KDEUI
KPixmapCache Class Reference
General-purpose pixmap cache for KDE. More...
#include <kpixmapcache.h>

Public Types | |
enum | RemoveStrategy { RemoveOldest, RemoveSeldomUsed, RemoveLeastRecentlyUsed } |
Public Member Functions | |
int | cacheLimit () const |
void | discard () |
virtual bool | find (const QString &key, QPixmap &pix) |
virtual void | insert (const QString &key, const QPixmap &pix) |
bool | isEnabled () const |
bool | isValid () const |
KPixmapCache (const QString &name) | |
QPixmap | loadFromFile (const QString &filename) |
QPixmap | loadFromSvg (const QString &filename, const QSize &size=QSize()) |
void | removeEntries (int newsize=0) |
RemoveStrategy | removeEntryStrategy () const |
void | setCacheLimit (int kbytes) |
void | setRemoveEntryStrategy (RemoveStrategy strategy) |
void | setTimestamp (unsigned int time) |
void | setUseQPixmapCache (bool use) |
int | size () const |
unsigned int | timestamp () const |
bool | useQPixmapCache () const |
virtual | ~KPixmapCache () |
Static Public Member Functions | |
static void | deleteCache (const QString &name) |
Protected Member Functions | |
void | ensureInited () const |
virtual bool | loadCustomData (QDataStream &stream) |
virtual bool | loadCustomIndexHeader (QDataStream &stream) |
bool | recreateCacheFiles () |
void | setValid (bool valid) |
virtual bool | writeCustomData (QDataStream &stream) |
virtual void | writeCustomIndexHeader (QDataStream &stream) |
Detailed Description
General-purpose pixmap cache for KDE.The pixmap cache can be used to store pixmaps which can later be loaded from the cache very quickly.
Its most common use is storing SVG images which might be expensive to render every time they are used. With the cache you can render each SVG only once and later use the stored version unless the SVG file or requested pixmap size changes.
KPixmapCache's API is similar to that of the QPixmapCache so if you're already using the latter then all you need to do is creating a KPixmapCache object (unlike QPixmapCache, KPixmapCache doesn't have many static methods) and calling insert() and find() method on that object:
// Create KPixmapCache object KPixmapCache* cache = new KPixmapCache("myapp-pixmaps"); // Load a pixmap QPixmap pix; if (!cache->find("pixmap-1", pix)) { // Pixmap isn't in the cache, create it and insert to cache pix = createPixmapFromData(); cache->insert("pixmap-1", pix); } // Use pix
The above example illustrates that you can also cache pixmaps created from some data. In case such data is updated, you might need to discard cache contents using discard() method:
// Discard the cache if it's too old if (cache->timestamp() < mydataTimestamp()) { cache->discard(); } // Now the cache contains up-to-date data
Definition at line 76 of file kpixmapcache.h.
Member Enumeration Documentation
Describes which entries will be removed first during cache cleanup.
- RemoveOldest oldest entries are removed first.
- RemoveSeldomUsed least used entries are removed first.
- RemoveLeastRecentlyUsed least recently used entries are removed first.
Definition at line 160 of file kpixmapcache.h.
Constructor & Destructor Documentation
KPixmapCache::KPixmapCache | ( | const QString & | name | ) | [explicit] |
Constucts the pixmap cache object.
- Parameters:
-
name unique name of the cache
Definition at line 998 of file kpixmapcache.cpp.
KPixmapCache::~KPixmapCache | ( | ) | [virtual] |
Definition at line 1011 of file kpixmapcache.cpp.
Member Function Documentation
int KPixmapCache::cacheLimit | ( | ) | const |
- Returns:
- maximum size of the cache (in kilobytes). Default setting is 3 megabytes.
Definition at line 1141 of file kpixmapcache.cpp.
void KPixmapCache::deleteCache | ( | const QString & | name | ) | [static] |
Deletes a pixmap cache.
- Parameters:
-
name unique name of the cache to be deleted
Definition at line 1243 of file kpixmapcache.cpp.
void KPixmapCache::discard | ( | ) |
void KPixmapCache::ensureInited | ( | ) | const [protected] |
Makes sure that the cache is initialized correctly.
Definition at line 1051 of file kpixmapcache.cpp.
Tries to load pixmap with the specified key from cache.
- Returns:
- true when pixmap was found and loaded from cache, false otherwise
Reimplemented in KIconCache.
Definition at line 1286 of file kpixmapcache.cpp.
Insert specified pixmap into the cache.
If the cache already contains pixmap with the specified key then it is overwritten.
Reimplemented in KIconCache.
