mirror of
https://github.com/JakubMelka/PDF4QT.git
synced 2025-06-05 21:59:17 +02:00
Document content flow basics
This commit is contained in:
Jakub Melka
@ -26,6 +26,483 @@
|
||||
namespace pdf
|
||||
{
|
||||
|
||||
|
||||
class PDFStructureTreeReferenceCollector : public PDFStructureTreeAbstractVisitor
|
||||
{
|
||||
public:
|
||||
explicit inline PDFStructureTreeReferenceCollector(std::map<PDFObjectReference, const PDFStructureItem*>* mapping) :
|
||||
m_mapping(mapping)
|
||||
{
|
||||
|
||||
}
|
||||
|
||||
virtual void visitStructureTree(const PDFStructureTree* structureTree) override;
|
||||
virtual void visitStructureElement(const PDFStructureElement* structureElement) override;
|
||||
virtual void visitStructureMarkedContentReference(const PDFStructureMarkedContentReference* structureMarkedContentReference) override;
|
||||
virtual void visitStructureObjectReference(const PDFStructureObjectReference* structureObjectReference) override;
|
||||
|
||||
private:
|
||||
void addReference(const PDFStructureItem* structureObjectReference);
|
||||
|
||||
std::map<PDFObjectReference, const PDFStructureItem*>* m_mapping;
|
||||
};
|
||||
|
||||
void PDFStructureTreeReferenceCollector::visitStructureTree(const PDFStructureTree* structureTree)
|
||||
{
|
||||
addReference(structureTree);
|
||||
acceptChildren(structureTree);
|
||||
}
|
||||
|
||||
void PDFStructureTreeReferenceCollector::visitStructureElement(const PDFStructureElement* structureElement)
|
||||
{
|
||||
addReference(structureElement);
|
||||
acceptChildren(structureElement);
|
||||
}
|
||||
|
||||
void PDFStructureTreeReferenceCollector::visitStructureMarkedContentReference(const PDFStructureMarkedContentReference* structureMarkedContentReference)
|
||||
{
|
||||
addReference(structureMarkedContentReference);
|
||||
acceptChildren(structureMarkedContentReference);
|
||||
}
|
||||
|
||||
void PDFStructureTreeReferenceCollector::visitStructureObjectReference(const PDFStructureObjectReference* structureObjectReference)
|
||||
{
|
||||
addReference(structureObjectReference);
|
||||
acceptChildren(structureObjectReference);
|
||||
}
|
||||
|
||||
void PDFStructureTreeReferenceCollector::addReference(const PDFStructureItem* structureItem)
|
||||
{
|
||||
if (structureItem->getSelfReference().isValid())
|
||||
{
|
||||
(*m_mapping)[structureItem->getSelfReference()] = structureItem;
|
||||
}
|
||||
}
|
||||
|
||||
struct PDFStructureTreeTextItem
|
||||
{
|
||||
enum class Type
|
||||
{
|
||||
StartTag,
|
||||
EndTag,
|
||||
Text
|
||||
};
|
||||
|
||||
PDFStructureTreeTextItem() = default;
|
||||
PDFStructureTreeTextItem(Type type, const PDFStructureItem* item, QString text) :
|
||||
type(type), item(item), text(qMove(text))
|
||||
{
|
||||
|
||||
}
|
||||
|
||||
static PDFStructureTreeTextItem createText(QString text) { return PDFStructureTreeTextItem(Type::Text, nullptr, qMove(text)); }
|
||||
static PDFStructureTreeTextItem createStartTag(const PDFStructureItem* item) { return PDFStructureTreeTextItem(Type::StartTag, item, QString()); }
|
||||
static PDFStructureTreeTextItem createEndTag(const PDFStructureItem* item) { return PDFStructureTreeTextItem(Type::EndTag, item, QString()); }
|
||||
|
||||
Type type = Type::Text;
|
||||
const PDFStructureItem* item = nullptr;
|
||||
QString text;
|
||||
};
|
||||
|
||||
using PDFStructureTreeTextSequence = std::vector<PDFStructureTreeTextItem>;
|
||||
|
||||
/// Text extractor for structure tree. Extracts sequences of structure items,
|
||||
/// page sequences are stored in \p textSequences. They can be accessed using
|
||||
/// getters.
