LabelingOptions(標籤選項)--GEOServer

來自http://geoserver.org/display/GEOSDOC/LabelingOptions
Controlling Label Placement(控制標籤位置)
1.Basic SLD Placement
1.1Point Geometries ("PointPlacement")
1.2Linear (line) geometries ("LinePlacement")

<xsd:element name="PointPlacement">
    <xsd:complexType>
      <xsd:sequence>
        <xsd:element ref="sld:AnchorPoint" minOccurs="0"/>--(a)
        <xsd:element ref="sld:Displacement" minOccurs="0"/>--(b)
        <xsd:element ref="sld:Rotation" minOccurs="0"/>--(c)
      </xsd:sequence>
    </xsd:complexType>
  </xsd:element>
  ...
  <xsd:element name="LinePlacement">    
      <xsd:complexType>
        <xsd:sequence>
          <xsd:element ref="sld:PerpendicularOffset" minOccurs="0"/>--(d)
        </xsd:sequence>
      </xsd:complexType>
  </xsd:element>

[b]a.AnchorPoint[/b]

<PointPlacement>
	<AnchorPoint>
	  <AnchorPointX>
	  0.5
	  </AnchorPointX>
	  <AnchorPointY>
	  0.5
	  </AnchorPointY>
	</AnchorPoint>
</PointPlacement>	

[b]b.Displacement[/b]

<PointPlacement>
 <Displacement>
   <DisplacementX>
      10--X的偏移值
   </DisplacementX>
   <DisplacementY>
       0--Y的偏移值
   </DisplacementY>
 </Displacement>
</PointPlacement>

c.Rotation(旋轉角度)

<Rotation>
  45
</Rotation>

d.LinePlacement

<LabelPlacement>
  <LinePlacement>
    <PerpendicularOffset>
       10
    </PerpendicularOffset>	       
  </LinePlacement>
</LabelPlacement>

[b]2.Priority Labeling [/b]
根據人口來區分標籤的級別 如果有衝突 高級別的會覆蓋低級別的
City Name | population
-------------+------------
Yonkers | 197,818
Jersey City | 237,681
Newark | 280,123
New York | 8,107,916

<Priority>
    <PropertyName>population</PropertyName>
</Priority>

[b]3.Grouping Geometries(<VendorOption name="group">)分組顯示[/b]
[table]
|[b]Geometry[/b]|[b]Representative Geometry[/b]
|Point Set|first point inside the view rectangle is used.
|Line Set|lines are (a) networked together (b) clipped to the view rectangle (c) middle of the longest network path is used.
|Polygon Set|polygons are (a) clipped to the view rectangle (b) the centroid of the largest polygon is used.
[/table]

<VendorOption name="group">yes</VendorOption>

[b]4.Overlapping and Separating Labels (<VendorOption name="spaceAround">)[/b]
By default geoserver will not put labels "on top of each other". By using the spaceAround option you can allow overlaps to overlap and you can also add extra space around a label.

<VendorOption name="spaceAround">10</VendorOption>

......