LabelCacheImpl (Geotools modules 25-SNAPSHOT API)

Object
- LabelCacheImpl

All Implemented Interfaces:

LabelCache
```
public 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

Nested Classes
Modifier and Type	Class and Description
`static class`	`LabelCacheImpl.LabelRenderingMode`

Field Summary

Fields
Modifier and Type	Field and Description
`static int[]`	`DEFAULT_DISPLACEMENT_ANGLES`
`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()

Constructors
Constructor and Description
`LabelCacheImpl()`

Method Summary

All Methods Instance Methods Concrete Methods
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`	`setConstructPainter(BiFunction<Graphics2D,LabelCacheImpl.LabelRenderingMode,LabelPainter> constructPainter)` Change the method used to construct LabelPainters.
`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
```
  - DEFAULT_DISPLACEMENT_ANGLES
```
public static final int[] DEFAULT_DISPLACEMENT_ANGLES
```
  - 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.
  - setConstructPainter
```
public void setConstructPainter(BiFunction<Graphics2D,LabelCacheImpl.LabelRenderingMode,LabelPainter> constructPainter)
```
    Change the method used to construct LabelPainters. Defaults to LabelPainter.LabelPainter(java.awt.Graphics2D, org.geotools.renderer.label.LabelCacheImpl.LabelRenderingMode).
  - 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
  - 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
    
    Parameters:
    
    area - The Area of the screen to reserve (in screen coordinates)
  - 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
  - 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!
  - 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.
    
    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
  - 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

Class LabelCacheImpl

Priority

Nested Class Summary

Field Summary

Constructor Summary

Method Summary

Methods inherited from class Object

Field Detail

DISABLE_LETTER_LEVEL_CONFLICT

DEFAULT_PRIORITY

DEFAULT_DISPLACEMENT_ANGLES

MIN_CURVED_DELTA

groupedLabelsLookup

labelCache

labelRenderingMode

styleFactory

Constructor Detail

LabelCacheImpl

Method Detail

enableLayer

getLabelRenderingMode

setLabelRenderingMode

setConstructPainter

stop

start

clear

clear

disableLayer

startLayer

getPriority

put

put

endLayer

orderedLabels

getActiveLabels

end

clipLineString

clipPolygon

processNodes

removeFromHash

addRenderListener