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Filter encoding functions

Contents

  1. SE functions
    1. FormatNumber
    2. FormatDate
    3. ChangeCase
    4. Concatenate
    5. Trim
    6. StringLength
    7. Substring
    8. StringPosition
    9. Categorize, Interpolate, Recode
  2. Custom geometry functions
    1. Area
    2. Length
    3. Centroid
    4. InteriorPoint
    5. IsPoint, IsCurve, IsSurface
    6. GeometryFromWKT
    7. MoveGeometry
  3. Other custom functions
    1. iDiv
    2. iMod
    3. ExtraProp
  4. General XPath functions
    1. Element name

This page documents the filter encoding functions supported by deegree 3.

These functions are mainly intended to be used in styling WMS layers, but can be used everywhere in deegree 3 where filter functions are processed (e.g. in WFS GetFeature requests). Find further styling / WMS details on style configuration or mapService configuration on dedicated pages.

1. SE functions

We support all of the functions defined in the OGC Specification on Symbology Encoding SE 1.1.0, section 11.6. Here's an overview, with some extra information on specific issues/limitations with these functions.

1.1. FormatNumber

This function is fully supported. 

<FormatNumber xmlns:ogc="http://www.opengis.net/ogc" xmlns:app="http://www.deegree.org/app" xmlns="http://www.opengis.net/se" fallbackValue="">
  <NumericValue>
    <ogc:PropertyName>app:SHAPE_LEN</ogc:PropertyName>
  </NumericValue>
  <Pattern>############.00</Pattern>
</FormatNumber>

1.2. FormatDate

This function is fully supported, although not fully tested with all available schema types mentioned in the spec. 

<FormatDate xmlns:ogc="http://www.opengis.net/ogc" xmlns:app="http://www.deegree.org/app" xmlns="http://www.opengis.net/se" fallbackValue="">
  <DateValue>
    <ogc:PropertyName>app:TIMESTAMP</ogc:PropertyName>
  </DateValue>
  <Pattern>DD</Pattern>
</FormatDate>

1.3. ChangeCase

This function is fully supported. 

<ChangeCase xmlns:ogc="http://www.opengis.net/ogc" xmlns:app="http://www.deegree.org/app" xmlns="http://www.opengis.net/se" fallbackValue="" direction="toUpper">
  <StringValue>
    <ogc:PropertyName>app:text</ogc:PropertyName>
  </StringValue>
</ChangeCase>

1.4. Concatenate

This function is fully supported. 

<Concatenate xmlns:ogc="http://www.opengis.net/ogc" xmlns:app="http://www.deegree.org/app" xmlns="http://www.opengis.net/se" fallbackValue="">
  <StringValue>
    <ogc:PropertyName>app:text1</ogc:PropertyName>
  </StringValue>
  <StringValue>
    <ogc:PropertyName>app:text2</ogc:PropertyName>
  </StringValue>
  <StringValue>
    <ogc:PropertyName>app:text3</ogc:PropertyName>
  </StringValue>
</Concatenate>

1.5. Trim

This function is fully supported. 

<Trim xmlns:ogc="http://www.opengis.net/ogc" xmlns:app="http://www.deegree.org/app" xmlns="http://www.opengis.net/se" fallbackValue="" stripOffPosition="both">
  <StringValue>
    <ogc:PropertyName>app:text</ogc:PropertyName>
  </StringValue>
</Trim>

1.6. StringLength

This function is fully supported. 

<StringLength xmlns:ogc="http://www.opengis.net/ogc" xmlns:app="http://www.deegree.org/app" xmlns="http://www.opengis.net/se" fallbackValue="">
  <StringValue>
    <ogc:PropertyName>app:text</ogc:PropertyName>
  </StringValue>
</StringLength>

1.7. Substring

This function is fully supported. Here's an example also using the StringPosition function at the same time: 

<Substring xmlns:ogc="http://www.opengis.net/ogc" xmlns:app="http://www.deegree.org/app" xmlns="http://www.opengis.net/se" fallbackValue="">
  <StringValue>
    <ogc:PropertyName>app:text</ogc:PropertyName>
  </StringValue>
  <Position>1</Position>
  <Length>
    <ogc:Sub>
      <StringPosition fallbackValue="" searchDirection="frontToBack">
        <LookupString>-</LookupString>
        <StringValue>
          <ogc:PropertyName>app:text</ogc:PropertyName>
        </StringValue>
      </StringPosition>
      <ogc:Literal>1</ogc:Literal>
    </ogc:Sub>
  </Length>
</Substring>

1.8. StringPosition

This function is fully supported. 

<StringPosition xmlns:app="http://www.deegree.org/app" xmlns="http://www.opengis.net/se" fallbackValue="" searchDirection="frontToBack">
  <LookupString>-</LookupString>
  <StringValue>
    <ogc:PropertyName xmlns:ogc="http://www.opengis.net/ogc">app:text</ogc:PropertyName>
  </StringValue>
</StringPosition>

1.9. Categorize, Interpolate, Recode

These functions can operate both on alphanumeric properties of features and on raster data. For color values we extended the syntax a bit to allow for an alpha channel: #99ff0000 is a red value with an alpha value of 0x99. This allows the user to create eg. an interpolation from completely transparent to a completely opaque color value. To work on raster data you'll have to replace the PropertyName values with Rasterdata.

For Interpolate only linear interpolation is currently supported. 