|
||||
class PDFStructureTreeTextExtractor
|
||||
{
|
||||
public:
|
||||
enum Option
|
||||
{
|
||||
None = 0x0000,
|
||||
SkipArtifact = 0x0001, ///< Skip content marked as 'Artifact'
|
||||
AdjustReversedText = 0x0002, ///< Adjust reversed text
|
||||
CreateTreeMapping = 0x0004, ///< Create text mapping to structure tree item
|
||||
};
|
||||
Q_DECLARE_FLAGS(Options, Option)
|
||||
|
||||
explicit PDFStructureTreeTextExtractor(const PDFDocument* document, const PDFStructureTree* tree, Options options);
|
||||
|
||||
/// Performs text extracting algorithm. Only \p pageIndices
|
||||
/// pages are processed for text extraction.
|
||||
/// \param pageIndices Page indices
|
||||
void perform(const std::vector<PDFInteger>& pageIndices);
|
||||
|
||||
/// Returns a list of errors/warnings
|
||||
const QList<PDFRenderError>& getErrors() const { return m_errors; }
|
||||
|
||||
/// Returns a list of unmatched text
|
||||
const QStringList& getUnmatchedText() const { return m_unmatchedText; }
|
||||
|
||||
/// Returns text sequence for given page. If page number is invalid,
|
||||
/// then empty text sequence is returned.
|
||||
/// \param pageNumber Page number
|
||||
const PDFStructureTreeTextSequence& getTextSequence(PDFInteger pageNumber) const;
|
||||
|
||||
/// Returns text for given structure tree item. If structure tree item
|
||||
/// is not found, then empty list is returned. This functionality
|
||||
/// requires, that \p CreateTreeMapping flag is being set.
|
||||
/// \param item Item
|
||||
const QStringList& getText(const PDFStructureItem* item) const;
|
||||
|
||||
private:
|
||||
QList<PDFRenderError> m_errors;
|
||||
const PDFDocument* m_document;
|
||||
const PDFStructureTree* m_tree;
|
||||
QStringList m_unmatchedText;
|
||||
std::map<PDFInteger, PDFStructureTreeTextSequence> m_textSequences;
|
||||
std::map<const PDFStructureItem*, QStringList> m_textForItems;
|
||||
Options m_options;
|
||||
};
|
||||
|
||||
Q_DECLARE_OPERATORS_FOR_FLAGS(PDFStructureTreeTextExtractor::Options)
|
||||
|
||||
class PDFStructureTreeTextContentProcessor : public PDFPageContentProcessor
|
||||
{
|
||||
using BaseClass = PDFPageContentProcessor;
|
||||
|
||||
public:
|
||||
explicit PDFStructureTreeTextContentProcessor(PDFRenderer::Features features,
|
||||
const PDFPage* page,
|
||||
const PDFDocument* document,
|
||||
const PDFFontCache* fontCache,
|
||||
const PDFCMS* cms,
|
||||
const PDFOptionalContentActivity* optionalContentActivity,
|
||||
QMatrix pagePointToDevicePointMatrix,
|
||||
const PDFMeshQualitySettings& meshQualitySettings,
|
||||
const PDFStructureTree* tree,
|
||||
const std::map<PDFObjectReference, const PDFStructureItem*>* mapping) :
|
||||
BaseClass(page, document, fontCache, cms, optionalContentActivity, pagePointToDevicePointMatrix, meshQualitySettings),
|
||||
m_features(features),
|
||||
m_tree(tree),
|
||||
m_mapping(mapping)
|
||||
{
|
||||
|
||||
}
|
||||
|
||||
PDFStructureTreeTextSequence& takeSequence() { return m_textSequence; }
|
||||
QStringList& takeUnmatchedTexts() { return m_unmatchedText; }
|
||||
|
||||
protected:
|
||||
virtual bool isContentSuppressedByOC(PDFObjectReference ocgOrOcmd) override;
|
||||
virtual bool isContentKindSuppressed(ContentKind kind) const override;
