Rule (Geotools modules 26-SNAPSHOT API)

All Superinterfaces:

Rule
```
public interface Rule
extends Rule
```
A rule is used to attach a condition to, and group, the individual symbolizers used for rendering. The Title and Abstract describe the rule and may be used to generate a legend, as may the LegendGraphic. The Filter, ElseFilter, MinScale and MaxScale elements allow the selection of features and rendering scales for a rule. The scale selection works as follows. When a map is to be rendered, the scale denominator is computed and all rules in all UserStyles that have a scale outside of the request range are dropped. (This also includes Rules that have an ElseFilter.) An ElseFilter is simply an ELSE condition to the conditions (Filters) of all other rules in the same UserStyle. The exact meaning of the ElseFilter is determined after Rules have been eliminated for not fitting the rendering scale. This definition of the behaviour of ElseFilters may seem a little strange, but it allows for scale-dependent and scale-independent ELSE conditions. For the Filter, only SqlExpression is available for specification, but this is a hack and should be replaced with Filter as defined in WFS. A missing Filter element means "always true". If a set of Rules has no ElseFilters, then some features may not be rendered (which is presumably the desired behavior). The Scales are actually scale denominators (as double floats), so "10e6" would be interpreted as 1:10M. A missing MinScale means there is no lower bound to the scale-denominator range (lim[x->0+](x)), and a missing MaxScale means there is no upper bound (infinity). 0.28mm
The details of this object are taken from the OGC Styled-Layer Descriptor Report (OGC 02-070) version 1.0.0.:
```
 <xsd:element name="Rule">
   <xsd:annotation>
     <xsd:documentation>
       A Rule is used to attach property/scale conditions to and group
       the individual symbolizers used for rendering.
     </xsd:documentation>
   </xsd:annotation>
   <xsd:complexType>
     <xsd:sequence>
       <xsd:element ref="sld:Name" minOccurs="0"/>
       <xsd:element ref="sld:Title" minOccurs="0"/>
       <xsd:element ref="sld:Abstract" minOccurs="0"/>
       <xsd:element ref="sld:LegendGraphic" minOccurs="0"/>
       <xsd:choice minOccurs="0">
         <xsd:element ref="ogc:Filter"/>
         <xsd:element ref="sld:ElseFilter"/>
       </xsd:choice>
       <xsd:element ref="sld:MinScaleDenominator" minOccurs="0"/>
       <xsd:element ref="sld:MaxScaleDenominator" minOccurs="0"/>
       <xsd:element ref="sld:Symbolizer" maxOccurs="unbounded"/>
     </xsd:sequence>
   </xsd:complexType>
 </xsd:element>
 
```

Method Summary

All Methods Instance Methods Abstract Methods Default Methods
Modifier and Type	Method and Description
`void`	`accept(StyleVisitor visitor)` Used to traverse the style data structure.
`Description`	`getDescription()` Description for this rule.
`Filter`	`getFilter()` This is the filter used to select content for this rule to display
`GraphicLegend`	`getLegend()` Returns a small Graphic that could be used by the rendering engine to draw a legend window.
`OnLineResource`	`getOnlineResource()` It is common to have a style coming from a external xml file, this method provide a way to get the original source if there is one.
`default Map<String,String>`	`getOptions()` Map of vendor options for the Rule.
`Symbolizer[]`	`getSymbolizers()` The symbolizers contain the actual styling information for different geometry types.
`default boolean`	`hasOption(String key)` Determines if a vendor option with the specific key has been set on this Rule.
`void`	`setDescription(Description description)` Description for this rule.
`void`	`setElseFilter(boolean isElse)`
`void`	`setFilter(Filter filter)` Filter used to select content for this rule to display.
`void`	`setLegend(GraphicLegend legend)`
`void`	`setMaxScaleDenominator(double scale)` The largest value for scale denominator at which symbolizers contained by this rule should be applied.
`void`	`setMinScaleDenominator(double scale)` The smallest value for scale denominator at which symbolizers contained by this rule should be applied.
`void`	`setName(String name)` Sets the name of the rule.
`void`	`setOnlineResource(OnLineResource resource)`
`List<Symbolizer>`	`symbolizers()` Symbolizers used, in order, to portray the features selected by this rule.

Methods inherited from interface Rule
accept, getMaxScaleDenominator, getMinScaleDenominator, getName, isElseFilter

- Method Detail
  - setName
```
void setName(String name)
```
    Sets the name of the rule.
    
