Rename 'digikam' folder to 'src'

Signed-off-by: Michele Calgaro <michele.calgaro@yahoo.it>

19 files changed, 3157 insertions, 0 deletions

diff --git a/src/libs/threadimageio/Makefile.am b/src/libs/threadimageio/Makefile.am
new file mode 100644
index 00000000..a301012e
--- /dev/null
+++ b/src/libs/threadimageio/Makefile.am
@@ -0,0 +1,23 @@
+METASOURCES = AUTO
+
+noinst_LTLIBRARIES = libthreadimageio.la
+
+libthreadimageio_la_SOURCES = loadsavethread.cpp \
+                              managedloadsavethread.cpp \
+                              sharedloadsavethread.cpp \
+                              previewloadthread.cpp \
+                              loadingdescription.cpp \
+                              loadsavetask.cpp \
+                              previewtask.cpp \
+                              loadingcache.cpp \
+                              loadingcacheinterface.cpp
+
+libthreadimageio_la_LDFLAGS = $(all_libraries) $(KDE_RPATH) $(LIB_TQT) -lDCOP $(LIB_TDECORE) $(LIB_TDEUI) -ltdefx $(LIB_TDEIO) -ltdetexteditor
+
+INCLUDES = -I$(top_srcdir)/src/libs/dimg \
+	       -I$(top_srcdir)/src/libs/dimg/loaders \
+	       -I$(top_srcdir)/src/libs/dmetadata \
+	       $(LIBKEXIV2_CFLAGS) \
+	       -I$(top_srcdir)/src/libs/jpegutils \
+	       -I$(top_srcdir)/src/digikam \
+	       $(LIBKDCRAW_CFLAGS) $(all_includes)
diff --git a/src/libs/threadimageio/loadingcache.cpp b/src/libs/threadimageio/loadingcache.cpp
new file mode 100644
index 00000000..04dd3e4f
--- /dev/null
+++ b/src/libs/threadimageio/loadingcache.cpp
@@ -0,0 +1,256 @@
+/* ============================================================
+ *
+ * This file is a part of digiKam project
+ * http://www.digikam.org
+ *
+ * Date        : 2006-01-11
+ * Description : shared image loading and caching
+ *
+ * Copyright (C) 2005-2007 by Marcel Wiesweg <marcel.wiesweg@gmx.de>
+ *
+ * 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, 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.
+ *
+ * ============================================================ */
+
+// TQt includes.
+
+#include <tqapplication.h>
+#include <tqvariant.h>
+
+// KDE includes.
+
+#include <kdirwatch.h>
+
+// Local includes.
+
+#include "ddebug.h"
+#include "loadingcache.h"
+#include "loadingcache.moc"
+
+namespace Digikam
+{
+
+class LoadingCachePriv
+{
+public:
+
+    TQCache<DImg> imageCache;
+    TQDict<LoadingProcess> loadingDict;
+    TQMutex mutex;
+    TQWaitCondition condVar;
+    KDirWatch *watch;
+    TQStringList watchedFiles;
+};
+
+
+LoadingCache *LoadingCache::m_instance = 0;
+
+LoadingCache *LoadingCache::cache()
+{
+    if (!m_instance)
+        m_instance = new LoadingCache;
+    return m_instance;
+}
+
+void LoadingCache::cleanUp()
+{
+    if (m_instance)
+        delete m_instance;
+}
+
+
+LoadingCache::LoadingCache()
+{
+    d = new LoadingCachePriv;
+
+    d->imageCache.setAutoDelete(true);
+    // default value: 60 MB of cache
+    setCacheSize(60);
+
+    d->watch = new KDirWatch;
+
+    connect(d->watch, TQ_SIGNAL(dirty(const TQString &)),
+            this, TQ_SLOT(slotFileDirty(const TQString &)));
+}
+
+LoadingCache::~LoadingCache()
+{
+    delete d->watch;
+    delete d;
+    m_instance = 0;
+}
+
+DImg *LoadingCache::retrieveImage(const TQString &cacheKey)
+{
+    return d->imageCache.find(cacheKey);
+}
+
+bool LoadingCache::putImage(const TQString &cacheKey, DImg *img, const TQString &filePath)
+{
+    bool successfulyInserted;
+
+    // use size of image as cache cost, take care for wrapped preview TQImages
+    int cost = img->numBytes();
+    TQVariant attribute(img->attribute("previewTQImage"));
+    if (attribute.isValid())
+    {
+        cost = attribute.toImage().numBytes();
+    }
+
+    if ( d->imageCache.insert(cacheKey, img, cost) )
+    {
+        if (!filePath.isEmpty())
+        {
+            // store file path as attribute for our own use
+            img->setAttribute("loadingCacheFilePath", TQVariant(filePath));
+        }
+        successfulyInserted = true;
+    }
+    else
+    {
+        // need to delete object if it was not successfuly inserted (too large)
+        delete img;
+        successfulyInserted = false;
+    }
+
+    if (!filePath.isEmpty())
+    {
+        // schedule update of file watch
+        // KDirWatch can only be accessed from main thread!
+        TQApplication::postEvent(this, new TQCustomEvent(TQEvent::User));
+    }
+    return successfulyInserted;
+}
+
+void LoadingCache::removeImage(const TQString &cacheKey)
+{
+    d->imageCache.remove(cacheKey);
+}
+
+void LoadingCache::removeImages()
+{
+    d->imageCache.clear();
+}
+
+void LoadingCache::slotFileDirty(const TQString &path)
+{
+    // Signal comes from main thread, we need to lock ourselves.
+    CacheLock lock(this);
+    //DDebug() << "LoadingCache slotFileDirty " << path << endl;
+    for (TQCacheIterator<DImg> it(d->imageCache); it.current(); ++it)
+    {
+        if (it.current()->attribute("loadingCacheFilePath").toString() == path)
+        {
+            //DDebug() << " removing watch and cache entry for " << path << endl;
+            d->imageCache.remove(it.currentKey());
+            d->watch->removeFile(path);
+            d->watchedFiles.remove(path);
+        }
+    }
+}
+
+void LoadingCache::customEvent(TQCustomEvent *)
+{
+    // Event comes from main thread, we need to lock ourselves.
+    CacheLock lock(this);
+
+    // get a list of files in cache that need watch
+    TQStringList toBeAdded;
+    TQStringList toBeRemoved = d->watchedFiles;
+    for (TQCacheIterator<DImg> it(d->imageCache); it.current(); ++it)
+    {
+        TQString watchPath = it.current()->attribute("loadingCacheFilePath").toString();
+        if (!watchPath.isEmpty())
+        {
+            if (!d->watchedFiles.contains(watchPath))
+                toBeAdded.append(watchPath);
+            toBeRemoved.remove(watchPath);
+        }
+    }
+
+    for (TQStringList::iterator it = toBeRemoved.begin(); it != toBeRemoved.end(); ++it)
+    {
+        //DDebug() << "removing watch for " << *it << endl;
+        d->watch->removeFile(*it);
+        d->watchedFiles.remove(*it);
+    }
+
+    for (TQStringList::iterator it = toBeAdded.begin(); it != toBeAdded.end(); ++it)
+    {
+        //DDebug() << "adding watch for " << *it << endl;
+        d->watch->addFile(*it);
+        d->watchedFiles.append(*it);
+    }
+
+}
+
+bool LoadingCache::isCacheable(const DImg *img)
+{
+    // return whether image fits in cache
+    return (uint)d->imageCache.maxCost() >= img->numBytes();
+}
+
+void LoadingCache::addLoadingProcess(LoadingProcess *process)
+{
+    d->loadingDict.insert(process->cacheKey(), process);
+}
+
+LoadingProcess *LoadingCache::retrieveLoadingProcess(const TQString &cacheKey)
+{
+    return d->loadingDict.find(cacheKey);
+}
+
+void LoadingCache::removeLoadingProcess(LoadingProcess *process)
+{
+    d->loadingDict.remove(process->cacheKey());
+}
+
+void LoadingCache::notifyNewLoadingProcess(LoadingProcess *process, LoadingDescription description)
+{
+    for (TQDictIterator<LoadingProcess> it(d->loadingDict); it.current(); ++it)
+    {
+        it.current()->notifyNewLoadingProcess(process, description);
+    }
+}
+
+void LoadingCache::setCacheSize(int megabytes)
+{
+    d->imageCache.setMaxCost(megabytes * 1024 * 1024);
+}
+
+//---------------------------------------------------------------------------------------------------
+
+LoadingCache::CacheLock::CacheLock(LoadingCache *cache)
+    : m_cache(cache)
+{
+    m_cache->d->mutex.lock();
+}
+
+LoadingCache::CacheLock::~CacheLock()
+{
+    m_cache->d->mutex.unlock();
+}
+
+void LoadingCache::CacheLock::wakeAll()
+{
+    // obviously the mutex is locked when this function is called
+    m_cache->d->condVar.wakeAll();
+}
+
+void LoadingCache::CacheLock::timedWait()
+{
+    // same as above, the mutex is certainly locked
+    m_cache->d->condVar.wait(&m_cache->d->mutex, 1000);
+}
+
+}   // namespace Digikam
+
diff --git a/src/libs/threadimageio/loadingcache.h b/src/libs/threadimageio/loadingcache.h
new file mode 100644
index 00000000..d4689305
--- /dev/null
+++ b/src/libs/threadimageio/loadingcache.h
@@ -0,0 +1,135 @@
+/* ============================================================
+ *
+ * This file is a part of digiKam project
+ * http://www.digikam.org
+ *
+ * Date        : 2006-01-11
+ * Description : shared image loading and caching
+ *
+ * Copyright (C) 2005-2007 by Marcel Wiesweg <marcel.wiesweg@gmx.de>
+ *
+ * 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, 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.
+ *
+ * ============================================================ */
+
+#ifndef LOADING_CACHE_H
+#define LOADING_CACHE_H
+
+#include <tqptrlist.h>
+#include <tqcache.h>
+#include <tqdict.h>
+#include <tqmutex.h>
+
+#include "dimg.h"
+#include "loadsavethread.h"
+
+namespace Digikam
+{
+
+class LoadingProcessListener
+{
+public:
+
+    virtual bool querySendNotifyEvent() = 0;
+    virtual TQObject *eventReceiver() = 0;
+    virtual LoadSaveThread::AccessMode accessMode() = 0;
+
+};
+
+class LoadingProcess
+{
+public:
+
+    virtual bool completed() = 0;
+    virtual TQString filePath() = 0;
+    virtual TQString cacheKey() = 0;
+    virtual void addListener(LoadingProcessListener *listener) = 0;
+    virtual void removeListener(LoadingProcessListener *listener) = 0;
+    virtual void notifyNewLoadingProcess(LoadingProcess *process, LoadingDescription description) = 0;
+
+};
+
+class LoadingCachePriv;
+
+class LoadingCache : public TQObject
+{
+
+    TQ_OBJECT
+  
+
+public:
+
+    static LoadingCache *cache();
+    static void cleanUp();
+    ~LoadingCache();
+
+    // all functions shall only be called when a CacheLock is held
+    class CacheLock
+    {
+    public:
+        CacheLock(LoadingCache *cache);
+        ~CacheLock();
+        void wakeAll();
+        void timedWait();
+    private:
+        LoadingCache *m_cache;
+    };
+
+    // Retrieves an image for the given string from the cache,
+    // or 0 if no image is found.
+    DImg *retrieveImage(const TQString &cacheKey);
+    // Returns whether the given DImg fits in the cache.
+    bool isCacheable(const DImg *img);
+    // Put image into for given string into the cache.
+    // Returns true if image has been put in the cache, false otherwise.
+    // Ownership of the DImg instance is passed to the cache.
+    // When it cannot be put in the cache it is deleted.
+    // The third parameter specifies a file path that will be watched.
+    // If this file changes, the object will be removed from the cache.
+    bool putImage(const TQString &cacheKey, DImg *img, const TQString &filePath);
+    void removeImage(const TQString &cacheKey);
+    void removeImages();
+
+    // Find the loading process for given cacheKey, or 0 if not found
+    LoadingProcess *retrieveLoadingProcess(const TQString &cacheKey);
+    // Add a loading process to the list. Only one loading process
+    // for the same cache key is registered at a time.
