From 8be6790c362663973cb01e746064d47f082a654c Mon Sep 17 00:00:00 2001
From: Kevin Hendricks <kevinhendricks@users.noreply.github.com>
Date: Thu, 30 Nov 2023 11:33:19 -0500
Subject: [PATCH] preserve media overlay active class selectors from being
 considered unused

---
 ChangeLog.txt                       |  3 +++
 src/MainUI/MainWindow.cpp           |  7 ++++++-
 src/ResourceObjects/OPFResource.cpp | 26 ++++++++++++++++++++++++++
 src/ResourceObjects/OPFResource.h   |  7 ++++++-
 4 files changed, 41 insertions(+), 2 deletions(-)

diff --git a/ChangeLog.txt b/ChangeLog.txt
index 9eebcfa14f..453a4cae12 100644
--- a/ChangeLog.txt
+++ b/ChangeLog.txt
@@ -3,9 +3,12 @@ pre-2.x.x
       - assign menu accelerators P - &Plugins, and K - Chec&kpoints (thank you BeckyEbook)
       - add ability to change keyboard focus using keyboard shortcuts or menus
           to BookBrowser, Preview, CodeView, ClipsWindow, and TableOfContents Windows
+      - preserve Media Overlay Active Classes when deleting unused classes
+
     Bug Fixes
       - patch Qt6.5.3 to avoid transient child window resize bug on Windows
       - fix QuickParser bug when parseing attribute names not properly ignoreing all legal whitespace
+      - make OPF parsing robust to alternative whitespace usage as well
 
 
 Sigil-2.0.2
diff --git a/src/MainUI/MainWindow.cpp b/src/MainUI/MainWindow.cpp
index c957fa222a..c8830a6324 100644
--- a/src/MainUI/MainWindow.cpp
+++ b/src/MainUI/MainWindow.cpp
@@ -2980,12 +2980,17 @@ bool MainWindow::DeleteUnusedStyles(bool in_automate)
         return false;
     }
 
+    // get list of any media overlay active class selectors from the opf
+    QStringList activeclassselectors = m_Book->GetOPF()->GetMediaOverlayActiveClassSelectors();
+    
     // This one handles all selector types
     QList<BookReports::StyleData *> css_selector_usage = BookReports::GetAllCSSSelectorsUsed(m_Book, true);
     QList<BookReports::StyleData *> css_selectors_to_delete;
     foreach(BookReports::StyleData *selector, css_selector_usage) {
         if (selector->html_filename.isEmpty()) {
-            css_selectors_to_delete.append(selector);
+            if (!activeclassselectors.contains(selector->css_selector_text)) {
+                css_selectors_to_delete.append(selector);
+            }
         }
     }
 
diff --git a/src/ResourceObjects/OPFResource.cpp b/src/ResourceObjects/OPFResource.cpp
index 4b7668da88..897a39a0b2 100644
--- a/src/ResourceObjects/OPFResource.cpp
+++ b/src/ResourceObjects/OPFResource.cpp
@@ -57,6 +57,8 @@
     #define QT_ENUM_KEEPEMPTYPARTS QString::KeepEmptyParts
 #endif
 
+static const QString MEDIA_PLAYBACK_ACTIVE_CLASS = "media:playback-active-class";
+static const QString MEDIA_ACTIVE_CLASS          = "media:active-class";
 static const QString SIGIL_VERSION_META_NAME  = "Sigil version";
 static const QString OPF_XML_NAMESPACE        = "http://www.idpf.org/2007/opf";
 static const QString FALLBACK_MIMETYPE        = "text/plain";
@@ -561,6 +563,30 @@ QStringList OPFResource::GetSpineOrderBookPaths() const
     return book_paths_in_reading_order;
 }
 
+
+QStringList OPFResource::GetMediaOverlayActiveClassSelectors() const
+{
+    QReadLocker locker(&GetLock());
+    QStringList activeclassselectors;
+    QString source = CleanSource::ProcessXML(GetText(),"application/oebps-package+xml");
+    OPFParser p;
+    p.parse(source);
+    for (int i=0; i < p.m_metadata.count(); ++i) {
+        if (p.m_metadata.at(i).m_name == "meta") {
+            MetaEntry me = p.m_metadata.at(i);
+            QString propval = me.m_atts.value("property", "");
+            if (propval == MEDIA_ACTIVE_CLASS) {
+                activeclassselectors << "." + me.m_content;
+            }
+            if (propval == MEDIA_PLAYBACK_ACTIVE_CLASS) {
+                activeclassselectors << "." + me.m_content;
+            }
+        }
+    }
+    return activeclassselectors;
+}
+
+
 QString OPFResource::GetPrimaryBookTitle() const
 {
     QString title = "";
diff --git a/src/ResourceObjects/OPFResource.h b/src/ResourceObjects/OPFResource.h
index 6cd8bf403b..75743fccb0 100644
--- a/src/ResourceObjects/OPFResource.h
+++ b/src/ResourceObjects/OPFResource.h
@@ -1,6 +1,6 @@
 /************************************************************************
 **
-**  Copyright (C) 2015-2020 Kevin B. Hendricks, Stratford ON
+**  Copyright (C) 2015-2023 Kevin B. Hendricks, Stratford ON
 **  Copyright (C) 2013      John Schember <john@nachtimwald.com>
 **  Copyright (C) 2009-2011 Strahinja Markovic  <strahinja.markovic@gmail.com>
 **
@@ -130,6 +130,11 @@ class OPFResource : public XMLResource
      */
     QList<MetaEntry> GetDCMetadata() const;
 
+    /**
+     * Returns list of any Media Overlay Active Class Selctors if defined in OPF metadata
+     */
+    QStringList GetMediaOverlayActiveClassSelectors() const;
+    
     /**
      * Returns the values for a specific dc: metadata name.
      *