|
||||
virtual void performOutputCharacter(const PDFTextCharacterInfo& info) override;
|
||||
virtual void performMarkedContentBegin(const QByteArray& tag, const PDFObject& properties) override;
|
||||
virtual void performMarkedContentEnd() override;
|
||||
|
||||
private:
|
||||
const PDFStructureItem* getStructureTreeItemFromMCID(PDFInteger mcid) const;
|
||||
void finishText();
|
||||
|
||||
struct MarkedContentInfo
|
||||
{
|
||||
QByteArray tag;
|
||||
PDFInteger mcid = -1;
|
||||
const PDFStructureItem* structureTreeItem = nullptr;
|
||||
};
|
||||
|
||||
PDFRenderer::Features m_features;
|
||||
const PDFStructureTree* m_tree;
|
||||
const std::map<PDFObjectReference, const PDFStructureItem*>* m_mapping;
|
||||
std::vector<MarkedContentInfo> m_markedContentInfoStack;
|
||||
QString m_currentText;
|
||||
PDFStructureTreeTextSequence m_textSequence;
|
||||
QStringList m_unmatchedText;
|
||||
};
|
||||
|
||||
void PDFStructureTreeTextContentProcessor::finishText()
|
||||
{
|
||||
m_currentText = m_currentText.trimmed();
|
||||
if (!m_currentText.isEmpty())
|
||||
{
|
||||
m_textSequence.emplace_back(PDFStructureTreeTextItem::createText(qMove(m_currentText)));
|
||||
}
|
||||
m_currentText = QString();
|
||||
}
|
||||
|
||||
void PDFStructureTreeTextContentProcessor::performMarkedContentBegin(const QByteArray& tag, const PDFObject& properties)
|
||||
{
|
||||
MarkedContentInfo info;
|
||||
info.tag = tag;
|
||||
|
||||
if (properties.isDictionary())
|
||||
{
|
||||
const PDFDictionary* dictionary = properties.getDictionary();
|
||||
PDFObject mcid = dictionary->get("MCID");
|
||||
if (mcid.isInt())
|
||||
{
|
||||
// We must finish text, because we can have a sequence of text,
|
||||
// then subitem, then text, and followed by another subitem. They
|
||||
// can be interleaved.
|
||||
finishText();
|
||||
|
||||
info.mcid = mcid.getInteger();
|
||||
info.structureTreeItem = getStructureTreeItemFromMCID(info.mcid);
|
||||
|
||||
if (!info.structureTreeItem)
|
||||
{
|
||||
reportRenderError(RenderErrorType::Error, PDFTranslationContext::tr("Structure tree item for MCID %1 not found.").arg(info.mcid));
|
||||
}
|
||||
|
||||
if (info.structureTreeItem)
|
||||
{
|
||||
m_textSequence.emplace_back(PDFStructureTreeTextItem::createStartTag(info.structureTreeItem));
|
||||
}
|
||||
}
|
||||
}
|
||||
|
||||
m_markedContentInfoStack.emplace_back(qMove(info));
|
||||
}
|
||||
|
||||
void PDFStructureTreeTextContentProcessor::performMarkedContentEnd()
|
||||
{
|
||||
MarkedContentInfo info = qMove(m_markedContentInfoStack.back());
|
||||
m_markedContentInfoStack.pop_back();
|
||||
|
||||
if (info.mcid != -1)
|
||||
{
|
||||
finishText();
|
||||
if (info.structureTreeItem)
|
||||
{
|
||||
m_textSequence.emplace_back(PDFStructureTreeTextItem::createEndTag(info.structureTreeItem));
|
||||
}
|
||||
}
|
||||
|
||||
// Check for text, which doesn't belong to any structure tree item
|
||||
if (m_markedContentInfoStack.empty())
|
||||
{
|
||||
m_currentText = m_currentText.trimmed();
|
||||
if (!m_currentText.isEmpty())
|
||||
{
|
||||
m_unmatchedText << qMove(m_currentText);
|
||||
}
|
||||
}
|
||||
}
|
||||
|
||||
const PDFStructureItem* PDFStructureTreeTextContentProcessor::getStructureTreeItemFromMCID(PDFInteger mcid) const
