Undo/redo manager, fixing form bugs

PdfForQtViewer/pdfundoredomanager.cpp

@@ -0,0 +1,92 @@
+//    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 "pdfundoredomanager.h"
+
+namespace pdfviewer
+{
+
+PDFUndoRedoManager::PDFUndoRedoManager(QObject* parent) :
+    BaseClass(parent)
+{
+
+}
+
+PDFUndoRedoManager::~PDFUndoRedoManager()
+{
+
+}
+
+void PDFUndoRedoManager::doUndo()
+{
+    if (!canUndo())
+    {
+        // Undo operation can't be performed
+        return;
+    }
+
+    UndoRedoItem item = m_undoSteps.back();
+    m_undoSteps.pop_back();
+    m_redoSteps.insert(m_redoSteps.begin(), item);
+    clampUndoRedoSteps();
+
+    emit undoRedoStateChanged();
+    emit documentChangeRequest(item.document, item.flags);
+}
+
+void PDFUndoRedoManager::doRedo()
+{
+    if (!canRedo())
+    {
+        // Redo operation can't be performed
+        return;
+    }
+
+    UndoRedoItem item = m_redoSteps.front();
+    m_redoSteps.erase(m_redoSteps.begin());
+    m_undoSteps.push_back(item);
+    clampUndoRedoSteps();
+
+    emit undoRedoStateChanged();
+    emit documentChangeRequest(item.document, item.flags);
+}
+
+void PDFUndoRedoManager::clear()
+{
+    if (canUndo() || canRedo())
+    {
+        m_undoSteps.clear();
+        m_redoSteps.clear();
+        emit undoRedoStateChanged();
+    }
+}
+
+void PDFUndoRedoManager::clampUndoRedoSteps()
+{
+    if (m_undoSteps.size() > m_undoLimit)
+    {
+        // We erase from oldest steps to newest
+        m_undoSteps.erase(m_undoSteps.begin(), std::next(m_undoSteps.begin(), m_undoSteps.size() - m_undoLimit));
+    }
+    if (m_redoSteps.size() > m_redoLimit)
+    {
+        // Newest steps are erased
+        m_redoSteps.resize(m_redoLimit);
+    }
+}
+
+}   // namespace pdfviewer