Issue #82: Hot reload function

Pdf4QtLib/sources/pdfdocument.h

@@ -452,14 +452,25 @@ public:
     /// header.
     QByteArray getVersion() const;
 
-    explicit PDFDocument(PDFObjectStorage&& storage, PDFVersion version) :
+    explicit PDFDocument(PDFObjectStorage&& storage, PDFVersion version, QByteArray sourceDataHash) :
-        m_pdfObjectStorage(std::move(storage))
+        m_pdfObjectStorage(std::move(storage)),
+        m_sourceDataHash(std::move(sourceDataHash))
     {
         init();
 
         m_info.version = version;
     }
 
+    /**
+     * @brief Retrieves the hash of the source data.
+     *
+     * This function returns the hash derived from the source data
+     * from which the document was originally read.
+     *
+     * @return Hash value of the source data.
+     */
+    const QByteArray& getSourceDataHash() const { return m_sourceDataHash; }
+
 private:
     friend class PDFDocumentReader;
     friend class PDFDocumentBuilder;
@@ -482,6 +493,10 @@ private:
 
     /// Catalog object
     PDFCatalog m_catalog;
+
+    /// Hash of the source byte array's data,
+    /// from which the document was created.
+    QByteArray m_sourceDataHash;
 };
 
 using PDFDocumentPointer = QSharedPointer<PDFDocument>;
@@ -507,6 +522,7 @@ public:
         Authorization       = 0x0010,   ///< Authorization has changed (for example, old document is granted user access, but for new, owner access)
         XFA_Pagination      = 0x0020,   ///< XFA pagination has been performed (this flag can be set only when Reset flag has been set and not any other flag)
         PreserveUndoRedo    = 0x0040,   ///< Preserve undo/red even when Reset flag is being set
+        PreserveView        = 0x0080,   ///< Try to preserve view
     };
 
     Q_DECLARE_FLAGS(ModificationFlags, ModificationFlag)
@@ -555,6 +571,7 @@ public:
     bool hasPageContentsChanged() const { return m_flags.testFlag(PageContents); }
     bool hasPreserveUndoRedo() const { return m_flags.testFlag(PreserveUndoRedo); }
     bool hasFlag(ModificationFlag flag) const { return m_flags.testFlag(flag); }
+    bool hasPreserveView() const { return m_flags.testFlag(PreserveView); }
 
     operator PDFDocument*() const { return m_document; }
     operator PDFDocumentPointer() const { return m_documentPointer; }

Pdf4QtLib/sources/pdfdocumentbuilder.cpp

@@ -704,7 +704,7 @@ void PDFDocumentBuilder::setDocument(const PDFDocument* document)
 PDFDocument PDFDocumentBuilder::build()
 {
     updateTrailerDictionary(m_storage.getObjects().size());
-    return PDFDocument(PDFObjectStorage(m_storage), m_version);
+    return PDFDocument(PDFObjectStorage(m_storage), m_version, QByteArray());
 }
 
 QByteArray PDFDocumentBuilder::getDecodedStream(const PDFStream* stream) const

Pdf4QtLib/sources/pdfdocumentreader.cpp

@@ -26,6 +26,7 @@
 #include "pdfdbgheap.h"
 
 #include <QFile>
+#include <QCryptographicHash>
 
 #include <regex>
 #include <cctype>
@@ -582,7 +583,7 @@ PDFDocument PDFDocumentReader::readFromBuffer(const QByteArray& buffer)
         processObjectStreams(&xrefTable, objects);
 
         PDFObjectStorage storage(std::move(objects), PDFObject(xrefTable.getTrailerDictionary()), qMove(m_securityHandler));
-        return PDFDocument(std::move(storage), m_version);
+        return PDFDocument(std::move(storage), m_version, hash(buffer));
     }
     catch (const PDFException &parserException)
     {
@@ -599,6 +600,11 @@ PDFDocument PDFDocumentReader::readFromBuffer(const QByteArray& buffer)
     return PDFDocument();
 }
 
