QgsGroupLayerRenderer Class Reference

Implementation of threaded rendering for group layers. More...

#include <qgsgrouplayerrenderer.h>

Inheritance diagram for QgsGroupLayerRenderer:

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).
Public Member Functions inherited from QgsMapLayerRenderer
	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
Protected Member Functions inherited from QgsMapLayerRenderer
void	appendRenderedItemDetails (QgsRenderedItemDetails *details)
	Appends the details of a rendered item to the renderer.
Protected Attributes inherited from QgsMapLayerRenderer
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.
Static Protected Attributes inherited from QgsMapLayerRenderer
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.

Detailed Description

Implementation of threaded rendering for group layers.

Note

not available in Python bindings

Since

QGIS 3.24

Definition at line 43 of file qgsgrouplayerrenderer.h.

Constructor & Destructor Documentation

QgsGroupLayerRenderer()

QgsGroupLayerRenderer::QgsGroupLayerRenderer	(	QgsGroupLayer *	layer,
		QgsRenderContext &	context
	)

Constructor for a QgsGroupLayerRenderer, for the specified layer.

Definition at line 26 of file qgsgrouplayerrenderer.cpp.

~QgsGroupLayerRenderer()

QgsGroupLayerRenderer::~QgsGroupLayerRenderer ( )

overridedefault

Member Function Documentation

feedback()

QgsFeedback * QgsGroupLayerRenderer::feedback ( ) const

overridevirtual

Access to feedback object of the layer renderer (may be nullptr)

Reimplemented from QgsMapLayerRenderer.

Definition at line 64 of file qgsgrouplayerrenderer.cpp.

forceRasterRender()

bool QgsGroupLayerRenderer::forceRasterRender ( ) const

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.

Since

QGIS 3.18

Reimplemented from QgsMapLayerRenderer.

Definition at line 137 of file qgsgrouplayerrenderer.cpp.

render()

bool QgsGroupLayerRenderer::render ( )

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.

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The documentation for this class was generated from the following files:

• /build/qgis-3.41.0+git20241122+3440c17df1d+99sid/src/core/qgsgrouplayerrenderer.h
• /build/qgis-3.41.0+git20241122+3440c17df1d+99sid/src/core/qgsgrouplayerrenderer.cpp