Abstract base class for file content caches, such as SVG or raster image caches. More...
#include <qgsabstractcontentcache.h>
Public Member Functions | |
| QgsAbstractContentCache (QObject *parent=nullptr, const QString &typeString=QString(), long maxCacheSize=20000000, int fileModifiedCheckTimeout=30000) | |
| Constructor for QgsAbstractContentCache, with the specified parent object. More... | |
| ~QgsAbstractContentCache () override | |
 Public Member Functions inherited from QgsAbstractContentCacheBase | |
| QgsAbstractContentCacheBase (QObject *parent) | |
| Constructor for QgsAbstractContentCacheBase, with the specified parent object. More... | |
Protected Member Functions | |
| T * | findExistingEntry (T *entryTemplate) |
| Returns the existing entry from the cache which matches entryTemplate (deleting entryTemplate when done), or if no existing entry is found then entryTemplate is transferred to the cache and returned. More... | |
| QByteArray | getContent (const QString &path, const QByteArray &missingContent, const QByteArray &fetchingContent, bool blocking=false) const |
| Gets the file content corresponding to the given path. More... | |
| void | onRemoteContentFetched (const QString &url, bool success) override |
| Triggered after remote content (i.e. More... | |
| void | trimToMaximumSize () |
| Removes the least used cache entries until the maximum cache size is under the predefined size limit. More... | |
| bool | waitForTaskFinished (QgsNetworkContentFetcherTask *task) const |
| Blocks the current thread until the task finishes (or user's preset network timeout expires) More... | |
| Protected Member Functions inherited from QgsAbstractContentCacheBase | |
| virtual bool | checkReply (QNetworkReply *reply, const QString &path) const |
| Runs additional checks on a network reply to ensure that the reply content is consistent with that required by the cache. More... | |
Protected Attributes | |
| long | mMaxCacheSize = 20000000 |
| Maximum cache size. More... | |
| QRecursiveMutex | mMutex |
| long | mTotalSize = 0 |
| Estimated total size of all cached content. More... | |
Friends | |
| class | TestQgsImageCache |
| class | TestQgsSvgCache |
Additional Inherited Members | |
| Signals inherited from QgsAbstractContentCacheBase | |
| void | remoteContentFetched (const QString &url) |
| Emitted when the cache has finished retrieving content from a remote url. More... | |
| Protected Slots inherited from QgsAbstractContentCacheBase | |
| virtual void | onRemoteContentFetched (const QString &url, bool success) |
| Triggered after remote content (i.e. More... | |
Detailed Description
class QgsAbstractContentCache< T >
Abstract base class for file content caches, such as SVG or raster image caches.
Handles trimming the maximum cached content size to a desired limit, fetching remote content (via HTTP), and automatically invalidating cached content when the corresponding file is changed.
- Note
- Not available in Python bindings.
- Since
- QGIS 3.6
Definition at line 193 of file qgsabstractcontentcache.h.
Constructor & Destructor Documentation
◆ QgsAbstractContentCache()
|
inline |
Constructor for QgsAbstractContentCache, with the specified parent object.
The maxCacheSize argument dictates the maximum allowable total size of the cache, in bytes. This in turn dictates the maximum allowable size for caching individual entries.
The fileModifiedCheckTimeout dictates the minimum time (in milliseconds) between consecutive checks of whether a file's content has been modified (and existing cache entries should be discarded).
Definition at line 209 of file qgsabstractcontentcache.h.
◆ ~QgsAbstractContentCache()
|
inlineoverride |
Definition at line 220 of file qgsabstractcontentcache.h.
Member Function Documentation
◆ findExistingEntry()
|
inlineprotected |
Returns the existing entry from the cache which matches entryTemplate (deleting entryTemplate when done), or if no existing entry is found then entryTemplate is transferred to the cache and returned.
I.e. either way ownership of entryTemplate is transferred by calling this method.
If an existing entry was found, then the corresponding file MAY be rechecked for changes (only if a suitable time has occurred since the last check).
Definition at line 325 of file qgsabstractcontentcache.h.
◆ getContent()
|
protected |
Gets the file content corresponding to the given path.
path may be a local file, remote (HTTP) url, or a base 64 encoded string (with a "base64:" prefix).
The missingContent byte array is returned if the path could not be resolved or is broken. If the path corresponds to a remote URL, then fetchingContent will be returned while the content is in the process of being fetched. The blocking boolean forces to wait for loading before returning result. The content is loaded in the same thread to ensure provided the remote content. WARNING: the blocking parameter must NEVER be true from GUI based applications (like the main QGIS application) or crashes will result. Only for use in external scripts or QGIS server.
Definition at line 25 of file qgsabstractcontentcache_p.h.
◆ onRemoteContentFetched()
|
inlineoverrideprotectedvirtual |
Triggered after remote content (i.e.
HTTP linked content at the given url) has been fetched.
The success argument will be true if the content was successfully fetched, or false if it was not fetched successfully.
Reimplemented from QgsAbstractContentCacheBase.
Definition at line 265 of file qgsabstractcontentcache.h.
◆ trimToMaximumSize()
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inlineprotected |
Removes the least used cache entries until the maximum cache size is under the predefined size limit.
Definition at line 230 of file qgsabstractcontentcache.h.
◆ waitForTaskFinished()
|
inlineprotected |
Blocks the current thread until the task finishes (or user's preset network timeout expires)
- Warning
- this method must NEVER be used from GUI based applications (like the main QGIS application) or crashes will result. Only for use in external scripts or QGIS server.
The result will be false if the wait timed out and true in any other case.
- Since
- QGIS 3.10
Definition at line 297 of file qgsabstractcontentcache.h.
Friends And Related Function Documentation
◆ TestQgsImageCache
|
friend |
Definition at line 490 of file qgsabstractcontentcache.h.
◆ TestQgsSvgCache
|
friend |
Definition at line 489 of file qgsabstractcontentcache.h.
Member Data Documentation
◆ mMaxCacheSize
|
protected |
Maximum cache size.
Definition at line 387 of file qgsabstractcontentcache.h.
◆ mMutex
|
mutableprotected |
Definition at line 381 of file qgsabstractcontentcache.h.
◆ mTotalSize
|
protected |
Estimated total size of all cached content.
Definition at line 384 of file qgsabstractcontentcache.h.
The documentation for this class was generated from the following files:
- /build/qgis-3.37.0+git20240325+fdefdf9c27f+17bookworm/src/core/qgsabstractcontentcache.h
- /build/qgis-3.37.0+git20240325+fdefdf9c27f+17bookworm/src/core/qgsabstractcontentcache_p.h
