Progress bar for windows taskbar button

PdfForQtLib/PdfForQtLib.pro

@@ -46,6 +46,7 @@ SOURCES += \
     sources/pdfdocument.cpp \
     sources/pdfdocumentreader.cpp \
     sources/pdfpattern.cpp \
+    sources/pdfprogress.cpp \
     sources/pdfsecurityhandler.cpp \
     sources/pdfutils.cpp \
     sources/pdfxreftable.cpp \
@@ -80,6 +81,7 @@ HEADERS += \
     sources/pdfdocument.h \
     sources/pdfdocumentreader.h \
     sources/pdfpattern.h \
+    sources/pdfprogress.h \
     sources/pdfsecurityhandler.h \
     sources/pdfxreftable.h \
     sources/pdfflatmap.h \

PdfForQtLib/sources/pdfdocumentreader.cpp

@@ -33,9 +33,10 @@
 namespace pdf
 {
 
-PDFDocumentReader::PDFDocumentReader(const std::function<QString(bool*)>& getPasswordCallback) :
+PDFDocumentReader::PDFDocumentReader(PDFProgress* progress, const std::function<QString(bool*)>& getPasswordCallback) :
     m_result(Result::OK),
-    m_getPasswordCallback(getPasswordCallback)
+    m_getPasswordCallback(getPasswordCallback),
+    m_progress(progress)
 {
 
 }
@@ -253,6 +254,8 @@ PDFDocument PDFDocumentReader::readFromBuffer(const QByteArray& buffer)
                     PDFParsingContext context(objectFetcher);
                     PDFObject object = getObject(&context, entry.offset, entry.reference);
 
+                    progressStep();
+
                     QMutexLocker lock(&m_mutex);
                     objects[entry.reference.objectNumber] = PDFObjectStorage::Entry(entry.reference.generation, object);
                 }
@@ -266,7 +269,9 @@ PDFDocument PDFDocumentReader::readFromBuffer(const QByteArray& buffer)
         };
 
         // Now, we are ready to scan all objects
+        progressStart(occupiedEntries.size());
         std::for_each(std::execution::parallel_policy(), occupiedEntries.cbegin(), occupiedEntries.cend(), processEntry);
+        progressFinish();
 
         if (m_result != Result::OK)
         {
@@ -351,8 +356,10 @@ PDFDocument PDFDocumentReader::readFromBuffer(const QByteArray& buffer)
         // decipher object streams here. 4) must be handled in the security handler.
         if (securityHandler->getMode() != EncryptionMode::None)
         {
-            auto decryptEntry = [encryptObjectReference, &securityHandler, &objects](const PDFXRefTable::Entry& entry)
+            auto decryptEntry = [this, encryptObjectReference, &securityHandler, &objects](const PDFXRefTable::Entry& entry)
             {
+                progressStep();
+
                 if (encryptObjectReference.objectNumber != 0 && encryptObjectReference == entry.reference)
                 {
                     // 2) - Encrypt dictionary
@@ -362,7 +369,9 @@ PDFDocument PDFDocumentReader::readFromBuffer(const QByteArray& buffer)
                 objects[entry.reference.objectNumber].object = securityHandler->decryptObject(objects[entry.reference.objectNumber].object, entry.reference);
             };
 
+            progressStart(occupiedEntries.size());
             std::for_each(std::execution::parallel_policy(), occupiedEntries.cbegin(), occupiedEntries.cend(), decryptEntry);
+            progressFinish();
         }
 
         // ------------------------------------------------------------------------------------------
@@ -520,4 +529,28 @@ int PDFDocumentReader::findFromEnd(const char* what, const QByteArray& byteArray
     return FIND_NOT_FOUND_RESULT;
 }
 
+void PDFDocumentReader::progressStart(size_t stepCount)
+{
+    if (m_progress)
+    {
+        m_progress->start(stepCount);
+    }
+}
+
+void PDFDocumentReader::progressStep()
+{
+    if (m_progress)
+    {
+        m_progress->step();
+    }
+}
+
+void PDFDocumentReader::progressFinish()
+{
+    if (m_progress)
+    {
+        m_progress->finish();
+    }
+}
+
 }   // namespace pdf

