User:Moresby/Understanding Mapnik/Revisiting our examples in XML

Understanding Mapnik

A Mapnik tutorial

• Contents

Starting with Python

• Setting a background colour
• Plotting points
• Placing images at points
• Plotting lines
• Specifying line colour and width
• Specifying line styles
• Using layers to draw points and lines
• Using filters to represent data
• Adding text to the map

Using XML and CSS

• Representing map designs in XML
• Revisiting our examples in XML
• CSS styling with Cascadenik

CartoCSS and PostGIS

• Using CartoCSS
• Specifying the drawing order
• Using PostgreSQL and PostGIS
• Specifying geometry types
• The Google Maps projection
• Specifying geometry constraints

Any map design built up using Python objects should also be representable using XML. For completeness, here are the XML files corresponding to our previous exercises:

110-background.xml

<?xml version='1.0'?>
<Map background-color='ghostwhite'/>

120-points.xml

<?xml version='1.0'?>
<Map background-color='ghostwhite'>
  <Style name='basic_style'>     
    <Rule>
      <PointSymbolizer/>         
    </Rule>
  </Style>
  <Layer name='main_map'>
    <StyleName>basic_style</StyleName>
    <Datasource>
      <Parameter name='file'>data-places.csv</Parameter>
      <Parameter name='type'>csv</Parameter>
    </Datasource>
  </Layer>
</Map>

121-points-images.xml

<?xml version='1.0'?>
<Map background-color='ghostwhite'>
  <Style name='basic_style'>
    <Rule>
      <PointSymbolizer file='circle_red_16x16.png'/>
    </Rule>
  </Style>
  <Layer name='main_map'>
    <StyleName>basic_style</StyleName>
    <Datasource>
      <Parameter name='file'>data-places.csv</Parameter>
      <Parameter name='type'>csv</Parameter>
    </Datasource>
  </Layer>
</Map>

130-lines.xml

<?xml version='1.0'?>
<Map background-color='ghostwhite'>
  <Style name='basic_style'>
    <Rule>
      <LineSymbolizer/>
    </Rule>
  </Style>
  <Layer name='main_map'>
    <StyleName>basic_style</StyleName>
    <Datasource>
      <Parameter name='file'>data-roads.csv</Parameter>
      <Parameter name='type'>csv</Parameter>
    </Datasource>
  </Layer>
</Map>

131-lines-colour.xml

<?xml version='1.0'?>
<Map background-color='ghostwhite'>
  <Style name='basic_style'>
    <Rule>
      <LineSymbolizer stroke='green' stroke-width='2'/>
    </Rule>
  </Style>
  <Layer name='main_map'>
    <StyleName>basic_style</StyleName>
    <Datasource>
      <Parameter name='file'>data-roads.csv</Parameter>
      <Parameter name='type'>csv</Parameter>
    </Datasource>
  </Layer>
</Map>

132-lines-stroke.xml

<?xml version='1.0'?>
<Map background-color='ghostwhite'>
  <Style name='basic_style'>
    <Rule>
      <LineSymbolizer stroke='green' stroke-width='2' stroke-dasharray='6, 2'/>
    </Rule>
  </Style>
  <Layer name='main_map'>
    <StyleName>basic_style</StyleName>
    <Datasource>
      <Parameter name='file'>data-roads.csv</Parameter>
      <Parameter name='type'>csv</Parameter>
    </Datasource>
  </Layer>
</Map>

140-layers.xml

<?xml version='1.0'?>
<Map background-color='ghostwhite'>
  <Style name='line_style'>
    <Rule>
      <LineSymbolizer/>
    </Rule>
  </Style>
  <Style name='point_style'>
    <Rule>
      <PointSymbolizer file='circle_red_16x16.png'/>
    </Rule>
  </Style>
  <Layer name='line_layer'>
    <StyleName>line_style</StyleName>
    <Datasource>
      <Parameter name='file'>data-roads.csv</Parameter>
      <Parameter name='type'>csv</Parameter>
    </Datasource>
  </Layer>
  <Layer name='point_layer'>
    <StyleName>point_style</StyleName>
    <Datasource>
      <Parameter name='file'>data-places.csv</Parameter>
      <Parameter name='type'>csv</Parameter>
    </Datasource>
  </Layer>
</Map>