Definition at line 1380 of file kpixmapcache.cpp.
bool KPixmapCache::isEnabled | ( | ) | const |
- Returns:
- true when the cache is enabled. Cache will be disabled when e.g. its data file cannot be created or read.
Definition at line 1067 of file kpixmapcache.cpp.
bool KPixmapCache::isValid | ( | ) | const |
- Returns:
- true when the cache is ready to be used. False usually means that some additional initing has to be done before the cache can be used.
Definition at line 1073 of file kpixmapcache.cpp.
bool KPixmapCache::loadCustomData | ( | QDataStream & | stream | ) | [protected, virtual] |
Can be used by subclasses to write custom data into the stream.
Reimplemented in KIconCache.
Definition at line 1375 of file kpixmapcache.cpp.
bool KPixmapCache::loadCustomIndexHeader | ( | QDataStream & | stream | ) | [protected, virtual] |
Can be used by subclasses to write custom data into cache's header.
Reimplemented in KIconCache.
Definition at line 1058 of file kpixmapcache.cpp.
Loads pixmap from given file, using the cache.
If file's modified-time is more recent than cache's timestamp() , then the cache is discarded.
Definition at line 1463 of file kpixmapcache.cpp.
Same as above, but uses SVG file instead.
- Parameters:
-
size size of the pixmap where the SVG is render to. If not given then SVG's default size is used.
Definition at line 1488 of file kpixmapcache.cpp.
bool KPixmapCache::recreateCacheFiles | ( | ) | [protected] |
void KPixmapCache::removeEntries | ( | int | newsize = 0 |
) |
Removes some of the entries in the cache according to current removeEntryStrategy().
- Parameters:
-
newsize wanted size of the cache, in bytes. If 0 is given then current cacheLimit() is used.
Definition at line 1272 of file kpixmapcache.cpp.
KPixmapCache::RemoveStrategy KPixmapCache::removeEntryStrategy | ( | ) | const |
- Returns:
- current entry removal strategy. Default is RemoveLeastRecentlyUsed.
Definition at line 1167 of file kpixmapcache.cpp.
void KPixmapCache::setCacheLimit | ( | int | kbytes | ) |
Sets the maximum size of the cache (in kilobytes).
If cache gets bigger the limit then some entries are removed (according to removeEntryStrategy() ). Setting cache limit to 0 disables automatic cache size limiting.
Note that the cleanup might not be done immediately, so the cache might temporarily (for a few seconds) grow bigger than the limit.
Definition at line 1146 of file kpixmapcache.cpp.
void KPixmapCache::setRemoveEntryStrategy | ( | KPixmapCache::RemoveStrategy | strategy | ) |
Sets the removeEntryStrategy used when removing entries.
Definition at line 1172 of file kpixmapcache.cpp.
void KPixmapCache::setTimestamp | ( | unsigned int | time | ) |
Sets the timestamp of app-specific cache.
It's saved in the cache file and can later be retrieved using timestamp()
method. By default the timestamp is set to the cache creation time.
Definition at line 1091 of file kpixmapcache.cpp.
void KPixmapCache::setUseQPixmapCache | ( | bool | use | ) |
Sets whether QPixmapCache (memory caching) should be used in addition to disk cache.
QPixmapCache is used by default.
Definition at line 1131 of file kpixmapcache.cpp.
void KPixmapCache::setValid | ( | bool | valid | ) | [protected] |
Can be used by subclasses to indicate that cache needs some additional initing before it can be used.
Definition at line 1079 of file kpixmapcache.cpp.
int KPixmapCache::size | ( | ) | const |
- Returns:
- approximate size of the cache, in kilobytes.
Definition at line 1122 of file kpixmapcache.cpp.
unsigned int KPixmapCache::timestamp | ( | ) | const |
- Returns:
- timestamp of the cache, set using the
setTimestamp
method. It can be used by the application to check whether app-specific cache has outdated.
Definition at line 1085 of file kpixmapcache.cpp.
bool KPixmapCache::useQPixmapCache | ( | ) | const |
Whether QPixmapCache should be used to cache pixmaps in memory in addition to caching them on the disk.
Definition at line 1136 of file kpixmapcache.cpp.
bool KPixmapCache::writeCustomData | ( | QDataStream & | stream | ) | [protected, virtual] |
Can be used by subclasses to load custom data from the stream.
Reimplemented in KIconCache.
Definition at line 1445 of file kpixmapcache.cpp.
void KPixmapCache::writeCustomIndexHeader | ( | QDataStream & | stream | ) | [protected, virtual] |
Can be used by subclasses to load custom data from cache's header.
Reimplemented in KIconCache.
Definition at line 1063 of file kpixmapcache.cpp.
The documentation for this class was generated from the following files: