KSharedPixmapCacheMixin Class
template <typename T> class KSharedPixmapCacheMixinA simple wrapping layer over KSharedDataCache to support caching images and pixmaps. More...
| Header: | #include <KImageCache> |
| CMake: | find_package(KF6 REQUIRED COMPONENTS GuiAddons)target_link_libraries(mytarget PRIVATE KF6::GuiAddons) |
| Since: | 4.5 |
Public Functions
| KSharedPixmapCacheMixin(const QString &cacheName, unsigned int defaultCacheSize, unsigned int expectedItemSize = 0) | |
| void | clear() |
| bool | findImage(const QString &key, QImage *destination) const |
| bool | findPixmap(const QString &key, QPixmap *destination) const |
| bool | insertImage(const QString &key, const QImage &image) |
| bool | insertPixmap(const QString &key, const QPixmap &pixmap) |
Detailed Description
This class can be used to share images between different processes, which is useful when it is known that such images will be used across many processes, or when creating the image is expensive.
In addition, the class also supports caching QPixmaps in a single process using the setPixmapCaching() function.
Tips for use: If you already have QPixmaps that you intend to use, and you do not need access to the actual image data, then try to store and retrieve QPixmaps for use.
On the other hand, if you will need to store and retrieve actual image data (to modify the image after retrieval for instance) then you should use QImage to save the conversion cost from QPixmap to QImage.
KSharedPixmapCacheMixin is a subclass of KSharedDataCache, so all of the methods that can be used with KSharedDataCache can be used with KSharedPixmapCacheMixin, with the exception of KSharedDataCache::insert() and KSharedDataCache::find().
Member Function Documentation
KSharedPixmapCacheMixin::KSharedPixmapCacheMixin(const QString &cacheName, unsigned int defaultCacheSize, unsigned int expectedItemSize = 0)
Constructs an image cache, named by cacheName, with a default size of defaultCacheSize.
cacheName Name of the cache to use.
defaultCacheSize The default size, in bytes, of the cache.
The actual on-disk size will be slightly larger. If the cache already exists, it will not be resized. If it is required to resize the cache then use the deleteCache() function to remove that cache first.
expectedItemSize The expected general size of the items to be added to the image cache, in bytes. Use 0 if you just want a default item size.
void KSharedPixmapCacheMixin::clear()
Removes all entries from the cache. In addition any cached pixmaps (as per setPixmapCaching()) are also removed.
bool KSharedPixmapCacheMixin::findImage(const QString &key, QImage *destination) const
Copies the cached image identified by key to destination. If no such image exists destination is unchanged.
Returns true if the image identified by key existed, false otherwise.
bool KSharedPixmapCacheMixin::findPixmap(const QString &key, QPixmap *destination) const
Copies the cached pixmap identified by key to destination. If no such pixmap exists destination is unchanged.
Returns true if the pixmap identified by key existed, false otherwise.
See also setPixmapCaching().
bool KSharedPixmapCacheMixin::insertImage(const QString &key, const QImage &image)
Inserts the image into the shared cache, accessible with key. This variant is preferred over insertPixmap() if your source data is already a QImage, if it is essential that the image be in shared memory (such as for SVG icons which have a high render time), or if it will need to be in QImage form after it is retrieved from the cache.
key Name to access image with.
image The image to add to the shared cache.
Returns true if the image was successfully cached, false otherwise.
bool KSharedPixmapCacheMixin::insertPixmap(const QString &key, const QPixmap &pixmap)
Inserts the pixmap given by pixmap to the cache, accessible with key. The pixmap must be converted to a QImage in order to be stored into shared memory. In order to prevent unnecessary conversions from taking place pixmap will also be cached (but not in shared memory) and would be accessible using findPixmap() if pixmap caching is enabled.
key Name to access pixmap with.
pixmap The pixmap to add to the cache.
Returns true if the pixmap was successfully cached, false otherwise.
See also setPixmapCaching().