org.geotools.styling

For many of us in geotools *this* is the reason we came along for the ride - a pretty picture. The contents of this package are adapted from the OpenGIS® Styled Layer Descriptor specification v1.0.0.

Conformance to SLD 1.0.0

We may experiment with our own (or SLD 1.1) ideas but will mark such experiments for you. This is only an issue of you are considering writing out these objects for interoptability with other systems.

General stratagy for supporting multiple SLD versions (and experiments):

• These interfaces will reflect the current published specification
• Our implementations will be BIGGER and more capabile then any one specification
• We cannot defined explicit interfaces tracking each version until we move to Java 5 (perferably GeoAPI would hold these anyways)
• We can provided javadocs indicating extentions, and isolate these using the normal java convention: TextSymbolizer and TextSymbolizer2 (In short you will have to go out of your way to work with a hack or experiment, you won't depend on one by accident)
• We can use Factories (aka SLD1Factory and SLD1_1Factory and SEFactory) to support the creation of conformant datastructures. Code (such as user interfaces) can be parameratized with these factories when they need to confirm to an exact version supported by an individual service. We hope that specifications are always adative, and will be forced to throw unsupported exceptions when functionality is removed from a specification.

Care and Feeding of Style Objects

SLD is an XML specification, the definition of objects capturing this information, the binding of objects to these XML documents, and the provision of events on object modification all need to be accounted for.

StyleFactory

  StyleFactory factory = StyleFactoryFinder.createStyleFactory();
  StyleLayerDescriptor sld = factory.createStyleLayerDescriptor();
  // an empty sld document
  sld.setTitle("Basic Black");
  sld.setAbstract("Grayscale style suitable for use with photocopiers");
  
  

When creating a complex data structure direct use of a Factory is a pain. Which leads us to the next section.

Notes:

• At this time one implementation of StyleFactory is available, this will not provide true in the future (as SLD experiments, and code generation are brought to bare on future specifications).

StyleBuilder

When constructing a complex data structure, such as an SLD document, the use of a Factory is a bit of a pain. That is where StyleBuilder is brought to bare. A Builder is simply a class that help you construct a complicated data structure, for a make involved/interesting example of a builder have a look at the graph package.

Example

    private Style buildStyle() throws Exception {
        StyleBuilder sb = new StyleBuilder();
        FilterFactory ff = sb.getFilterFactory();
        Style style = sb.createStyle();
        style.setName("MyStyle");

        // "testPoint" feature type style
        Mark testMark = sb.createMark(sb.attributeExpression("name"),
                sb.createFill(Color.RED, 0.5), null);
        Graphic graph = sb.createGraphic(null, new Mark[] { testMark }, null,
                sb.literalExpression(1), sb.attributeExpression("size"),
                sb.attributeExpression("rotation"));
        style.addFeatureTypeStyle(sb.createFeatureTypeStyle("testPoint",
                new Symbolizer[] { sb.createPointSymbolizer(graph) }));

        // "labelPoint" feature type style
        AnchorPoint anchorPoint = sb.createAnchorPoint(sb.attributeExpression("X"),
                sb.attributeExpression("Y"));
        PointPlacement pointPlacement = sb.createPointPlacement(anchorPoint, null,
                sb.literalExpression(0));
        TextSymbolizer textSymbolizer = sb.createTextSymbolizer(sb.createFill(Color.BLACK),
                new Font[] { sb.createFont("Lucida Sans", 10), sb.createFont("Arial", 10) },
                sb.createHalo(), sb.attributeExpression("name"), pointPlacement, null);
        Mark circle = sb.createMark(StyleBuilder.MARK_CIRCLE, Color.RED);
        Graphic graph2 = sb.createGraphic(null, circle, null, 1, 4, 0);
        PointSymbolizer pointSymbolizer = sb.createPointSymbolizer(graph2);
        style.addFeatureTypeStyle(sb.createFeatureTypeStyle("labelPoint",
                new Symbolizer[] { textSymbolizer, pointSymbolizer }));

        return style;
    }

 <xs:element name="ColorMap">
 <xs:complexType>
 <xs:choice minOccurs="0" maxOccurs="unbounded">
 <xs:element ref="sld:ColorMapEntry"/>
 </xs:choice>
 </xs:complexType>
 </xs:element>
 

 
 <xsd:element name="Extent">
 <xsd:annotation>
 <xsd:documentation>         An Extent gives
 feature/coverage/raster/matrix dimension extent.