|
||||
{
|
||||
auto it = m_mapping->find(m_tree->getParent(getStructuralParentKey(), mcid));
|
||||
if (it != m_mapping->cend())
|
||||
{
|
||||
return it->second;
|
||||
}
|
||||
return nullptr;
|
||||
}
|
||||
|
||||
bool PDFStructureTreeTextContentProcessor::isContentSuppressedByOC(PDFObjectReference ocgOrOcmd)
|
||||
{
|
||||
if (m_features.testFlag(PDFRenderer::IgnoreOptionalContent))
|
||||
{
|
||||
return false;
|
||||
}
|
||||
|
||||
return PDFPageContentProcessor::isContentSuppressedByOC(ocgOrOcmd);
|
||||
}
|
||||
|
||||
bool PDFStructureTreeTextContentProcessor::isContentKindSuppressed(ContentKind kind) const
|
||||
{
|
||||
switch (kind)
|
||||
{
|
||||
case ContentKind::Shapes:
|
||||
case ContentKind::Text:
|
||||
case ContentKind::Images:
|
||||
case ContentKind::Shading:
|
||||
return true;
|
||||
|
||||
case ContentKind::Tiling:
|
||||
return false; // Tiling can have text
|
||||
|
||||
default:
|
||||
{
|
||||
Q_ASSERT(false);
|
||||
break;
|
||||
}
|
||||
}
|
||||
|
||||
return false;
|
||||
}
|
||||
|
||||
void PDFStructureTreeTextContentProcessor::performOutputCharacter(const PDFTextCharacterInfo& info)
|
||||
{
|
||||
if (!isContentSuppressed())
|
||||
{
|
||||
if (!info.character.isNull())
|
||||
{
|
||||
m_currentText.push_back(info.character);
|
||||
}
|
||||
}
|
||||
}
|
||||
|
||||
PDFStructureTreeTextExtractor::PDFStructureTreeTextExtractor(const PDFDocument* document, const PDFStructureTree* tree, Options options) :
|
||||
m_document(document),
|
||||
m_tree(tree),
|
||||
m_options(options)
|
||||
{
|
||||
|
||||
}
|
||||
|
||||
void PDFStructureTreeTextExtractor::perform(const std::vector<PDFInteger>& pageIndices)
|
||||
{
|
||||
std::map<PDFObjectReference, const PDFStructureItem*> mapping;
|
||||
PDFStructureTreeReferenceCollector referenceCollector(&mapping);
|
||||
m_tree->accept(&referenceCollector);
|
||||
|
||||
PDFFontCache fontCache(DEFAULT_FONT_CACHE_LIMIT, DEFAULT_REALIZED_FONT_CACHE_LIMIT);
|
||||
|
||||
QMutex mutex;
|
||||
PDFCMSGeneric cms;
|
||||
PDFMeshQualitySettings mqs;
|
||||
PDFOptionalContentActivity oca(m_document, OCUsage::Export, nullptr);
|
||||
pdf::PDFModifiedDocument md(const_cast<PDFDocument*>(m_document), &oca);
|
||||
fontCache.setDocument(md);
|
||||
fontCache.setCacheShrinkEnabled(nullptr, false);
|
||||
|
||||
auto generateTextLayout = [&, this](PDFInteger pageIndex)
|
||||
{
|
||||
const PDFCatalog* catalog = m_document->getCatalog();
|
||||
if (!catalog->getPage(pageIndex))
|
||||
{
|
||||
// Invalid page index
|
||||
return;
|
||||
}
|
||||
|
||||
const PDFPage* page = catalog->getPage(pageIndex);
|
||||
Q_ASSERT(page);
|
||||
|
||||
PDFStructureTreeTextContentProcessor processor(PDFRenderer::IgnoreOptionalContent, page, m_document, &fontCache, &cms, &oca, QMatrix(), mqs, m_tree, &mapping);
|
||||
QList<PDFRenderError> errors = processor.processContents();
|
||||
|
||||
QMutexLocker lock(&mutex);
|
||||
m_textSequences[pageIndex] = qMove(processor.takeSequence());
|
||||
m_unmatchedText << qMove(processor.takeUnmatchedTexts());
|
||||
m_errors.append(qMove(errors));
|
||||
};
|
||||
|
||||
PDFExecutionPolicy::execute(PDFExecutionPolicy::Scope::Page, pageIndices.begin(), pageIndices.end(), generateTextLayout);