+    void addLoadingProcess(LoadingProcess *process);
+    // Remove loading process for given cache key
+    void removeLoadingProcess(LoadingProcess *process);
+    // Notify all currently registered loading processes
+    void notifyNewLoadingProcess(LoadingProcess *process, LoadingDescription description);
+
+    void setCacheSize(int megabytes);
+
+protected:
+
+    virtual void customEvent (TQCustomEvent *event);
+
+private slots:
+
+    void slotFileDirty(const TQString &path);
+
+private:
+
+    static LoadingCache *m_instance;
+
+    LoadingCache();
+
+    friend class CacheLock;
+    LoadingCachePriv *d;
+
+};
+
+}   // namespace Digikam
+
+#endif
diff --git a/src/libs/threadimageio/loadingcacheinterface.cpp b/src/libs/threadimageio/loadingcacheinterface.cpp
new file mode 100644
index 00000000..8cfa5ab9
--- /dev/null
+++ b/src/libs/threadimageio/loadingcacheinterface.cpp
@@ -0,0 +1,73 @@
+/* ============================================================
+ *
+ * This file is a part of digiKam project
+ * http://www.digikam.org
+ *
+ * Date        : 2006-02-06
+ * Description : shared image loading and caching
+ *
+ * Copyright (C) 2005-2007 by Marcel Wiesweg <marcel.wiesweg@gmx.de>
+ *
+ * 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, 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.
+ *
+ * ============================================================ */
+
+
+#include "loadingcacheinterface.h"
+#include "loadingcache.h"
+
+namespace Digikam
+{
+
+void LoadingCacheInterface::cleanUp()
+{
+    LoadingCache::cleanUp();
+}
+
+void LoadingCacheInterface::cleanFromCache(const TQString &filePath)
+{
+    LoadingCache *cache = LoadingCache::cache();
+    LoadingCache::CacheLock lock(cache);
+    TQStringList possibleCacheKeys = LoadingDescription::possibleCacheKeys(filePath);
+    for (TQStringList::iterator it = possibleCacheKeys.begin(); it != possibleCacheKeys.end(); ++it)
+    {
+        cache->removeImage(*it);
+    }
+}
+
+void LoadingCacheInterface::cleanCache()
+{
+    LoadingCache *cache = LoadingCache::cache();
+    LoadingCache::CacheLock lock(cache);
+    cache->removeImages();
+}
+
+void LoadingCacheInterface::putImage(const TQString &filePath, const DImg &img)
+{
+    LoadingCache *cache = LoadingCache::cache();
+    LoadingCache::CacheLock lock(cache);
+    if (cache->isCacheable(&img))
+    {
+        DImg *copy = new DImg(img);
+        copy->detach();
+        cache->putImage(filePath, copy, filePath);
+    }
+}
+
+void LoadingCacheInterface::setCacheOptions(int cacheSize)
+{
+    LoadingCache *cache = LoadingCache::cache();
+    LoadingCache::CacheLock lock(cache);
+    cache->setCacheSize(cacheSize);
+}
+
+}   // namespace Digikam
diff --git a/src/libs/threadimageio/loadingcacheinterface.h b/src/libs/threadimageio/loadingcacheinterface.h
new file mode 100644
index 00000000..ab3f4eca
--- /dev/null
+++ b/src/libs/threadimageio/loadingcacheinterface.h
@@ -0,0 +1,56 @@
+/* ============================================================
+ *
+ * This file is a part of digiKam project
+ * http://www.digikam.org
+ *
+ * Date        : 2006-02-06
+ * Description : shared image loading and caching
+ *
+ * Copyright (C) 2005-2007 by Marcel Wiesweg <marcel.wiesweg@gmx.de>
+ *
+ * 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, 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.
+ *
+ * ============================================================ */
+
+#ifndef LOADING_CACHE_INTERFACE_H
+#define LOADING_CACHE_INTERFACE_H
+
+#include <tqstring.h>
+
+#include "digikam_export.h"
+#include "dimg.h"
+
+namespace Digikam
+{
+
+class DIGIKAM_EXPORT LoadingCacheInterface
+{
+public:
+    // clean up cache at shutdown
+    static void cleanUp();
+    // remove an image from the cache
+    // (e.g. when image has changed on disk)
+    static void cleanFromCache(const TQString &filePath);
+    // remove all images from the cache
+    // (e.g. when loading settings changed)
+    static void cleanCache();
+    // add a copy of the image to cache
+    static void putImage(const TQString &filePath, const DImg &img);
+    // Set cache size in Megabytes.
+    // Set to 0 to disable caching.
+    static void setCacheOptions(int cacheSize);
+};
+
+}   // namespace Digikam
+
+#endif
+
diff --git a/src/libs/threadimageio/loadingdescription.cpp b/src/libs/threadimageio/loadingdescription.cpp
new file mode 100644
index 00000000..423ee99c
--- /dev/null
+++ b/src/libs/threadimageio/loadingdescription.cpp
@@ -0,0 +1,152 @@
+/* ============================================================
+ *
+ * This file is a part of digiKam project
+ * http://www.digikam.org
+ *
+ * Date        : 2007-02-03
+ * Description : Loading parameters for multithreaded loading
+ *
+ * Copyright (C) 2006-2007 by Marcel Wiesweg <marcel.wiesweg@gmx.de>
+ *
+ * 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, 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.
+ *
+ * ============================================================ */
+
+// Local includes.
+
+#include "loadingdescription.h"
+
+namespace Digikam
+{
+
+bool LoadingDescription::PreviewParameters::operator==(const PreviewParameters &other) const
+{
+    return isPreview  == other.isPreview
+            && size       == other.size
+            && exifRotate == other.exifRotate;
+}
+
+LoadingDescription::LoadingDescription(const TQString &filePath)
+    : filePath(filePath)
+{
+    rawDecodingSettings = DRawDecoding();
+}
+
+LoadingDescription::LoadingDescription(const TQString &filePath, DRawDecoding settings)
+    : filePath(filePath), rawDecodingSettings(settings)
+{
+}
+
+LoadingDescription::LoadingDescription(const TQString &filePath, int size, bool exifRotate)
+    : filePath(filePath)
+{
+    rawDecodingSettings = DRawDecoding();
+    previewParameters.isPreview  = false;
+    previewParameters.size       = size;
+    previewParameters.exifRotate = exifRotate;
+}
+
+TQString LoadingDescription::cacheKey() const
+{
+    // Here we have the knowledge which LoadingDescriptions / RawFileDecodingSettings
+    // must be cached separately.
+    // Current assumption:
+    // Eight-bit images are needed for LightTable, and if 16-bit is enabled,
+    // 16-bit half size images for the histogram sidebar,
+    // and 16-bit full size images for the image editor.
+    // Use previewParameters.size, not isPreview - if it is 0, full loading is used.
+
+    TQString suffix = rawDecodingSettings.sixteenBitsImage ? "-16" : "-8";
+
+    if (rawDecodingSettings.halfSizeColorImage)
+        return filePath + suffix + "-halfSizeColorImage";
+    else if (previewParameters.size)
+        return filePath + suffix + "-previewImage";
+    else
+        return filePath + suffix;
+}
+
+TQStringList LoadingDescription::lookupCacheKeys() const
+{
+    // Build a hierarchy which cache entries may be used for this LoadingDescription.
+    // Typically, the first is the best, but an actual loading operation may use a
+    // lower-quality loading and will effectively only add the last entry of the
+    // list to the cache, although it can accept the first if already available.
+    // Sixteen-bit images cannot be used used instead of eight-bit ones because
+    // color management is needed to display them.
+
+    TQString suffix = rawDecodingSettings.sixteenBitsImage ? "-16" : "-8";
+
+    TQStringList keys;
+    keys.append(filePath + suffix);
+    if (rawDecodingSettings.halfSizeColorImage)
+        keys.append(filePath + suffix + "-halfSizeColorImage");
+    if (previewParameters.size)
+        keys.append(filePath + suffix + "-previewImage");
+    return keys;
+}
+
+bool LoadingDescription::isReducedVersion() const
+{
+    // return true if this loads anything but the full version
+    return rawDecodingSettings.halfSizeColorImage
+        || previewParameters.isPreview;
+}
+
+bool LoadingDescription::operator==(const LoadingDescription &other) const
+{
+    return filePath == other.filePath &&
+            rawDecodingSettings == other.rawDecodingSettings &&
+            previewParameters == other.previewParameters;
+}
+
+bool LoadingDescription::equalsIgnoreReducedVersion(const LoadingDescription &other) const
+{
+    return filePath == other.filePath;
+}
+
+bool LoadingDescription::equalsOrBetterThan(const LoadingDescription &other) const
+{
+    // This method is similar to operator==. But it returns true as well if other
+    // Loads a "better" version than this.
+    // Preview parameters must have the same size, or other has no size restriction.
+    // All raw decoding settings must be equal, only the half size parameter is allowed to vary.
+
+    DRawDecoding fullSize = other.rawDecodingSettings;
+    fullSize.halfSizeColorImage = false;
+
+    return filePath == other.filePath &&
+            (
+             rawDecodingSettings == other.rawDecodingSettings ||
+             rawDecodingSettings == fullSize
+            ) &&
+            (
+             (previewParameters.size == other.previewParameters.size) ||
+              other.previewParameters.size
+            );
+}
+
+TQStringList LoadingDescription::possibleCacheKeys(const TQString &filePath)
+{
+    TQStringList keys;
+    keys.append(filePath + "-16");
+    keys.append(filePath + "-16-halfSizeColorImage");
+    keys.append(filePath + "-16-previewImage");
+    keys.append(filePath + "-8");
+    keys.append(filePath + "-8-halfSizeColorImage");
+    keys.append(filePath + "-8-previewImage");
+    return keys;
+}
+
+
+} // namespace Digikam
+
diff --git a/src/libs/threadimageio/loadingdescription.h b/src/libs/threadimageio/loadingdescription.h
new file mode 100644
index 00000000..848f2b17
--- /dev/null
+++ b/src/libs/threadimageio/loadingdescription.h
@@ -0,0 +1,135 @@
+/* ============================================================
+ *
+ * This file is a part of digiKam project
+ * http://www.digikam.org
+ *
+ * Date        : 2006-01-16
+ * Description : image file IO threaded interface.
+ *
+ * Copyright (C) 2006-2007 by Marcel Wiesweg <marcel.wiesweg@gmx.de>
+ *
+ * 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, 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.
+ *
+ * ============================================================ */
+
+#ifndef LOADING_DESCRIPTION_H
+#define LOADING_DESCRIPTION_H
+
+// Digikam includes.
+
+#include "dimg.h"
+#include "digikam_export.h"
+
+namespace Digikam
+{
+
+class DIGIKAM_EXPORT LoadingDescription
+{
+public:
+
+    class PreviewParameters
+    {
+    public:
+        PreviewParameters()
+        {
+            isPreview  = false;
+            size       = 0;
+            exifRotate = false;
+        }
+
+        bool isPreview;
+        int  size;
+        bool exifRotate;
+
+        bool operator==(const PreviewParameters &other) const;
+    };
+
+    /**
+     * An invalid LoadingDescription
+     */
+    LoadingDescription()
+    {
+    }
+
+    /**
+     * Use this for files that are not raw files.
+     * Stores only the filePath.
+     */
+    LoadingDescription(const TQString &filePath);
+
+    /**
+     * For raw files:
+     * Stores filePath and RawDecodingSettings
+     */
+    LoadingDescription(const TQString &filePath, DRawDecoding settings);
+
+    /**
+     * For preview jobs:
+     * Stores preview max size and exif rotation.
+     * Exif Rotation:
+     *    The exif rotation is only a hint.
+     *    Call LoadSaveThread::exifRotate to make sure that the image is really
+     *    rotated. It is safe to call this method even if the image is rotated.
+     * Raw files:
+     *    If size is not 0, the embedded preview will be loaded if available.
+     *    If size is 0, DImg based loading will be used with default raw decoding settings.
+     */
+    LoadingDescription(const TQString &filePath, int size, bool exifRotate);
+
+    TQString                          filePath;
+    DRawDecoding rawDecodingSettings;
+    PreviewParameters                previewParameters;
+
+    /**
+     * Return the cache key this description shall be stored as
+     */
+    TQString             cacheKey() const;
+    /**
+     * Return all possible cache keys, starting with the best choice,
+     * for which a result may be found in the cache for this description.
+     * Included in the list are better quality versions, if this description is reduced.
+     */
+    TQStringList         lookupCacheKeys() const;
+    /**
+     * Returns whether this description describes a loading operation which
+     * loads the image in a reduced version (quality, size etc.)
+     */
+    bool                isReducedVersion() const;
+
+    /**
+     * Returns whether the other loading task equals this one
+     */
+    bool operator==(const LoadingDescription &other) const;
+    bool operator!=(const LoadingDescription &other) const
+        { return !operator==(other); }
+    /**
+     * Returns whether the other loading task equals this one
+     * ignoring parameters used to specify a reduced version.