There are two types of fill: solid-color and repeated graphic fill.

The details of this object are taken from the OGC Styled-Layer Descriptor Report (OGC 02-070) version 1.0.0.:

 <xsd:element name="Fill">
 <xsd:annotation>
 <xsd:documentation>
 A "Fill" specifies the pattern for filling an area geometry.
 The allowed CssParameters are: "fill" (color) and "fill-opacity".
 </xsd:documentation>
 </xsd:annotation>
 <xsd:complexType>
 <xsd:sequence>
 <xsd:element ref="sld:GraphicFill" minOccurs="0"/>
 <xsd:element ref="sld:CssParameter" minOccurs="0"
 maxOccurs="unbounded"/>
 </xsd:sequence>
 </xsd:complexType>
 </xsd:element>
 

Renderers can use this information when displaying styled features, though it must be remembered that not all renderers will be able to fully represent strokes as set out by this interface.

A "graphic" can very informally be defined as "a little picture" and can be of either a raster or vector graphic source type.

The details of this object are taken from the OGC Styled-Layer Descriptor Report (OGC 02-070) version 1.0.0.:

 <xsd:element name="Halo">
 <xsd:annotation>
 <xsd:documentation>
 A "Halo" fills an extended area outside the glyphs of a rendered
 text label to make the label easier to read over a background.
 </xsd:documentation>
 </xsd:annotation>
 <xsd:complexType>
 <xsd:sequence>
 <xsd:element ref="sld:Radius" minOccurs="0"/>
 <xsd:element ref="sld:Fill" minOccurs="0"/>
 </xsd:sequence>
 </xsd:complexType>
 </xsd:element>
 

Renderers can use this information when displaying styled features, though it must be remembered that not all renderers will be able to fully represent strokes as set out by this interface.

The details of this object are taken from the OGC Styled-Layer Descriptor Report (OGC 02-070) version 1.0.0.:

 <xsd:element name="LabelPlacement">
 <xsd:annotation>
 <xsd:documentation>
 The "LabelPlacement" specifies where and how a text label should
 be rendered relative to a geometry.

 
 <xsd:element name="LayerFeatureConstraints">
 <xsd:annotation>
 <xsd:documentation>         LayerFeatureConstraints define what
 features & feature types are         referenced in a
 layer.

The symbolizer describes not just the shape that should appear but also such graphical properties as color and opacity.

A symbolizer is obtained by specifying one of a small number of different types of symbolizer and then supplying parameters to override its default behaviour.

The details of this object are taken from the OGC Styled-Layer Descriptor Report (OGC 02-070) version 1.0.0.:

 <xsd:element name="LineSymbolizer" substitutionGroup="sld:Symbolizer">
 <xsd:annotation>
 <xsd:documentation>
 A LineSymbolizer is used to render a "stroke" along a linear geometry.
 </xsd:documentation>
 </xsd:annotation>
 <xsd:complexType>
 <xsd:complexContent>
 <xsd:extension base="sld:SymbolizerType">
 <xsd:sequence>
 <xsd:element ref="sld:Geometry" minOccurs="0"/>
 <xsd:element ref="sld:Stroke" minOccurs="0"/>
 </xsd:sequence>
 </xsd:extension>
 </xsd:complexContent>
 </xsd:complexType>
 </xsd:element>
 

Renderers can use this information when displaying styled features, though it must be remembered that not all renderers will be able to fully represent strokes as set out by this interface.

The details of this object are taken from the OGC Styled-Layer Descriptor Report (OGC 02-070) version 1.0.0.:

 <xsd:element name="Mark">
 <xsd:annotation>
 <xsd:documentation>
 A "Mark" specifies a geometric shape and applies coloring to it.
 </xsd:documentation>
 </xsd:annotation>
 <xsd:complexType>
 <xsd:sequence>
 <xsd:element ref="sld:WellKnownName" minOccurs="0"/>
 <xsd:element ref="sld:Fill" minOccurs="0"/>
 <xsd:element ref="sld:Stroke" minOccurs="0"/>
 </xsd:sequence>
 </xsd:complexType>
 </xsd:element>
 

Renderers can use this information when displaying styled features, though it must be remembered that not all renderers will be able to fully represent strokes as set out by this interface.

 
 <xsd:element name="OverlapBehavior">
 <xsd:annotation>
 <xsd:documentation>         "OverlapBehavior" tells a
 system how to behave when multiple         raster images in
 a layer overlap each other, for example with
 satellite-image scenes.

