Class: QgsRenderContext¶
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class
qgis.core.
QgsRenderContext
¶ Bases:
sip.wrapper
Contains information about the context of a rendering operation. The context of a rendering operation defines properties such as the conversion ratio between screen and map units, the extents to be rendered etc.
Enums
Methods
Converts a size from map units to the specified units.
Convert meter distances to active MapUnit values for QgsUnitTypes.RenderMetersInMapUnits note When the sourceCrs() is geographic, the center of the Extent will be used
Converts a size from the specified units to map units.
Converts a size from the specified units to painter units (pixels).
Returns the current coordinate transform for the context.
A general purpose distance and area calculator, capable of performing ellipsoid based calculations.
Gets the expression context.
When rendering a map layer, calling this method returns the “clipping” extent for the layer (in the layer’s CRS).
Gets the filter feature provider used for additional filtering of rendered features.
Returns combination of flags used for rendering.
create initialized QgsRenderContext instance from given
QgsMapSettings
Creates a default render context given a pixel based QPainter destination.
Returns pointer to the unsegmentized geometry
Returns the original extent of the map being rendered.
Returns the destination QPainter for the render operation.
Returns the path resolver for conversion between relative and absolute paths during rendering operations, e.g.
Returns the renderer map scale.
Returns the scaling factor for the render to convert painter units to physical sizes.
Gets the segmentation tolerance applied when rendering curved geometries
Gets segmentation tolerance type (maximum angle or maximum difference between curve and approximation)
Sets the current coordinate transform for the context.
A general purpose distance and area calculator, capable of performing ellipsoid based calculations.
Sets the expression context.
When rendering a map layer, calling this method sets the “clipping” extent for the layer (in the layer’s CRS).
Set a filter feature provider used for additional filtering of rendered features.
Enable or disable a particular flag (other flags are not affected)
Set combination of flags that will be used for rendering.
Sets pointer to original (unsegmentized) geometry
Sets the original
extent
of the map being rendered.Sets the destination QPainter for the render operation.
Sets the path
resolver
for conversion between relative and absolute paths during rendering operations, e.g.Sets the renderer map scale.
Sets the scaling factor for the render to convert painter units to physical sizes.
Sets the segmentation tolerance applied when rendering curved geometries
Sets segmentation tolerance type (maximum angle or maximum difference between curve and approximation)
Sets whether vector selections should be shown in the rendered map
Sets the text render
format
, which dictates how text is rendered (e.g.Sets the context’s coordinate transform
context
, which stores various information regarding which datum transforms should be used when transforming points from a source to destination coordinate reference system.Used to enable or disable advanced effects such as blend modes
Returns true if vector selections should be shown in the rendered map
Check whether a particular flag is enabled.
Returns the text render format, which dictates how text is rendered (e.g.
Returns the context’s coordinate transform context, which stores various information regarding which datum transforms should be used when transforming points from a source to destination coordinate reference system.
Returns true if advanced effects such as blend modes such be used
Returns true if the rendering optimization (geometry simplification) can be executed
Added in QGIS v2.4
Signals
Attributes
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Antialiasing
= 128¶
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DrawEditingInfo
= 1¶
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DrawSelection
= 16¶
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DrawSymbolBounds
= 32¶
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class
Flag
¶ Bases:
int
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class
Flags
¶ Bases:
sip.wrapper
QgsRenderContext.Flags(Union[QgsRenderContext.Flags, QgsRenderContext.Flag]) QgsRenderContext.Flags(QgsRenderContext.Flags)
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ForceVectorOutput
= 2¶
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RenderMapTile
= 64¶
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RenderPartialOutput
= 256¶
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RenderPreviewJob
= 512¶
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TextFormatAlwaysOutlines
= 0¶
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TextFormatAlwaysText
= 1¶
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class
TextRenderFormat
¶ Bases:
int
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UseAdvancedEffects
= 4¶
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UseRenderingOptimization
= 8¶
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convertFromMapUnits
(self, sizeInMapUnits: float, outputUnit: QgsUnitTypes.RenderUnit) → float¶ Converts a size from map units to the specified units.
See also
New in version 3.0.
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convertMetersToMapUnits
(self, meters: float) → float¶ Convert meter distances to active MapUnit values for QgsUnitTypes.RenderMetersInMapUnits note When the sourceCrs() is geographic, the center of the Extent will be used
New in version 3.0.
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convertToMapUnits
(self, size: float, unit: QgsUnitTypes.RenderUnit, scale: QgsMapUnitScale = QgsMapUnitScale()) → float¶ Converts a size from the specified units to map units. The conversion respects the limits specified by the optional scale parameter.
