tdf#162002 DOCX import, font embed: only discard subset fonts with few glyphs

Commit a9f3c11375525a7708378dd3648febc40db1ad20 (tdf#162002 DOCX import:
ignore subsetted embedded fonts for editing, 2024-07-12) decided to
ignore all subsetted fonts for editing, improve this a little so we only
ignore subsetted fonts when they can't even provide an English alphabet
in any form (lowercase, uppercase).

This avoids the possible problem that a font is marked as subsetted but
it's good enough in practice and we would still throw it away for
editing.

Change-Id: I0bc0e14ffc0c039f029220991bd16d9e3254f059
Reviewed-on: https://gerrit.libreoffice.org/c/core/+/170570
Reviewed-by: Miklos Vajna <vmiklos@collabora.com>
Tested-by: Jenkins

4 files changed, 27 insertions, 9 deletions

diff --git a/sw/qa/writerfilter/dmapper/FontTable.cxx b/sw/qa/writerfilter/dmapper/FontTable.cxx
index 798d68d0a193..2fe3dced2e1f 100644
--- a/sw/qa/writerfilter/dmapper/FontTable.cxx
+++ b/sw/qa/writerfilter/dmapper/FontTable.cxx
@@ -39,6 +39,24 @@ CPPUNIT_TEST_FIXTURE(Test, testSubsettedEmbeddedFont)
     // during editing may be missing from the subsetted font:
     CPPUNIT_ASSERT(aUrl.isEmpty());
 }
+
+CPPUNIT_TEST_FIXTURE(Test, testSubsettedFullEmbeddedFont)
+{
+#if !defined(MACOSX) // FIXME fails on macOS
+    // Given a document with an embedded font (marked as subsetted, but otherwise full in practice),
+    // loaded for editing:
+    loadFromFile(u"subsetted-full-embedded-font.docx");
+
+    // When checking if the font is available:
+    OUString aUrl = EmbeddedFontsHelper::fontFileUrl(
+        u"IBM Plex Serif Light", FAMILY_ROMAN, ITALIC_NONE, WEIGHT_NORMAL, PITCH_VARIABLE,
+        EmbeddedFontsHelper::FontRights::ViewingAllowed);
+
+    // Then make sure the subsetted font is available, given that it has the reasonable amount of
+    // glyphs:
+    CPPUNIT_ASSERT(!aUrl.isEmpty());
+#endif
+}
 }
 
 /* vim:set shiftwidth=4 softtabstop=4 expandtab: */
diff --git a/sw/qa/writerfilter/dmapper/data/subsetted-full-embedded-font.docx b/sw/qa/writerfilter/dmapper/data/subsetted-full-embedded-font.docx
new file mode 100644
index 000000000000..7cdbaf271d6b
--- /dev/null
+++ b/sw/qa/writerfilter/dmapper/data/subsetted-full-embedded-font.docx
diff --git a/sw/source/writerfilter/dmapper/FontTable.cxx b/sw/source/writerfilter/dmapper/FontTable.cxx
index 3262d732e2fb..7cc8a39b3ef1 100644
--- a/sw/source/writerfilter/dmapper/FontTable.cxx
+++ b/sw/source/writerfilter/dmapper/FontTable.cxx
@@ -236,11 +236,13 @@ bool FontTable::IsReadOnly() const
 
 void FontTable::addEmbeddedFont(const css::uno::Reference<css::io::XInputStream>& stream,
                                 const OUString& fontName, std::u16string_view extra,
-                                std::vector<unsigned char> const & key)
+                                std::vector<unsigned char> const & key,
+                                bool bSubsetted)
 {
     if (!m_pImpl->xEmbeddedFontHelper)
         m_pImpl->xEmbeddedFontHelper.reset(new EmbeddedFontsHelper);
-    m_pImpl->xEmbeddedFontHelper->addEmbeddedFont(stream, fontName, extra, key);
+    m_pImpl->xEmbeddedFontHelper->addEmbeddedFont(stream, fontName, extra, key,
+            /*eot=*/false, bSubsetted);
 }
 
 EmbeddedFontHandler::EmbeddedFontHandler(FontTable& rFontTable, OUString _fontName, std::u16string_view style )
@@ -256,11 +258,6 @@ EmbeddedFontHandler::~EmbeddedFontHandler()
     if( !m_inputStream.is())
         return;
 
-    if (m_bSubsetted && !m_fontTable.IsReadOnly())
-    {
-        return;
-    }
-
     std::vector< unsigned char > key( 32 );
     if( !m_fontKey.isEmpty())
     {   // key for unobfuscating
@@ -280,7 +277,9 @@ EmbeddedFontHandler::~EmbeddedFontHandler()
             key[ i + 16 ] = val;
         }
     }
-    m_fontTable.addEmbeddedFont( m_inputStream, m_fontName, m_style, key );
+    // Ignore the "subsetted" flag if we're not editing anyway.
+    bool bSubsetted = m_bSubsetted && !m_fontTable.IsReadOnly();
+    m_fontTable.addEmbeddedFont( m_inputStream, m_fontName, m_style, key, bSubsetted );
     m_inputStream->closeInput();
 }
 
diff --git a/sw/source/writerfilter/dmapper/FontTable.hxx b/sw/source/writerfilter/dmapper/FontTable.hxx
index 9ad092befe79..babb43d8aebb 100644
--- a/sw/source/writerfilter/dmapper/FontTable.hxx
+++ b/sw/source/writerfilter/dmapper/FontTable.hxx
@@ -53,7 +53,8 @@ class FontTable : public LoggedProperties, public LoggedTable
 
     void addEmbeddedFont(const css::uno::Reference<css::io::XInputStream>& stream,
                          const OUString& fontName, std::u16string_view extra,
-                         std::vector<unsigned char> const & key);
+                         std::vector<unsigned char> const & key,
+                         bool bSubsetted);
     bool IsReadOnly() const;
 
  private: