LuciadCPillar 2023.1.02
luciad::FeatureCanvas::LabelDrawCommand Class Referenceabstract

Command to draw labels for a feature. More...

#include <luciad/layers/features/FeatureCanvas.h>

Public Member Functions

virtual ~LabelDrawCommand ()=default
 
virtual LabelDrawCommandanchor (std::shared_ptr< Geometry > anchor)=0
 Sets the anchor of the label. More...
 
virtual LabelDrawCommandanchorDraped (bool draped)=0
 Specify whether the anchor is draped or not. More...
 
virtual LabelDrawCommandicon (std::shared_ptr< IIcon > icon)=0
 Sets the icon to use for the label. More...
 
virtual LabelDrawCommandinPath ()=0
 Configure the LabelDrawCommand to paint the label inside the anchor. More...
 
virtual LabelDrawCommandlabelGroup (LabelGroup labelGroup)=0
 Set the LabelGroup for label decluttering. More...
 
virtual LabelDrawCommandonPath (OnPathLabelStyle onPathLabelStyle)=0
 Configure the LabelDrawCommand to position a single label along a line. More...
 
virtual LabelDrawCommandonPath (PathLabelPosition verticalPosition, double additionalVerticalOffset)=0
 Configure the LabelDrawCommand to position a single label along a line. More...
 
virtual LabelDrawCommandpinStyle (PinStyle pinStyle)=0
 This method enables pins for labels and defines their styling. More...
 
virtual LabelDrawCommandpointPositions (std::vector< RelativePosition > positions)=0
 Specifies the possible positions to place a Point label. More...
 
virtual LabelDrawCommandpriority (Priority priority)=0
 Sets the priority that is used to determine the order in which labels are placed. More...
 
virtual LabelDrawCommandqueryable (bool queryable)=0
 Indicates whether or not the label should be considered when a Map::queryFeatures is requested. More...
 
virtual void submit ()=0
 Submits this draw command. More...
 
virtual LabelDrawCommandtext (std::string text)=0
 Sets the text to use for the label. More...
 
virtual LabelDrawCommandtext (std::vector< std::string > text, HorizontalAlignment alignment=HorizontalAlignment::Left)=0
 Sets the text to use for the label. More...
 
virtual LabelDrawCommandtext (TextBlock text)=0
 Sets the text block to use for the label. More...
 
virtual LabelDrawCommandtextStyle (TextStyle textStyle)=0
 Sets the styling for the text. More...
 

Detailed Description

Command to draw labels for a feature.

It is mandatory to specify at least the following:

Label content

The label content can be

It is mandatory to call at least one of these methods. If not, an exception will be thrown when submitting this label draw command. If these methods are called multiple times, only the last one is used.

Label positions

It is possible to explicitly specify a label position. This can be done using one of the following methods:

  • the pointPositions method: to anchor a label to a Point geometry
  • the onPath method: to place a label along a line
  • the inPath method: to place a label inside an area

If these methods are called multiple times, only the last one is used. If none of these methods is called, a default label positions is chosen using the LabelDrawCommand::anchor geometry.

Label decluttering

Labels that are added using this class are automatically decluttered:

  • Multiple label locations are tried to avoid overlapping labels
  • Labels for which no good location can be found (i.e. that would always overlap with an other label) are dropped.

See the related guide for a more extensive overview of the labeling API.

Since
2020.2

Constructor & Destructor Documentation

◆ ~LabelDrawCommand()

virtual luciad::FeatureCanvas::LabelDrawCommand::~LabelDrawCommand ( )
virtualdefault

Member Function Documentation

◆ anchor()

virtual LabelDrawCommand & luciad::FeatureCanvas::LabelDrawCommand::anchor ( std::shared_ptr< Geometry anchor)
pure virtual

Sets the anchor of the label.

This property is mandatory.

Parameters
anchorthe anchor of the label, cannot be nullptr.
Returns
this
Exceptions
luciad::NullArgumentExceptionif the anchor is nullptr.