|
||||
|
||||
fontCache.setCacheShrinkEnabled(nullptr, true);
|
||||
|
||||
if (m_options.testFlag(CreateTreeMapping))
|
||||
{
|
||||
for (const auto& sequence : m_textSequences)
|
||||
{
|
||||
std::stack<const PDFStructureItem*> stack;
|
||||
for (const PDFStructureTreeTextItem& sequenceItem : sequence.second)
|
||||
{
|
||||
switch (sequenceItem.type)
|
||||
{
|
||||
case PDFStructureTreeTextItem::Type::StartTag:
|
||||
stack.push(sequenceItem.item);
|
||||
break;
|
||||
case PDFStructureTreeTextItem::Type::EndTag:
|
||||
stack.pop();
|
||||
break;
|
||||
case PDFStructureTreeTextItem::Type::Text:
|
||||
if (!stack.empty())
|
||||
{
|
||||
m_textForItems[stack.top()] << sequenceItem.text;
|
||||
}
|
||||
break;
|
||||
}
|
||||
}
|
||||
}
|
||||
}
|
||||
}
|
||||
|
||||
const PDFStructureTreeTextSequence& PDFStructureTreeTextExtractor::getTextSequence(PDFInteger pageIndex) const
|
||||
{
|
||||
auto it = m_textSequences.find(pageIndex);
|
||||
if (it != m_textSequences.cend())
|
||||
{
|
||||
return it->second;
|
||||
}
|
||||
|
||||
static PDFStructureTreeTextSequence dummy;
|
||||
return dummy;
|
||||
}
|
||||
|
||||
const QStringList& PDFStructureTreeTextExtractor::getText(const PDFStructureItem* item) const
|
||||
{
|
||||
auto it = m_textForItems.find(item);
|
||||
if (it != m_textForItems.cend())
|
||||
{
|
||||
return it->second;
|
||||
}
|
||||
|
||||
static const QStringList dummy;
|
||||
return dummy;
|
||||
}
|
||||
|
||||
|
||||
class PDFStructureTreeTextFlowCollector : public PDFStructureTreeAbstractVisitor
|
||||
{
|
||||
public:
|
||||
explicit PDFStructureTreeTextFlowCollector(PDFDocumentTextFlow::Items* items, const PDFStructureTreeTextExtractor* extractor) :
|
||||
m_items(items),
|
||||
m_extractor(extractor)
|
||||
{
|
||||
|
||||
}
|
||||
|
||||
virtual void visitStructureTree(const PDFStructureTree* structureTree) override;
|
||||
virtual void visitStructureElement(const PDFStructureElement* structureElement) override;
|
||||
virtual void visitStructureMarkedContentReference(const PDFStructureMarkedContentReference* structureMarkedContentReference) override;
|
||||
virtual void visitStructureObjectReference(const PDFStructureObjectReference* structureObjectReference) override;
|
||||
|
||||
private:
|
||||
PDFDocumentTextFlow::Items* m_items;
|
||||
const PDFStructureTreeTextExtractor* m_extractor;
|
||||
std::vector<bool> m_hasContentStack;
|
||||
};
|
||||
|
||||
void PDFStructureTreeTextFlowCollector::visitStructureTree(const PDFStructureTree* structureTree)
|
||||
{
|
||||
m_items->push_back(PDFDocumentTextFlow::Item{PDFDocumentTextFlow::StructureItemStart, -1, QString()});
|
||||
acceptChildren(structureTree);
|
||||
m_items->push_back(PDFDocumentTextFlow::Item{PDFDocumentTextFlow::StructureItemEnd, -1, QString()});
|
||||
}
|
||||
|
||||
void PDFStructureTreeTextFlowCollector::visitStructureElement(const PDFStructureElement* structureElement)
|
||||
{
|
||||
size_t index = m_items->size();
|
||||
m_items->push_back(PDFDocumentTextFlow::Item{PDFDocumentTextFlow::StructureItemStart, -1, QString()});
|
||||
|
||||
// Mark stack so we can delete unused items
|
||||
m_hasContentStack.push_back(false);
|
||||
|
||||