150-filters.xml

<?xml version='1.0'?>
<Map background-color='ghostwhite'>
  <Style name='line_style'>
    <Rule>
      <Filter>[type]='rail'</Filter>
      <LineSymbolizer stroke-width='2' stroke-dasharray='6, 2'/>
    </Rule>
    <Rule>
      <Filter>[type]='road'</Filter>
      <LineSymbolizer/>
    </Rule>
    <Rule>
      <Filter>[type]='mainroad'</Filter>
      <LineSymbolizer stroke-width='2'/>
    </Rule>
    <Rule>
      <Filter>[type]='motorway'</Filter>
      <LineSymbolizer stroke='lightblue' stroke-width='4'/>
    </Rule>
  </Style>
  <Style name='point_style'>
    <Rule>
      <Filter>[type]='town'</Filter>
      <PointSymbolizer file='circle_red_8x8.png'/>
    </Rule>
    <Rule>
      <Filter>[type]='city'</Filter>
      <PointSymbolizer file='circle_red_16x16.png'/>
    </Rule>
  </Style>
  <Layer name='line_layer'>
    <StyleName>line_style</StyleName>
    <Datasource>
      <Parameter name='file'>data-roads.csv</Parameter>
      <Parameter name='type'>csv</Parameter>
    </Datasource>
  </Layer>
  <Layer name='point_layer'>
    <StyleName>point_style</StyleName>
    <Datasource>
      <Parameter name='file'>data-places.csv</Parameter>
      <Parameter name='type'>csv</Parameter>
    </Datasource>
  </Layer>
</Map>

160-text.xml

<?xml version='1.0'?>
<Map background-color='ghostwhite'>
  <Style name='line_style'>
    <Rule>
      <Filter>[type]='rail'</Filter>
      <LineSymbolizer stroke-width='2' stroke-dasharray='6, 2'/>
    </Rule>
    <Rule>
      <Filter>[type]='road'</Filter>
      <LineSymbolizer/>
      <TextSymbolizer face-name='DejaVu Sans Book' halo-radius='2' placement='line'>[name]</TextSymbolizer>
    </Rule>
    <Rule>
      <Filter>[type]='mainroad'</Filter>
      <LineSymbolizer stroke-width='2'/>
      <TextSymbolizer face-name='DejaVu Sans Book' halo-radius='2' placement='line'>[name]</TextSymbolizer>
    </Rule>
    <Rule>
      <Filter>[type]='motorway'</Filter>
      <LineSymbolizer stroke='lightblue' stroke-width='4'/>
      <TextSymbolizer face-name='DejaVu Sans Book' halo-radius='2' placement='line'>[name]</TextSymbolizer>
    </Rule>
  </Style>
  <Style name='point_style'>
    <Rule>
      <Filter>[type]='town'</Filter>
      <PointSymbolizer file='circle_red_8x8.png'/>
      <TextSymbolizer face-name='DejaVu Sans Book' halo-radius='3' dy='7'>[name]</TextSymbolizer>
    </Rule>
    <Rule>
      <Filter>[type]='city'</Filter>
      <PointSymbolizer file='circle_red_16x16.png'/>
      <TextSymbolizer face-name='DejaVu Sans Book' size='12' fill='red' halo-radius='3' dy='11'>[name]</TextSymbolizer>
    </Rule>
  </Style>
  <Layer name='line_layer'>
    <StyleName>line_style</StyleName>
    <Datasource>
      <Parameter name='file'>data-roads.csv</Parameter>
      <Parameter name='type'>csv</Parameter>
    </Datasource>
  </Layer>
  <Layer name='point_layer'>
    <StyleName>point_style</StyleName>
    <Datasource>
      <Parameter name='file'>data-places.csv</Parameter>
      <Parameter name='type'>csv</Parameter>
    </Datasource>
  </Layer>
</Map>