See also
New in version 3.0.
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convertToPainterUnits
(self, size: float, unit: QgsUnitTypes.RenderUnit, scale: QgsMapUnitScale = QgsMapUnitScale()) → float¶ Converts a size from the specified units to painter units (pixels). The conversion respects the limits specified by the optional scale parameter.
See also
New in version 3.0.
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coordinateTransform
(self) → QgsCoordinateTransform¶ Returns the current coordinate transform for the context.
This represents the coordinate transform required to transform a layer which is being rendered back to the CRS of the rendered map. If no coordinate transformation is required, or the render context is not associated with a map layer render, then an invalid coordinate transformation is returned.
See also
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distanceArea
(self) → QgsDistanceArea¶ A general purpose distance and area calculator, capable of performing ellipsoid based calculations.
New in version 3.0.
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drawEditingInformation
(self) → bool¶
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expressionContext
(self) → QgsExpressionContext¶ Gets the expression context. This context should be used for all expression evaluation associated with this render context.
See also
New in version 2.12.
-
extent
(self) → QgsRectangle¶ When rendering a map layer, calling this method returns the “clipping” extent for the layer (in the layer’s CRS).
This extent is a “worst-case” scenario, which is guaranteed to cover the complete visible portion of the layer when it is rendered to a map. It is often larger than the actual visible portion of that layer.
Warning
For some layers, depending on the visible extent and the coordinate transforms involved, this extent will represent the entire globe. This method should never be used to determine the actual visible extent of a map render.
See also
See also
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featureFilterProvider
(self) → QgsFeatureFilterProvider¶ Gets the filter feature provider used for additional filtering of rendered features.
- Returns
the filter feature provider
See also
New in version 2.14.
-
flags
(self) → QgsRenderContext.Flags¶ Returns combination of flags used for rendering.
New in version 2.14.
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forceVectorOutput
(self) → bool¶
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fromMapSettings
(mapSettings: QgsMapSettings) → QgsRenderContext¶ create initialized QgsRenderContext instance from given
QgsMapSettings
New in version 2.4.
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fromQPainter
(painter: QPainter) → QgsRenderContext¶ Creates a default render context given a pixel based QPainter destination. If no painter is specified or the painter has no device, then a default DPI of 88 will be assumed.
New in version 3.0.
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geometry
(self) → QgsAbstractGeometry¶ Returns pointer to the unsegmentized geometry
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mapExtent
(self) → QgsRectangle¶ Returns the original extent of the map being rendered.
Unlike extent(), this extent is always in the final destination CRS for the map render and represents the exact bounds of the map being rendered.
See also
See also
New in version 3.4.8.
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mapToPixel
(self) → QgsMapToPixel¶
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painter
(self) → QPainter¶ Returns the destination QPainter for the render operation.
See also
-
pathResolver
(self) → QgsPathResolver¶ Returns the path resolver for conversion between relative and absolute paths during rendering operations, e.g. for resolving relative symbol paths.
See also
New in version 3.0.
-
rendererScale
(self) → float¶ Returns the renderer map scale. This will match the desired scale denominator for the rendered map, eg 1000.0 for a 1:1000 map render.
See also
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renderingStopped
(self) → bool¶
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scaleFactor
(self) → float¶ Returns the scaling factor for the render to convert painter units to physical sizes. This is usually equal to the number of pixels per millimeter.
See also
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segmentationTolerance
(self) → float¶ Gets the segmentation tolerance applied when rendering curved geometries
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segmentationToleranceType
(self) → QgsAbstractGeometry.SegmentationToleranceType¶ Gets segmentation tolerance type (maximum angle or maximum difference between curve and approximation)
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selectionColor
(self) → QColor¶
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setCoordinateTransform
(self, t: QgsCoordinateTransform)¶ Sets the current coordinate transform for the context.
This represents the coordinate transform required to transform the layer which is being rendered back to the CRS of the rendered map.
Set to an invalid QgsCoordinateTransform to indicate that no transformation is required.
See also
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setDistanceArea
(self, distanceArea: QgsDistanceArea)¶ A general purpose distance and area calculator, capable of performing ellipsoid based calculations. Will be used to convert meter distances to active MapUnit values for QgsUnitTypes.RenderMetersInMapUnits
New in version 3.0.
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setDrawEditingInformation
(self, b: bool)¶
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setExpressionContext
(self, context: QgsExpressionContext)¶ Sets the expression context. This context is used for all expression evaluation associated with this render context.
See also
New in version 2.12.
-
setExtent
(self, extent: QgsRectangle)¶ When rendering a map layer, calling this method sets the “clipping” extent for the layer (in the layer’s CRS).
