Bugfixing: correct handling of optional content

PdfForQtLib/sources/pdfoptionalcontent.cpp

@@ -516,7 +516,17 @@ PDFOptionalContentMembershipObject PDFOptionalContentMembershipObject::create(co
         {
             // First, scan all optional content groups
             PDFDocumentDataLoaderDecorator loader(document);
-            std::vector<PDFObjectReference> ocgs = loader.readReferenceArrayFromDictionary(dictionary, "OCGs");
+            std::vector<PDFObjectReference> ocgs;
+
+            PDFObject singleOCG = dictionary->get("OCGs");
+            if (singleOCG.isReference())
+            {
+                ocgs = { singleOCG.getReference() };
+            }
+            else
+            {
+                ocgs = loader.readReferenceArrayFromDictionary(dictionary, "OCGs");
+            }
 
             if (!ocgs.empty())
             {

PdfForQtLib/sources/pdfpagecontentprocessor.cpp

@@ -2741,29 +2741,29 @@ void PDFPageContentProcessor::operatorPaintXObject(PDFPageContentProcessor::PDFO
 
     if (m_xobjectDictionary)
     {
-        // According to the specification, XObjects are skipped entirely, as no operator was invoked.
-        if (m_xobjectDictionary->hasKey("OC"))
-        {
-            const PDFObject& object = m_xobjectDictionary->get("OC");
-            if (object.isReference())
-            {
-                if (isContentSuppressedByOC(object.getReference()))
-                {
-                    return;
-                }
-            }
-            else
-            {
-                throw PDFRendererException(RenderErrorType::Error, PDFTranslationContext::tr("Reference to optional content expected."));
-            }
-        }
-
         const PDFObject& object = m_document->getObject(m_xobjectDictionary->get(name.name));
         if (object.isStream())
         {
             const PDFStream* stream = object.getStream();
             const PDFDictionary* streamDictionary = stream->getDictionary();
 
+            // According to the specification, XObjects are skipped entirely, as no operator was invoked.
+            if (streamDictionary->hasKey("OC"))
+            {
+                const PDFObject& object = streamDictionary->get("OC");
+                if (object.isReference())
+                {
+                    if (isContentSuppressedByOC(object.getReference()))
+                    {
+                        return;
+                    }
+                }
+                else
+                {
+                    throw PDFRendererException(RenderErrorType::Error, PDFTranslationContext::tr("Reference to optional content expected."));
+                }
+            }
+
             PDFDocumentDataLoaderDecorator loader(m_document);
             QByteArray subtype = loader.readNameFromDictionary(streamDictionary, "Subtype");
             if (subtype == "Image")

PdfForQtLib/sources/pdfpainter.cpp

@@ -413,6 +413,27 @@ void PDFPrecompiledPageGenerator::performImagePainting(const QImage& image)
         return;
     }
 
+    if (isTransparencyGroupActive())
+    {
+        PDFReal alpha = getEffectiveFillingAlpha();
+        if (alpha != 1.0)
+        {
+            // Try to approximate transparency group using alpha channel
+            QImage imageWithAlpha = image;
+            QImage alphaChannel = imageWithAlpha.convertToFormat(QImage::Format_Alpha8);
+            uchar* bits = alphaChannel.bits();
+
+            for (qsizetype i = 0, sizeInBytes = alphaChannel.sizeInBytes(); i < sizeInBytes; ++i)
+            {
+                bits[i] *= alpha;
+            }
+
+            imageWithAlpha.setAlphaChannel(alphaChannel);
+            m_precompiledPage->addImage(imageWithAlpha);
+            return;
+        }
+    }
+
     m_precompiledPage->addImage(image);
 }
 

PdfForQtLib/sources/pdfpainter.h

@@ -72,6 +72,9 @@ protected:
     /// Returns, if feature is turned on
     bool hasFeature(PDFRenderer::Feature feature) const { return m_features.testFlag(feature); }
 
+    /// Is transparency group active?
+    bool isTransparencyGroupActive() const { return !m_transparencyGroupDataStack.empty(); }
+
 private:
     /// Returns current pen (implementation)
     QPen getCurrentPenImpl() const;