QGIS API Documentation 3.39.0-Master (d85f3c2a281)
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Implementation of threaded rendering for group layers. More...
#include <qgsgrouplayerrenderer.h>
Public Member Functions | |
QgsGroupLayerRenderer (QgsGroupLayer *layer, QgsRenderContext &context) | |
Constructor for a QgsGroupLayerRenderer, for the specified layer. | |
~QgsGroupLayerRenderer () override | |
QgsFeedback * | feedback () const override |
Access to feedback object of the layer renderer (may be nullptr ) | |
bool | forceRasterRender () const override |
Returns true if the renderer must be rendered to a raster paint device (e.g. | |
bool | render () override |
Do the rendering (based on data stored in the class). | |
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QgsMapLayerRenderer (const QString &layerID, QgsRenderContext *context=nullptr) | |
Constructor for QgsMapLayerRenderer, with the associated layerID and render context. | |
virtual | ~QgsMapLayerRenderer () |
QStringList | errors () const |
Returns list of errors (problems) that happened during the rendering. | |
virtual Qgis::MapLayerRendererFlags | flags () const |
Returns flags which control how the map layer rendering behaves. | |
bool | isReadyToCompose () const |
Returns whether the renderer has already drawn (at least partially) some data. | |
QString | layerId () const |
Gets access to the ID of the layer rendered by this class. | |
QgsRenderContext * | renderContext () |
Returns the render context associated with the renderer. | |
const QgsRenderContext * | renderContext () const |
Returns the render context associated with the renderer. | |
virtual void | setLayerRenderingTimeHint (int time) |
Sets approximate render time (in ms) for the layer to render. | |
QList< QgsRenderedItemDetails * > | takeRenderedItemDetails () |
Takes the list of rendered item details from the renderer. | |
Additional Inherited Members | |
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void | appendRenderedItemDetails (QgsRenderedItemDetails *details) |
Appends the details of a rendered item to the renderer. | |
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QStringList | mErrors |
QString | mLayerID |
bool | mReadyToCompose = true |
The flag must be set to false in renderer's constructor if wants to use the smarter map redraws functionality https://github.com/qgis/QGIS-Enhancement-Proposals/issues/181. | |
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static constexpr int | MAX_TIME_TO_USE_CACHED_PREVIEW_IMAGE = 3000 |
Maximum time (in ms) to allow display of a previously cached preview image while rendering layers, before switching to a progressive rendering display. | |
Implementation of threaded rendering for group layers.
Definition at line 43 of file qgsgrouplayerrenderer.h.
QgsGroupLayerRenderer::QgsGroupLayerRenderer | ( | QgsGroupLayer * | layer, |
QgsRenderContext & | context | ||
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Constructor for a QgsGroupLayerRenderer, for the specified layer.
Definition at line 26 of file qgsgrouplayerrenderer.cpp.
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overridedefault |
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overridevirtual |
Access to feedback object of the layer renderer (may be nullptr
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Reimplemented from QgsMapLayerRenderer.
Definition at line 64 of file qgsgrouplayerrenderer.cpp.
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overridevirtual |
Returns true
if the renderer must be rendered to a raster paint device (e.g.
QImage).
Some layer settings require layers to be effectively "flattened" while rendering maps, which is achieved by first rendering the layer onto a raster paint device and then compositing the resultant image onto the final map render.
E.g. if a layer contains features with transparency or alternative blending modes, and the effects of these opacity or blending modes should be restricted to only affect other features within the SAME layer, then a flattened raster based render is required.
Subclasses should return true
whenever their corresponding layer settings require the layer to always be rendered using a raster paint device.
Reimplemented from QgsMapLayerRenderer.
Definition at line 137 of file qgsgrouplayerrenderer.cpp.
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overridevirtual |
Do the rendering (based on data stored in the class).
Returns true
if the layer was completely rendered successfully (i.e. the render was not canceled early).
Implements QgsMapLayerRenderer.
Definition at line 69 of file qgsgrouplayerrenderer.cpp.