Subgroup: Map
Class: QgsMapRendererCache¶
-
class
qgis.core.
QgsMapRendererCache
¶ Bases:
PyQt5.QtCore.QObject
This class is responsible for keeping cache of rendered images resulting from a map rendering job.
Once a job has a rendered image stored in the cache (using setCacheImage(…)), the cache listens to repaintRequested() signals from dependent layers. If triggered, the cache removes the rendered image (and disconnects from the layers).
The class is thread-safe (multiple classes can access the same instance safely).
New in version 2.4: Methods
cacheImage
Returns the cached image for the specified cacheKey
.childEvent
clear
Invalidates the cache contents, clearing all cached images. clearCacheImage
Removes an image from the cache with matching cacheKey
.connectNotify
customEvent
dependentLayers
Returns a list of map layers on which an image in the cache depends. disconnectNotify
hasCacheImage
Returns true if the cache contains an image with the specified cacheKey
.init
Initialize cache: set new parameters and clears the cache if any parameters have changed since last initialization. isSignalConnected
receivers
sender
senderSignalIndex
setCacheImage
Set the cached image
for a particularcacheKey
.timerEvent
Signals
Attributes
-
cacheImage
(self, cacheKey: str) → QImage¶ Returns the cached image for the specified
cacheKey
. ThecacheKey
usually matches the QgsMapLayer.id() which the image is a render of. Returns a null image if it is not cached.See also
See also
-
childEvent
()¶
-
clear
(self)¶ Invalidates the cache contents, clearing all cached images.
See also
-
clearCacheImage
(self, cacheKey: str)¶ Removes an image from the cache with matching
cacheKey
.See also
-
connectNotify
()¶
-
customEvent
()¶
-
dependentLayers
(self, cacheKey: str) → List[QgsMapLayer]¶ Returns a list of map layers on which an image in the cache depends.
New in version 3.0.
-
disconnectNotify
()¶
-
hasCacheImage
(self, cacheKey: str) → bool¶ Returns true if the cache contains an image with the specified
cacheKey
.See also
New in version 3.0.
-
init
(self, extent: QgsRectangle, scale: float) → bool¶ Initialize cache: set new parameters and clears the cache if any parameters have changed since last initialization.
Returns: flag whether the parameters are the same as last time
-
isSignalConnected
()¶
-
receivers
()¶
-
sender
()¶
-
senderSignalIndex
()¶
-
setCacheImage
(self, cacheKey: str, image: QImage, dependentLayers: Iterable[QgsMapLayer] = [])¶ Set the cached
image
for a particularcacheKey
. ThecacheKey
usually matches the QgsMapLayer.id() which the image is a render of. A list ofdependentLayers
should be passed containing all layer on which this cache image is dependent. If any of these layers triggers a repaint then the cache image will be cleared.See also
-
timerEvent
()¶
-