Ability to draw on a page trough page content stream builder

PdfExampleGenerator/main.cpp

@@ -25,4 +25,5 @@ int main(int argc, char *argv[])
     PDFExamplesGenerator::generateAnnotationsExample();
     PDFExamplesGenerator::generatePageBoxesExample();
     PDFExamplesGenerator::generateOutlineExample();
+    PDFExamplesGenerator::generatePageDrawExample();
 }

PdfExampleGenerator/pdfexamplesgenerator.cpp

@@ -358,3 +358,31 @@ void PDFExamplesGenerator::generateOutlineExample()
     pdf::PDFDocumentWriter writer(nullptr);
     writer.write("Ex_Outline.pdf", &document, false);
 }
+
+void PDFExamplesGenerator::generatePageDrawExample()
+{
+    pdf::PDFDocumentBuilder builder;
+    builder.setDocumentTitle("Test document - Page draw");
+    builder.setDocumentAuthor("Jakub Melka");
+    builder.setDocumentCreator(QCoreApplication::applicationName());
+    builder.setDocumentSubject("Testing page draw");
+    builder.setLanguage(QLocale::system());
+
+    QPainter* painter = nullptr;
+    pdf::PDFPageContentStreamBuilder pageContentStreamBuilder(&builder);
+
+    painter = pageContentStreamBuilder.beginNewPage(QRectF(0, 0, 300, 480));
+    painter->drawEllipse(QPointF(150, 240), 65, 25);
+    painter->fillRect(QRectF(0, 0, 50, 50), Qt::green);
+    pageContentStreamBuilder.end(painter);
+
+    painter = pageContentStreamBuilder.beginNewPage(QRectF(0, 0, 300, 480));
+    painter->drawText(QPointF(50, 50), "This is testing text!");
+    pageContentStreamBuilder.end(painter);
+
+    // Write result to a file
+    pdf::PDFDocument document = builder.build();
+    pdf::PDFDocumentWriter writer(nullptr);
+    writer.write("Ex_PageDraw.pdf", &document, false);
+}
+

PdfExampleGenerator/pdfexamplesgenerator.h

@@ -26,6 +26,7 @@ public:
     static void generateAnnotationsExample();
     static void generatePageBoxesExample();
     static void generateOutlineExample();
+    static void generatePageDrawExample();
 };
 
 #endif // PDFEXAMPLESGENERATOR_H

PdfForQtLib/sources/pdfdocumentbuilder.cpp

@@ -666,6 +666,82 @@ std::array<PDFReal, 4> PDFDocumentBuilder::getAnnotationReductionRectangle(const
     return { qAbs(innerRect.left() - boundingRect.left()), qAbs(boundingRect.bottom() - innerRect.bottom()), qAbs(boundingRect.right() - innerRect.right()), qAbs(boundingRect.top() - innerRect.top()) };
 }
 
+PDFPageContentStreamBuilder::PDFPageContentStreamBuilder(PDFDocumentBuilder* builder) :
+    m_documentBuilder(builder),
+    m_contentStreamBuilder(nullptr)
+{
+
+}
+
+QPainter* PDFPageContentStreamBuilder::begin(PDFObjectReference page)
+{
+    if (m_contentStreamBuilder)
+    {
+        // Invalid call to begin function
+        return nullptr;
+    }
+
+    const PDFObjectStorage* storage = m_documentBuilder->getStorage();
+    const PDFDictionary* pageDictionary = storage->getDictionaryFromObject(storage->getObject(page));
+    if (!pageDictionary)
+    {
+        return nullptr;
+    }
+
+    PDFDocumentDataLoaderDecorator loader(storage);
+    QRectF mediaBox = loader.readRectangle(pageDictionary->get("MediaBox"), QRectF());
+    if (!mediaBox.isValid())
+    {
+        return nullptr;
+    }
+
+    m_pageReference = page;
+    m_contentStreamBuilder = new PDFContentStreamBuilder(mediaBox.size(), PDFContentStreamBuilder::CoordinateSystem::Qt);
+    return m_contentStreamBuilder->begin();
+}
+
+QPainter* PDFPageContentStreamBuilder::beginNewPage(QRectF mediaBox)
+{
+    return begin(m_documentBuilder->appendPage(mediaBox));
+}
+
+void PDFPageContentStreamBuilder::end(QPainter* painter)
+{
+    if (!m_contentStreamBuilder)
+    {
+        return;
+    }
+
+    PDFContentStreamBuilder::ContentStream contentStream = m_contentStreamBuilder->end(painter);
+
+    delete m_contentStreamBuilder;
+    m_contentStreamBuilder = nullptr;
+
+    // Update page's content stream
+
+    std::vector<PDFObject> copiedObjects = m_documentBuilder->copyFrom({ contentStream.resources, contentStream.contents }, contentStream.document.getStorage(), true);
+    Q_ASSERT(copiedObjects.size() == 2);
+
+    PDFObjectReference resourcesReference = copiedObjects[0].getReference();
+    PDFObjectReference contentsReference = copiedObjects[1].getReference();
+
+    PDFObjectFactory pageUpdateFactory;
+
+    pageUpdateFactory.beginDictionary();
+
+    pageUpdateFactory.beginDictionaryItem("Contents");
+    pageUpdateFactory << contentsReference;
+    pageUpdateFactory.endDictionaryItem();
+
+    pageUpdateFactory.beginDictionaryItem("Resources");
+    pageUpdateFactory << resourcesReference;
+    pageUpdateFactory.endDictionaryItem();
+
+    pageUpdateFactory.endDictionary();
+
+    m_documentBuilder->mergeTo(m_pageReference, pageUpdateFactory.takeObject());
+}
+
 void PDFDocumentBuilder::updateAnnotationAppearanceStreams(PDFObjectReference annotationReference)
 {
     PDFAnnotationPtr annotation = PDFAnnotation::parse(&m_storage, annotationReference);
@@ -4436,7 +4512,6 @@ void PDFDocumentBuilder::updateTrailerDictionary(PDFInteger objectCount)
     updateDocumentInfo(qMove(updatedInfoDictionary));
 }
 
-
 /* END GENERATED CODE */
 
 }   // namespace pdf

PdfForQtLib/sources/pdfdocumentbuilder.h

@@ -246,6 +246,41 @@ private:
     QPainter* m_painter;
 };
 
+/// This class can create page content streams, using the Qt's QPainter
+/// to draw graphics elements on it. Content stream can have various
+/// resources, which can, if selected be dereferenced, so content
+/// stream is encapsulated and doesn't contain references.
+class PDFFORQTLIBSHARED_EXPORT PDFPageContentStreamBuilder
+{
+public:
+    PDFPageContentStreamBuilder(PDFDocumentBuilder* builder);
+
+    /// Starts painting onto the page. Old page content is erased. This
+    /// function returns painter, onto which can be graphics drawn. Painter
+    /// uses Qt's coordinate system. Calling begin multiple times, without
+    /// subsequent calls to end function, is invalid and can result
+    /// in undefined behaviour. This function can return nullptr,
+    /// if error occurs.
+    /// \param page Page, onto which we want to draw
+    QPainter* begin(PDFObjectReference page);
+
+    /// This function is similar to function \p begin(), but it appends
+    /// a new page to the end of the document.
+    /// \param mediaBox Page's media box
+    QPainter* beginNewPage(QRectF mediaBox);
+
+    /// Finishes painting on a page content stream. This function updates
+    /// page content stream, which is associated with this page. This function
+    /// must be called with painter, which has been returned with call to begin function.
+    /// \param painter Painter, which was returned with function begin()
+    void end(QPainter* painter);
+
+private:
+    PDFDocumentBuilder* m_documentBuilder;
+    PDFContentStreamBuilder* m_contentStreamBuilder;
+    PDFObjectReference m_pageReference;
+};
+
 class PDFFORQTLIBSHARED_EXPORT PDFDocumentBuilder
 {
 public: