A class to render labels. More...

#include <qgslabel.h>

Collaboration diagram for QgsLabel:

Classes
struct	labelpoint

Public Types
enum	LabelField { Text = 0, Family, Size, SizeType, Bold, Italic, Underline, Color, XCoordinate, YCoordinate, XOffset, YOffset, Angle, Alignment, BufferEnabled, BufferSize, BufferColor, BufferBrush, BorderWidth, BorderColor, BorderStyle, MultilineEnabled, StrikeOut, LabelFieldCount }

Public Member Functions
	QgsLabel (const QgsFields &fields)
	~QgsLabel ()
void	renderLabel (QgsRenderContext &renderContext, QgsFeature &feature, bool selected, QgsLabelAttributes *classAttributes=0)
	render label
void	readXML (const QDomNode &node)
	Reads the renderer configuration from an XML file.
void	writeXML (QDomNode &label_node, QDomDocument &document) const
	Writes the contents of the renderer to a configuration file.
void	addRequiredFields (QgsAttributeList &fields) const
	add vector of required fields to existing list of fields
void	setFields (const QgsFields &fields)
	Set available fields.
QgsFields &	fields ()
	Available vector fields.
QgsLabelAttributes *	labelAttributes ()
	Pointer to default attributes.
void	setLabelField (int attr, int fieldIndex)
	Set label field.
QString	labelField (int attr) const
	label field
QString	fieldValue (int attr, QgsFeature &feature)
	Get field value if : 1) field name is not empty 2) field exists 3) value is defined otherwise returns empty string.
void	setMinScale (float theMinScale)
	Accessor and mutator for the minimum scale member.
float	minScale () const
void	setMaxScale (float theMaxScale)
	Accessor and mutator for the maximum scale member.
float	maxScale () const
void	setScaleBasedVisibility (bool theVisibilityFlag)
	Accessor and mutator for the scale based visilibility flag.
bool	scaleBasedVisibility () const

Private Member Functions
void	renderLabel (QgsRenderContext &renderContext, QgsPoint point, QString text, QFont font, QPen pen, int dx, int dy, double xoffset, double yoffset, double ang, int width, int height, int alignment)
	Does the actual rendering of a label at the given point.
bool	readLabelField (QDomElement &el, int attr, QString prefix)
void	labelPoint (std::vector< labelpoint > &, QgsFeature &feature)
	Get label point for simple feature in map units.
const unsigned char *	labelPoint (labelpoint &point, const unsigned char *wkb, size_t wkblen)
	Get label point for the given feature in wkb format.

Private Attributes
QColor	mSelectionColor
	Color to draw selected features.
QgsLabelAttributes *	mLabelAttributes
	Default layer attributes.
QgsFields	mFields
	Available layer fields.
std::vector< QString >	mLabelField
	Label fields.
std::vector< int >	mLabelFieldIdx
	Label field indexes.
float	mMinScale
	Minimum scale at which this label should be displayed.
float	mMaxScale
	Maximum scale at which this label should be displayed.
bool	mScaleBasedVisibility
	A flag that tells us whether to use the above vars to restrict the label's visibility.

Detailed Description

A class to render labels.

Label rendering properties can be either specified directly or in most cases determined dynamically based on the value of an attribute.

Definition at line 52 of file qgslabel.h.

Member Enumeration Documentation

enum QgsLabel::LabelField

Enumerator:

Text
Family
Size
SizeType
Bold
Italic
Underline
Color
XCoordinate
YCoordinate
XOffset
YOffset
Angle
Alignment
BufferEnabled
BufferSize
BufferColor
BufferBrush
BorderWidth
BorderColor
BorderStyle
MultilineEnabled
StrikeOut
LabelFieldCount

Definition at line 60 of file qgslabel.h.

Constructor & Destructor Documentation

QgsLabel::QgsLabel ( const QgsFields & fields )

Definition at line 47 of file qgslabel.cpp.

References fields(), LabelFieldCount, mFields, mLabelAttributes, and mLabelFieldIdx.

QgsLabel::~QgsLabel ( )

Definition at line 61 of file qgslabel.cpp.

References mLabelAttributes.

Member Function Documentation

void QgsLabel::addRequiredFields ( QgsAttributeList & fields ) const

add vector of required fields to existing list of fields

Definition at line 459 of file qgslabel.cpp.