+     */
+    bool equalsIgnoreReducedVersion(const LoadingDescription &other) const;
+
+    /**
+     * Returns whether this loading task equals the other one
+     * or is superior to it, if the other one is a reduced version
+     */
+    bool equalsOrBetterThan(const LoadingDescription &other) const;
+
+    /**
+     * Returns all possible cacheKeys for the given file path
+     * (all cache keys under which the given file could be stored in the cache).
+     */
+    static TQStringList possibleCacheKeys(const TQString &filePath);
+};
+
+}   // namespace Digikam
+
+#endif // LOADING_DESCRIPTION_H
diff --git a/src/libs/threadimageio/loadsavetask.cpp b/src/libs/threadimageio/loadsavetask.cpp
new file mode 100644
index 00000000..6879e533
--- /dev/null
+++ b/src/libs/threadimageio/loadsavetask.cpp
@@ -0,0 +1,424 @@
+/* ============================================================
+ *
+ * This file is a part of digiKam project
+ * http://www.digikam.org
+ *
+ * Date        : 2005-12-17
+ * Description : image file IO threaded interface.
+ *
+ * Copyright (C) 2005-2007 by Marcel Wiesweg <marcel.wiesweg@gmx.de>
+ * Copyright (C) 2005-2007 by Gilles Caulier <caulier dot gilles at gmail dot com>
+ *
+ * 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, 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.
+ *
+ * ============================================================ */
+
+#include "loadsavetask.h"
+
+// TQt includes.
+
+#include <tqapplication.h>
+
+// Local includes.
+
+#include "ddebug.h"
+#include "loadsavethread.h"
+#include "managedloadsavethread.h"
+#include "sharedloadsavethread.h"
+#include "loadingcache.h"
+
+namespace Digikam
+{
+
+void LoadingProgressEvent::notify(LoadSaveThread *thread)
+{
+    thread->loadingProgress(m_loadingDescription, m_progress);
+}
+
+void SavingProgressEvent::notify(LoadSaveThread *thread)
+{
+    thread->savingProgress(m_filePath, m_progress);
+}
+
+void StartedLoadingEvent::notify(LoadSaveThread *thread)
+{
+    thread->imageStartedLoading(m_loadingDescription);
+}
+
+void StartedSavingEvent::notify(LoadSaveThread *thread)
+{
+    thread->imageStartedSaving(m_filePath);
+}
+
+void LoadedEvent::notify(LoadSaveThread *thread)
+{
+    thread->imageLoaded(m_loadingDescription, m_img);
+}
+
+void MoreCompleteLoadingAvailableEvent::notify(LoadSaveThread *thread)
+{
+    thread->moreCompleteLoadingAvailable(m_oldDescription, m_newDescription);
+}
+
+void SavedEvent::notify(LoadSaveThread *thread)
+{
+    thread->imageSaved(m_filePath, m_success);
+}
+
+//---------------------------------------------------------------------------------------------------
+
+void LoadingTask::execute()
+{
+    if (m_loadingTaskStatus == LoadingTaskStatusStopping)
+        return;
+    DImg img(m_loadingDescription.filePath, this, m_loadingDescription.rawDecodingSettings);
+    m_thread->taskHasFinished();
+    TQApplication::postEvent(m_thread, new LoadedEvent(m_loadingDescription.filePath, img));
+}
+
+LoadingTask::TaskType LoadingTask::type()
+{
+    return TaskTypeLoading;
+}
+
+void LoadingTask::progressInfo(const DImg *, float progress)
+{
+    if (m_loadingTaskStatus == LoadingTaskStatusLoading)
+    {
+        if (m_thread->querySendNotifyEvent())
+            TQApplication::postEvent(m_thread, new LoadingProgressEvent(m_loadingDescription.filePath, progress));
+    }
+}
+
+bool LoadingTask::continueQuery(const DImg *)
+{
+    return m_loadingTaskStatus != LoadingTaskStatusStopping;
+}
+
+void LoadingTask::setStatus(LoadingTaskStatus status)
+{
+    m_loadingTaskStatus = status;
+}
+
+
+// This is a hack needed to prevent hanging when a TDEProcess-based loader (raw loader)
+// is waiting for the process to finish, but the main thread is waiting
+// for the thread to finish and no TDEProcess events are delivered.
+// Remove when porting to TQt4.
+bool LoadingTask::isShuttingDown()
+{
+    return m_thread->isShuttingDown();
+}
+
+//---------------------------------------------------------------------------------------------------
+
+void SharedLoadingTask::execute()
+{
+    if (m_loadingTaskStatus == LoadingTaskStatusStopping)
+        return;
+    // send StartedLoadingEvent from each single Task, not via LoadingProcess list
+    TQApplication::postEvent(m_thread, new StartedLoadingEvent(m_loadingDescription.filePath));
+
+    LoadingCache *cache = LoadingCache::cache();
+    {
+        LoadingCache::CacheLock lock(cache);
+
+        // find possible cached images
+        DImg *cachedImg = 0;
+        TQStringList lookupKeys = m_loadingDescription.lookupCacheKeys();
+        for ( TQStringList::Iterator it = lookupKeys.begin(); it != lookupKeys.end(); ++it ) {
+            if ( (cachedImg = cache->retrieveImage(*it)) )
+                break;
+        }
+
+        if (cachedImg)
+        {
+            // image is found in image cache, loading is successful
+            DImg img(*cachedImg);
+            if (accessMode() == LoadSaveThread::AccessModeReadWrite)
+                img = img.copy();
+            TQApplication::postEvent(m_thread, new LoadedEvent(m_loadingDescription.filePath, img));
+            return;
+        }
+        else
+        {
+            // find possible running loading process
+            m_usedProcess = 0;
+            for ( TQStringList::Iterator it = lookupKeys.begin(); it != lookupKeys.end(); ++it ) {
+                if ( (m_usedProcess = cache->retrieveLoadingProcess(*it)) )
+                {
+                    break;
+                }
+            }
+
+            if (m_usedProcess)
+            {
+                // Other process is right now loading this image.
+                // Add this task to the list of listeners and
+                // attach this thread to the other thread, wait until loading
+                // has finished.
+                m_usedProcess->addListener(this);
+                // break loop when either the loading has completed, or this task is being stopped
+                while ( !m_usedProcess->completed() && m_loadingTaskStatus != LoadingTaskStatusStopping )
+                    lock.timedWait();
+                // remove listener from process
+                m_usedProcess->removeListener(this);
+                // wake up the process which is waiting until all listeners have removed themselves
+                lock.wakeAll();
+                // set to 0, as checked in setStatus
+                m_usedProcess = 0;
+                //DDebug() << "SharedLoadingTask " << this << ": waited" << endl;
+                return;
+            }
+            else
+            {
+                // Neither in cache, nor currently loading in different thread.
+                // Load it here and now, add this LoadingProcess to cache list.
+                cache->addLoadingProcess(this);
+                // Add this to the list of listeners
+                addListener(this);
+                // for use in setStatus
+                m_usedProcess = this;
+                // Notify other processes that we are now loading this image.
+                // They might be interested - see notifyNewLoadingProcess below
+                cache->notifyNewLoadingProcess(this, m_loadingDescription);
+            }
+        }
+    }
+
+    // load image
+    DImg img(m_loadingDescription.filePath, this, m_loadingDescription.rawDecodingSettings);
+
+    bool isCached = false;
+    {
+        LoadingCache::CacheLock lock(cache);
+        // put (valid) image into cache of loaded images
+        if (!img.isNull())
+            isCached = cache->putImage(m_loadingDescription.cacheKey(), new DImg(img), m_loadingDescription.filePath);
+        // remove this from the list of loading processes in cache
+        cache->removeLoadingProcess(this);
+    }
+
+    // following the golden rule to avoid deadlocks, do this when CacheLock is not held
+    m_thread->taskHasFinished();
+
+    {
+        LoadingCache::CacheLock lock(cache);
+        //DDebug() << "SharedLoadingTask " << this << ": image loaded, " << img.isNull() << endl;
+        // indicate that loading has finished so that listeners can stop waiting
+        m_completed = true;
+
+        // Optimize so that no unnecessary copying is done.
+        // If image has been put in cache, the initial copy has been consumed for this.
+        // If image is too large for cache, the initial copy is still available.
+        bool usedInitialCopy = isCached;
+        // dispatch image to all listeners, including this
+        for (LoadingProcessListener *l = m_listeners.first(); l; l = m_listeners.next())
+        {
+            // This code sends a copy only when ReadWrite access is requested.
+            // Otherwise, the image from the cache is sent.
+            // As the image in the cache will be deleted from any thread, the explicit sharing
+            // needs to be thread-safe to avoid the risk of memory leaks.
+            // This is the case only for TQt4, so uncomment this code when porting.
+            /*
+            if (l->accessMode() == LoadSaveThread::AccessModeReadWrite)
+            {
+                // If a listener requested ReadWrite access, it gets a deep copy.
+                // DImg is explicitly shared.
+                DImg copy = img.copy();
+                TQApplication::postEvent(l->eventReceiver(), new LoadedEvent(m_loadingDescription.filePath, copy));
+            }
+            else
+                TQApplication::postEvent(l->eventReceiver(), new LoadedEvent(m_loadingDescription.filePath, img));
+            */
+            // TQt3: The same copy for all Read listeners (it is assumed that they will delete it only in the main thread),
+            // an extra copy for each ReadWrite listener
+            DImg readerCopy;
+            if (l->accessMode() == LoadSaveThread::AccessModeReadWrite)
+            {
+                // If a listener requested ReadWrite access, it gets a deep copy.
+                // DImg is explicitly shared.
+                DImg copy;
+                if (usedInitialCopy)
+                {
+                    copy = img.copy();
+                }
+                else
+                {
+                    copy = img;
+                    usedInitialCopy = true;
+                }
+                TQApplication::postEvent(l->eventReceiver(), new LoadedEvent(m_loadingDescription, copy));
+            }
+            else
+            {
+                if (readerCopy.isNull())
+                {
+                    if (usedInitialCopy)
+                    {
+                        readerCopy = img.copy();
+                    }
+                    else
+                    {
+                        readerCopy = img;
+                        usedInitialCopy = true;
+                    }
+                }
+                TQApplication::postEvent(l->eventReceiver(), new LoadedEvent(m_loadingDescription, readerCopy));
+            }
+        }
+
+        // remove myself from list of listeners
+        removeListener(this);
+        // wake all listeners waiting on cache condVar, so that they remove themselves
+        lock.wakeAll();
+        // wait until all listeners have removed themselves
+        while (m_listeners.count() != 0)
+            lock.timedWait();
+        // set to 0, as checked in setStatus
+        m_usedProcess = 0;
+    }
+}
+
+void SharedLoadingTask::progressInfo(const DImg *, float progress)
+{
+    if (m_loadingTaskStatus == LoadingTaskStatusLoading)
+    {
+        LoadingCache *cache = LoadingCache::cache();
+        LoadingCache::CacheLock lock(cache);
+
+        for (LoadingProcessListener *l = m_listeners.first(); l; l = m_listeners.next())
+        {
+            if (l->querySendNotifyEvent())
+                TQApplication::postEvent(l->eventReceiver(), new LoadingProgressEvent(m_loadingDescription, progress));
+        }
+    }
+}
+
+bool SharedLoadingTask::continueQuery(const DImg *)
+{
+    // If this is called, the thread is currently loading an image.
+    // In shared loading, we cannot stop until all listeners have been removed as well
+    return (m_loadingTaskStatus != LoadingTaskStatusStopping) || (m_listeners.count() != 0);
+}
+
+void SharedLoadingTask::setStatus(LoadingTaskStatus status)
+{
+    m_loadingTaskStatus = status;
+    if (m_loadingTaskStatus == LoadingTaskStatusStopping)
+    {
+        LoadingCache *cache = LoadingCache::cache();
+        LoadingCache::CacheLock lock(cache);
+
+        // check for m_usedProcess, to avoid race condition that it has finished before
+        if (m_usedProcess)
+        {
+            // remove this from list of listeners - check in continueQuery() of active thread
+            m_usedProcess->removeListener(this);
+            // wake all listeners - particularly this - from waiting on cache condvar
+            lock.wakeAll();
+        }
+    }
+}
+
+bool SharedLoadingTask::completed()
+{
+    return m_completed;
+}
+
+TQString SharedLoadingTask::filePath()
+{
+    return m_loadingDescription.filePath;
+}
+
+TQString SharedLoadingTask::cacheKey()
+{
+    return m_loadingDescription.cacheKey();
+}
+
+void SharedLoadingTask::addListener(LoadingProcessListener *listener)
+{
+    m_listeners.append(listener);
+}
+
+void SharedLoadingTask::removeListener(LoadingProcessListener *listener)
+{
+    m_listeners.remove(listener);
+}
+
+void SharedLoadingTask::notifyNewLoadingProcess(LoadingProcess *process, LoadingDescription description)
+{
+    // Ok, we are notified that another task has been started in another thread.
