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DocDiff application: detect moved pages

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This commit is contained in:
Jakub Melka
2021-09-19 19:46:02 +02:00
parent 3e327f8201
commit c00939f536
6 changed files with 186 additions and 6 deletions
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75
Pdf4QtLib/sources/pdfdiff.cpp
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@ -198,11 +198,13 @@ struct PDFDiffPageContext
PDFInteger pageIndex = 0;
std::array<uint8_t, 64> pageHash = { };
PDFPrecompiledPage::GraphicPieceInfos graphicPieces;
PDFDocumentTextFlow text;
};
void PDFDiff::performPageMatching(const std::vector<PDFDiffPageContext>& leftPreparedPages,
const std::vector<PDFDiffPageContext>& rightPreparedPages,
PDFAlgorithmLongestCommonSubsequenceBase::Sequence& pageSequence)
PDFAlgorithmLongestCommonSubsequenceBase::Sequence& pageSequence,
std::map<size_t, size_t>& pageMatches)
{
// Match pages. We will use following algorithm: exact solution can fail, because
// we are using hashes and due to numerical instability, hashes can be different
@ -210,7 +212,6 @@ void PDFDiff::performPageMatching(const std::vector<PDFDiffPageContext>& leftPre
// So, we use longest common subsequence algorithm to detect same page ranges,
// and then we match the rest. We assume the number of failing pages is relatively small.
std::map<size_t, size_t> pageMatches;
auto comparePages = [&](const PDFDiffPageContext& left, const PDFDiffPageContext& right)
{
if (left.pageHash == right.pageHash)
@ -311,6 +312,7 @@ void PDFDiff::performSteps(const std::vector<PDFInteger>& leftPages, const std::
std::vector<PDFDiffPageContext> rightPreparedPages;
PDFDiffHelper::PageSequence pageSequence;
std::map<size_t, size_t> pageMatches; // Indices are real page indices, not indices to page contexts
auto createDiffPageContext = [](auto pageIndex)
{
@ -381,7 +383,7 @@ void PDFDiff::performSteps(const std::vector<PDFInteger>& leftPages, const std::
// StepMatchPages
if (!m_cancelled)
{
performPageMatching(leftPreparedPages, rightPreparedPages, pageSequence);
performPageMatching(leftPreparedPages, rightPreparedPages, pageSequence, pageMatches);
stepProgress();
}
@ -391,6 +393,16 @@ void PDFDiff::performSteps(const std::vector<PDFInteger>& leftPages, const std::
pdf::PDFDocumentTextFlowFactory factoryLeftDocumentTextFlow;
factoryLeftDocumentTextFlow.setCalculateBoundingBoxes(true);
PDFDocumentTextFlow leftTextFlow = factoryLeftDocumentTextFlow.create(m_leftDocument, leftPages, PDFDocumentTextFlowFactory::Algorithm::Auto);
std::map<PDFInteger, PDFDocumentTextFlow> splittedText = leftTextFlow.split(PDFDocumentTextFlow::Text);
for (PDFDiffPageContext& leftContext : leftPreparedPages)
{
auto it = splittedText.find(leftContext.pageIndex);
if (it != splittedText.cend())
{
leftContext.text = std::move(it->second);
splittedText.erase(it);
}
}
stepProgress();
}
@ -400,16 +412,61 @@ void PDFDiff::performSteps(const std::vector<PDFInteger>& leftPages, const std::
pdf::PDFDocumentTextFlowFactory factoryRightDocumentTextFlow;
factoryRightDocumentTextFlow.setCalculateBoundingBoxes(true);
PDFDocumentTextFlow rightTextFlow = factoryRightDocumentTextFlow.create(m_rightDocument, rightPages, PDFDocumentTextFlowFactory::Algorithm::Auto);
std::map<PDFInteger, PDFDocumentTextFlow> splittedText = rightTextFlow.split(PDFDocumentTextFlow::Text);
for (PDFDiffPageContext& rightContext : rightPreparedPages)
{
auto it = splittedText.find(rightContext.pageIndex);
if (it != splittedText.cend())
{
rightContext.text = std::move(it->second);
splittedText.erase(it);
}
}
stepProgress();
}
// StepCompare
if (!m_cancelled)
{
performCompare(leftPreparedPages, rightPreparedPages, pageSequence, pageMatches);
stepProgress();
}
}
void PDFDiff::performCompare(const std::vector<PDFDiffPageContext>& leftPreparedPages,
const std::vector<PDFDiffPageContext>& rightPreparedPages,
PDFAlgorithmLongestCommonSubsequenceBase::Sequence& pageSequence,
const std::map<size_t, size_t>& pageMatches)
{
using AlgorithmLCS = PDFAlgorithmLongestCommonSubsequenceBase;
auto modifiedRanges = AlgorithmLCS::getModifiedRanges(pageSequence);
// First find all moved pages
for (const AlgorithmLCS::SequenceItem& item : pageSequence)
{
if (item.isMovedLeft())
{
Q_ASSERT(pageMatches.contains(leftPreparedPages.at(item.index1).pageIndex));
const PDFInteger leftIndex = leftPreparedPages[item.index1].pageIndex;
const PDFInteger rightIndex = pageMatches.at(leftIndex);
m_result.addPageMoved(leftIndex, rightIndex);
}
if (item.isMoved())
{
m_result.addPageMoved(leftPreparedPages[item.index1].pageIndex, rightPreparedPages[item.index2].pageIndex);
}
}
for (const auto& range : modifiedRanges)
{
AlgorithmLCS::SequenceItemFlags flags = AlgorithmLCS::collectFlags(range);
const bool isAdded = flags.testFlag(AlgorithmLCS::Added);
const bool isRemoved = flags.testFlag(AlgorithmLCS::Removed);
}
}
void PDFDiff::finalizeGraphicsPieces(PDFDiffPageContext& context)
{
std::sort(context.graphicPieces.begin(), context.graphicPieces.end());
@ -473,6 +530,18 @@ PDFDiffResult::PDFDiffResult() :
}
void PDFDiffResult::addPageMoved(PDFInteger pageIndex1, PDFInteger pageIndex2)
{
Difference difference;
difference.type = Type::PageMoved;
difference.pageIndex1 = pageIndex1;
difference.pageIndex2 = pageIndex2;
difference.message = PDFDiff::tr("Page no. %1 from old document has been moved to a new document at page no. %2.").arg(pageIndex1 + 1).arg(pageIndex2 + 1);
m_differences.emplace_back(std::move(difference));
}
PDFDiffHelper::Differences PDFDiffHelper::calculateDifferences(const GraphicPieceInfos& left,
const GraphicPieceInfos& right,
PDFReal epsilon)