Issue #118: First part of splitting

Pdf4QtLibCore/sources/pdfprogress.cpp

@@ -0,0 +1,67 @@
+//    Copyright (C) 2019-2022 Jakub Melka
+//
+//    This file is part of PDF4QT.
+//
+//    PDF4QT 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
+//    with the written consent of the copyright owner, any later version.
+//
+//    PDF4QT 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 PDF4QT.  If not, see <https://www.gnu.org/licenses/>.
+
+#include "pdfprogress.h"
+#include "pdfdbgheap.h"
+
+namespace pdf
+{
+
+PDFProgress::PDFProgress(QObject* parent) :
+    QObject(parent)
+{
+    qRegisterMetaType<pdf::ProgressStartupInfo>();
+}
+
+void PDFProgress::start(size_t stepCount, ProgressStartupInfo startupInfo)
+{
+    Q_ASSERT(stepCount > 0);
+
+    m_currentStep = 0;
+    m_stepCount = stepCount;
+    m_percentage = 0;
+
+    Q_EMIT progressStarted(qMove(startupInfo));
+}
+
+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)
+    {
+        Q_EMIT progressStep(newPercentage);
+    }
+}
+
+void PDFProgress::finish()
+{
+    Q_EMIT progressFinished();
+}
+
+} // namespace pdf