Timeline preview: refactor and move all functions into a new previewmanager class

src/doc/kdenlivedoc.cpp

@@ -294,7 +294,6 @@ KdenliveDoc::KdenliveDoc(const QUrl &url, const QUrl &projectFolder, QUndoGroup
     QDir dir2(QStandardPaths::writableLocation(QStandardPaths::CacheLocation));
     dir2.mkdir(documentId);
     updateProjectFolderPlacesEntry();
-    connect(this, &KdenliveDoc::cleanupOldPreviews, this, &KdenliveDoc::doCleanupOldPreviews);
 }
 
 void KdenliveDoc::slotSetDocumentNotes(const QString &notes)
@@ -313,23 +312,6 @@ KdenliveDoc::~KdenliveDoc()
         if (!m_autosave->fileName().isEmpty()) m_autosave->remove();
         delete m_autosave;
     }
-    // Remove all timeline preview undo data
-    QString id = m_documentProperties.value(QStringLiteral("documentid"));
-    if (id.isEmpty() || id.toLong() == 0) {
-        // Something is wrong, make sure we don't trash valuable data
-        // id should be a number (ms since epoch)
-        return;
-    }
-    QDir dir = getCacheDir();
-    if (m_url.isEmpty()) {
-        // Doc was not saved, double check path and delete folder
-        if (dir.dirName() == id)
-            dir.removeRecursively();
-    } else {
-        if (dir.cd("undo") && dir.absolutePath().contains(id)) {
-            dir.removeRecursively();
-        }
-    }
 }
 
 int KdenliveDoc::setSceneList()
@@ -1638,91 +1620,6 @@ void KdenliveDoc::doAddAction(const QString &name, QAction *a, QKeySequence shor
     pCore->window()->actionCollection()->setDefaultShortcut(a, shortcut);
 }
 
-QDir KdenliveDoc::getCacheDir()
-{
-    QString documentId = m_documentProperties.value(QStringLiteral("documentid"));
-    return QDir(QStandardPaths::writableLocation(QStandardPaths::CacheLocation) + "/"+ documentId);
-}
-
-void KdenliveDoc::invalidatePreviews(QList <int> chunks)
-{
-    // We are not at the bottom of undo stack, chunks have already been archived previously
-    QMutexLocker lock(&m_previewMutex);
-    QDir dir = getCacheDir();
-    QString ext = m_documentProperties.value(QStringLiteral("previewextension"));
-    if (m_commandStack->index() == m_commandStack->count() && !dir.exists(QString("undo/%1").arg(m_commandStack->index() - 1))) {
-        // Archive just created chunks
-        int ix = m_commandStack->index() - 1;
-        if (!dir.exists("undo"))
-            dir.mkdir("undo");
-        if (!dir.exists("undo")) {
-            // Cannot create undo dir, abort
-            return;
-        }
-        dir.mkdir(QString("undo/%1").arg(ix));
-        bool foundPreviews = false;
-        foreach(int i, chunks) {
-            QString current = QString("%1.%2").arg(i).arg(ext);
-            if (dir.rename(current, QString("undo/%1/%2").arg(ix).arg(current))) {
-                foundPreviews = true;
-            }
-        }
-        if (!foundPreviews) {
-            if (dir.cd(QString("undo/%1").arg(ix)) && dir.absolutePath().contains("/undo/")) {
-                dir.removeRecursively();
-            }
-        }
-        else emit cleanupOldPreviews(ix);
-    } else {
-        // Restore existing chunks, delete others
-        QDir srcdir(dir);
-        QStringList filters;
-        filters << QString("*.%1").arg(ext);
-        QList <int> foundChunks;
-        // Check if we just undo the last stack action, then backup, otherwise delete
-        bool lastUndo = false;
-        int max = m_commandStack->count();
-        if (m_commandStack->index() == max - 1) {
-            if (!srcdir.exists(QString("undo/%1").arg(max))) {
-                lastUndo = true;
-                bool foundPreviews = false;
-                dir.mkdir(QString("undo/%1").arg(max));
-                foreach(int i, chunks) {
-                    QString current = QString("%1.%2").arg(i).arg(ext);
-                    if (dir.rename(current, QString("undo/%1/%2").arg(max).arg(current))) {
-                        foundPreviews = true;
-                    }
-                }
-                if (!foundPreviews) {
-                    QDir tmpDir = dir;
-                    if (tmpDir.cd(QString("undo/%1").arg(max)) && tmpDir.absolutePath().contains("/undo/")) {
-                        tmpDir.removeRecursively();
-                    }
-                }
-            }
-        }
-        if (!lastUndo) {
-            foreach(int i, chunks) {
-                srcdir.remove(QString("%1.%2").arg(i).arg(ext));
-            }
-        }
-        if (!dir.cd(QString("undo/%1").arg(m_commandStack->index())))
-            return;
-        QStringList filesnames = dir.entryList(filters, QDir::Files);
-        foreach(const QString & fname, filesnames) {
-            int existingChunk = fname.section(".", 0, 0).toInt();
-            if (chunks.contains(existingChunk)) {
-                // Restore chunks
-                foundChunks << existingChunk;
-                QFile::copy(dir.absoluteFilePath(fname), srcdir.absoluteFilePath(fname));
-            }
-        }
-        qSort(foundChunks);
-        emit reloadChunks(foundChunks);
-    }
-    setModified(true);
-}
-
 void KdenliveDoc::previewProgress(int p)
 {
     pCore->window()->setPreviewProgress(p);
@@ -1783,40 +1680,13 @@ void KdenliveDoc::selectPreviewProfile()
     }
 }
 