    Parameters:
    
    name - The name of the rule. This provides a way to identify a rule.
  - getDescription
```
Description getDescription()
```
    Description for this rule.
    
    Specified by:
    
    getDescription in interface Rule
    
    Returns:
    
    Human readable description for use in user interfaces
    
    Since:
    
    2.5.x
  - setDescription
```
void setDescription(Description description)
```
    Description for this rule.
    
    Parameters:
    
    description - Human readable title and abstract.
  - setMinScaleDenominator
```
void setMinScaleDenominator(double scale)
```
    The smallest value for scale denominator at which symbolizers contained by this rule should be applied.
    
    Parameters:
    
    scale - The smallest (inclusive) denominator value that this rule will be active for.
  - setMaxScaleDenominator
```
void setMaxScaleDenominator(double scale)
```
    The largest value for scale denominator at which symbolizers contained by this rule should be applied.
    
    Parameters:
    
    scale - The largest (exclusive) denominator value that this rule will be active for.
  - getFilter
```
Filter getFilter()
```
    This is the filter used to select content for this rule to display
    
    Specified by:
    
    getFilter in interface Rule
    
    Returns:
    
    Filter use to select content for this rule to display, Filter.INCLUDES to include all content; or use Filter.EXCLUDES to mark this as an "else" Rule accepting all remaining content
  - setFilter
```
void setFilter(Filter filter)
```
    Filter used to select content for this rule to display.
    This filter is only consulted if isElseFilter is false.
  - setElseFilter
```
void setElseFilter(boolean isElse)
```
    Parameters:
    
    isElse - if this rule should accept any features not already rendered
  - getLegend
```
GraphicLegend getLegend()
```
    Description copied from interface: Rule
    
    Returns a small Graphic that could be used by the rendering engine to draw a legend window.
    A nice user interface may want to present the user with a legend that indicates how features of a given type are being portrayed. Through its LegendGraphic property, a Rule may provide a custom picture to be used in such a legend window.
    
    Specified by:
    
    getLegend in interface Rule
  - setLegend
```
void setLegend(GraphicLegend legend)
```
    Parameters:
    
    legend -
  - getSymbolizers
```
Symbolizer[] getSymbolizers()
```
    The symbolizers contain the actual styling information for different geometry types. A single feature may be rendered by more than one of the symbolizers returned by this method. It is important that the symbolizers be applied in the order in which they are returned if the end result is to be as intended. All symbolizers should be applied to all features which make it through the filters in this rule regardless of the features' geometry. For example, a polygon symbolizer should be applied to line geometries and even points. If this is not the desired beaviour, ensure that either the filters block inappropriate features or that the FeatureTypeStyler which contains this rule has its FeatureTypeName or SemanticTypeIdentifier set appropriately.
    
    Returns:
    
    An array of symbolizers to be applied, in sequence, to all of the features addressed by the FeatureTypeStyler which contains this rule.
  - symbolizers
```
List<Symbolizer> symbolizers()
```
    Symbolizers used, in order, to portray the features selected by this rule.
    Please note that this list may be modified direct.
    
    Specified by:
    
    symbolizers in interface Rule
    
    Returns:
    
    the list of Symbolizer
  - getOnlineResource
```
OnLineResource getOnlineResource()
```
    Description copied from interface: Rule
    
    It is common to have a style coming from a external xml file, this method provide a way to get the original source if there is one. OGC SLD specification can use this method to know if a style must be written completely or if writing the online resource path is enough.
    
    Specified by:
    
    getOnlineResource in interface Rule
    
    Returns:
    
    Location where this style is defined; file or server; or null if unknown
  - setOnlineResource
```
void setOnlineResource(OnLineResource resource)
```
    Parameters:
    
    resource - Indicates where this style is defined
  - hasOption
```
default boolean hasOption(String key)
```
    Determines if a vendor option with the specific key has been set on this Rule.
  - getOptions
```
default Map<String,String> getOptions()
```
    Map of vendor options for the Rule.
    Client code looking for the existence of a single option should use hasOption(String)
  - accept
```
void accept(StyleVisitor visitor)
```
    Used to traverse the style data structure.

Interface Rule

Method Summary

Methods inherited from interface Rule

Method Detail

setName

getDescription

setDescription

setMinScaleDenominator

setMaxScaleDenominator

getFilter

setFilter

setElseFilter

getLegend

setLegend

getSymbolizers

symbolizers

getOnlineResource

setOnlineResource

hasOption

getOptions

accept