for (const QString& string : m_extractor->getText(structureElement))
|
||||
{
|
||||
for (size_t i = 0; i < m_hasContentStack.size(); ++i)
|
||||
{
|
||||
m_hasContentStack[i] = true;
|
||||
}
|
||||
m_items->push_back(PDFDocumentTextFlow::Item{PDFDocumentTextFlow::Text, -1, string});
|
||||
}
|
||||
|
||||
acceptChildren(structureElement);
|
||||
|
||||
const bool hasContent = m_hasContentStack.back();
|
||||
m_hasContentStack.pop_back();
|
||||
|
||||
m_items->push_back(PDFDocumentTextFlow::Item{PDFDocumentTextFlow::StructureItemEnd, -1, QString()});
|
||||
|
||||
if (!hasContent)
|
||||
{
|
||||
// Delete unused content
|
||||
m_items->erase(std::next(m_items->begin(), index), m_items->end());
|
||||
}
|
||||
}
|
||||
|
||||
void PDFStructureTreeTextFlowCollector::visitStructureMarkedContentReference(const PDFStructureMarkedContentReference* structureMarkedContentReference)
|
||||
{
|
||||
acceptChildren(structureMarkedContentReference);
|
||||
}
|
||||
|
||||
void PDFStructureTreeTextFlowCollector::visitStructureObjectReference(const PDFStructureObjectReference* structureObjectReference)
|
||||
{
|
||||
acceptChildren(structureObjectReference);
|
||||
}
|
||||
|
||||
PDFDocumentTextFlow PDFDocumentTextFlowFactory::create(const PDFDocument* document, const std::vector<PDFInteger>& pageIndices, Algorithm algorithm)
|
||||
{
|
||||
PDFDocumentTextFlow result;
|
||||
@ -121,9 +598,39 @@ PDFDocumentTextFlow PDFDocumentTextFlowFactory::create(const PDFDocument* docume
|
||||
break;
|
||||
}
|
||||
|
||||
PDFStructureTreeTextExtractor extractor(document, &structureTree);
|
||||
PDFStructureTreeTextExtractor extractor(document, &structureTree, PDFStructureTreeTextExtractor::SkipArtifact | PDFStructureTreeTextExtractor::AdjustReversedText | PDFStructureTreeTextExtractor::CreateTreeMapping);
|
||||
extractor.perform(pageIndices);
|
||||
|
||||
PDFDocumentTextFlow::Items flowItems;
|
||||
PDFStructureTreeTextFlowCollector collector(&flowItems, &extractor);
|
||||
structureTree.accept(&collector);
|
||||
|
||||
result = PDFDocumentTextFlow(qMove(flowItems));
|
||||
m_errors.append(extractor.getErrors());
|
||||
break;
|
||||
}
|
||||
|
||||
case Algorithm::Content:
|
||||
{
|
||||
PDFStructureTreeTextExtractor extractor(document, &structureTree, PDFStructureTreeTextExtractor::None);
|
||||
extractor.perform(pageIndices);
|
||||
|
||||
PDFDocumentTextFlow::Items flowItems;
|
||||
for (PDFInteger pageIndex : pageIndices)
|
||||
{
|
||||
flowItems.emplace_back(PDFDocumentTextFlow::Item{ PDFDocumentTextFlow::PageStart, pageIndex, PDFTranslationContext::tr("Page %1").arg(pageIndex + 1) });
|
||||
for (const PDFStructureTreeTextItem& sequenceItem : extractor.getTextSequence(pageIndex))
|
||||
{
|
||||
if (sequenceItem.type == PDFStructureTreeTextItem::Type::Text)
|
||||
{
|
||||
flowItems.emplace_back(PDFDocumentTextFlow::Item{ PDFDocumentTextFlow::Text, pageIndex, sequenceItem.text });
|
||||
}
|
||||
}
|
||||
flowItems.emplace_back(PDFDocumentTextFlow::Item{ PDFDocumentTextFlow::PageEnd, pageIndex, QString() });
|
||||
}
|
||||
|
||||
result = PDFDocumentTextFlow(qMove(flowItems));
|
||||
m_errors.append(extractor.getErrors());
|
||||
break;
|
||||
}
|
||||
|
||||
|
||||
Reference in New Issue
Block a user