-void KdenliveDoc::doCleanupOldPreviews(int ix)
+void KdenliveDoc::checkPreviewStack()
 {
-    QDir dir = getCacheDir();
-    if (!dir.cd("undo"))
-        return;
-    QStringList dirs = dir.entryList(QDir::Dirs | QDir::NoDotAndDotDot);
-    bool ok;
-    foreach (const QString &num, dirs) {
-        int nb = num.toInt(&ok);
-        if (ok && nb < ix - 5) {
-            QDir tmp = dir;
-            if (tmp.cd(num) && tmp.absolutePath().contains("/undo/")) {
-                tmp.removeRecursively();
-            }
-        }
-    }
+    // A command was pushed in the middle of the stack, remove all cached data from last undos
+    emit removeInvalidUndo(m_commandStack->count());
 }
 
-void KdenliveDoc::checkPreviewStack()
+void KdenliveDoc::saveMltPlaylist(const QString fileName)
 {
-    // A command was pushed in the middle of the stack, remove all cached data from last undos
-    int max = m_commandStack->count();
-    QDir dir = getCacheDir();
-    if (!dir.cd("undo"))
-        return;
-    QStringList dirs = dir.entryList(QDir::Dirs | QDir::NoDotAndDotDot);
-    bool ok;
-    foreach (const QString &num, dirs) {
-        int nb = num.toInt(&ok);
-        if (ok && nb >= max) {
-            QDir tmp = dir;
-            if (tmp.cd(num) && tmp.absolutePath().contains("/undo/")) {
-                tmp.removeRecursively();
-            }
-        }
-    }
+    m_render->preparePreviewRendering(fileName);
 }

src/doc/kdenlivedoc.h

@@ -32,7 +32,6 @@
 #include <QObject>
 #include <QTimer>
 #include <QUrl>
-#include <QMutex>
 
 #include <kautosavefile.h>
 #include <KDirWatch>
@@ -132,6 +131,8 @@ public:
     QDomDocument xmlSceneList(const QString &scene);
     /** @brief Saves the project file xml to a file. */
     bool saveSceneList(const QString &path, const QString &scene);
+    /** @brief Saves only the MLT xml to a file for preview rendering. */
+    void saveMltPlaylist(const QString fileName);
     void cacheImage(const QString &fileId, const QImage &img) const;
     void setProjectFolder(QUrl url);
     void setZone(int start, int end);
@@ -173,8 +174,6 @@ public:
     void previewProgress(int p);
     /** @brief Select most appropriate rendering profile for timeline preview based on fps / size. */
     void selectPreviewProfile();
-    /** @brief Get the directory to store timeline previews */
-    QDir getCacheDir();
 
 private:
     QUrl m_url;
@@ -193,7 +192,6 @@ private:
     ClipManager *m_clipManager;
     MltVideoProfile m_profile;
     QString m_searchFolder;
-    QMutex m_previewMutex;
 
     /** @brief Tells whether the current document has been changed after being saved. */
     bool m_modified;
@@ -241,7 +239,6 @@ private slots:
     void slotSetDocumentNotes(const QString &notes);
     void switchProfile(MltVideoProfile profile, const QString &id, const QDomElement &xml);
     void slotSwitchProfile();
-    void doCleanupOldPreviews(int ix);
     /** @brief Check if we did a new action invalidating more recent undo items. */
     void checkPreviewStack();
 