◆ anchorDraped()

virtual LabelDrawCommand & luciad::FeatureCanvas::LabelDrawCommand::anchorDraped ( bool  draped)
pure virtual

Specify whether the anchor is draped or not.

If this method is not invoked, the draping status will be the same as when rendering the anchor: if all Z components equal to 0, draping is enabled and the label will be on the ground. Otherwise, the label will be placed at anchor elevation.

Parameters
drapedwhether the anchor is draped or not.
Returns
this

◆ icon()

virtual LabelDrawCommand & luciad::FeatureCanvas::LabelDrawCommand::icon ( std::shared_ptr< IIcon icon)
pure virtual

Sets the icon to use for the label.

This property is optional, though it is mandatory that at least one method is used to specify the label content. See the class documentation for more info.

Parameters
iconthe icon to use for the label, cannot be nullptr
Returns
this
Exceptions
luciad::NullArgumentExceptionwhen the icon is nullptr.

◆ inPath()

virtual LabelDrawCommand & luciad::FeatureCanvas::LabelDrawCommand::inPath ( )
pure virtual

Configure the LabelDrawCommand to paint the label inside the anchor.

The anchor is used as follows:

  • The anchor must be a closed ring or a surface, or contain one. If it's not the case, an exception is thrown in the submit method.
  • If the anchor is a multi geometry, only the biggest one is considered.
  • If the anchor is an extruded one, the base geometry is considered.
  • If the anchor is a Patch, the base geometry is considered.
  • For other geometries, the label is positioned in such a way that it's inside the anchor geometry.

Calling this method is optional. See LabelDrawCommand for more information.

Returns
this LabelDrawCommand

◆ labelGroup()

virtual LabelDrawCommand & luciad::FeatureCanvas::LabelDrawCommand::labelGroup ( LabelGroup  labelGroup)
pure virtual

Set the LabelGroup for label decluttering.

A label declutter group is a collection of labels that are positioned independently from other label declutter groups. I.e. labels from one group will never affect labels from other groups. This also means that labels from different groups are allowed to overlap.

Parameters
labelGroupdeclutter group for this label. See LabelGroup for more information.
Returns
this LabelDrawCommand
Since
2021.0

◆ onPath() [1/2]

virtual LabelDrawCommand & luciad::FeatureCanvas::LabelDrawCommand::onPath ( OnPathLabelStyle  onPathLabelStyle)
pure virtual

Configure the LabelDrawCommand to position a single label along a line.

Depending on how the given OnPathLabelStyle is configured, it can be located

  • somewhere along the line, but also within the view extent
  • at a specific location along the line, for example exactly in the middle

When this method is called, the anchor must be a Curve.

If an anchor is specified that is not supported by this labeling method, an exception will be thrown when the label command is submitted.

Calling this method is optional. See LabelDrawCommand for more information.

Parameters
onPathLabelStylespecifies all parameters needed to place the label at a specific location along the line, cannot be nullptr.
Returns
this LabelDrawCommand
Since
2021.0

◆ onPath() [2/2]

virtual LabelDrawCommand & luciad::FeatureCanvas::LabelDrawCommand::onPath ( PathLabelPosition  verticalPosition,
double  additionalVerticalOffset 
)
pure virtual

Configure the LabelDrawCommand to position a single label along a line.

The label will also be placed within the view extent if possible.

When this method is called, the anchor must be a Curve or consist of one in case of:

Also Bounds geometries are supported.

If an anchor is specified that is not supported by this labeling method, an exception will be thrown when the label command is submitted.

Calling this method is optional. See LabelDrawCommand for more information.

Parameters
verticalPositionspecifies where the label is placed wrt to a position on the line.
additionalVerticalOffsetan additional perpendicular offset from the position on the line at which a label will be placed. This offset is expressed in pixels. If the value is positive, the label position is moved away from the line. If the value is negative, the label positions is moved towards the line. There is no maximum limit to the negative values, but keep in mind that large negative values will push the label to the opposite side of the line. The default offset is 0.
Returns
this LabelDrawCommand

◆ pinStyle()

virtual LabelDrawCommand & luciad::FeatureCanvas::LabelDrawCommand::pinStyle ( PinStyle  pinStyle)
pure virtual

This method enables pins for labels and defines their styling.