+    // We are of course only interested if the task loads the same file,
+    // and we are right now loading a reduced version, and the other task is loading the full version.
+    // In this case, we notify our own thread (a signal to the API user is emitted) of this.
+    // The fact that we are receiving the method call shows that this task is registered with the LoadingCache,
+    // somewhere in between the calls to addLoadingProcess(this) and removeLoadingProcess(this) above.
+    if (process != this &&
+        m_loadingDescription.isReducedVersion() &&
+        m_loadingDescription.equalsIgnoreReducedVersion(description) &&
+        !description.isReducedVersion()
+       )
+    {
+        for (LoadingProcessListener *l = m_listeners.first(); l; l = m_listeners.next())
+        {
+            TQApplication::postEvent(l->eventReceiver(), new MoreCompleteLoadingAvailableEvent(m_loadingDescription, description));
+        }
+    }
+}
+
+bool SharedLoadingTask::querySendNotifyEvent()
+{
+    return m_thread->querySendNotifyEvent();
+}
+
+TQObject *SharedLoadingTask::eventReceiver()
+{
+    return m_thread;
+}
+
+LoadSaveThread::AccessMode SharedLoadingTask::accessMode()
+{
+    return m_accessMode;
+}
+
+//---------------------------------------------------------------------------------------------------
+
+void SavingTask::execute()
+{
+    bool success = m_img.save(m_filePath, m_format, this);
+    m_thread->taskHasFinished();
+    TQApplication::postEvent(m_thread, new SavedEvent(m_filePath, success));
+};
+
+LoadingTask::TaskType SavingTask::type()
+{
+    return TaskTypeSaving;
+}
+
+void SavingTask::progressInfo(const DImg *, float progress)
+{
+    if (m_thread->querySendNotifyEvent())
+        TQApplication::postEvent(m_thread, new SavingProgressEvent(m_filePath, progress));
+}
+
+bool SavingTask::continueQuery(const DImg *)
+{
+    return m_savingTaskStatus != SavingTaskStatusStopping;
+}
+
+void SavingTask::setStatus(SavingTaskStatus status)
+{
+    m_savingTaskStatus = status;
+}
+
+}   //namespace Digikam
diff --git a/src/libs/threadimageio/loadsavetask.h b/src/libs/threadimageio/loadsavetask.h
new file mode 100644
index 00000000..833f86fa
--- /dev/null
+++ b/src/libs/threadimageio/loadsavetask.h
@@ -0,0 +1,360 @@
+/* ============================================================
+ *
+ * This file is a part of digiKam project
+ * http://www.digikam.org
+ *
+ * Date        : 2006-01-20
+ * Description : image file IO threaded interface.
+ *
+ * Copyright (C) 2005-2007 by Marcel Wiesweg <marcel.wiesweg@gmx.de>
+ * Copyright (C) 2005-2007 by Gilles Caulier <caulier dot gilles at gmail dot com>
+ *
+ * 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, 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.
+ *
+ * ============================================================ */
+
+
+#ifndef LOAD_SAVE_TASK_H
+#define LOAD_SAVE_TASK_H
+
+// TQt includes.
+
+#include <tqevent.h>
+
+// Local includes.
+
+#include "dimg.h"
+#include "dimgloaderobserver.h"
+#include "loadingdescription.h"
+#include "loadingcache.h"
+
+namespace Digikam
+{
+
+class LoadSaveThread;
+
+class LoadSaveTask
+{
+public:
+
+    LoadSaveTask(LoadSaveThread* thread)
+        : m_thread(thread)
+        {};
+    virtual ~LoadSaveTask() {};
+
+    virtual void execute() = 0;
+
+    enum TaskType
+    {
+        TaskTypeLoading,
+        TaskTypeSaving
+    };
+
+    virtual TaskType type() = 0;
+
+protected:
+
+    LoadSaveThread *m_thread;
+};
+
+//---------------------------------------------------------------------------------------------------
+
+class NotifyEvent : public TQCustomEvent
+{
+public:
+
+    static TQEvent::Type notifyEventId()
+        { return TQEvent::User; };
+
+    NotifyEvent() : TQCustomEvent(notifyEventId()) {};
+
+    virtual void notify(LoadSaveThread *thread) = 0;
+};
+
+//---------------------------------------------------------------------------------------------------
+
+class ProgressEvent : public NotifyEvent
+{
+public:
+
+    ProgressEvent(float progress)
+        : m_progress(progress)
+        {};
+
+protected:
+
+    float m_progress;
+};
+
+//---------------------------------------------------------------------------------------------------
+
+class LoadingProgressEvent : public ProgressEvent
+{
+public:
+
+    LoadingProgressEvent(const LoadingDescription &loadingDescription, float progress)
+        : ProgressEvent(progress),
+          m_loadingDescription(loadingDescription)
+        {};
+
+    virtual void notify(LoadSaveThread *thread);
+
+private:
+
+    LoadingDescription m_loadingDescription;
+};
+
+//---------------------------------------------------------------------------------------------------
+
+class SavingProgressEvent : public ProgressEvent
+{
+public:
+
+    SavingProgressEvent(const TQString& filePath, float progress)
+        : ProgressEvent(progress),
+          m_filePath(filePath)
+        {};
+
+    virtual void notify(LoadSaveThread *thread);
+
+private:
+
+    TQString m_filePath;
+};
+
+//---------------------------------------------------------------------------------------------------
+
+class StartedLoadingEvent : public NotifyEvent
+{
+public:
+
+    StartedLoadingEvent(const LoadingDescription &loadingDescription)
+        : m_loadingDescription(loadingDescription)
+        {};
+
+    virtual void notify(LoadSaveThread *thread);
+
+private:
+
+    LoadingDescription m_loadingDescription;
+};
+
+//---------------------------------------------------------------------------------------------------
+
+class StartedSavingEvent : public NotifyEvent
+{
+public:
+
+    StartedSavingEvent(const TQString& filePath)
+    : m_filePath(filePath)
+    {};
+
+    virtual void notify(LoadSaveThread *thread);
+
+private:
+
+    TQString m_filePath;
+};
+
+//---------------------------------------------------------------------------------------------------
+
+class LoadedEvent : public NotifyEvent
+{
+public:
+
+    LoadedEvent(const LoadingDescription &loadingDescription, DImg &img)
+        : m_loadingDescription(loadingDescription), m_img(img)
+        {};
+
+    virtual void notify(LoadSaveThread *thread);
+
+private:
+
+    LoadingDescription m_loadingDescription;
+    DImg    m_img;
+};
+
+//---------------------------------------------------------------------------------------------------
+
+class MoreCompleteLoadingAvailableEvent : public NotifyEvent
+{
+public:
+
+    MoreCompleteLoadingAvailableEvent(const LoadingDescription &oldLoadingDescription,
+                                      const LoadingDescription &newLoadingDescription)
+        : m_oldDescription(oldLoadingDescription), m_newDescription(newLoadingDescription)
+        {};
+
+    virtual void notify(LoadSaveThread *thread);
+
+private:
+
+    LoadingDescription m_oldDescription;
+    LoadingDescription m_newDescription;
+};
+
+//---------------------------------------------------------------------------------------------------
+
+class LoadingTask : public LoadSaveTask, public DImgLoaderObserver
+{
+public:
+
+    enum LoadingTaskStatus
+    {
+        LoadingTaskStatusLoading,
+        LoadingTaskStatusPreloading,
+        LoadingTaskStatusStopping
+    };
+
+    LoadingTask(LoadSaveThread* thread, LoadingDescription description,
+                LoadingTaskStatus loadingTaskStatus = LoadingTaskStatusLoading)
+        : LoadSaveTask(thread), m_loadingDescription(description), m_loadingTaskStatus(loadingTaskStatus)
+        {}
+
+    // LoadSaveTask
+
+    virtual void execute();
+    virtual TaskType type();
+
+    // DImgLoaderObserver
+
+    virtual void progressInfo(const DImg *, float progress);
+    virtual bool continueQuery(const DImg *);
+    virtual bool isShuttingDown();
+
+    virtual void setStatus(LoadingTaskStatus status);
+
+    LoadingTaskStatus status() const
+    {
+        return m_loadingTaskStatus;
+    }
+
+    TQString filePath() const
+    {
+        return m_loadingDescription.filePath;
+    }
+
+    LoadingDescription loadingDescription() const
+    {
+        return m_loadingDescription;
+    }
+
+protected:
+
+    LoadingDescription m_loadingDescription;
+    LoadingTaskStatus m_loadingTaskStatus;
+};
+
+//---------------------------------------------------------------------------------------------------
+
+class SharedLoadingTask : public LoadingTask, public LoadingProcess, public LoadingProcessListener
+{
+public:
+
+    SharedLoadingTask(LoadSaveThread* thread, LoadingDescription description,
+                      LoadSaveThread::AccessMode mode = LoadSaveThread::AccessModeReadWrite,
+                      LoadingTaskStatus loadingTaskStatus = LoadingTaskStatusLoading)
+        : LoadingTask(thread, description, loadingTaskStatus),
+          m_accessMode(mode), m_completed(false), m_usedProcess(0)
+        {}
+
+    virtual void execute();
+    virtual void progressInfo(const DImg *, float progress);
+    virtual bool continueQuery(const DImg *);
+    virtual void setStatus(LoadingTaskStatus status);
+
+    // LoadingProcess
+
+    virtual bool completed();
+    virtual TQString filePath();
+    virtual TQString cacheKey();
+    virtual void addListener(LoadingProcessListener *listener);
+    virtual void removeListener(LoadingProcessListener *listener);
+    virtual void notifyNewLoadingProcess(LoadingProcess *process, LoadingDescription description);
+
+    // LoadingProcessListener
+
+    virtual bool querySendNotifyEvent();
+    virtual TQObject *eventReceiver();
+    virtual LoadSaveThread::AccessMode accessMode();
+
+protected:
+
+    LoadSaveThread::AccessMode m_accessMode;
+    bool m_completed;
+    LoadingProcess *m_usedProcess;
+    TQPtrList<LoadingProcessListener> m_listeners;
+};
+
+//---------------------------------------------------------------------------------------------------
+
+class SavedEvent : public NotifyEvent
+{
+public:
+
+    SavedEvent(const TQString &filePath, bool success)
+        : m_filePath(filePath), m_success(success)
+        {};
+
+    virtual void notify(LoadSaveThread *thread);
+
+private:
+
+    TQString m_filePath;
+    bool m_success;
+};
+
+//---------------------------------------------------------------------------------------------------
+
+class SavingTask : public LoadSaveTask, public DImgLoaderObserver
+{
+public:
+
+    enum SavingTaskStatus
+    {
+        SavingTaskStatusSaving,
+        SavingTaskStatusStopping
+    };
+
+    SavingTask(LoadSaveThread* thread, DImg &img, const TQString &filePath, const TQString &format)
+        : LoadSaveTask(thread), m_img(img), m_filePath(filePath), m_format(format)
+        {};
+
+    virtual void execute();
+    virtual TaskType type();
+
+    virtual void progressInfo(const DImg *, float progress);
+    virtual bool continueQuery(const DImg *);
+
+    virtual void setStatus(SavingTaskStatus status);
+
+    SavingTaskStatus status() const
+    {
+        return m_savingTaskStatus;
+    }
+
+    TQString filePath() const
+    {
+        return m_filePath;
+    }
+
+private:
+
+    DImg        m_img;
+    TQString     m_filePath;
+    TQString     m_format;
+    SavingTaskStatus m_savingTaskStatus;
+};
+
+}   // namespace Digikam
+
+#endif // LOAD_SAVE_TASK_H
diff --git a/src/libs/threadimageio/loadsavethread.cpp b/src/libs/threadimageio/loadsavethread.cpp
new file mode 100644
index 00000000..188592e9
--- /dev/null
+++ b/src/libs/threadimageio/loadsavethread.cpp
@@ -0,0 +1,331 @@
+/* ============================================================
+ *
+ * This file is a part of digiKam project
+ * http://www.digikam.org
+ *
+ * Date        : 2005-12-17
+ * Description : image file IO threaded interface.
+ *
+ * Copyright (C) 2005-2007 by Marcel Wiesweg <marcel.wiesweg@gmx.de>
+ * Copyright (C) 2005-2007 by Gilles Caulier <caulier dot gilles at gmail dot com>
+ *
+ * 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, 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.