@@ -263,10 +260,8 @@ signals:
     void reloadEffects();
     /** @brief Fps was changed, update timeline */
     void updateFps(bool changed);
-    /** @brief Some timeline preview chunks restored, reload them */
-    void reloadChunks(QList <int> chunks);
-    /** @brief Only keep 5 undo levels of timeline previews, ask for cleanup */
-    void cleanupOldPreviews(int ix);
+    /** @brief If a command is pushed when we are in the middle of undo stack, invalidate further undo history */
+    void removeInvalidUndo(int ix);
 
 };
 

src/project/dialogs/projectsettings.cpp

@@ -79,7 +79,7 @@ ProjectSettings::ProjectSettings(KdenliveDoc *doc, QMap <QString, QString> metad
         m_proxyextension = doc->getDocumentProperty(QStringLiteral("proxyextension"));
         m_previewparams = doc->getDocumentProperty(QStringLiteral("previewparameters"));
         m_previewextension = doc->getDocumentProperty(QStringLiteral("previewextension"));
-        m_previewDir = doc->getCacheDir();
+        m_previewDir = doc->getDocumentProperty(QStringLiteral("cachedir"));
     }
     else {
         currentProf = KdenliveSettings::default_profile();
@@ -288,7 +288,7 @@ void ProjectSettings::slotDeleteProxies()
 
 void ProjectSettings::slotDeletePreviews()
 {
-    if (KMessageBox::warningContinueCancel(this, i18n("Deleting these preview files will invalidate all timeline previews for this project.")) != KMessageBox::Continue) return;
+    if (KMessageBox::warningContinueCancel(this, i18n("Deleting the project preview files in this folder will invalidate all timeline previews:\n%1", m_previewDir.absolutePath())) != KMessageBox::Continue) return;
     buttonBox->setEnabled(false);
     //TODO
     emit disablePreviews();

src/renderer.cpp

@@ -72,8 +72,7 @@ Render::Render(Kdenlive::MonitorId rendererName, BinController *binController, G
     m_isLoopMode(false),
     m_blackClip(NULL),
     m_isActive(false),
-    m_isRefreshing(false),
-    m_abortPreview(false)
+    m_isRefreshing(false)
 {
     qRegisterMetaType<stringMap> ("stringMap");
     analyseAudio = KdenliveSettings::monitor_audio();
@@ -102,7 +101,6 @@ Render::Render(Kdenlive::MonitorId rendererName, BinController *binController, G
 
 Render::~Render()
 {
-    m_abortPreview = true;
     closeMlt();
 }
 
@@ -113,7 +111,6 @@ void Render::closeMlt()
     delete m_mltConsumer;
     delete m_mltProducer;
     delete m_blackClip;
-    m_previewThread.waitForFinished();
 }
 
 void Render::slotSwitchFullscreen()
@@ -1618,23 +1615,9 @@ void Render::updateSlowMotionProducers(const QString &id, QMap <QString, QString
     }
 }
 
