Document text flow (first part)

PdfForQtLib/sources/pdfdocumenttextflow.cpp

@@ -0,0 +1,122 @@
+//    Copyright (C) 2020 Jakub Melka
+//
+//    This file is part of PdfForQt.
+//
+//    PdfForQt is free software: you can redistribute it and/or modify
+//    it under the terms of the GNU Lesser General Public License as published by
+//    the Free Software Foundation, either version 3 of the License, or
+//    (at your option) any later version.
+//
+//    PdfForQt is distributed in the hope that it will be useful,
+//    but WITHOUT ANY WARRANTY; without even the implied warranty of
+//    MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE.  See the
+//    GNU Lesser General Public License for more details.
+//
+//    You should have received a copy of the GNU Lesser General Public License
+//    along with PDFForQt.  If not, see <https://www.gnu.org/licenses/>.
+
+#include "pdfdocumenttextflow.h"
+#include "pdfdocument.h"
+#include "pdfstructuretree.h"
+#include "pdfcompiler.h"
+#include "pdfexecutionpolicy.h"
+#include "pdfconstants.h"
+#include "pdfcms.h"
+
+namespace pdf
+{
+
+PDFDocumentTextFlow PDFDocumentTextFlowFactory::create(const PDFDocument* document, const std::vector<PDFInteger>& pageIndices, Algorithm algorithm)
+{
+    PDFDocumentTextFlow result;
+    PDFStructureTree structureTree;
+
+    const PDFCatalog* catalog = document->getCatalog();
+    if (algorithm == Algorithm::Auto || algorithm == Algorithm::Structure)
+    {
+        structureTree = PDFStructureTree::parse(&document->getStorage(), catalog->getStructureTreeRoot());
+    }
+
+    if (algorithm == Algorithm::Auto)
+    {
+        // Determine algorithm
+        if (catalog->isLogicalStructureMarked() && structureTree.isValid())
+        {
+            algorithm = Algorithm::Structure;
+        }
+        else
+        {
+            algorithm = Algorithm::Layout;
+        }
+    }
+
+    Q_ASSERT(algorithm != Algorithm::Auto);
+
+    QMutex mutex;
+
+    // Perform algorithm to retrieve document text
+    switch (algorithm)
+    {
+        case Algorithm::Layout:
+        {
+            PDFFontCache fontCache(DEFAULT_FONT_CACHE_LIMIT, DEFAULT_REALIZED_FONT_CACHE_LIMIT);
+            fontCache.setCacheShrinkEnabled(nullptr, false);
+
+            std::map<PDFInteger, PDFDocumentTextFlow::Items> items;
+
+            PDFCMSGeneric cms;
+            PDFMeshQualitySettings mqs;
+            PDFOptionalContentActivity oca(document, OCUsage::Export, nullptr);
+
+            auto generateTextLayout = [this, &items, &mutex, &fontCache, &cms, &mqs, &oca, document, catalog](PDFInteger pageIndex)
+            {
+                if (!catalog->getPage(pageIndex))
+                {
+                    // Invalid page index
+                    return;
+                }
+
+                const PDFPage* page = catalog->getPage(pageIndex);
+                Q_ASSERT(page);
+
+                PDFTextLayoutGenerator generator(PDFRenderer::IgnoreOptionalContent, page, document, &fontCache, &cms, &oca, QMatrix(), mqs);
+                QList<PDFRenderError> errors = generator.processContents();
+                PDFTextLayout textLayout = generator.createTextLayout();
+                PDFTextFlows textFlows = PDFTextFlow::createTextFlows(textLayout, PDFTextFlow::FlowFlags(PDFTextFlow::SeparateBlocks) | PDFTextFlow::RemoveSoftHyphen, pageIndex);
+
+                PDFDocumentTextFlow::Items flowItems;
+                flowItems.emplace_back(PDFDocumentTextFlow::Item{ PDFDocumentTextFlow::PageStart, pageIndex, QString() });
+                for (const PDFTextFlow& textFlow : textFlows)
+                {
+                    flowItems.emplace_back(PDFDocumentTextFlow::Item{ PDFDocumentTextFlow::Text, pageIndex, textFlow.getText() });
+                }
+                flowItems.emplace_back(PDFDocumentTextFlow::Item{ PDFDocumentTextFlow::PageEnd, pageIndex, QString() });
+
+                QMutexLocker lock(&mutex);
+                items[pageIndex] = qMove(flowItems);
+                m_errors.append(qMove(errors));
+            };
+
+            PDFExecutionPolicy::execute(PDFExecutionPolicy::Scope::Page, pageIndices.begin(), pageIndices.end(), generateTextLayout);
+
+            fontCache.setCacheShrinkEnabled(nullptr, true);
+
+            PDFDocumentTextFlow::Items flowItems;
+            for (const auto& item : items)
+            {
+                flowItems.insert(flowItems.end(), std::make_move_iterator(item.second.begin()), std::make_move_iterator(item.second.end()));
+            }
+
+            result = PDFDocumentTextFlow(qMove(flowItems));
+            break;
+        }
+
+        default:
+            Q_ASSERT(false);
+            break;
+    }
+
+    return result;
+}
+
+}   // namespace pdf