PdfForQtLib/sources/pdfdocumentreader.h

@@ -21,6 +21,7 @@
 
 #include "pdfglobal.h"
 #include "pdfdocument.h"
+#include "pdfprogress.h"
 
 #include <QtCore>
 #include <QIODevice>
@@ -36,7 +37,7 @@ class PDFFORQTLIBSHARED_EXPORT PDFDocumentReader
     Q_DECLARE_TR_FUNCTIONS(pdf::PDFDocumentReader)
 
 public:
-    explicit PDFDocumentReader(const std::function<QString(bool*)>& getPasswordCallback);
+    explicit PDFDocumentReader(PDFProgress* progress, const std::function<QString(bool*)>& getPasswordCallback);
 
     constexpr inline PDFDocumentReader(const PDFDocumentReader&) = delete;
     constexpr inline PDFDocumentReader(PDFDocumentReader&&) = delete;
@@ -86,6 +87,10 @@ private:
     /// \returns Position of string, or FIND_NOT_FOUND_RESULT
     int findFromEnd(const char* what, const QByteArray& byteArray, int limit);
 
+    void progressStart(size_t stepCount);
+    void progressStep();
+    void progressFinish();
+
     /// Mutex for access to variables of this reader from more threads
     /// (providing thread safety)
     QMutex m_mutex;
@@ -101,6 +106,9 @@ private:
 
     /// Callback to obtain password from the user
     std::function<QString(bool*)> m_getPasswordCallback;
+
+    /// Progress indicator
+    PDFProgress* m_progress;
 };
 
 }   // namespace pdf

PdfForQtLib/sources/pdfprogress.cpp

@@ -0,0 +1,60 @@
+//    Copyright (C) 2019 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 "pdfprogress.h"
+
+namespace pdf
+{
+
+void PDFProgress::start(size_t stepCount)
+{
+    Q_ASSERT(stepCount > 0);
+
+    m_currentStep = 0;
+    m_stepCount = stepCount;
+    m_percentage = 0;
+
+    emit progressStarted();
+}
+
+void PDFProgress::step()
+{
+    // Atomically increment by one. We must add + 1 to the current step,
+    // because fetch_add will return old value. Then we must test, if percentage
+    // has been changed.
+    size_t currentStep = m_currentStep.fetch_add(1) + 1;
+
+    int newPercentage = int((size_t(100) * currentStep) / m_stepCount);
+    int oldPercentage = m_percentage.load(std::memory_order_acquire);
+    bool emitSignal = oldPercentage < newPercentage;
+    do
+    {
+        emitSignal = oldPercentage < newPercentage;
+    } while (oldPercentage < newPercentage && !m_percentage.compare_exchange_weak(oldPercentage, newPercentage, std::memory_order_release, std::memory_order_relaxed));
+
+    if (emitSignal)
+    {
+        progressStep(newPercentage);
+    }
+}
+
+void PDFProgress::finish()
+{
+    emit progressFinished();
+}
+
+} // namespace pdf

PdfForQtLib/sources/pdfprogress.h

@@ -0,0 +1,54 @@
+//    Copyright (C) 2019 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/>.
+
+#ifndef PDFPROGRESS_H
+#define PDFPROGRESS_H
+
+#include "pdfglobal.h"
+
+#include <QObject>
+
+#include <atomic>
+
+namespace pdf
+{
+
+class PDFFORQTLIBSHARED_EXPORT PDFProgress : public QObject
+{
+    Q_OBJECT
+
+public:
+    explicit PDFProgress(QObject* parent) : QObject(parent) { }
+
+    void start(size_t stepCount);
+    void step();
+    void finish();
+
+signals:
+    void progressStarted();
+    void progressStep(int percentage);
+    void progressFinished();
+
+private:
+    std::atomic<size_t> m_currentStep = 0;
+    std::atomic<size_t> m_stepCount = 0;
+    std::atomic<int> m_percentage = 0;
+};
+
+}   // namespace pdf
+
+#endif // PDFPROGRESS_H