+QByteArray PDFDocumentReader::hash(const QByteArray& sourceData)
+{
+    return QCryptographicHash::hash(sourceData, QCryptographicHash::Sha256);
+}
+
 std::vector<std::pair<int, int>> PDFDocumentReader::findObjectByteOffsets(const QByteArray& buffer) const
 {
     std::vector<std::pair<int, int>> offsets;
@@ -767,7 +773,7 @@ PDFDocument PDFDocumentReader::readDamagedDocumentFromBuffer(const QByteArray& b
         }
 
         PDFObjectStorage storage(std::move(objects), PDFObject(trailerDictionaryObject), qMove(m_securityHandler));
-        return PDFDocument(std::move(storage), m_version);
+        return PDFDocument(std::move(storage), m_version, QByteArray());
     }
     catch (const PDFException &parserException)
     {

Pdf4QtLib/sources/pdfdocumentreader.h

@@ -81,6 +81,8 @@ public:
     /// Returns warning messages
     const QStringList& getWarnings() const { return m_warnings; }
 
+    static QByteArray hash(const QByteArray& sourceData);
+
 private:
     static constexpr const int FIND_NOT_FOUND_RESULT = -1;
 

Pdf4QtLib/sources/pdfdocumentsanitizer.h

@@ -69,7 +69,7 @@ public:
 
     /// Returns sanitized document. Object storage is cleared after
     /// this function call.
-    PDFDocument takeSanitizedDocument() { return PDFDocument(qMove(m_storage), PDFVersion(2, 0)); }
+    PDFDocument takeSanitizedDocument() { return PDFDocument(qMove(m_storage), PDFVersion(2, 0), QByteArray()); }
 
     SanitizationFlags getFlags() const;
     void setFlags(SanitizationFlags flags);

Pdf4QtLib/sources/pdfoptimizer.h

@@ -70,7 +70,7 @@ public:
 
     /// Returns optimized document. Object storage is cleared after
     /// this function call.
-    PDFDocument takeOptimizedDocument() { return PDFDocument(qMove(m_storage), PDFVersion(2, 0)); }
+    PDFDocument takeOptimizedDocument() { return PDFDocument(qMove(m_storage), PDFVersion(2, 0), QByteArray()); }
 
     OptimizationFlags getFlags() const;
     void setFlags(OptimizationFlags flags);

Pdf4QtViewer/pdfdocumentpropertiesdialog.h

@@ -42,6 +42,7 @@ namespace pdfviewer
 struct PDFFileInfo
 {
     QString originalFileName;
+    QString absoluteFilePath;
     QString fileName;
     QString path;
     pdf::PDFInteger fileSize = 0;

Pdf4QtViewer/pdfprogramcontroller.cpp

@@ -335,7 +335,7 @@ PDFProgramController::PDFProgramController(QObject* parent) :
     m_isFactorySettingsBeingRestored(false),
     m_progress(nullptr)
 {
-
+    connect(&m_fileWatcher, &QFileSystemWatcher::fileChanged, this, &PDFProgramController::onFileChanged);
 }
 
 PDFProgramController::~PDFProgramController()
@@ -530,6 +530,10 @@ void PDFProgramController::initialize(Features features,
     {
         connect(action, &QAction::triggered, this, &PDFProgramController::onActionGetSource);
     }
+    if (QAction* action = m_actionManager->getAction(PDFActionManager::AutomaticDocumentRefresh))
+    {
+        connect(action, &QAction::triggered, this, &PDFProgramController::onActionAutomaticDocumentRefresh);
+    }
 
     if (m_recentFileManager)
     {
@@ -1042,7 +1046,6 @@ void PDFProgramController::onActionRenderingOptionTriggered(bool checked)
 