References LabelFieldCount, and mLabelFieldIdx.

Referenced by QgsVectorLayer::drawLabels().

QgsFields & QgsLabel::fields ( void )

Available vector fields.

Definition at line 486 of file qgslabel.cpp.

References mFields.

Referenced by QgsLabel(), and setFields().

QString QgsLabel::fieldValue	(	int	attr,
		QgsFeature &	feature
	)

Get field value if : 1) field name is not empty 2) field exists 3) value is defined otherwise returns empty string.

Definition at line 66 of file qgslabel.cpp.

References QgsFeature::attribute(), and mLabelFieldIdx.

Referenced by renderLabel().

QgsLabelAttributes * QgsLabel::labelAttributes ( void )

Pointer to default attributes.

Note: this replaces the to-be-deprecated layerAttributes method.; introduced in QGIS 1.4

Definition at line 510 of file qgslabel.cpp.

References mLabelAttributes.

QString QgsLabel::labelField ( int attr ) const

label field

Definition at line 499 of file qgslabel.cpp.

References QgsFields::count(), LabelFieldCount, mFields, and mLabelFieldIdx.

Referenced by QgsVectorLayer::writeSymbology(), and writeXML().

void QgsLabel::labelPoint	(	std::vector< labelpoint > &	points,
		QgsFeature &	feature
	)

private

Get label point for simple feature in map units.

Definition at line 515 of file qgslabel.cpp.

References QgsGeometry::asWkb(), QgsFeature::geometry(), QgsDebugMsg, QGis::WKBLineString, QGis::WKBLineString25D, QGis::WKBMultiLineString, QGis::WKBMultiLineString25D, QGis::WKBMultiPoint, QGis::WKBMultiPoint25D, QGis::WKBMultiPolygon, QGis::WKBMultiPolygon25D, QGis::WKBPoint, QGis::WKBPoint25D, QGis::WKBPolygon, QGis::WKBPolygon25D, QgsGeometry::wkbSize(), and QgsGeometry::wkbType().

Referenced by renderLabel().

const unsigned char * QgsLabel::labelPoint	(	labelpoint &	point,
		const unsigned char *	wkb,
		size_t	wkblen
	)

private

Get label point for the given feature in wkb format.

Definition at line 563 of file qgslabel.cpp.

References QgsLabel::labelpoint::angle, QgsLabel::labelpoint::p, QgsDebugMsg, QgsPoint::set(), QGis::WKBLineString, QGis::WKBLineString25D, QGis::WKBPoint, QGis::WKBPoint25D, QGis::WKBPolygon, and QGis::WKBPolygon25D.

float QgsLabel::maxScale ( ) const

Definition at line 1397 of file qgslabel.cpp.

References mMaxScale.

Referenced by QgsVectorLayer::drawLabels(), and QgsVectorLayer::writeSymbology().

float QgsLabel::minScale ( ) const

Definition at line 1387 of file qgslabel.cpp.

References mMinScale.

Referenced by QgsVectorLayer::drawLabels(), and QgsVectorLayer::writeSymbology().

bool QgsLabel::readLabelField	(	QDomElement &	el,
		int	attr,
		QString	prefix = `"field"`
	)

private

Definition at line 694 of file qgslabel.cpp.

References QgsFields::count(), mFields, and mLabelFieldIdx.

Referenced by readXML().

void QgsLabel::readXML ( const QDomNode & node )

Reads the renderer configuration from an XML file.

Parameters

node	the Dom node to read

Definition at line 729 of file qgslabel.cpp.

Referenced by QgsVectorLayer::readSymbology().

void QgsLabel::renderLabel	(	QgsRenderContext &	renderContext,
		QgsFeature &	feature,
		bool	selected,
		QgsLabelAttributes *	classAttributes = `0`
	)

render label

Parameters

renderContext	the render context
feature	feature to render the label for
selected	feature is selected
classAttributes	attributes to create the label from

Note: added in 1.2

Definition at line 72 of file qgslabel.cpp.

Referenced by QgsVectorLayer::drawLabels().

void QgsLabel::renderLabel	(	QgsRenderContext &	renderContext,
		QgsPoint	point,
		QString	text,
		QFont	font,
		QPen	pen,
		int	dx,
		int	dy,
		double	xoffset,
		double	yoffset,
		double	ang,
		int	width,
		int	height,
		int	alignment
	)