tdf#50879 PDF export: ensure only built-in fonts are used for forms

Alternative would be to embed the whole font, which is unusual: PDF
typically just embeds the used subset.

Change-Id: Ic0b7e121b3ae38804c1a396ea36104ebcc0b9588
Reviewed-on: https://gerrit.libreoffice.org/c/core/+/99032
Reviewed-by: Miklos Vajna <vmiklos@collabora.com>
Tested-by: Jenkins

3 files changed, 56 insertions, 3 deletions

diff --git a/vcl/qa/cppunit/pdfexport/data/form-font-name.odt b/vcl/qa/cppunit/pdfexport/data/form-font-name.odt
new file mode 100644
index 000000000000..a7430c9a8a6e
--- /dev/null
+++ b/vcl/qa/cppunit/pdfexport/data/form-font-name.odt
diff --git a/vcl/qa/cppunit/pdfexport/pdfexport.cxx b/vcl/qa/cppunit/pdfexport/pdfexport.cxx
index dc6c01fcf719..607d89f8b630 100644
--- a/vcl/qa/cppunit/pdfexport/pdfexport.cxx
+++ b/vcl/qa/cppunit/pdfexport/pdfexport.cxx
@@ -130,6 +130,7 @@ public:
     void testVersion15();
     void testDefaultVersion();
     void testMultiPagePDF();
+    void testFormFontName();
 
 
     CPPUNIT_TEST_SUITE(PdfExportTest);
@@ -175,6 +176,7 @@ public:
     CPPUNIT_TEST(testVersion15);
     CPPUNIT_TEST(testDefaultVersion);
     CPPUNIT_TEST(testMultiPagePDF);
+    CPPUNIT_TEST(testFormFontName);
     CPPUNIT_TEST_SUITE_END();
 };
 
@@ -2264,6 +2266,50 @@ void PdfExportTest::testMultiPagePDF()
 #endif
 }
 
+void PdfExportTest::testFormFontName()
+{
+    // Import the bugdoc and export as PDF.
+    OUString aURL = m_directories.getURLFromSrc(DATA_DIRECTORY) + "form-font-name.odt";
+    mxComponent = loadFromDesktop(aURL);
+
+    uno::Reference<frame::XStorable> xStorable(mxComponent, uno::UNO_QUERY);
+    utl::MediaDescriptor aMediaDescriptor;
+    aMediaDescriptor["FilterName"] <<= OUString("writer_pdf_Export");
+    xStorable->storeToURL(maTempFile.GetURL(), aMediaDescriptor.getAsConstPropertyValueList());
+
+    // Parse the export result with pdfium.
+    SvFileStream aFile(maTempFile.GetURL(), StreamMode::READ);
+    SvMemoryStream aMemory;
+    aMemory.WriteStream(aFile);
+    ScopedFPDFDocument pPdfDocument(
+        FPDF_LoadMemDocument(aMemory.GetData(), aMemory.GetSize(), /*password=*/nullptr));
+    CPPUNIT_ASSERT(pPdfDocument);
+
+    // The document has one page.
+    CPPUNIT_ASSERT_EQUAL(1, FPDF_GetPageCount(pPdfDocument.get()));
+    ScopedFPDFPage pPdfPage(FPDF_LoadPage(pPdfDocument.get(), /*page_index=*/0));
+    CPPUNIT_ASSERT(pPdfPage);
+
+    // The page has one annotation.
+    CPPUNIT_ASSERT_EQUAL(1, FPDFPage_GetAnnotCount(pPdfPage.get()));
+    ScopedFPDFAnnotation pAnnot(FPDFPage_GetAnnot(pPdfPage.get(), 0));
+
+    // Examine the default appearance.
+    CPPUNIT_ASSERT(FPDFAnnot_HasKey(pAnnot.get(), "DA"));
+    CPPUNIT_ASSERT_EQUAL(FPDF_OBJECT_STRING, FPDFAnnot_GetValueType(pAnnot.get(), "DA"));
+    size_t nDALength = FPDFAnnot_GetStringValue(pAnnot.get(), "DA", nullptr, 0);
+    std::vector<FPDF_WCHAR> aDABuf(nDALength);
+    FPDFAnnot_GetStringValue(pAnnot.get(), "DA", aDABuf.data(), nDALength);
+    OUString aDA(reinterpret_cast<sal_Unicode*>(aDABuf.data()));
+
+    // Without the accompanying fix in place, this test would have failed with:
+    // - Expected: 0 0 0 rg /TiRo 12 Tf
+    // - Actual  : 0 0 0 rg /F2 12 Tf
+    // i.e. Liberation Serif was exposed as a form font as-is, without picking the closest built-in
+    // font.
+    CPPUNIT_ASSERT_EQUAL(OUString("0 0 0 rg /TiRo 12 Tf"), aDA);
+}
+
 CPPUNIT_TEST_SUITE_REGISTRATION(PdfExportTest);
 
 }
diff --git a/vcl/source/gdi/pdfwriter_impl.cxx b/vcl/source/gdi/pdfwriter_impl.cxx
index 686635b5b5dc..e40cc7c00872 100644
--- a/vcl/source/gdi/pdfwriter_impl.cxx
+++ b/vcl/source/gdi/pdfwriter_impl.cxx
@@ -3602,6 +3602,13 @@ Font PDFWriterImpl::replaceFont( const vcl::Font& rControlFont, const vcl::Font&
 sal_Int32 PDFWriterImpl::getBestBuildinFont( const vcl::Font& rFont )
 {
     sal_Int32 nBest = 4; // default to Helvetica
+
+    if (rFont.GetFamilyType() == FAMILY_ROMAN)
+    {
+        // Serif: default to Times-Roman.
+        nBest = 8;
+    }
+
     OUString aFontName( rFont.GetFamilyName() );
     aFontName = aFontName.toAsciiLowerCase();
 
@@ -3748,14 +3755,14 @@ void PDFWriterImpl::createDefaultEditAppearance( PDFWidget& rEdit, const PDFWrit
 
     // prepare font to use, draw field border
     Font aFont = drawFieldBorder( rEdit, rWidget, rSettings );
-    sal_Int32 nBest = getSystemFont( aFont );
+    // Get the built-in font which is closest to aFont.
+    sal_Int32 nBest = getBestBuildinFont(aFont);
 
     // prepare DA string
     OStringBuffer aDA( 32 );
     appendNonStrokingColor( replaceColor( rWidget.TextColor, rSettings.GetFieldTextColor() ), aDA );
     aDA.append( ' ' );
-    aDA.append( "/F" );
-    aDA.append( nBest );
+    aDA.append(pdf::BuildinFontFace::Get(nBest).getNameObject());
 
     OStringBuffer aDR( 32 );
     aDR.append( "/Font " );