org.geotools.renderer.label

Class LabelCacheImpl

Object

LabelCacheImpl

All Implemented Interfaces:

LabelCache

public final class LabelCacheImpl
extends Object
implements LabelCache

Default LabelCache Implementation.

The label cache sports a number of features that are enabled depending on the programmatic configuration and the TextSymbolizer options.

The basic functionality of the label cache consist in finding the best label position for each Feature according to the TextSymbolizer specifications, and drawing it, provided it does not overlap with other labels.

This basic behaviour can be customised in a number of ways.

Priority

TextSymbolizer.getPriority() OGC Expression controls a label priority.

A label with high priority will be drawn before others, increasing its likeliness to appear on the screen

Author:

jeichar, dblasby, Andrea Aime - OpenGeo

Nested Class Summary

Nested Classes

Modifier and Type	Class and Description
static class	LabelCacheImpl.LabelRenderingMode

Field Summary

Fields

Modifier and Type	Field and Description
double	DEFAULT_PRIORITY
static boolean	DISABLE_LETTER_LEVEL_CONFLICT
protected Map<LabelCacheItem,LabelCacheItem>	groupedLabelsLookup Used to locate grouped labels quickly
protected ArrayList<LabelCacheItem>	labelCache labels get thrown in here, in insertion order
protected LabelCacheImpl.LabelRenderingMode	labelRenderingMode
static double	MIN_CURVED_DELTA The angle delta at which we switch from curved rendering to straight rendering
protected SLDStyleFactory	styleFactory

Constructor Summary

Constructors

Constructor and Description
LabelCacheImpl()

Method Summary

Modifier and Type	Method and Description
void	addRenderListener(RenderListener listener) adds a listener that responds to error events of feature rendered events.
void	clear() Clears the cache completely
void	clear(String layerId) Clears the cache of all information relating to the layer identified.
MultiLineString	clipLineString(LineString line) try to be more robust dont bother returning points This will try to solve robustness problems, but read code as to what it does.
MultiPolygon	clipPolygon(Polygon poly, Polygon bbox, Envelope displayGeomEnv) try to do a more robust way of clipping a polygon to a bounding box.
void	disableLayer(String layerId) Leaves the label information in the cache but ignores it when calculating what labels are drawn.
void	enableLayer(String layerId) Enable a layer after being disabled.
void	end(Graphics2D graphics, Rectangle displayArea) Called to indicate that the map is done rendering.
void	endLayer(String layerId, Graphics2D graphics, Rectangle displayArea) Called to indicate that a layer is done rendering.
List<LabelCacheItem>	getActiveLabels() Returns a list of all active labels
LabelCacheImpl.LabelRenderingMode	getLabelRenderingMode()
double	getPriority(TextSymbolizer symbolizer, Feature feature) get the priority from the symbolizer its an expression, so it will try to evaluate it: 1. if its missing --> DEFAULT_PRIORITY 2. if its a number, return that number 3. if its not a number, convert to string and try to parse the number; return the number 4. otherwise, return DEFAULT_PRIORITY
List<LabelCacheItem>	orderedLabels() Return a list with all the values in priority order.
List<LineString>	processNodes(List<LineString> edges, Map<Coordinate,List<LineString>> nodes) pull a line from the list, and: 1. if nothing connects to it (its issolated), add it to "result" 2. otherwise, merge it at the start/end with the LONGEST line there. 3. remove the original line, and the lines it merged with from the hashtables 4. go again, with the merged line
void	put(Rectangle2D area) Reserve the provided geometry prior to sorting out where labels can go.
void	put(String layerId, TextSymbolizer symbolizer, Feature feature, LiteShape2 shape, NumberRange scaleRange) Puts a Label in the cache.
void	removeFromHash(Map<Coordinate,List<LineString>> nodes, LineString ls)
void	setLabelRenderingMode(LabelCacheImpl.LabelRenderingMode mode) Sets the text rendering mode.
void	start() Called by renderer to indicate that the rendering process is starting.
void	startLayer(String layerId) Called by renderer to indication the start of rendering a layer.
void	stop() Tells the cache to stop labelling.

Methods inherited from class Object

clone, equals, finalize, getClass, hashCode, notify, notifyAll, toString, wait, wait, wait

Field Detail

DISABLE_LETTER_LEVEL_CONFLICT

public static boolean DISABLE_LETTER_LEVEL_CONFLICT

DEFAULT_PRIORITY

public double DEFAULT_PRIORITY

MIN_CURVED_DELTA

public static double MIN_CURVED_DELTA

The angle delta at which we switch from curved rendering to straight rendering

groupedLabelsLookup

protected Map<LabelCacheItem,LabelCacheItem> groupedLabelsLookup

Used to locate grouped labels quickly

labelCache

protected ArrayList<LabelCacheItem> labelCache

labels get thrown in here, in insertion order

labelRenderingMode

protected LabelCacheImpl.LabelRenderingMode labelRenderingMode

styleFactory

protected SLDStyleFactory styleFactory

Constructor Detail

LabelCacheImpl

public LabelCacheImpl()

Method Detail

enableLayer

public void enableLayer(String layerId)

Description copied from interface: LabelCache

Enable a layer after being disabled. If startLayer is called this does not need to be called as start layer implicitely activates the layer.