 void PDFProgramController::performSaveAs()
 {
-
     QFileInfo fileInfo(m_fileInfo.originalFileName);
     QString saveFileName = QFileDialog::getSaveFileName(m_mainWindow, tr("Save As"), fileInfo.dir().absoluteFilePath(m_fileInfo.originalFileName), tr("Portable Document (*.pdf);;All files (*.*)"));
     if (!saveFileName.isEmpty())
@@ -1058,6 +1061,8 @@ void PDFProgramController::performSave()
 
 void PDFProgramController::saveDocument(const QString& fileName)
 {
+    updateFileWatcher(true);
+
     pdf::PDFDocumentWriter writer(nullptr);
     pdf::PDFOperationResult result = writer.write(fileName, m_pdfDocument.data(), true);
     if (result)
@@ -1079,6 +1084,8 @@ void PDFProgramController::saveDocument(const QString& fileName)
     {
         QMessageBox::critical(m_mainWindow, tr("Error"), result.getErrorMessage());
     }
+
+    updateFileWatcher();
 }
 
 bool PDFProgramController::isFactorySettingsBeingRestored() const
@@ -1266,7 +1273,7 @@ void PDFProgramController::onActionEncryptionTriggered()
         pdf::PDFObjectStorage storage = m_pdfDocument->getStorage();
         storage.setSecurityHandler(qMove(clonedSecurityHandler));
 
-        pdf::PDFDocumentPointer pointer(new pdf::PDFDocument(qMove(storage), m_pdfDocument->getInfo()->version));
+        pdf::PDFDocumentPointer pointer(new pdf::PDFDocument(qMove(storage), m_pdfDocument->getInfo()->version, QByteArray()));
         pdf::PDFModifiedDocument document(qMove(pointer), m_optionalContentActivity, pdf::PDFModifiedDocument::Authorization);
         onDocumentModified(qMove(document));
     }
@@ -1585,6 +1592,53 @@ void PDFProgramController::onColorManagementSystemChanged()
     m_settings->setColorManagementSystemSettings(m_CMSManager->getSettings());
 }
 
+void PDFProgramController::onFileChanged(const QString& fileName)
+{
+    QAction* autoRefreshDocumentAction = m_actionManager->getAction(PDFActionManager::AutomaticDocumentRefresh);
+
+    if (!autoRefreshDocumentAction || // We do not have action
+        !autoRefreshDocumentAction->isChecked() || // Auto refresh is not enabled
+        m_fileInfo.originalFileName != fileName) // File is different
+    {
+        return;
+    }
+
+    if (m_undoRedoManager && !m_undoRedoManager->isCurrentSaved())
+    {
+        // If document is modified, we do not reload it
+        return;
+    }
+
+    QFile file(fileName);
+    if (file.open(QFile::ReadOnly))
+    {
+        QByteArray data = file.readAll();
+        file.close();
+
+        QByteArray hash = pdf::PDFDocumentReader::hash(data);
+        if (m_pdfDocument && m_pdfDocument->getSourceDataHash() != hash)
+        {
+            auto queryPassword = [this](bool* ok)
+            {
+                *ok = false;
+                return QString();
+            };
+
+            // Try to open a new document
+            pdf::PDFDocumentReader reader(m_progress, qMove(queryPassword), true, false);
+            pdf::PDFDocument document = reader.readFromFile(fileName);
+
+            if (reader.getReadingResult() == pdf::PDFDocumentReader::Result::OK)
+            {
+                pdf::PDFDocumentPointer pointer(new pdf::PDFDocument(std::move(document)));
+                pdf::PDFModifiedDocument modifiedDocument(std::move(pointer), m_optionalContentActivity, pdf::PDFModifiedDocument::ModificationFlags(pdf::PDFModifiedDocument::Reset | pdf::PDFModifiedDocument::PreserveView));
+                onDocumentModified(std::move(modifiedDocument));
+                m_undoRedoManager->setIsCurrentSaved();
+            }
+        }
+    }
+}
+
 void PDFProgramController::updateFileInfo(const QString& fileName)
 {
     QFileInfo fileInfo(fileName);
@@ -1596,6 +1650,27 @@ void PDFProgramController::updateFileInfo(const QString& fileName)
     m_fileInfo.creationTime = fileInfo.birthTime();
     m_fileInfo.lastModifiedTime = fileInfo.lastModified();
     m_fileInfo.lastReadTime = fileInfo.lastRead();
+    m_fileInfo.absoluteFilePath = fileInfo.absoluteFilePath();
+
+    updateFileWatcher(false);
+}
+
+void PDFProgramController::updateFileWatcher(bool forceDisable)
+{
+    QStringList oldFiles = m_fileWatcher.files();
+    QStringList newFiles;
+
+    QAction* action = m_actionManager->getAction(PDFActionManager::AutomaticDocumentRefresh);
+    if (!forceDisable && !m_fileInfo.absoluteFilePath.isEmpty() && action && action->isChecked())
+    {
+        newFiles << m_fileInfo.absoluteFilePath;
+    }
+
+    if (oldFiles != newFiles)
+    {
+        m_fileWatcher.removePaths(oldFiles);
+        m_fileWatcher.addPaths(newFiles);
+    }
 }
 
