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SVG Functions

A collection of PostgreSQL functions which allow easily creating SVG graphics. The main goal of the API is to allow converting PostGIS geometries into styled SVG documents. The API also supports simple geometry generated without PostGIS.

Installation

psql < pg-svg-lib.sql

Sometimes function signatures can change. The old function must be removed. To generate DROP FUNCTION commands use this query:

SELECT 'DROP FUNCTION ' || oid::regprocedure
FROM   pg_proc
WHERE  proname LIKE 'svg%' AND pg_function_is_visible(oid);

Usage

See the API doc.

Example

This example demonstrates:

  • generating a shape from a PostGIS geometry
  • overlaying a text element sourced from a column value
  • using SVG CSS styling to set colors and font properties.
WITH wa(abbrev, geom) AS (VALUES
  ('WA', 'POLYGON ((-122.6 48.4, -122.5 48.5, -122.5 48.8, -122.7 48.8, -122.8 49, -117 49, -117 46.4, -116.9 46, -119 46, -119.1 45.9, -119.6 45.9, -120.4 45.7, -120.6 45.7, -121.2 45.6, -121.3 45.7, -121.8 45.7, -122.2 45.5, -122.8 45.6, -122.8 45.9, -122.9 46.1, -123.2 46.2, -123.3 46.1, -123.5 46.3, -124.1 46.3, -124.1 46.6, -124 46.6, -123.8 46.7, -124.1 46.7, -124.1 46.9, -123.8 47, -124.1 47, -124.2 46.9, -124.2 47.3, -124.3 47.3, -124.4 47.6, -124.6 47.9, -124.7 48.2, -124.7 48.4, -124 48.2, -123.4 48.1, -123.1 48.1, -122.8 48.1, -122.7 47.9, -122.9 47.8, -122.9 47.6, -122.8 47.7, -122.5 47.9, -122.5 47.8, -122.6 47.7, -122.5 47.5, -122.6 47.3, -122.5 47.3, -122.3 47.3, -122.4 47.8, -122.2 48, -122.5 48.3, -122.6 48.4))'::geometry)
),
shape AS (SELECT geom, 
    svgShape( geom,
            title => 'Washington State',
            style => svgStyleProp(  fill => '#99b7ff',
                                    stroke => '#255580',
                                    strokewidth => '.1'  )) AS svg 
        FROM wa
    UNION ALL (SELECT NULL,
        svgText(ST_Centroid(geom), abbrev, 
                style => svgStyleProp( fill=> '#27863a', font=> 'bold 2px serif',
                      css=> ARRAY[ 'text-anchor', 'middle' ] ))
        FROM wa
    )
)
SELECT svgDoc( array_agg( svg ),
    viewbox => svgViewbox( ST_Expand( ST_Extent(geom), 2))
  ) AS svg FROM shape;

Generate an SVG file for this example using:

psql -A -t -o wa.svg  < wa.sql