Subgroup: Paint
Class: QgsPaintEffect¶
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class
qgis.core.
QgsPaintEffect
¶ Bases:
sip.wrapper
Base class for visual effects which can be applied to QPicture drawings
QgsPaintEffect objects can be used to modify QPicture drawings prior to rendering them with a QPainter operation. There are two methods for drawing using an effect, either drawing a picture directly, or by intercepting drawing operations to a render context.
To directly draw a picture, use the render() method with a source QPicture and destination render context.
Intercepting drawing operations to a render context is achieved by first calling the begin() method, passing a render context. Any drawing operations performed on the render context will not directly affect the context’s paint device. When the drawing operations have been completed, call the end() method. This will perform the paint effect on the intercepted drawing operations and render the result to the render context’s paint device.
See also
New in version 2.9: Methods
begin
Begins intercepting paint operations to a render context. boundingRect
Returns the bounding rect required for drawing the effect. clone
Duplicates an effect by creating a deep copy of the effect draw
Handles drawing of the effect’s result on to the specified render context. drawMode
Returns the draw mode for the effect. drawSource
Draws the source QPicture onto the specified painter. enabled
Returns whether the effect is enabled end
Ends interception of paint operations to a render context, and draws the result to the render context after being modified by the effect. fixQPictureDpi
Applies a workaround to a QPainter to avoid an issue with incorrect scaling when drawing QPictures. imageOffset
Returns the offset which should be used when drawing the source image on to a destination render context. properties
Returns the properties describing the paint effect encoded in a string format. readProperties
Reads a string map of an effect’s properties and restores the effect to the state described by the properties map. render
Renders a picture using the effect. saveProperties
Saves the current state of the effect to a DOM element. setDrawMode
Sets the draw mode for the effect. setEnabled
Sets whether the effect is enabled source
Returns the source QPicture. sourceAsImage
Returns the source QPicture rendered to a new QImage. type
Returns the effect type. Attributes
Modifier
ModifyAndRender
Render
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class
DrawMode
¶ Bases:
int
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Modifier
= 0¶
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ModifyAndRender
= 2¶
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Render
= 1¶
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begin
(self, context: QgsRenderContext)¶ Begins intercepting paint operations to a render context. When the corresponding end() member is called all intercepted paint operations will be drawn to the render context after being modified by the effect.
Parameters: context – destination render context See also
See also
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boundingRect
(self, rect: QRectF, context: QgsRenderContext) → QRectF¶ Returns the bounding rect required for drawing the effect. This method can be used to expand the bounding rect of a source picture to account for offset or blurring effects.
Parameters: - rect – original source bounding rect
- context – destination render context
Returns: modified bounding rect
See also
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clone
(self) → QgsPaintEffect¶ Duplicates an effect by creating a deep copy of the effect
Returns: clone of paint effect
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draw
(self, context: QgsRenderContext)¶ Handles drawing of the effect’s result on to the specified render context. Derived classes must reimplement this method to apply any transformations to the source QPicture and draw the result using the context’s painter.
Parameters: context – destination render context See also
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drawMode
(self) → QgsPaintEffect.DrawMode¶ Returns the draw mode for the effect. This property only has an effect if the paint effect is used in a
QgsEffectStack
.Returns: draw mode for effect See also
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drawSource
(self, painter: QPainter)¶ Draws the source QPicture onto the specified painter. Handles scaling of the picture to account for the destination painter’s DPI.
Parameters: painter – destination painter See also
See also
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enabled
(self) → bool¶ Returns whether the effect is enabled
Returns: true if effect is enabled See also
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end
(self, context: QgsRenderContext)¶ Ends interception of paint operations to a render context, and draws the result to the render context after being modified by the effect.
Parameters: context – destination render context See also
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fixQPictureDpi
(self, painter: QPainter)¶ Applies a workaround to a QPainter to avoid an issue with incorrect scaling when drawing QPictures. This may need to be called by derived classes prior to rendering results onto a painter.
Parameters: painter – destination painter
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imageOffset
(self, context: QgsRenderContext) → QPointF¶ Returns the offset which should be used when drawing the source image on to a destination render context.
Parameters: context – destination render context Returns: point offset for image top left corner See also
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properties
(self) → Dict[str, str]¶ Returns the properties describing the paint effect encoded in a string format.
Returns: string map of properties, in the form property key, value See also
See also
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readProperties
(self, props: Dict[str, str])¶ Reads a string map of an effect’s properties and restores the effect to the state described by the properties map.
Parameters: props – effect properties encoded in a string map See also
readProperties(self, element: QDomElement) -> bool Restores the effect to the state described by a DOM element.
Parameters: element – DOM element describing an effect’s state Returns: true if read was successful See also
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render
(self, picture: QPicture, context: QgsRenderContext)¶ Renders a picture using the effect.
Parameters: - picture – source QPicture to render
- context – destination render context
See also
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saveProperties
(self, doc: QDomDocument, element: QDomElement) → bool¶ Saves the current state of the effect to a DOM element. The default behavior is to save the properties string map returned by properties().
Parameters: - doc – destination DOM document
- element – destination DOM element
Returns: true if save was successful
See also
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setDrawMode
(self, drawMode: QgsPaintEffect.DrawMode)¶ Sets the draw mode for the effect. This property only has an effect if the paint effect is used in a
QgsEffectStack
.Parameters: drawMode – draw mode for effect See also
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setEnabled
(self, enabled: bool)¶ Sets whether the effect is enabled
Parameters: enabled – set to false to disable the effect See also
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source
(self) → QPicture¶ Returns the source QPicture. The draw() member can utilize this when drawing the effect.
Returns: source QPicture See also
See also
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sourceAsImage
(self, context: QgsRenderContext) → QImage¶ Returns the source QPicture rendered to a new QImage. The draw() member can utilize this when drawing the effect. The image will be padded or cropped from the original source QPicture by the results of the boundingRect() method. The result is cached to speed up subsequent calls to sourceAsImage.
Returns: source QPicture rendered to an image See also
See also
See also
See also
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type
(self) → str¶ Returns the effect type.
Returns: unique string representation of the effect type
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class