<Categorize xmlns:app="http://www.deegree.org/app" xmlns="http://www.opengis.net/se" xmlns:ogc="http://www.opengis.net/ogc" fallbackValue="#fefdC3">
  <LookupValue>
    <ogc:PropertyName>app:POP2000</ogc:PropertyName>
  </LookupValue>
  <Value>#FFE9D8</Value>
  <Threshold>1000</Threshold>
  <Value>#FBCFAC</Value>
  <Threshold>10000</Threshold>
  <Value>#FAAC6F</Value>
  <Threshold>25000</Threshold>
  <Value>#FD913D</Value>
  <Threshold>100000</Threshold>
  <Value>#FF7000</Value>
</Categorize>


<Interpolate xmlns:ogc="http://www.opengis.net/ogc" xmlns:app="http://www.deegree.org/app" xmlns="http://www.opengis.net/se" fallbackValue="#005C29" method="color">
  <LookupValue>
    <ogc:PropertyName>app:CODE</ogc:PropertyName>
  </LookupValue>
  <InterpolationPoint>
    <Data>-1</Data>
    <Value>#005C29</Value>
  </InterpolationPoint>
  <InterpolationPoint>
    <Data>100</Data>
    <Value>#067A3A</Value>
  </InterpolationPoint>
  <InterpolationPoint>
    <Data>300</Data>
    <Value>#03A64C</Value>
  </InterpolationPoint>
  <InterpolationPoint>
    <Data>500</Data>
    <Value>#00CF5D</Value>
  </InterpolationPoint>
  <InterpolationPoint>
    <Data>1000</Data>
    <Value>#ffffff</Value>
  </InterpolationPoint>
</Interpolate>


<Recode xmlns:app="http://www.deegree.org/app" xmlns="http://www.opengis.net/se" fallbackValue="">
  <LookupValue>app:code</LookupValue>
  <MapItem>
    <Data>1000</Data>
    <Value>water</Value>
  </MapItem>
  <MapItem>
    <Data>2000</Data>
    <Value>nuclear</Value>
  </MapItem>
  <MapItem>
    <Data>3000</Data>
    <Value>solar</Value>
  </MapItem>
  <MapItem>
    <Data>4000</Data>
    <Value>wind</Value>
  </MapItem>
</Recode>

2. Custom geometry functions

These functions are mostly intended to be used within SLD/SE, but can also be used in WFS query filters or anywhere else where standard filter encoding is used.

2.1. Area

This function calculates the area of a polygon. If multiple geometry nodes are selected, multiple area values are calculated. 

<Function xmlns:app="http://www.deegree.org/app" xmlns="http://www.opengis.net/ogc" name="Area">
  <PropertyName>app:geometry</PropertyName>
</Function>

2.2. Length

This function calculates the length of a linestring/perimeter of a polygon. If multiple geometry nodes are selected, multiple length values are calculated. 

<Function xmlns:app="http://www.deegree.org/app" xmlns="http://www.opengis.net/ogc" name="Length">
  <PropertyName>app:geometry</PropertyName>
</Function>

2.3. Centroid

This function calculates the centroid of a polygon. If multiple geometry nodes are selected, multiple centroids are calculated. 

<Function xmlns:app="http://www.deegree.org/app" xmlns="http://www.opengis.net/ogc" name="Centroid">
  <PropertyName>app:geometry</PropertyName>
</Function>

2.4. InteriorPoint

This function calculates an interior point within a polygon. If multiple geometry nodes are selected, multiple centroids are calculated. Useful to place text on a point within a polygon (centroids may not actually be a point on the polygon). 

<Function xmlns:app="http://www.deegree.org/app" xmlns="http://www.opengis.net/ogc" name="InteriorPoint">
  <PropertyName>app:geometry</PropertyName>
</Function>

2.5. IsPoint, IsCurve, IsSurface

Takes one parameter, which must evaluate to exactly one geometry node.

This function returns true, if the geometry is a point/multipoint, curve/multicurve or surface/multisurface, respectively. 

<Function xmlns:app="http://www.deegree.org/app" xmlns="http://www.opengis.net/ogc" name="IsCurve">
  <PropertyName>app:geometry</PropertyName>
</Function>

2.6. GeometryFromWKT

Useful to create a constant geometry valued expression. 

<Function xmlns="http://www.opengis.net/ogc" name="GeometryFromWKT">
  <Literal>EPSG:4326</Literal>
  <Literal>POINT(0.6 0.7)</Literal>
</Function>

2.7. MoveGeometry

Useful to displace geometries by a certain value in x and/or y direction.

To shift 20 geometry units in y direction: 

<Function xmlns:app="http://www.deegree.org/app" xmlns="http://www.opengis.net/ogc" name="MoveGeometry">
  <PropertyName>app:geometry</PropertyName>
  <Literal>0</Literal>
  <Literal>20</Literal>
</Function>

3. Other custom functions

3.1. iDiv

Integer division discarding the remainder. 

<Function xmlns:app="http://www.deegree.org/app" xmlns="http://www.opengis.net/ogc" name="idiv">
  <PropertyName>app:count</PropertyName>
  <Literal>20</Literal>
</Function>

3.2. iMod

Integer division resulting in the remainder only. 

<Function xmlns:app="http://www.deegree.org/app" xmlns="http://www.opengis.net/ogc" name="imod">
  <PropertyName>app:count</PropertyName>
  <Literal>20</Literal>
</Function>

3.3. ExtraProp

Access extra (hidden) properties attached to feature objects. The availability of such properties depends on the loading/storage mechanism used. 

<Function xmlns="http://www.opengis.net/ogc" name="ExtraProp">
  <Literal>planArt</Literal>
</Function>

4. General XPath functions

Many useful things can be done by simply using standard XPath 1.0 functions in PropertyName elements.

4.1. Element name

Access the (local) name of an element (e.g. the name of a referenced feature / subfeature). 

<PropertyName xmlns:app="http://www.deegree.org/app">app:subfeature/*/local-name()</PropertyName>

CategoryDeegree3

2018-04-20 12:04