+ *
+ * ============================================================ */
+
+// Local includes.
+
+#include "ddebug.h"
+#include "dmetadata.h"
+#include "loadsavethread.h"
+#include "managedloadsavethread.h"
+#include "sharedloadsavethread.h"
+#include "loadsavetask.h"
+
+namespace Digikam
+{
+
+class LoadSaveThreadPriv
+{
+public:
+
+    LoadSaveThreadPriv()
+    {
+        running           = true;
+        blockNotification = false;
+        lastTask          = 0;
+    }
+
+    bool  running;
+    bool  blockNotification;
+    LoadSaveTask *lastTask;
+
+    TQTime notificationTime;
+};
+
+//---------------------------------------------------------------------------------------------------
+
+LoadSaveThread::LoadSaveThread()
+{
+    d = new LoadSaveThreadPriv;
+    m_currentTask        = 0;
+    m_notificationPolicy = NotificationPolicyTimeLimited;
+
+    start();
+}
+
+LoadSaveThread::~LoadSaveThread()
+{
+    d->running = false;
+    {
+        TQMutexLocker lock(&m_mutex);
+        m_condVar.wakeAll();
+    }
+
+    wait();
+
+    if (d->lastTask)
+        delete d->lastTask;
+    delete d;
+}
+
+void LoadSaveThread::load(LoadingDescription description)
+{
+    TQMutexLocker lock(&m_mutex);
+    m_todo.append(new LoadingTask(this, description));
+    m_condVar.wakeAll();
+}
+
+void LoadSaveThread::save(DImg &image, const TQString& filePath, const TQString &format)
+{
+    TQMutexLocker lock(&m_mutex);
+    m_todo.append(new SavingTask(this, image, filePath, format));
+    m_condVar.wakeAll();
+}
+
+void LoadSaveThread::run()
+{
+    while (d->running)
+    {
+        {
+            TQMutexLocker lock(&m_mutex);
+            if (d->lastTask)
+            {
+                delete d->lastTask;
+                d->lastTask = 0;
+            }
+            m_currentTask = m_todo.getFirst();
+            if (m_currentTask)
+            {
+                m_todo.removeFirst();
+                if (m_notificationPolicy == NotificationPolicyTimeLimited)
+                {
+                    // set timing values so that first event is sent only
+                    // after an initial time span.
+                    d->notificationTime = TQTime::currentTime();
+                    d->blockNotification = true;
+                }
+            }
+            else
+                m_condVar.wait(&m_mutex, 1000);
+        }
+        if (m_currentTask)
+            m_currentTask->execute();
+    }
+}
+
+void LoadSaveThread::taskHasFinished()
+{
+    // This function is called by the tasks before they send their final message.
+    // This is to guarantee the user of the API that at least the final message
+    // is sent after load() has been called. This might not been the case
+    // if m_currentTask is currently loading the same image and a race condition
+    // between the return from execute and the next run of the loop above occurs.
+    TQMutexLocker lock(&m_mutex);
+    d->lastTask = m_currentTask;
+    m_currentTask = 0;
+}
+
+void LoadSaveThread::customEvent(TQCustomEvent *event)
+{
+    if (event->type() == NotifyEvent::notifyEventId())
+    {
+        switch (m_notificationPolicy)
+        {
+            case NotificationPolicyDirect:
+                d->blockNotification = false;
+                break;
+            case NotificationPolicyTimeLimited:
+                break;
+        }
+        ((NotifyEvent *)event)->notify(this);
+    }
+}
+
+void LoadSaveThread::setNotificationPolicy(NotificationPolicy notificationPolicy)
+{
+    m_notificationPolicy = notificationPolicy;
+    d->blockNotification  = false;
+}
+
+bool LoadSaveThread::querySendNotifyEvent()
+{
+    // This function is called from the thread to ask for permission to send a notify event.
+    switch (m_notificationPolicy)
+    {
+        case NotificationPolicyDirect:
+            // Note that m_blockNotification is not protected by a mutex. However, if there is a
+            // race condition, the worst case is that one event is not sent, which is no problem.
+            if (d->blockNotification)
+                return false;
+            else
+            {
+                d->blockNotification = true;
+                return true;
+            }
+            break;
+        case NotificationPolicyTimeLimited:
+            // Current default time value: 100 millisecs.
+            if (d->blockNotification)
+                d->blockNotification = d->notificationTime.msecsTo(TQTime::currentTime()) < 100;
+
+            if (d->blockNotification)
+                return false;
+            else
+            {
+                d->notificationTime = TQTime::currentTime();
+                d->blockNotification = true;
+                return true;
+            }
+            break;
+    }
+    return false;
+}
+
+
+// This is a hack needed to prevent hanging when a TDEProcess-based loader (raw loader)
+// is waiting for the process to finish, but the main thread is waiting
+// for the thread to finish and no TDEProcess events are delivered.
+// Remove when porting to TQt4.
+bool LoadSaveThread::isShuttingDown()
+{
+    // the condition is met after d->running is set to false in the destructor
+    return running() && !d->running;
+}
+
+bool LoadSaveThread::exifRotate(DImg &image, const TQString& filePath)
+{
+    TQVariant attribute(image.attribute("exifRotated"));
+    if (attribute.isValid() && attribute.toBool())
+        return false;
+
+    // Raw files are already rotated properlly by dcraw. Only perform auto-rotation with JPEG/PNG/TIFF file.
+    // We don't have a feedback from dcraw about auto-rotated RAW file during decoding. Return true anyway.
+
+    attribute = image.attribute("fromRawEmbeddedPreview");
+    if (DImg::fileFormat(filePath) == DImg::RAW && !(attribute.isValid() && attribute.toBool()) )
+    {
+        return true;
+    }
+
+    // Rotate thumbnail based on metadata orientation information
+
+    DMetadata metadata(filePath);
+    DMetadata::ImageOrientation orientation = metadata.getImageOrientation();
+
+    bool rotatedOrFlipped = false;
+
+    if(orientation != DMetadata::ORIENTATION_NORMAL)
+    {
+        switch (orientation) 
+        {
+            case DMetadata::ORIENTATION_NORMAL:
+            case DMetadata::ORIENTATION_UNSPECIFIED:
+                break;
+
+            case DMetadata::ORIENTATION_HFLIP:
+                image.flip(DImg::HORIZONTAL);
+                rotatedOrFlipped = true;
+                break;
+
+            case DMetadata::ORIENTATION_ROT_180:
+                image.rotate(DImg::ROT180);
+                rotatedOrFlipped = true;
+                break;
+
+            case DMetadata::ORIENTATION_VFLIP:
+                image.flip(DImg::VERTICAL);
+                rotatedOrFlipped = true;
+                break;
+
+            case DMetadata::ORIENTATION_ROT_90_HFLIP:
+                image.rotate(DImg::ROT90);
+                image.flip(DImg::HORIZONTAL);
+                rotatedOrFlipped = true;
+                break;
+
+            case DMetadata::ORIENTATION_ROT_90:
+                image.rotate(DImg::ROT90);
+                rotatedOrFlipped = true;
+                break;
+
+            case DMetadata::ORIENTATION_ROT_90_VFLIP:
+                image.rotate(DImg::ROT90);
+                image.flip(DImg::VERTICAL);
+                rotatedOrFlipped = true;
+                break;
+
+            case DMetadata::ORIENTATION_ROT_270:
+                image.rotate(DImg::ROT270);
+                rotatedOrFlipped = true;
+                break;
+        }
+    }
+
+    image.setAttribute("exifRotated", true);
+    return rotatedOrFlipped;
+
+    /*
+    if (orientation == DMetadata::ORIENTATION_NORMAL ||
+        orientation == DMetadata::ORIENTATION_UNSPECIFIED)
+        return;
+
+    TQWMatrix matrix;
+
+    switch (orientation)
+    {
+        case DMetadata::ORIENTATION_NORMAL:
+        case DMetadata::ORIENTATION_UNSPECIFIED:
+            break;
+
+        case DMetadata::ORIENTATION_HFLIP:
+            matrix.scale(-1, 1);
+            break;
+
+        case DMetadata::ORIENTATION_ROT_180:
+            matrix.rotate(180);
+            break;
+
+        case DMetadata::ORIENTATION_VFLIP:
+            matrix.scale(1, -1);
+            break;
+
+        case DMetadata::ORIENTATION_ROT_90_HFLIP:
+            matrix.scale(-1, 1);
+            matrix.rotate(90);
+            break;
+
+        case DMetadata::ORIENTATION_ROT_90:
+            matrix.rotate(90);
+            break;
+
+        case DMetadata::ORIENTATION_ROT_90_VFLIP:
+            matrix.scale(1, -1);
+            matrix.rotate(90);
+            break;
+
+        case DMetadata::ORIENTATION_ROT_270:
+            matrix.rotate(270);
+            break;
+    }
+
+    // transform accordingly
+    thumb = thumb.xForm( matrix );
+    */
+}
+
+
+
+
+}   // namespace Digikam
+
+#include "loadsavethread.moc"
diff --git a/src/libs/threadimageio/loadsavethread.h b/src/libs/threadimageio/loadsavethread.h
new file mode 100644
index 00000000..c935e47a
--- /dev/null
+++ b/src/libs/threadimageio/loadsavethread.h
@@ -0,0 +1,184 @@
+/* ============================================================
+ *
+ * This file is a part of digiKam project
+ * http://www.digikam.org
+ *
+ * Date        : 2005-12-17
+ * Description : image file IO threaded interface.
+ *
+ * Copyright (C) 2005-2006 by Marcel Wiesweg <marcel.wiesweg@gmx.de>
+ * Copyright (C) 2005-2006 by Gilles Caulier <caulier dot gilles at gmail dot com>
+ *
+ * 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, 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.
+ *
+ * ============================================================ */
+
+#ifndef LOAD_SAVE_THREAD_H
+#define LOAD_SAVE_THREAD_H
+
+// TQt includes.
+
+#include <tqthread.h>
+#include <tqobject.h>
+#include <tqmutex.h>
+#include <tqptrlist.h>
+#include <tqdatetime.h>
+#include <tqwaitcondition.h>
+
+// Digikam includes.
+
+#include "dimg.h"
+#include "digikam_export.h"
+#include "loadingdescription.h"
+
+namespace Digikam
+{
+
+class LoadSaveThreadPriv;
+class LoadSaveTask;
+
+class DIGIKAM_EXPORT LoadSaveThread : public TQObject, public TQThread
+{
+
+    TQ_OBJECT
+  
+
+public:
+
+    enum NotificationPolicy
+    {
+        /** Always send notification, unless the last event is still in the event queue */
+        NotificationPolicyDirect,
+        /**
+         * Always wait for a certain amount of time after the last event sent.
+         * In particular, the first event will be sent only after waiting for this time span.
+         * (Or no event will be sent, when the loading has finished before)
+         * This is the default.
+         */
+        NotificationPolicyTimeLimited
+    };
+
+    // used by SharedLoadSaveThread only
+    enum AccessMode
+    {
+        // image will only be used for reading
+        AccessModeRead,
+        // image data will possibly be changed
+        AccessModeReadWrite
+    };
+
+    LoadSaveThread();
+    /**
+     * Destructor:
+     * The thread will execute all pending tasks and wait for this upon destruction
+     */
+    ~LoadSaveThread();
+
+    /** Append a task to load the given file to the task list */
+    void load(LoadingDescription description);
+    /** Append a task to save the image to the task list */
+    void save(DImg &image, const TQString& filePath, const TQString &format);
+
+    void setNotificationPolicy(NotificationPolicy notificationPolicy);
+
+    bool isShuttingDown();
+
+    /**
+     * Utility to make sure that an image is rotated according to exif tag.
+     * Detects if an image has previously already been rotated: You can
+     * call this method more than one time on the same image.
+     * Returns true if the image has actually been rotated or flipped.
+     * Returns false if a rotation was not needed.
+     */
+    static bool exifRotate(DImg &image, const TQString& filePath);
+
+signals:
+
+    /** This signal is emitted when the loading process begins. */
+    void signalImageStartedLoading(const LoadingDescription &loadingDescription);
+    /**
+     * This signal is emitted whenever new progress info is available
+     * and the notification policy allows emitting the signal.
+     * No progress info will be sent for preloaded images (ManagedLoadSaveThread).
+     */
+    void signalLoadingProgress(const LoadingDescription &loadingDescription, float progress);
+    /**
+     * This signal is emitted when the loading process has finished.
+     * If the process failed, img is null.