The symbolizer defines not just the shape that should appear but also such graphical properties as color and opacity.

A symbolizer is obtained by specifying one of a small number of different types of symbolizer and then supplying parameters to overide its default behaviour.

The details of this object are taken from the OGC Styled-Layer Descriptor Report (OGC 02-070) version 1.0.0.:

 <xsd:element name="PointSymbolizer" substitutionGroup="sld:Symbolizer">
 <xsd:annotation>
 <xsd:documentation>
 A "PointSymbolizer" specifies the rendering of a "graphic symbol"
 at a point.
 </xsd:documentation>
 </xsd:annotation>
 <xsd:complexType>
 <xsd:complexContent>
 <xsd:extension base="sld:SymbolizerType">
 <xsd:sequence>
 <xsd:element ref="sld:Geometry" minOccurs="0"/>
 <xsd:element ref="sld:Graphic" minOccurs="0"/>
 </xsd:sequence>
 </xsd:extension>
 </xsd:complexContent>
 </xsd:complexType>
 </xsd:element>
 

Renderers can use this information when displaying styled features, though it must be remembered that not all renderers will be able to fully represent strokes as set out by this interface.

The symbolizer describes not just the shape that should appear but also such graphical properties as color and opacity.

A symbolizer is obtained by specifying one of a small number of different types of symbolizer and then supplying parameters to overide its default behaviour.

The details of this object are taken from the OGC Styled-Layer Descriptor Report (OGC 02-070) version 1.0.0.:

 <xsd:element name="PolygonSymbolizer" substitutionGroup="sld:Symbolizer">
 <xsd:annotation>
 <xsd:documentation>
 A "PolygonSymbolizer" specifies the rendering of a polygon or
 area geometry, including its interior fill and border stroke.
 </xsd:documentation>
 </xsd:annotation>
 <xsd:complexType>
 <xsd:complexContent>
 <xsd:extension base="sld:SymbolizerType">
 <xsd:sequence>
 <xsd:element ref="sld:Geometry" minOccurs="0"/>
 <xsd:element ref="sld:Fill" minOccurs="0"/>
 <xsd:element ref="sld:Stroke" minOccurs="0"/>
 </xsd:sequence>
 </xsd:extension>
 </xsd:complexContent>
 </xsd:complexType>
 </xsd:element>
 

Renderers can use this information when displaying styled features, though it must be remembered that not all renderers will be able to fully represent strokes as set out by this interface.

There are three basic types of stroke: solid color, graphic fill (stipple), and repeated linear graphic stroke. A repeated linear graphic is plotted linearly and has its graphic symbol bent around the curves of the line string.

This interface is bound to version 1.0 of the SLD specification.

For many of us in geotools this is the reason we came along for the ride - a pretty picture.

This class is based on version 1.0 of the SLD specification.

For many of us in geotools this is the reason we came along for the ride - a pretty picture.

A symbolizer describes how a feature should appear on a map.

A symbolizer is obtained by specifying one of a small number of different types of symbolizer and then supplying parameters to override its default behaviour.

The text symbolizer describes how to display text labels and the like.

The details of this object are taken from the OGC Styled-Layer Descriptor Report (OGC 02-070) version 1.0.0.:

 <xsd:element name="TextSymbolizer" substitutionGroup="sld:Symbolizer">
 <xsd:annotation>
 <xsd:documentation>
 A "TextSymbolizer" is used to render text labels according to
 various graphical parameters.
 </xsd:documentation>
 </xsd:annotation>
 <xsd:complexType>
 <xsd:complexContent>
 <xsd:extension base="sld:SymbolizerType">
 <xsd:sequence>
 <xsd:element ref="sld:Geometry" minOccurs="0"/>
 <xsd:element ref="sld:Label" minOccurs="0"/>
 <xsd:element ref="sld:Font" minOccurs="0"/>
 <xsd:element ref="sld:LabelPlacement" minOccurs="0"/>
 <xsd:element ref="sld:Halo" minOccurs="0"/>
 <xsd:element ref="sld:Fill" minOccurs="0"/>
 </xsd:sequence>
 </xsd:extension>
 </xsd:complexContent>
 </xsd:complexType>
 </xsd:element>
 

Renderers can use this information when displaying styled features, though it must be remembered that not all renderers will be able to fully represent strokes as set out by this interface.