Specified by:

enableLayer in interface LabelCache

Parameters:

layerId - layer to activate.

getLabelRenderingMode

public LabelCacheImpl.LabelRenderingMode getLabelRenderingMode()

setLabelRenderingMode

public void setLabelRenderingMode(LabelCacheImpl.LabelRenderingMode mode)

Sets the text rendering mode.

stop

public void stop()

Description copied from interface: LabelCache

Tells the cache to stop labelling.

Specified by:

stop in interface LabelCache

start

public void start()

Description copied from interface: LabelCache

Called by renderer to indicate that the rendering process is starting.

Specified by:

start in interface LabelCache

See Also:

LabelCache.start()

clear

public void clear()

Description copied from interface: LabelCache

Clears the cache completely

Specified by:

clear in interface LabelCache

clear

public void clear(String layerId)

Description copied from interface: LabelCache

Clears the cache of all information relating to the layer identified.

Specified by:

clear in interface LabelCache

Parameters:

layerId - id of the layer

disableLayer

public void disableLayer(String layerId)

Description copied from interface: LabelCache

Leaves the label information in the cache but ignores it when calculating what labels are drawn.

Specified by:

disableLayer in interface LabelCache

Parameters:

layerId - id of the layer to disable.

startLayer

public void startLayer(String layerId)

Description copied from interface: LabelCache

Called by renderer to indication the start of rendering a layer. Will add the layer to the set of active layers.

Specified by:

startLayer in interface LabelCache

Parameters:

layerId - an id for the layer

See Also:

LabelCache.startLayer(String)

getPriority

public double getPriority(TextSymbolizer symbolizer,
                          Feature feature)

get the priority from the symbolizer its an expression, so it will try to evaluate it: 1. if its missing --> DEFAULT_PRIORITY 2. if its a number, return that number 3. if its not a number, convert to string and try to parse the number; return the number 4. otherwise, return DEFAULT_PRIORITY

Parameters:

symbolizer -

feature -

put

public void put(String layerId,
                TextSymbolizer symbolizer,
                Feature feature,
                LiteShape2 shape,
                NumberRange scaleRange)

Description copied from interface: LabelCache

Puts a Label in the cache.

Specified by:

put in interface LabelCache

Parameters:

layerId - id indicating the layer the feature is part of

symbolizer - The symbolizer containing the style information

feature - the feature that has the information required for the symbolizer to calculate the required render information.

shape - the shape to be labeled. This is in screen coordinates.

scaleRange - the scaleRange that the symbolizer is legal

See Also:

LabelCache.put(String,TextSymbolizer,Feature, LiteShape2,NumberRange)

put

public void put(Rectangle2D area)

Description copied from interface: LabelCache

Reserve the provided geometry prior to sorting out where labels can go.

This facility is used to reserve an area so that labels do not end up overlapping on screen constructs like scalebars or north arrows etc...

Specified by:

put in interface LabelCache

endLayer

public void endLayer(String layerId,
                     Graphics2D graphics,
                     Rectangle displayArea)

Description copied from interface: LabelCache

Called to indicate that a layer is done rendering. The method may draw labels if appropriate for the labeling algorithm

Specified by:

endLayer in interface LabelCache

Parameters:

layerId - an id for the layer

graphics - the graphics to draw on.

displayArea - The size of the display area

See Also:

LabelCache.endLayer(String,Graphics2D,Rectangle)

orderedLabels

public List<LabelCacheItem> orderedLabels()

Return a list with all the values in priority order. Both grouped and non-grouped

Specified by:

orderedLabels in interface LabelCache

Returns:

list with all values in priority order

getActiveLabels

public List<LabelCacheItem> getActiveLabels()

Returns a list of all active labels

Returns:

end

public void end(Graphics2D graphics,
                Rectangle displayArea)

Description copied from interface: LabelCache

Called to indicate that the map is done rendering. The method may draw labels if appropriate for the labeling algorithm

Specified by:

end in interface LabelCache

Parameters:

graphics - the graphics to draw on.

displayArea - The size of the display area.

See Also:

LabelCache.end(java.awt.Graphics2D, java.awt.Rectangle)

clipLineString

public MultiLineString clipLineString(LineString line)

try to be more robust dont bother returning points This will try to solve robustness problems, but read code as to what it does. It might return the unclipped line if there's a problem!

Parameters:

line -

clipPolygon

public MultiPolygon clipPolygon(Polygon poly,
                                Polygon bbox,
                                Envelope displayGeomEnv)

try to do a more robust way of clipping a polygon to a bounding box. This might return the orginal polygon if it cannot clip TODO: this is a bit simplistic, there's lots more to do.

Parameters:

poly -

bbox -

displayGeomEnv -

Returns:

a MutliPolygon

processNodes

public List<LineString> processNodes(List<LineString> edges,
                                     Map<Coordinate,List<LineString>> nodes)

pull a line from the list, and: 1. if nothing connects to it (its issolated), add it to "result" 2. otherwise, merge it at the start/end with the LONGEST line there. 3. remove the original line, and the lines it merged with from the hashtables 4. go again, with the merged line

Parameters:

edges -

nodes -

removeFromHash

public void removeFromHash(Map<Coordinate,List<LineString>> nodes,
                           LineString ls)

addRenderListener

public void addRenderListener(RenderListener listener)

adds a listener that responds to error events of feature rendered events.

Parameters:

listener - the listener to add.

See Also:

RenderListener