+     */
+    void signalImageLoaded(const LoadingDescription &loadingDescription, const DImg& img);
+    /**
+     * This signal is emitted if
+     *  - you are doing shared loading (SharedLoadSaveThread)
+     *  - you started a loading operation with a LoadingDescription for
+     *    a reduced version of the image
+     *  - another thread started a loading operation for a more complete version
+     * You may want to cancel the current operation and start with the given loadingDescription
+     */
+    void signalMoreCompleteLoadingAvailable(const LoadingDescription &oldLoadingDescription,
+                                            const LoadingDescription &newLoadingDescription);
+
+    void signalImageStartedSaving(const TQString& filePath);
+    void signalSavingProgress(const TQString& filePath, float progress);
+    void signalImageSaved(const TQString& filePath, bool success);
+
+public:
+
+    void imageStartedLoading(const LoadingDescription &loadingDescription)
+            { emit signalImageStartedLoading(loadingDescription); };
+
+    void loadingProgress(const LoadingDescription &loadingDescription, float progress)
+            { emit signalLoadingProgress(loadingDescription, progress); };
+
+    void imageLoaded(const LoadingDescription &loadingDescription, const DImg& img)
+            { emit signalImageLoaded(loadingDescription, img); };
+
+    void moreCompleteLoadingAvailable(const LoadingDescription &oldLoadingDescription,
+                                      const LoadingDescription &newLoadingDescription)
+            { emit signalMoreCompleteLoadingAvailable(oldLoadingDescription, newLoadingDescription); }
+
+    void imageStartedSaving(const TQString& filePath)
+            { emit signalImageStartedSaving(filePath); };
+
+    void savingProgress(const TQString& filePath, float progress)
+            { emit signalSavingProgress(filePath, progress); };
+
+    void imageSaved(const TQString& filePath, bool success)
+            { emit signalImageSaved(filePath, success); };
+
+    virtual bool querySendNotifyEvent();
+    virtual void taskHasFinished();
+
+protected:
+
+    virtual void run();
+    virtual void customEvent(TQCustomEvent *event);
+
+    TQMutex               m_mutex;
+
+    TQWaitCondition       m_condVar;
+
+    TQPtrList<LoadSaveTask> m_todo;
+
+    LoadSaveTask        *m_currentTask;
+
+    NotificationPolicy   m_notificationPolicy;
+
+private:
+
+    LoadSaveThreadPriv* d;
+
+};
+
+}      // namespace Digikam
+
+#endif // LOAD_SAVE_THREAD_H
diff --git a/src/libs/threadimageio/managedloadsavethread.cpp b/src/libs/threadimageio/managedloadsavethread.cpp
new file mode 100644
index 00000000..51d9f1b7
--- /dev/null
+++ b/src/libs/threadimageio/managedloadsavethread.cpp
@@ -0,0 +1,362 @@
+/* ============================================================
+ *
+ * This file is a part of digiKam project
+ * http://www.digikam.org
+ *
+ * Date        : 2006-01-20
+ * Description : image file IO threaded interface.
+ *
+ * Copyright (C) 2005-2007 by Marcel Wiesweg <marcel.wiesweg@gmx.de>
+ * Copyright (C) 2005-2007 by Gilles Caulier <caulier dot gilles at gmail dot com>
+ *
+ * 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, 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.
+ *
+ * ============================================================ */
+
+// Local includes.
+
+#include "ddebug.h"
+#include "managedloadsavethread.h"
+#include "loadsavetask.h"
+#include "previewtask.h"
+
+namespace Digikam
+{
+
+ManagedLoadSaveThread::ManagedLoadSaveThread()
+{
+    m_terminationPolicy  = TerminationPolicyTerminateLoading;
+}
+
+ManagedLoadSaveThread::~ManagedLoadSaveThread()
+{
+    LoadingTask *loadingTask;
+    switch (m_terminationPolicy)
+    {
+        case TerminationPolicyTerminateLoading:
+        {
+            TQMutexLocker lock(&m_mutex);
+            if ( (loadingTask = checkLoadingTask(m_currentTask, LoadingTaskFilterAll)) )
+                loadingTask->setStatus(LoadingTask::LoadingTaskStatusStopping);
+            removeLoadingTasks(LoadingDescription(TQString()), LoadingTaskFilterAll);
+            break;
+        }
+        case TerminationPolicyTerminatePreloading:
+        {
+            TQMutexLocker lock(&m_mutex);
+            if ( (loadingTask = checkLoadingTask(m_currentTask, LoadingTaskFilterPreloading)) )
+                loadingTask->setStatus(LoadingTask::LoadingTaskStatusStopping);
+            removeLoadingTasks(LoadingDescription(TQString()), LoadingTaskFilterPreloading);
+            break;
+        }
+        case TerminationPolicyWait:
+            break;
+    }
+}
+
+LoadingTask *ManagedLoadSaveThread::checkLoadingTask(LoadSaveTask *task, LoadingTaskFilter filter)
+{
+    if (task && task->type() == LoadSaveTask::TaskTypeLoading)
+    {
+        LoadingTask *loadingTask = (LoadingTask *)task;
+        if (filter == LoadingTaskFilterAll)
+            return loadingTask;
+        else if (filter == LoadingTaskFilterPreloading)
+            if (loadingTask->status() == LoadingTask::LoadingTaskStatusPreloading)
+                return loadingTask;
+    }
+    return 0;
+}
+
+LoadingTask *ManagedLoadSaveThread::findExistingTask(const LoadingDescription &loadingDescription)
+{
+    LoadingTask *loadingTask;
+    if (m_currentTask)
+    {
+        if (m_currentTask->type() == LoadSaveTask::TaskTypeLoading)
+        {
+            loadingTask = (LoadingTask *)m_currentTask;
+            LoadingDescription taskDescription = loadingTask->loadingDescription();
+            if (taskDescription == loadingDescription)
+                return loadingTask;
+        }
+    }
+    for (LoadSaveTask *task = m_todo.first(); task; task = m_todo.next())
+    {
+        if (task->type() == LoadSaveTask::TaskTypeLoading)
+        {
+            loadingTask = (LoadingTask *)task;
+            if (loadingTask->loadingDescription() == loadingDescription)
+                return loadingTask;
+        }
+    }
+    return 0;
+}
+
+void ManagedLoadSaveThread::setTerminationPolicy(TerminationPolicy terminationPolicy)
+{
+    m_terminationPolicy = terminationPolicy;
+}
+
+void ManagedLoadSaveThread::load(LoadingDescription description, LoadingPolicy policy)
+{
+    load(description, LoadingModeNormal, policy);
+}
+
+void ManagedLoadSaveThread::load(LoadingDescription description, LoadingMode loadingMode, LoadingPolicy policy, AccessMode accessMode)
+{
+    TQMutexLocker lock(&m_mutex);
+    LoadingTask *loadingTask = 0;
+    LoadingTask *existingTask = findExistingTask(description);
+
+    //DDebug() << "ManagedLoadSaveThread::load " << description.filePath << ", policy " << policy << endl;
+    switch(policy)
+    {
+        case LoadingPolicyFirstRemovePrevious:
+            // reuse task if it exists
+            if (existingTask)
+            {
+                existingTask->setStatus(LoadingTask::LoadingTaskStatusLoading);
+            }
+            // stop current task
+            if (m_currentTask && m_currentTask != existingTask)
+            {
+                if ( (loadingTask = checkLoadingTask(m_currentTask, LoadingTaskFilterAll)) )
+                    loadingTask->setStatus(LoadingTask::LoadingTaskStatusStopping);
+            }
+            //DDebug() << "LoadingPolicyFirstRemovePrevious, Existing task " << existingTask <<
+             //", m_currentTask " << m_currentTask << ", loadingTask " << loadingTask << endl;
+            // remove all loading tasks
+            for (LoadSaveTask *task = m_todo.first(); task; task = m_todo.next())
+            {
+                if (task != existingTask && checkLoadingTask(task, LoadingTaskFilterAll))
+                {
+                    //DDebug() << "Removing task " << task << " from list" << endl;
+                    m_todo.remove();
+                    m_todo.prev();
+                }
+            }
+            // append new, exclusive loading task
+            if (existingTask)
+                break;
+            m_todo.append(createLoadingTask(description, false, loadingMode, accessMode));
+            break;
+        case LoadingPolicyPrepend:
+            if (existingTask)
+            {
+                existingTask->setStatus(LoadingTask::LoadingTaskStatusLoading);
+            }
+            // stop and postpone current task if it is a preloading task
+            if (m_currentTask)
+            {
+                if ( (loadingTask = checkLoadingTask(m_currentTask, LoadingTaskFilterPreloading)) )
+                {
+                    loadingTask->setStatus(LoadingTask::LoadingTaskStatusStopping);
+                    load(loadingTask->filePath(), LoadingPolicyPreload);
+                }
+            }
+            //DDebug() << "LoadingPolicyPrepend, Existing task " << existingTask << ", m_currentTask " << m_currentTask << endl;
+            // prepend new loading task
+            if (existingTask)
+                break;
+            m_todo.prepend(createLoadingTask(description, false, loadingMode, accessMode));
+            break;
+        case LoadingPolicyAppend:
+            if (existingTask)
+            {
+                existingTask->setStatus(LoadingTask::LoadingTaskStatusLoading);
+            }
+            // stop and postpone current task if it is a preloading task
+            if (m_currentTask)
+            {
+                if ( (loadingTask = checkLoadingTask(m_currentTask, LoadingTaskFilterPreloading)) )
+                {
+                    loadingTask->setStatus(LoadingTask::LoadingTaskStatusStopping);
+                    load(loadingTask->filePath(), LoadingPolicyPreload);
+                }
+            }
+            if (existingTask)
+                break;
+            //DDebug() << "LoadingPolicyAppend, Existing task " << existingTask << ", m_currentTask " << m_currentTask << endl;
+            // append new loading task, put it in front of preloading tasks
+            for (uint i = 0; i<m_todo.count(); i++)
+            {
+                LoadSaveTask *task = m_todo.at(i);
+                if ( (loadingTask = checkLoadingTask(task, LoadingTaskFilterPreloading)) )
+                {
+                    m_todo.insert(i, createLoadingTask(description, false, loadingMode, accessMode));
+                    break;
+                }
+            }
+            break;
+        case LoadingPolicyPreload:
+            // append to the very end of the list
+            //DDebug() << "LoadingPolicyPreload, Existing task " << existingTask << endl;
+            if (existingTask)
+                break;
+            m_todo.append(createLoadingTask(description, true, loadingMode, accessMode));
+            break;
+    }
+    m_condVar.wakeAll();
+}
+
+void ManagedLoadSaveThread::loadPreview(LoadingDescription description)
+{
+    // This is similar to the LoadingPolicyFirstRemovePrevious policy with normal loading tasks.
+    // Preview threads typically only support preview tasks,
+    // so no need to differentiate with normal loading tasks.