-void Render::abortPreview()
+void Render::preparePreviewRendering(const QString sceneListFile)
 {
-    if (m_previewThread.isRunning()) {
-        m_abortPreview = true;
-        m_previewThread.waitForFinished();
-    }
-}
-
-void Render::previewRendering(QList <int> frames, const QString &cacheDir, QStringList consumerParams, const QString extension)
-{
-    abortPreview();
-    m_previewChunks << frames;
-    qSort(m_previewChunks);
-    QDir dir(cacheDir);
-    dir.mkpath(QStringLiteral("."));
     // Save temporary scenelist
-    QString sceneListFile = dir.absoluteFilePath("preview.mlt");
     Mlt::Consumer xmlConsumer(*m_qmlView->profile(), "xml", sceneListFile.toUtf8().constData());
     if (!xmlConsumer.is_valid())
         return;
@@ -1645,52 +1628,5 @@ void Render::previewRendering(QList <int> frames, const QString &cacheDir, QStri
         return;
     xmlConsumer.connect(prod);
     xmlConsumer.run();
-    m_previewThread = QtConcurrent::run(this, &Render::doPreviewRender, dir, sceneListFile, consumerParams, extension);
-}
-
-void Render::doPreviewRender(QDir folder, QString scene, QStringList consumerParams, const QString &extension)
-{
-    int progress;
-    int chunkSize = KdenliveSettings::timelinechunks();
-    consumerParams << "an=1";
-    emit previewRender(0, QString(), 0);
-    int ct = 0;
-    while (!m_previewChunks.isEmpty()) {
-        int i = m_previewChunks.takeFirst();
-        ct++;
-        if (m_abortPreview) {
-            m_previewChunks.prepend(i);
-            emit previewRender(0, QString(), 1000);
-            break;
-        }
-        QString fileName = QString("%1.%2").arg(i).arg(extension);
-        if (m_previewChunks.isEmpty()) {
-            progress = 1000;
-        } else {
-            progress = (double) (ct) / (ct + m_previewChunks.count()) * 1000;
-        }
-        if (folder.exists(fileName)) {
-            // This chunk already exists
-            emit previewRender(i, folder.absoluteFilePath(fileName), progress);
-            continue;
-        }
-        // Build rendering process
-        QStringList args;
-        args << scene;
-        args << "in=" + QString::number(i);
-        args << "out=" + QString::number(i + chunkSize - 1);
-        args << "-consumer" << "avformat:" + folder.absoluteFilePath(fileName);
-        args << consumerParams;
-        int result = QProcess::execute(KdenliveSettings::rendererpath(), args);
-        if (result != 0) {
-            // Something is wrong, abort
-            qDebug()<<"+++++++++\n++ ERROR  ++\n++++++";
-            emit previewRender(i, QString(), -1);
-            QFile::remove(folder.absoluteFilePath(fileName));
-            break;
-        }
-        emit previewRender(i, folder.absoluteFilePath(fileName), progress);
-    }
-    QFile::remove(scene);
-    m_abortPreview = false;
 }
+

src/renderer.h

@@ -251,8 +251,7 @@ class Render: public AbstractRender
     void prepareProfileReset(double fps);
     void finishProfileReset();
     void updateSlowMotionProducers(const QString &id, QMap <QString, QString> passProperties);
-    void previewRendering(QList <int> frames, const QString &cacheDir, QStringList consumerParams, const QString extension);
-    void abortPreview();
+    void preparePreviewRendering(const QString sceneListFile);
 
 private:
 
@@ -265,7 +264,6 @@ private:
     Mlt::Producer * m_mltProducer;
     Mlt::Event *m_showFrameEvent;
     Mlt::Event *m_pauseEvent;
-    QFuture <void> m_previewThread;
     BinController *m_binController;
     GLWidget *m_qmlView;
     double m_fps;
@@ -289,10 +287,8 @@ private:
     bool m_isActive;
     /** @brief True if the consumer is currently refreshing itself. */
     bool m_isRefreshing;
-    bool m_abortPreview;
     void closeMlt();
     QMap<QString, Mlt::Producer *> m_slowmotionProducers;
-    QList <int> m_previewChunks;
 
     /** @brief Build the MLT Consumer object with initial settings.
      *  @param profileName The MLT profile to use for the consumer */
@@ -312,7 +308,6 @@ private slots:
     /** @brief Refreshes the monitor display. */
     void refresh();
     void slotCheckSeeking();
-    void doPreviewRender(QDir folder, QString scene, QStringList consumerParams, const QString &extension);
 
 signals:
     /** @brief The renderer stopped, either playing or rendering. */
@@ -349,7 +344,6 @@ signals:
     void mltFrameReceived(Mlt::Frame *);
     /** @brief We want to replace a clip with another, but before we need to change clip producer id so that there is no interference*/
     void prepareTimelineReplacement(const QString &);
-    void previewRender(int frame, const QString &file, int progress);
 
 public slots:
 

src/timeline/CMakeLists.txt

@@ -25,5 +25,6 @@ set(kdenlive_SRCS
   timeline/managers/guidemanager.cpp
   timeline/managers/razormanager.cpp
   timeline/managers/selectmanager.cpp
+  timeline/managers/previewmanager.cpp
   PARENT_SCOPE)
 

