/**************************************************************************** ** ** Copyright (C) 2009 Nokia Corporation and/or its subsidiary(-ies). ** All rights reserved. ** Contact: Nokia Corporation (qt-info@nokia.com) ** ** This file is part of the QtGui module of the Qt Toolkit. ** ** $QT_BEGIN_LICENSE:LGPL$ ** No Commercial Usage ** This file contains pre-release code and may not be distributed. ** You may use this file in accordance with the terms and conditions ** contained in the Technology Preview License Agreement accompanying ** this package. ** ** GNU Lesser General Public License Usage ** Alternatively, this file may be used under the terms of the GNU Lesser ** General Public License version 2.1 as published by the Free Software ** Foundation and appearing in the file LICENSE.LGPL included in the ** packaging of this file. Please review the following information to ** ensure the GNU Lesser General Public License version 2.1 requirements ** will be met: http://www.gnu.org/licenses/old-licenses/lgpl-2.1.html. ** ** In addition, as a special exception, Nokia gives you certain additional ** rights. These rights are described in the Nokia Qt LGPL Exception ** version 1.1, included in the file LGPL_EXCEPTION.txt in this package. ** ** If you have questions regarding the use of this file, please contact ** Nokia at qt-info@nokia.com. ** ** ** ** ** ** ** ** ** $QT_END_LICENSE$ ** ****************************************************************************/ #include "qpixmapcache.h" #include "qcache.h" #include "qobject.h" #include "qdebug.h" #include "qpaintengine.h" #include #include QT_BEGIN_NAMESPACE /*! \class QPixmapCache \brief The QPixmapCache class provides an application-wide cache for pixmaps. \ingroup environment \ingroup multimedia This class is a tool for optimized drawing with QPixmap. You can use it to store temporary pixmaps that are expensive to generate without using more storage space than cacheLimit(). Use insert() to insert pixmaps, find() to find them, and clear() to empty the cache. QPixmapCache contains no member data, only static functions to access the global pixmap cache. It creates an internal QCache object for caching the pixmaps. The cache associates a pixmap with a string (key). If two pixmaps are inserted into the cache using equal keys, then the last pixmap will hide the first pixmap. The QHash and QCache classes do exactly the same. The cache becomes full when the total size of all pixmaps in the cache exceeds cacheLimit(). The initial cache limit is 1024 KB (1 MB); it is changed with setCacheLimit(). A pixmap takes roughly (\e{width} * \e{height} * \e{depth})/8 bytes of memory. The \e{Qt Quarterly} article \l{http://qt.nokia.com/doc/qq/qq12-qpixmapcache.html}{Optimizing with QPixmapCache} explains how to use QPixmapCache to speed up applications by caching the results of painting. \sa QCache, QPixmap */ #if defined(Q_WS_QWS) || defined(Q_OS_WINCE) static int cache_limit = 2048; // 2048 KB cache limit for embedded #else static int cache_limit = 10240; // 10 MB cache limit for desktop #endif // XXX: hw: is this a general concept we need to abstract? class QDetachedPixmap : public QPixmap { public: QDetachedPixmap(const QPixmap &pix) : QPixmap(pix) { if (data && data->classId() == QPixmapData::RasterClass) { QRasterPixmapData *d = static_cast(data); if (!d->image.isNull() && d->image.d->paintEngine && !d->image.d->paintEngine->isActive()) { delete d->image.d->paintEngine; d->image.d->paintEngine = 0; } } } }; class QPMCache : public QObject, public QCache { Q_OBJECT public: QPMCache() : QObject(0), QCache(cache_limit * 1024), theid(0), ps(0), t(false) { } ~QPMCache() { } void timerEvent(QTimerEvent *); bool insert(const QString& key, const QPixmap &pixmap, int cost); bool remove(const QString &key); QPixmap *object(const QString &key) const; private: QHash cacheKeys; int theid; int ps; bool t; }; QT_BEGIN_INCLUDE_NAMESPACE #include "qpixmapcache.moc" QT_END_INCLUDE_NAMESPACE /* This is supposed to cut the cache size down by about 80-90% in a minute once the application becomes idle, to let any inserted pixmap remain in the cache for some time before it becomes a candidate for cleaning-up, and to not cut down the size of the cache while the cache is in active use. When the last pixmap has been deleted from the cache, kill the timer so Qt won't keep the CPU from going into sleep mode. */ void QPMCache::timerEvent(QTimerEvent *) { int mc = maxCost(); bool nt = totalCost() == ps; setMaxCost(nt ? totalCost() * 3 / 4 : totalCost() -1); setMaxCost(mc); ps = totalCost(); QHash::iterator it = cacheKeys.begin(); while (it != cacheKeys.end()) { if (!contains(it.value())) { it = cacheKeys.erase(it); } else { ++it; } } if (!size()) { killTimer(theid); theid = 0; } else if (nt != t) { killTimer(theid); theid = startTimer(nt ? 10000 : 30000); t = nt; } } QPixmap *QPMCache::object(const QString &key) const { return QCache::object(cacheKeys.value(key, -1)); } bool QPMCache::insert(const QString& key, const QPixmap &pixmap, int cost) { qint64 cacheKey = pixmap.cacheKey(); if (QCache::object(cacheKey)) { cacheKeys.insert(key, cacheKey); return true; } qint64 oldCacheKey = cacheKeys.value(key, -1); //If for the same key we add already a pixmap we should delete it if (oldCacheKey != -1) QCache::remove(oldCacheKey); bool success = QCache::insert(cacheKey, new QDetachedPixmap(pixmap), cost); if (success) { cacheKeys.insert(key, cacheKey); if (!theid) { theid = startTimer(30000); t = false; } } return success; } bool QPMCache::remove(const QString &key) { qint64 cacheKey = cacheKeys.value(key, -1); cacheKeys.remove(key); return QCache::remove(cacheKey); } Q_GLOBAL_STATIC(QPMCache, pm_cache) /*! \obsolete \overload Returns the pixmap associated with the \a key in the cache, or null if there is no such pixmap. \warning If valid, you should copy the pixmap immediately (this is fast). Subsequent insertions into the cache could cause the pointer to become invalid. For this reason, we recommend you use find(const QString&, QPixmap&) instead. Example: \snippet doc/src/snippets/code/src_gui_image_qpixmapcache.cpp 0 */ QPixmap *QPixmapCache::find(const QString &key) { return pm_cache()->object(key); } /*! Looks for a cached pixmap associated with the \a key in the cache. If the pixmap is found, the function sets \a pm to that pixmap and returns true; otherwise it leaves \a pm alone and returns false. Example: \snippet doc/src/snippets/code/src_gui_image_qpixmapcache.cpp 1 */ bool QPixmapCache::find(const QString &key, QPixmap& pm) { QPixmap *ptr = pm_cache()->object(key); if (ptr) pm = *ptr; return ptr != 0; } /*! Inserts a copy of the pixmap \a pm associated with the \a key into the cache. All pixmaps inserted by the Qt library have a key starting with "$qt", so your own pixmap keys should never begin "$qt". When a pixmap is inserted and the cache is about to exceed its limit, it removes pixmaps until there is enough room for the pixmap to be inserted. The oldest pixmaps (least recently accessed in the cache) are deleted when more space is needed. The function returns true if the object was inserted into the cache; otherwise it returns false. \sa setCacheLimit() */ bool QPixmapCache::insert(const QString &key, const QPixmap &pm) { return pm_cache()->insert(key, pm, pm.width() * pm.height() * pm.depth() / 8); } /*! Returns the cache limit (in kilobytes). The default cache limit is 2048 KB for Embedded, 10240 KB for Desktops. \sa setCacheLimit() */ int QPixmapCache::cacheLimit() { return cache_limit; } /*! Sets the cache limit to \a n kilobytes. The default setting is 2048 KB for Embedded, 10240 KB for Desktops. \sa cacheLimit() */ void QPixmapCache::setCacheLimit(int n) { cache_limit = n; pm_cache()->setMaxCost(1024 * cache_limit); } /*! Removes the pixmap associated with \a key from the cache. */ void QPixmapCache::remove(const QString &key) { pm_cache()->remove(key); } /*! Removes all pixmaps from the cache. */ void QPixmapCache::clear() { pm_cache()->clear(); } QT_END_NAMESPACE