+
+    TQMutexLocker lock(&m_mutex);
+    LoadingTask *loadingTask = 0;
+    LoadingTask *existingTask = findExistingTask(description);
+
+    // reuse task if it exists
+    if (existingTask)
+    {
+        existingTask->setStatus(LoadingTask::LoadingTaskStatusLoading);
+    }
+    // stop current task
+    if (m_currentTask && m_currentTask != existingTask)
+    {
+        if ( (loadingTask = checkLoadingTask(m_currentTask, LoadingTaskFilterAll)) )
+            loadingTask->setStatus(LoadingTask::LoadingTaskStatusStopping);
+    }
+    // remove all loading tasks
+    for (LoadSaveTask *task = m_todo.first(); task; task = m_todo.next())
+    {
+        if (task != existingTask && checkLoadingTask(task, LoadingTaskFilterAll))
+        {
+            m_todo.remove();
+            m_todo.prev();
+        }
+    }
+    //DDebug()<<"loadPreview for " << description.filePath << " existingTask " << existingTask << " currentTask " << m_currentTask << endl;
+    // append new loading task
+    if (existingTask)
+        return;
+    m_todo.append(new PreviewLoadingTask(this, description));
+    m_condVar.wakeAll();
+}
+
+
+LoadingTask *ManagedLoadSaveThread::createLoadingTask(const LoadingDescription &description,
+         bool preloading, LoadingMode loadingMode, AccessMode accessMode)
+{
+    if (loadingMode == LoadingModeShared)
+    {
+        if (preloading)
+            return new SharedLoadingTask(this, description, accessMode, LoadingTask::LoadingTaskStatusPreloading);
+        else
+            return new SharedLoadingTask(this, description, accessMode);
+    }
+    else
+    {
+        if (preloading)
+            return new LoadingTask(this, description, LoadingTask::LoadingTaskStatusPreloading);
+        else
+            return new LoadingTask(this, description);
+    }
+}
+
+void ManagedLoadSaveThread::stopLoading(const TQString& filePath, LoadingTaskFilter filter)
+{
+    TQMutexLocker lock(&m_mutex);
+    removeLoadingTasks(LoadingDescription(filePath), filter);
+}
+
+void ManagedLoadSaveThread::stopLoading(const LoadingDescription& desc, LoadingTaskFilter filter)
+{
+    TQMutexLocker lock(&m_mutex);
+    removeLoadingTasks(desc, filter);
+}
+
+void ManagedLoadSaveThread::stopSaving(const TQString& filePath)
+{
+    TQMutexLocker lock(&m_mutex);
+
+    // stop current task if it is matching the criteria
+    if (m_currentTask && m_currentTask->type() == LoadSaveTask::TaskTypeSaving)
+    {
+        SavingTask *savingTask = (SavingTask *)m_currentTask;
+        if (filePath.isNull() || savingTask->filePath() == filePath)
+        {
+            savingTask->setStatus(SavingTask::SavingTaskStatusStopping);
+        }
+    }
+
+    // remove relevant tasks from list
+    for (LoadSaveTask *task = m_todo.first(); task; task = m_todo.next())
+    {
+        if (task->type() ==  LoadSaveTask::TaskTypeSaving)
+        {
+            SavingTask *savingTask = (SavingTask *)m_currentTask;
+            if (filePath.isNull() || savingTask->filePath() == filePath)
+            {
+                m_todo.remove();
+                m_todo.prev();
+            }
+        }
+    }
+}
+
+
+void ManagedLoadSaveThread::removeLoadingTasks(const LoadingDescription &description, LoadingTaskFilter filter)
+{
+    LoadingTask *loadingTask;
+
+    // stop current task if it is matching the criteria
+    if ( (loadingTask = checkLoadingTask(m_currentTask, filter)) )
+    {
+        if (description.filePath.isNull() || loadingTask->loadingDescription() == description)
+        {
+            loadingTask->setStatus(LoadingTask::LoadingTaskStatusStopping);
+        }
+    }
+
+    // remove relevant tasks from list
+    for (LoadSaveTask *task = m_todo.first(); task; task = m_todo.next())
+    {
+        if ( (loadingTask = checkLoadingTask(task, filter)) )
+        {
+            if (description.filePath.isNull() || loadingTask->loadingDescription() == description)
+            {
+                m_todo.remove();
+                m_todo.prev();
+            }
+        }
+    }
+}
+
+void ManagedLoadSaveThread::save(DImg &image, const TQString& filePath, const TQString &format)
+{
+    TQMutexLocker lock(&m_mutex);
+    LoadingTask *loadingTask;
+
+    // stop and postpone current task if it is a preloading task
+    if (m_currentTask && (loadingTask = checkLoadingTask(m_currentTask, LoadingTaskFilterPreloading)))
+    {
+        loadingTask->setStatus(LoadingTask::LoadingTaskStatusStopping);
+        load(loadingTask->filePath(), LoadingPolicyPreload);
+    }
+    // append new loading task, put it in front of preloading tasks
+    uint i;
+    for (i = 0; i<m_todo.count(); i++)
+    {
+        LoadSaveTask *task = m_todo.at(i);
+        if ( (loadingTask = checkLoadingTask(task, LoadingTaskFilterPreloading)) )
+            break;
+    }
+    m_todo.insert(i, new SavingTask(this, image, filePath, format));
+}
+
+}   // namespace Digikam
+
diff --git a/src/libs/threadimageio/managedloadsavethread.h b/src/libs/threadimageio/managedloadsavethread.h
new file mode 100644
index 00000000..ec6a563c
--- /dev/null
+++ b/src/libs/threadimageio/managedloadsavethread.h
@@ -0,0 +1,134 @@
+/* ============================================================
+ *
+ * This file is a part of digiKam project
+ * http://www.digikam.org
+ *
+ * Date        : 2006-01-16
+ * Description : image file IO threaded interface.
+ *
+ * Copyright (C) 2005-2007 by Marcel Wiesweg <marcel.wiesweg@gmx.de>
+ * Copyright (C) 2005-2007 by Gilles Caulier <caulier dot gilles at gmail dot com>
+ *
+ * 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, 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.
+ *
+ * ============================================================ */
+
+#ifndef MANAGED_LOAD_SAVE_THREAD_H
+#define MANAGED_LOAD_SAVE_THREAD_H
+
+#include "loadsavethread.h"
+
+namespace Digikam
+{
+
+class LoadingTask;
+
+class DIGIKAM_EXPORT ManagedLoadSaveThread : public LoadSaveThread
+{
+
+public:
+
+    // Termination is controlled by setting the TerminationPolicy
+    // Default is TerminationPolicyTerminateLoading
+    ManagedLoadSaveThread();
+    ~ManagedLoadSaveThread();
+
+    enum LoadingPolicy
+    {
+        // Load image immediately, remove and stop all previous loading tasks.
+        LoadingPolicyFirstRemovePrevious,
+        // Prepend loading in front of all other tasks, but wait for the current task to finish.
+        // No other tasks will be removed, preloading tasks will be stopped and postponed.
+        LoadingPolicyPrepend,
+        // Append loading task to the end of the list, but in front of all preloading tasks.
+        // No other tasks will be removed, preloading tasks will be stopped and postponed.
+        // This is similar to the simple load() operation from LoadSaveThread, except for the
+        // special care taken for preloading.
+        LoadingPolicyAppend,
+        // Preload image, i.e. load it with low priority when no other tasks are scheduled.
+        // All other tasks will take precedence, and preloading tasks will be stopped and
+        // postponed when another task is added.
+        // No progress info will be sent for preloaded images
+        LoadingPolicyPreload
+    };
+
+    enum TerminationPolicy
+    {
+        // Wait for saving tasks, stop and remove loading tasks
+        // This is the default.
+        TerminationPolicyTerminateLoading,
+        // Wait for loading and saving tasks, stop and remove preloading tasks
+        TerminationPolicyTerminatePreloading,
+        // Wait for all pending tasks
+        TerminationPolicyWait
+    };
+
+    enum LoadingTaskFilter
+    {
+        // filter all loading tasks
+        LoadingTaskFilterAll,
+        // filter only tasks with preloading policy
+        LoadingTaskFilterPreloading
+    };
+
+    // used by SharedLoadSaveThread only
+    enum LoadingMode
+    {
+        // no sharing of loading process, no caching of image
+        LoadingModeNormal,
+        // loading process is shared, image is cached
+        LoadingModeShared
+    };
+
+    // Append a task to load the given file to the task list.
+    // If there is already a task for the given file, it will possibly be rescheduled,
+    // but no second task will be added.
+    // Only loading tasks will - if required by the policy - be stopped or removed,
+    // saving tasks will not be touched.
+    void load(LoadingDescription description, LoadingPolicy policy = LoadingPolicyAppend);
+
+    // Stop and remove tasks filtered by filePath and policy.
+    // If filePath isNull, applies to all file paths.
+    void stopLoading(const TQString& filePath = TQString(), LoadingTaskFilter filter = LoadingTaskFilterAll);
+
+    // Same than previous method, but Stop and remove tasks filtered by LoadingDescription.
+    void stopLoading(const LoadingDescription& desc, LoadingTaskFilter filter = LoadingTaskFilterAll);
+
+    // Stop and remove saving tasks filtered by filePath.
+    // If filePath isNull, applies to all file paths.
+    void stopSaving(const TQString& filePath = TQString());
+
+    // Append a task to save the image to the task list
+    void save(DImg &image, const TQString& filePath, const TQString &format);
+
+    void setTerminationPolicy(TerminationPolicy terminationPolicy);
+
+protected:
+
+    void load(LoadingDescription description, LoadingMode loadingMode,
+              LoadingPolicy policy = LoadingPolicyAppend, AccessMode mode = AccessModeReadWrite);
+    void loadPreview(LoadingDescription description);
+
+private:
+
+    LoadingTask *checkLoadingTask(class LoadSaveTask *task, LoadingTaskFilter filter);
+    LoadingTask *findExistingTask(const LoadingDescription &description);
+    LoadingTask *createLoadingTask(const LoadingDescription &description, bool preloading, LoadingMode loadingMode, AccessMode accessMode);
+    void removeLoadingTasks(const LoadingDescription &description, LoadingTaskFilter filter);
+
+    TerminationPolicy m_terminationPolicy;
+};
+
+}   // namespace Digikam
+
+
+#endif // MANAGED_LOAD_SAVE_THREAD_H
diff --git a/src/libs/threadimageio/previewloadthread.cpp b/src/libs/threadimageio/previewloadthread.cpp
new file mode 100644
index 00000000..d243ab32
--- /dev/null
+++ b/src/libs/threadimageio/previewloadthread.cpp
@@ -0,0 +1,52 @@
+/* ============================================================
+ *
+ * This file is a part of digiKam project
+ * http://www.digikam.org
+ *
+ * Date        : 2006-01-20
+ * Description : image file IO threaded interface.
+ *
+ * Copyright (C) 2005-2007 by Marcel Wiesweg <marcel.wiesweg@gmx.de>
+ * Copyright (C) 2005-2007 by Gilles Caulier <caulier dot gilles at gmail dot com>
+ *
+ * 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, 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.
+ *
+ * ============================================================ */
+
+// Local includes.
+
+#include "previewtask.h"
+#include "previewloadthread.h"
+#include "previewloadthread.moc"
+
+namespace Digikam
+{
+
+PreviewLoadThread::PreviewLoadThread()
+{
+}
+
+void PreviewLoadThread::load(LoadingDescription description)
+{
+    description.rawDecodingSettings.sixteenBitsImage = false;
+    ManagedLoadSaveThread::loadPreview(description);
+}
+
+void PreviewLoadThread::loadHighQuality(LoadingDescription description)
+{
+    description.rawDecodingSettings.optimizeTimeLoading();
+    description.rawDecodingSettings.sixteenBitsImage = false;
+    ManagedLoadSaveThread::load(description, LoadingModeShared, LoadingPolicyFirstRemovePrevious);
+}
+
+}   // namespace Digikam
+
diff --git a/src/libs/threadimageio/previewloadthread.h b/src/libs/threadimageio/previewloadthread.h
new file mode 100644
index 00000000..59cc6d72
--- /dev/null
+++ b/src/libs/threadimageio/previewloadthread.h
@@ -0,0 +1,57 @@
+/* ============================================================
+ *
+ * This file is a part of digiKam project
+ * http://www.digikam.org
+ *
+ * Date        : 2006-01-16
+ * Description : image file IO threaded interface.
+ *
+ * Copyright (C) 2006-2007 by Marcel Wiesweg <marcel.wiesweg@gmx.de>
+ *
+ * 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, 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.
+ *
+ * ============================================================ */
+
+#ifndef PREVIEW_LOAD_THREAD_H
+#define PREVIEW_LOAD_THREAD_H
+
+#include "managedloadsavethread.h"
+
+namespace Digikam
+{
+
+class DIGIKAM_EXPORT PreviewLoadThread : public ManagedLoadSaveThread
+{
+    TQ_OBJECT
+  
+
+public:
+
+    PreviewLoadThread();
+
+    /**
+     * Load a preview that is optimized for fast loading.
+     */
+    void load(LoadingDescription description);
+    /**
+     * Load a preview with higher resolution, trading more quality
+     * for less speed.
+     * In the LoadingDescription container, provide "0" as maximum size.
+     */
+    void loadHighQuality(LoadingDescription description);
+
+};
+
+}   // namespace Digikam
+
+
+#endif // SHARED_LOAD_SAVE_THREAD_H
diff --git a/src/libs/threadimageio/previewtask.cpp b/src/libs/threadimageio/previewtask.cpp
new file mode 100644
index 00000000..5f277481
--- /dev/null
+++ b/src/libs/threadimageio/previewtask.cpp
@@ -0,0 +1,258 @@
+/* ============================================================
+ *
+ * This file is a part of digiKam project
+ * http://www.digikam.org
+ *
+ * Date        : 2006-12-26
+ * Description : Multithreaded loader for previews
+ *
+ * Copyright (C) 2006-2007 by Marcel Wiesweg <marcel.wiesweg@gmx.de>
+ * Copyright (C) 2006-2008 by Gilles Caulier <caulier dot gilles at gmail dot com>
+ *
+ * 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, 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.
+ *
+ * ============================================================ */
+
+// C++ includes.
+
+#include <cmath>
+
+// TQt includes.
+
+#include <tqapplication.h>
+#include <tqimage.h>
+#include <tqvariant.h>
+#include <tqwmatrix.h>
+
+// LibKDcraw includes.