 void PDFProgramController::openDocument(const QString& fileName)
@@ -1809,7 +1884,7 @@ void PDFProgramController::setDocument(pdf::PDFModifiedDocument document, bool i
         plugin.second->setDocument(document);
     }
 
-    if (m_pdfDocument && document.hasReset())
+    if (m_pdfDocument && document.hasReset() && !document.hasPreserveView())
     {
         const pdf::PDFCatalog* catalog = m_pdfDocument->getCatalog();
         setPageLayout(catalog->getPageLayout());
@@ -1831,6 +1906,7 @@ void PDFProgramController::closeDocument()
     m_pdfDocument.reset();
     updateActionsAvailability();
     updateTitle();
+    updateFileInfo(QString());
 }
 
 void PDFProgramController::updateRenderingOptionActions()
@@ -2382,6 +2458,11 @@ void PDFProgramController::onActionGetSource()
     QDesktopServices::openUrl(QUrl("https://github.com/JakubMelka/PDF4QT"));
 }
 
+void PDFProgramController::onActionAutomaticDocumentRefresh()
+{
+    updateFileWatcher();
+}
+
 void PDFProgramController::onPageRenderingErrorsChanged(pdf::PDFInteger pageIndex, int errorsCount)
 {
     if (errorsCount > 0)

Pdf4QtViewer/pdfprogramcontroller.h

@@ -29,6 +29,7 @@
 #include <QAction>
 #include <QToolButton>
 #include <QActionGroup>
+#include <QFileSystemWatcher>
 
 #include <array>
 
@@ -81,6 +82,7 @@ public:
         Open,
         Close,
         Quit,
+        AutomaticDocumentRefresh,
         ZoomIn,
         ZoomOut,
         Find,
@@ -349,6 +351,7 @@ private:
     void onActionCloseTriggered();
     void onActionDeveloperCreateInstaller();
     void onActionGetSource();
+    void onActionAutomaticDocumentRefresh();
 
     void onDrawSpaceChanged();
     void onPageLayoutChanged();
@@ -359,6 +362,7 @@ private:
     void onPageRenderingErrorsChanged(pdf::PDFInteger pageIndex, int errorsCount);
     void onViewerSettingsChanged();
     void onColorManagementSystemChanged();
+    void onFileChanged(const QString& fileName);
 
     void updateMagnifierToolSettings();
     void updateUndoRedoSettings();
@@ -369,6 +373,7 @@ private:
 
     void setPageLayout(pdf::PageLayout pageLayout);
     void updateFileInfo(const QString& fileName);
+    void updateFileWatcher(bool forceDisable = false);
 
     enum SettingFlag
     {
@@ -408,6 +413,7 @@ private:
     pdf::PDFFormManager* m_formManager;
 
