Class: QgsImageCache¶
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class
qgis.core.
QgsImageCache
(parent: QObject = None)¶ Bases:
qgis._core.QgsAbstractContentCacheBase
Constructor for QgsImageCache, with the specified
parent
object.A cache for images derived from raster files.
QgsImageCache stores pre-rendered resampled versions of raster image files, allowing efficient reuse without incurring the cost of resampling on every render.
QgsImageCache is not usually directly created, but rather accessed through
QgsApplication.imageCache()
New in version 3.6: Enums
Methods
Returns the original size (in pixels) of the image at the specified
path
.Returns the specified
path
rendered as an image.Signals
Emitted when the cache has finished retrieving an image file from a remote
url
.Attributes
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checkReply
()¶
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childEvent
()¶
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connectNotify
()¶
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customEvent
()¶
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disconnectNotify
()¶
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isSignalConnected
()¶
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onRemoteContentFetched
()¶
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originalSize
(self, path: str) → QSize¶ Returns the original size (in pixels) of the image at the specified
path
.path
may be a local file, remote (HTTP) url, or a base 64 encoded string (with a “base64:” prefix).If
path
is a remote file, then an invalid size may be returned while the image is in the process of being fetched.If the image could not be read then an invalid QSize is returned.
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pathAsImage
(self, path: str, size: QSize, keepAspectRatio: bool, opacity: float) → Tuple[QImage, bool]¶ Returns the specified
path
rendered as an image. If possible, a pre-existing cached version of the image will be used. If not, the image is fetched and resampled to the desired size, and then the result cached for subsequent lookups.path
may be a local file, remote (HTTP) url, or a base 64 encoded string (with a “base64:” prefix).The
size
parameter dictates the target size of the image. An invalid size indicates the original raster image size (with no resampling). A size in which the width or height is set to zero will have the zeroed value automatically computed when keepAspectRatio isTrue
.If
keepAspectRatio
isTrue
, then the original raster aspect ratio will be maintained during any resampling operations.An
opacity
parameter dictates the opacity of the image.If the resultant raster was of a sufficiently small size to store in the cache, then
fitsInCache
will be set toTrue
.
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receivers
()¶
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remoteImageFetched
¶ Emitted when the cache has finished retrieving an image file from a remote
url
. [signal]
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sender
()¶
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senderSignalIndex
()¶
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timerEvent
()¶
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