By default, there's no pin for labels.

Pins are only supported when a label is attached to a point. No pin will be painted when onPath or inPath label positioning is used.

Parameters
pinStylethe styling for the pin. See PinStyle::newBuilder. This property is optional. By default, there's no pin for labels.
Returns
this

◆ pointPositions()

virtual LabelDrawCommand & luciad::FeatureCanvas::LabelDrawCommand::pointPositions ( std::vector< RelativePosition positions)
pure virtual

Specifies the possible positions to place a Point label.

If the anchor is not a point geometry, an exception is thrown in the submit method.

Calling this method is optional. See LabelDrawCommand for more information.

Parameters
positionsthe possible positions for a point label. If empty, an exception is thrown.
Returns
this LabelDrawCommand
Exceptions
luciad::InvalidArgumentExceptionif the list of positions is empty.

◆ priority()

virtual LabelDrawCommand & luciad::FeatureCanvas::LabelDrawCommand::priority ( Priority  priority)
pure virtual

Sets the priority that is used to determine the order in which labels are placed.

  • Using a high priority will make it more likely for a label to be placed.
  • Using a low priority will make it more likely for the label to be omitted during label placement, because other labels with a higher priority may already occupy its space.

Label priorities work across layers. This means that it is possible to give a high priority to a label, regardless of where the layer is located in the Map's LayerList.

This property is optional. The default is Priority::normal().

Parameters
prioritythe priority for this label
Returns
this

◆ queryable()

virtual LabelDrawCommand & luciad::FeatureCanvas::LabelDrawCommand::queryable ( bool  queryable)
pure virtual

Indicates whether or not the label should be considered when a Map::queryFeatures is requested.

The default is true.

Parameters
queryabletrue if the label should be considered.
Returns
this TextDrawCommand.
Since
2020.2

◆ submit()

virtual void luciad::FeatureCanvas::LabelDrawCommand::submit ( )
pure virtual

Submits this draw command.

Nothing will be painted if the draw command is not submitted.

Exceptions
LogicExceptionif anchor is not a luciad::Point and the pointPositions method is used.

◆ text() [1/3]

virtual LabelDrawCommand & luciad::FeatureCanvas::LabelDrawCommand::text ( std::string  text)
pure virtual

Sets the text to use for the label.

This property is optional, though it is mandatory that at least one method is used to specify the label content. See the class documentation for more info.

Parameters
textthe text to use for the label.
Returns
this

◆ text() [2/3]

virtual LabelDrawCommand & luciad::FeatureCanvas::LabelDrawCommand::text ( std::vector< std::string >  text,
HorizontalAlignment  alignment = HorizontalAlignment::Left 
)
pure virtual

Sets the text to use for the label.

Each string in this vector is rendered as a separate line.

This property is optional, though it is mandatory that at least one method is used to specify the label content. See the class documentation for more info.

Parameters
textthe text to use for the label.
alignmentside where text is aligned. By default text is aligned on the left.
Returns
this

◆ text() [3/3]

virtual LabelDrawCommand & luciad::FeatureCanvas::LabelDrawCommand::text ( TextBlock  text)
pure virtual

Sets the text block to use for the label.

A text block is composed of multiple texts with different styling each. See TextBlock and TextBlock::Builder.

This property is optional, though it is mandatory that at least one method is used to specify the label content. See the class documentation for more info.

Parameters
textthe text block to use for the label.
Returns
this
Since
2021.0

◆ textStyle()

virtual LabelDrawCommand & luciad::FeatureCanvas::LabelDrawCommand::textStyle ( TextStyle  textStyle)
pure virtual

Sets the styling for the text.

This property is optional. See the text style builder for the default values.

Parameters
textStylethe styling for the text.
Returns
this