     PDFFileInfo m_fileInfo;
+    QFileSystemWatcher m_fileWatcher;
     pdf::PDFCertificateStore m_certificateStore;
     std::vector<pdf::PDFSignatureVerificationResult> m_signatures;
 

Pdf4QtViewer/pdfviewermainwindow.cpp

@@ -103,6 +103,7 @@ PDFViewerMainWindow::PDFViewerMainWindow(QWidget* parent) :
     // Initialize actions
     m_actionManager->setAction(PDFActionManager::Open, ui->actionOpen);
     m_actionManager->setAction(PDFActionManager::Close, ui->actionClose);
+    m_actionManager->setAction(PDFActionManager::AutomaticDocumentRefresh, ui->actionAutomaticDocumentRefresh);
     m_actionManager->setAction(PDFActionManager::Quit, ui->actionQuit);
     m_actionManager->setAction(PDFActionManager::ZoomIn, ui->actionZoom_In);
     m_actionManager->setAction(PDFActionManager::ZoomOut, ui->actionZoom_Out);

Pdf4QtViewer/pdfviewermainwindow.ui

@@ -29,6 +29,7 @@
     </property>
     <addaction name="actionOpen"/>
     <addaction name="actionClose"/>
+    <addaction name="actionAutomaticDocumentRefresh"/>
     <addaction name="separator"/>
     <addaction name="actionSave"/>
     <addaction name="actionSave_As"/>
@@ -936,6 +937,17 @@
     <string>Sanitize document to remove sensitive information.</string>
    </property>
   </action>
+  <action name="actionAutomaticDocumentRefresh">
+   <property name="checkable">
+    <bool>true</bool>
+   </property>
+   <property name="text">
+    <string>Automatic Document Refresh</string>
+   </property>
+   <property name="statusTip">
+    <string>Automatically reloads the document if a change made by an external program is detected.</string>
+   </property>
+  </action>
  </widget>
  <layoutdefault spacing="6" margin="11"/>
  <resources>

Pdf4QtViewer/pdfviewermainwindowlite.cpp

@@ -102,6 +102,7 @@ PDFViewerMainWindowLite::PDFViewerMainWindowLite(QWidget* parent) :
     // Initialize actions
     m_actionManager->setAction(PDFActionManager::Open, ui->actionOpen);
     m_actionManager->setAction(PDFActionManager::Close, ui->actionClose);
+    m_actionManager->setAction(PDFActionManager::AutomaticDocumentRefresh, ui->actionAutomaticDocumentRefresh);
     m_actionManager->setAction(PDFActionManager::Quit, ui->actionQuit);
     m_actionManager->setAction(PDFActionManager::ZoomIn, ui->actionZoom_In);
     m_actionManager->setAction(PDFActionManager::ZoomOut, ui->actionZoom_Out);

Pdf4QtViewer/pdfviewermainwindowlite.ui

@@ -29,7 +29,7 @@
     </property>
     <addaction name="actionOpen"/>
     <addaction name="actionClose"/>
-    <addaction name="separator"/>
+	<addaction name="actionAutomaticDocumentRefresh"/>
     <addaction name="separator"/>
     <addaction name="actionSend_by_E_Mail"/>
     <addaction name="actionPrint"/>
@@ -458,6 +458,17 @@
    <property name="text">
     <string>Certificates...</string>
    </property>
+  </action>
+    <action name="actionAutomaticDocumentRefresh">
+   <property name="checkable">
+    <bool>true</bool>
+   </property>
+   <property name="text">
+    <string>Automatic Document Refresh</string>
+   </property>
+   <property name="statusTip">
+    <string>Automatically reloads the document if a change made by an external program is detected.</string>
+   </property>
   </action>
  </widget>
  <layoutdefault spacing="6" margin="11"/>