+
+#include <libkdcraw/kdcraw.h>
+
+// Local includes.
+
+#include "ddebug.h"
+#include "dmetadata.h"
+#include "jpegutils.h"
+#include "previewloadthread.h"
+#include "previewtask.h"
+
+namespace Digikam
+{
+
+void PreviewLoadingTask::execute()
+{
+    if (m_loadingTaskStatus == LoadingTaskStatusStopping)
+        return;
+
+    LoadingCache *cache = LoadingCache::cache();
+    {
+        LoadingCache::CacheLock lock(cache);
+
+        // find possible cached images
+        DImg *cachedImg = 0;
+        TQStringList lookupKeys = m_loadingDescription.lookupCacheKeys();
+        // lookupCacheKeys returns "best first". Prepend the cache key to make the list "fastest first":
+        // Scaling a full version takes longer!
+        lookupKeys.push_front(m_loadingDescription.cacheKey());
+        for ( TQStringList::Iterator it = lookupKeys.begin(); it != lookupKeys.end(); ++it ) {
+            if ( (cachedImg = cache->retrieveImage(*it)) )
+                break;
+        }
+
+        if (cachedImg)
+        {
+            // image is found in image cache, loading is successful
+
+            DImg img(*cachedImg);
+
+            // rotate if needed - images are unrotated in the cache,
+            // except for RAW images, which are already rotated by dcraw.
+            if (m_loadingDescription.previewParameters.exifRotate)
+            {
+                img = img.copy();
+                LoadSaveThread::exifRotate(img, m_loadingDescription.filePath);
+            }
+
+            TQApplication::postEvent(m_thread, new LoadedEvent(m_loadingDescription.filePath, img));
+            return;
+        }
+        else
+        {
+            // find possible running loading process
+            m_usedProcess = 0;
+            for ( TQStringList::Iterator it = lookupKeys.begin(); it != lookupKeys.end(); ++it ) {
+                if ( (m_usedProcess = cache->retrieveLoadingProcess(*it)) )
+                {
+                    break;
+                }
+            }
+            // do not wait on other loading processes?
+            //m_usedProcess = cache->retrieveLoadingProcess(m_loadingDescription.cacheKey());
+
+            if (m_usedProcess)
+            {
+                // Other process is right now loading this image.
+                // Add this task to the list of listeners and
+                // attach this thread to the other thread, wait until loading
+                // has finished.
+                m_usedProcess->addListener(this);
+                // break loop when either the loading has completed, or this task is being stopped
+                while ( !m_usedProcess->completed() && m_loadingTaskStatus != LoadingTaskStatusStopping )
+                    lock.timedWait();
+                // remove listener from process
+                m_usedProcess->removeListener(this);
+                // wake up the process which is waiting until all listeners have removed themselves
+                lock.wakeAll();
+                // set to 0, as checked in setStatus
+                m_usedProcess = 0;
+                return;
+            }
+            else
+            {
+                // Neither in cache, nor currently loading in different thread.
+                // Load it here and now, add this LoadingProcess to cache list.
+                cache->addLoadingProcess(this);
+                // Add this to the list of listeners
+                addListener(this);
+                // for use in setStatus
+                m_usedProcess = this;
+                // Notify other processes that we are now loading this image.
+                // They might be interested - see notifyNewLoadingProcess below
+                cache->notifyNewLoadingProcess(this, m_loadingDescription);
+            }
+        }
+    }
+
+    // load image
+    int  size = m_loadingDescription.previewParameters.size;
+
+    DImg img;
+    TQImage qimage;
+    bool fromEmbeddedPreview = false;
+
+    // -- Get the image preview --------------------------------
+
+    // First the TQImage-dependent loading methods
+    // Trying to load with dcraw: RAW files.
+    if (KDcrawIface::KDcraw::loadEmbeddedPreview(qimage, m_loadingDescription.filePath))
+        fromEmbeddedPreview = true;
+
+    if (qimage.isNull())
+    {
+        //TODO: Use DImg based loader instead?
+        KDcrawIface::KDcraw::loadHalfPreview(qimage, m_loadingDescription.filePath);
+    }
+
+    // Try to extract Exif/Iptc preview.
+    if (qimage.isNull())
+    {
+        loadImagePreview(qimage, m_loadingDescription.filePath);
+    }
+
+    if (!qimage.isNull())
+    {
+        // convert from TQImage
+        img = DImg(qimage);
+        // mark as embedded preview (for exif rotation)
+        if (fromEmbeddedPreview)
+            img.setAttribute("fromRawEmbeddedPreview", true);
+        // free memory
+        qimage = TQImage();
+    }
+
+    // DImg-dependent loading methods
+    if (img.isNull())
+    {
+        // Set a hint to try to load a JPEG with the fast scale-before-decoding method
+        img.setAttribute("jpegScaledLoadingSize", size);
+        img.load(m_loadingDescription.filePath, this, m_loadingDescription.rawDecodingSettings);
+    }
+
+    if (img.isNull())
+    {
+        DWarning() << "Cannot extract preview for " << m_loadingDescription.filePath << endl;
+    }
+
+    img.convertToEightBit();
+
+    // Reduce size of image:
+    // - only scale down if size is considerably larger
+    // - only scale down, do not scale up
+    TQSize scaledSize = img.size();
+    if (needToScale(scaledSize, size))
+    {
+        scaledSize.scale(size, size, TQSize::ScaleMin);
+        img = img.smoothScale(scaledSize.width(), scaledSize.height());
+    }
+
+    // Scale if hinted, Store previews rotated in the cache (?)
+    if (m_loadingDescription.previewParameters.exifRotate)
+        LoadSaveThread::exifRotate(img, m_loadingDescription.filePath);
+
+    {
+        LoadingCache::CacheLock lock(cache);
+        // put (valid) image into cache of loaded images
+        if (!img.isNull())
+            cache->putImage(m_loadingDescription.cacheKey(), new DImg(img), m_loadingDescription.filePath);
+        // remove this from the list of loading processes in cache
+        cache->removeLoadingProcess(this);
+    }
+
+    // following the golden rule to avoid deadlocks, do this when CacheLock is not held
+    m_thread->taskHasFinished();
+
+    {
+        LoadingCache::CacheLock lock(cache);
+        // indicate that loading has finished so that listeners can stop waiting
+        m_completed = true;
+
+        // dispatch image to all listeners, including this
+        for (LoadingProcessListener *l = m_listeners.first(); l; l = m_listeners.next())
+        {
+            TQApplication::postEvent(l->eventReceiver(), new LoadedEvent(m_loadingDescription, img));
+        }
+
+        // remove myself from list of listeners
+        removeListener(this);
+        // wake all listeners waiting on cache condVar, so that they remove themselves
+        lock.wakeAll();
+        // wait until all listeners have removed themselves
+        while (m_listeners.count() != 0)
+            lock.timedWait();
+        // set to 0, as checked in setStatus
+        m_usedProcess = 0;
+    }
+}
+
+bool PreviewLoadingTask::needToScale(const TQSize &imageSize, int previewSize)
+{
+    int maxSize = imageSize.width() > imageSize.height() ? imageSize.width() : imageSize.height();
+    int acceptableUpperSize = lround(1.25 * (double)previewSize);
+    return  maxSize >= acceptableUpperSize;
+}
+
+// -- Exif/IPTC preview extraction using Exiv2 --------------------------------------------------------
+
+bool PreviewLoadingTask::loadImagePreview(TQImage& image, const TQString& path)
+{
+    DMetadata metadata(path);
+    if (metadata.getImagePreview(image))
+    {
+        DDebug() << "Use Exif/Iptc preview extraction. Size of image: "
+                  << image.width() << "x" << image.height() << endl;
+        return true;
+    }
+
+    return false;
+}
+
+} // namespace Digikam
diff --git a/src/libs/threadimageio/previewtask.h b/src/libs/threadimageio/previewtask.h
new file mode 100644
index 00000000..f5715499
--- /dev/null
+++ b/src/libs/threadimageio/previewtask.h
@@ -0,0 +1,57 @@
+/* ============================================================
+ *
+ * This file is a part of digiKam project
+ * http://www.digikam.org
+ *
+ * Date        : 2006-12-26
+ * Description : Multithreaded loader for previews
+ *
+ * Copyright (C) 2006-2007 by Marcel Wiesweg <marcel.wiesweg@gmx.de>
+ * Copyright (C) 2006-2008 by Gilles Caulier <caulier dot gilles at gmail dot com>
+ *
+ * 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, 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.
+ *
+ * ============================================================ */
+
+#ifndef PREVIEW_TASK_H
+#define PREVIEW_TASK_H
+
+// TQt includes.
+
+#include <tqimage.h>
+
+// Local includes.
+
+#include "loadsavetask.h"
+
+namespace Digikam
+{
+
+class PreviewLoadingTask : public SharedLoadingTask
+{
+public:
+
+    PreviewLoadingTask(LoadSaveThread* thread, LoadingDescription description)
+        : SharedLoadingTask(thread, description, LoadSaveThread::AccessModeRead, LoadingTaskStatusLoading)
+        {}
+
+    virtual void execute();
+
+private:
+
+    bool needToScale(const TQSize &imageSize, int previewSize);
+    bool loadImagePreview(TQImage& image, const TQString& path);
+};
+
+} // namespace Digikam
+
+#endif // PREVIEW_TASK_H
diff --git a/src/libs/threadimageio/sharedloadsavethread.cpp b/src/libs/threadimageio/sharedloadsavethread.cpp
new file mode 100644
index 00000000..6a9cccbf
--- /dev/null
+++ b/src/libs/threadimageio/sharedloadsavethread.cpp
@@ -0,0 +1,65 @@
+/* ============================================================
+ *
+ * This file is a part of digiKam project
+ * http://www.digikam.org
+ *
+ * Date        : 2006-01-20
+ * Description : image file IO threaded interface.
+ *
+ * Copyright (C) 2005-2007 by Marcel Wiesweg <marcel.wiesweg@gmx.de>
+ * Copyright (C) 2005-2007 by Gilles Caulier <caulier dot gilles at gmail dot com>
+ *
+ * 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, 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.
+ *
+ * ============================================================ */
+
+// Local includes.
+
+#include "ddebug.h"
+#include "sharedloadsavethread.h"
+#include "loadingcache.h"
+#include "loadsavetask.h"
+
+namespace Digikam
+{
+
+void SharedLoadSaveThread::load(LoadingDescription description, AccessMode mode, LoadingPolicy policy)
+{
+    ManagedLoadSaveThread::load(description, LoadingModeShared, policy, mode);
+}
+
+DImg SharedLoadSaveThread::cacheLookup(const TQString& filePath, AccessMode /*accessMode*/)
+{
+    LoadingCache *cache = LoadingCache::cache();
+    LoadingCache::CacheLock lock(cache);
+    DImg *cachedImg = cache->retrieveImage(filePath);
+    // TQt4: uncomment this code.
+    // See comments in SharedLoadingTask::execute for explanation.
+    /*
+    if (cachedImg)
+    {
+        if (accessMode == AccessModeReadWrite)
+            return cachedImg->copy();
+        else
+            return *cachedImg;
+    }
+    else
+        return DImg();
+    */
+    if (cachedImg)
+        return cachedImg->copy();
+    else
+        return DImg();
+}
+
+}   // namespace Digikam
+
diff --git a/src/libs/threadimageio/sharedloadsavethread.h b/src/libs/threadimageio/sharedloadsavethread.h
new file mode 100644
index 00000000..aa03a708
--- /dev/null
+++ b/src/libs/threadimageio/sharedloadsavethread.h
@@ -0,0 +1,43 @@
+/* ============================================================
+ *
+ * This file is a part of digiKam project
+ * http://www.digikam.org
+ *
+ * Date        : 2006-01-16
+ * Description : image file IO threaded interface.
+ *
+ * Copyright (C) 2006-2007 by Marcel Wiesweg <marcel.wiesweg@gmx.de>
+ *
+ * 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, 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.
+ *
+ * ============================================================ */
+
+#ifndef SHARED_LOAD_SAVE_THREAD_H
+#define SHARED_LOAD_SAVE_THREAD_H
+
+#include "managedloadsavethread.h"
+
+namespace Digikam
+{
+
+class DIGIKAM_EXPORT SharedLoadSaveThread : public ManagedLoadSaveThread
+{
+public:
+
+    void load(LoadingDescription description, AccessMode mode, LoadingPolicy policy = LoadingPolicyAppend);
+    DImg cacheLookup(const TQString& filePath, AccessMode mode);
+};
+
+}   // namespace Digikam
+
+
+#endif // SHARED_LOAD_SAVE_THREAD_H