This extent should be a “worst-case” scenario, which is guaranteed to completely cover the entire visible portion of the layer when it is rendered to the map. It may be larger than the actual visible area, but MUST contain at least the entire visible area.
See also
See also
-
setFeatureFilterProvider
(self, ffp: QgsFeatureFilterProvider)¶ Set a filter feature provider used for additional filtering of rendered features.
- Parameters
ffp – the filter feature provider
See also
New in version 2.14.
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setFlag
(self, flag: QgsRenderContext.Flag, on: bool = True)¶ Enable or disable a particular flag (other flags are not affected)
New in version 2.14.
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setFlags
(self, flags: Union[QgsRenderContext.Flags, QgsRenderContext.Flag])¶ Set combination of flags that will be used for rendering.
New in version 2.14.
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setForceVectorOutput
(self, force: bool)¶
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setGeometry
(self, geometry: QgsAbstractGeometry)¶ Sets pointer to original (unsegmentized) geometry
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setMapExtent
(self, extent: QgsRectangle)¶ Sets the original
extent
of the map being rendered.Unlike setExtent(), this extent is always in the final destination CRS for the map render and represents the exact bounds of the map being rendered.
See also
See also
New in version 3.4.8.
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setMapToPixel
(self, mtp: QgsMapToPixel)¶
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setPainter
(self, p: QPainter)¶ Sets the destination QPainter for the render operation. Ownership of the painter is not transferred and the QPainter destination must stay alive for the duration of any rendering operations.
See also
-
setPathResolver
(self, resolver: QgsPathResolver)¶ Sets the path
resolver
for conversion between relative and absolute paths during rendering operations, e.g. for resolving relative symbol paths.See also
New in version 3.0.
-
setRendererScale
(self, scale: float)¶ Sets the renderer map scale. This should match the desired scale denominator for the rendered map, eg 1000.0 for a 1:1000 map render.
See also
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setRenderingStopped
(self, stopped: bool)¶
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setScaleFactor
(self, factor: float)¶ Sets the scaling factor for the render to convert painter units to physical sizes. This should usually be equal to the number of pixels per millimeter.
See also
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setSegmentationTolerance
(self, tolerance: float)¶ Sets the segmentation tolerance applied when rendering curved geometries
- Parameters
tolerance – the segmentation tolerance*
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setSegmentationToleranceType
(self, type: QgsAbstractGeometry.SegmentationToleranceType)¶ Sets segmentation tolerance type (maximum angle or maximum difference between curve and approximation)
- Parameters
type – the segmentation tolerance typename*
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setSelectionColor
(self, color: Union[QColor, Qt.GlobalColor, QGradient])¶
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setShowSelection
(self, showSelection: bool)¶ Sets whether vector selections should be shown in the rendered map
- Parameters
showSelection – set to true if selections should be shown
See also
See also
New in version 2.4.
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setTextRenderFormat
(self, format: QgsRenderContext.TextRenderFormat)¶ Sets the text render
format
, which dictates how text is rendered (e.g. as paths or real text objects).See also
New in version 3.4.3.
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setTransformContext
(self, context: QgsCoordinateTransformContext)¶ Sets the context’s coordinate transform
context
, which stores various information regarding which datum transforms should be used when transforming points from a source to destination coordinate reference system.See also
New in version 3.0.
-
setUseAdvancedEffects
(self, enabled: bool)¶ Used to enable or disable advanced effects such as blend modes
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setUseRenderingOptimization
(self, enabled: bool)¶
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setVectorSimplifyMethod
(self, simplifyMethod: QgsVectorSimplifyMethod)¶
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showSelection
(self) → bool¶ Returns true if vector selections should be shown in the rendered map
- Returns
true if selections should be shown
See also
See also
New in version 2.4.
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testFlag
(self, flag: QgsRenderContext.Flag) → bool¶ Check whether a particular flag is enabled.
New in version 2.14.
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textRenderFormat
(self) → QgsRenderContext.TextRenderFormat¶ Returns the text render format, which dictates how text is rendered (e.g. as paths or real text objects).
See also
New in version 3.4.3.
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transformContext
(self) → QgsCoordinateTransformContext¶ Returns the context’s coordinate transform context, which stores various information regarding which datum transforms should be used when transforming points from a source to destination coordinate reference system.
See also
New in version 3.0.
-
useAdvancedEffects
(self) → bool¶ Returns true if advanced effects such as blend modes such be used
-
useRenderingOptimization
(self) → bool¶ Returns true if the rendering optimization (geometry simplification) can be executed
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vectorSimplifyMethod
(self) → QgsVectorSimplifyMethod¶ Added in QGIS v2.4
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