e33f8 100644
+--- a/src/lib/EPUBTextGenerator.cpp
++++ b/src/lib/EPUBTextGenerator.cpp
+@@ -67,6 +67,7 @@ public:
+   bool m_inPageSpan;
+   bool m_inHeader;
+   bool m_inFooter;
++  bool m_inHeading;
+ 
+   RVNGPropertyList m_pageSpanProps;
+   shared_ptr<EPUBTextElements> m_currentHeader;
+@@ -88,6 +89,7 @@ EPUBTextGenerator::Impl::Impl(EPUBPackage *const package, const EPUBSplitMethod
+   , m_inPageSpan(false)
+   , m_inHeader(false)
+   , m_inFooter(false)
++  , m_inHeading(false)
+   , m_pageSpanProps()
+   , m_currentHeader()
+   , m_currentFooter()
+@@ -260,6 +262,7 @@ void EPUBTextGenerator::openParagraph(const librevenge::RVNGPropertyList &propLi
+   const RVNGProperty *const outlineLevel = propList["text:outline-level"];
+   if (outlineLevel && m_impl->getSplitGuard().splitOnHeading(outlineLevel->getInt()))
+     m_impl->startNewHtmlFile();
++  m_impl->m_inHeading = outlineLevel != nullptr;
+ 
+   m_impl->getSplitGuard().openLevel();
+ 
+@@ -366,6 +369,9 @@ void EPUBTextGenerator::insertText(const librevenge::RVNGString &text)
+   if (m_impl->m_inHeader || m_impl->m_inFooter)
+     m_impl->m_currentHeaderOrFooter->addInsertText(text);
+ 
++  if (m_impl->m_inHeading)
++    m_impl->getHtmlManager().insertHeadingText(text.cstr());
++
+   m_impl->getSplitGuard().incrementSize(text.len());
+ 
+   m_impl->getHtml()->insertText(text);
+-- 
+2.12.3
+