src/timeline/customruler.cpp

@@ -510,17 +510,21 @@ void CustomRuler::activateZone()
     update();
 }
 
-void CustomRuler::updatePreview(int frame, bool rendered, bool refresh)
+bool CustomRuler::updatePreview(int frame, bool rendered, bool refresh)
 {
+    bool result = false;
     if (rendered) {
         m_renderingPreviews << frame;
         m_dirtyRenderingPreviews.removeAll(frame);
     } else {
-        m_renderingPreviews.removeAll(frame);
-        m_dirtyRenderingPreviews << frame;
+        if (m_renderingPreviews.removeAll(frame) > 0) {
+            m_dirtyRenderingPreviews << frame;
+            result = true;
+        }
     }
     if (refresh)
         update(frame * m_factor - offset(), MAX_HEIGHT - 3, KdenliveSettings::timelinechunks() * m_factor + 1, 3);
+    return result;
 }
 
 void CustomRuler::updatePreviewDisplay(int start, int end)
@@ -553,9 +557,10 @@ bool CustomRuler::hasPreviewRange() const
     return (!m_dirtyRenderingPreviews.isEmpty() || !m_renderingPreviews.isEmpty());
 }
 
-void CustomRuler::addChunks(QList <int> chunks, bool add)
+QList <int> CustomRuler::addChunks(QList <int> chunks, bool add)
 {
     qSort(chunks);
+    QList <int> toProcess;
     if (add) {
         foreach(int frame, chunks) {
             if (m_renderingPreviews.contains(frame)) {
@@ -569,10 +574,14 @@ void CustomRuler::addChunks(QList <int> chunks, bool add)
         }
     } else {
         foreach(int frame, chunks) {
-            m_renderingPreviews.removeAll(frame);
+            if (m_renderingPreviews.removeAll(frame) > 0) {
+                // A preview file existed for this chunk, ask deletion
+                toProcess << frame;
+            }
             m_dirtyRenderingPreviews.removeAll(frame);
         }
     }
     update(chunks.first() * m_factor - offset(), MAX_HEIGHT - 3, (chunks.last() - chunks.first()) * KdenliveSettings::timelinechunks() * m_factor + 1, 3);
+    return toProcess;
 }
 

src/timeline/customruler.h

@@ -50,12 +50,12 @@ public:
     void updateProjectFps(const Timecode &t);
     void updateFrameSize();
     void activateZone();
-    void updatePreview(int frame, bool rendered = true, bool refresh = false);
+    bool updatePreview(int frame, bool rendered = true, bool refresh = false);
     /** @brief Returns a list of rendered timeline preview chunks */
     const QStringList previewChunks() const;
     /** @brief Returns a list of dirty timeline preview chunks (that need to be generated) */
     const QList <int> getDirtyChunks() const;
-    void addChunks(QList <int> chunks, bool add);
+    QList <int> addChunks(QList <int> chunks, bool add);
     /** @brief Returns true if a timeline preview zone has already be defined */
     bool hasPreviewRange() const;
     /** @brief Refresh timeline preview range */

src/timeline/managers/previewmanager.cpp

+/***************************************************************************
+ *   Copyright (C) 2016 by Jean-Baptiste Mardelle (jb@kdenlive.org)        *
+ *                                                                         *
+ *   This program is free software; you can redistribute it and/or modify  *
+ *   it under the terms of the GNU General Public License as published by  *
+ *   the Free Software Foundation; either version 2 of the License, or     *
+ *   (at your option) any later version.                                   *
+ *                                                                         *
+ *   This program 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 General Public License for more details.                          *
+ *                                                                         *
+ *   You should have received a copy of the GNU General Public License     *
+ *   along with this program; if not, write to the                         *
+ *   Free Software Foundation, Inc.,                                       *
+ *   51 Franklin Street, Fifth Floor, Boston, MA  02110-1301  USA          *
+ ***************************************************************************/
+
+
+#include "previewmanager.h"
+#include "../customruler.h"
+#include "kdenlivesettings.h"
+#include "doc/kdenlivedoc.h"
+
+#include <QtConcurrent>
+#include <QStandardPaths>
+#include <QProcess>
+
+PreviewManager::PreviewManager(KdenliveDoc *doc, CustomRuler *ruler) : QObject()
+    , m_doc(doc)
+    , m_ruler(ruler)
+    , m_initialized(false)
+    , m_abortPreview(false)
+{
+}
+
+PreviewManager::~PreviewManager()
+{
+    if (m_initialized) {
+        abortRendering();
+        m_undoDir.removeRecursively();
+        if (m_cacheDir.entryList(QDir::NoDotAndDotDot).count() == 0) {
+            m_cacheDir.removeRecursively();
+        }
+    }
+}
+
+bool PreviewManager::initialize()
+{
+    QString documentId = m_doc->getDocumentProperty(QStringLiteral("documentid"));
+    m_initialized = true;
+    if (documentId.isEmpty() || documentId.toLong() == 0) {
+        // Something is wrong, documentId should be a number (ms since epoch), abort
+        return false;
+    }
+    QString cacheDir = m_doc->getDocumentProperty(QStringLiteral("cachedir"));
+    if (!cacheDir.isEmpty() && QFile::exists(cacheDir)) {
+        m_cacheDir = QDir(cacheDir);
+    } else {
+        m_cacheDir = QDir(QStandardPaths::writableLocation(QStandardPaths::CacheLocation));
+        m_cacheDir.mkdir(documentId);
+        if (!m_cacheDir.cd(documentId)) {
+            return false;
+        }
+    }
+    if (m_cacheDir.dirName() != documentId || (!m_cacheDir.exists("undo") && !m_cacheDir.mkdir("undo"))) {
+        // TODO: cannot create undo folder, abort
+        return false;
+    }
+    if (!loadParams()) {
+        return false;
+    }
+    m_doc->setDocumentProperty(QStringLiteral("cachedir"), m_cacheDir.absolutePath());
+    m_undoDir = QDir(m_cacheDir.absoluteFilePath("undo"));
+    connect(this, &PreviewManager::cleanupOldPreviews, this, &PreviewManager::doCleanupOldPreviews);
+    connect(m_doc, &KdenliveDoc::removeInvalidUndo, this, &PreviewManager::slotRemoveInvalidUndo);
+    m_previewTimer.setSingleShot(true);
+    m_previewTimer.setInterval(3000);
+    connect(&m_previewTimer, &QTimer::timeout, this, &PreviewManager::startPreviewRender);
+    m_initialized = true;
+    return true;
+}
+
+bool PreviewManager::loadParams()
+{
+    m_extension= m_doc->getDocumentProperty(QStringLiteral("previewextension"));
+    m_consumerParams = m_doc->getDocumentProperty(QStringLiteral("previewparameters")).split(" ");
+
+    if (m_consumerParams.isEmpty() || m_extension.isEmpty()) {
+        m_doc->selectPreviewProfile();
+        m_consumerParams = m_doc->getDocumentProperty(QStringLiteral("previewparameters")).split(" ");
+        m_extension= m_doc->getDocumentProperty(QStringLiteral("previewextension"));
+    }
+    if (m_consumerParams.isEmpty() || m_extension.isEmpty()) {
+        return false;
+    }
+    m_consumerParams << "an=1";
+    return true;
+}
+
+void PreviewManager::invalidatePreviews(QList <int> chunks)
+{
+    // We are not at the bottom of undo stack, chunks have already been archived previously
+    QMutexLocker lock(&m_previewMutex);
+    m_previewTimer.stop();
+    int stackIx = m_doc->commandStack()->index();
+    int stackMax = m_doc->commandStack()->count();
+    abortRendering();
+    if (stackIx == stackMax && !m_undoDir.exists(QString::number(stackIx - 1))) {
+        // We just added a new command in stack, archive existing chunks
+        int ix = stackIx - 1;
+        m_undoDir.mkdir(QString::number(ix));
+        bool foundPreviews = false;
+        foreach(int i, chunks) {
+            QString current = QString("%1.%2").arg(i).arg(m_extension);
+            if (m_cacheDir.rename(current, QString("undo/%1/%2").arg(ix).arg(current))) {
+                foundPreviews = true;
+            }
+        }
+        if (!foundPreviews) {
+            // No preview files found, remove undo folder
+            m_undoDir.rmdir(QString::number(ix));
+        } else {
+            // new chunks archived, cleanup old ones
+            emit cleanupOldPreviews();
+        }
+    } else {
+        // Restore existing chunks, delete others
+        // Check if we just undo the last stack action, then backup, otherwise delete
+        bool lastUndo = false;
+        if (stackIx == stackMax - 1) {
+            if (!m_undoDir.exists(QString::number(stackMax))) {
+                lastUndo = true;
+                bool foundPreviews = false;
+                m_undoDir.mkdir(QString::number(stackMax));
+                foreach(int i, chunks) {
+                    QString current = QString("%1.%2").arg(i).arg(m_extension);
+                    if (m_cacheDir.rename(current, QString("undo/%1/%2").arg(stackMax).arg(current))) {
+                        foundPreviews = true;
+                    }