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 functions also support 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);

Functions

svgDoc

Creates an SVG doc element from an array of content elements.

• content - an array of text values output as the content of the <svg> element
• viewbox - [optional] value of SVG viewBox attribute ( x y width height )
  • see svgViewbox
• width - [optional] width of view
• height - [optional] height of view
• style - [optional] specifies CSS styling at the document level
  • see svgStyle
• def - [optional] specifies a definition
  • see svgLinearGradient

svgViewbox

Returns an SVG viewBox attribute value determined from the envelope of a geometry.

• extent - a geometry providing the envelope to encode.

The PostGIS ST_Extent aggregate function can be use to determine the overall envelope of the geometries being encoded.

svgLinearGradient

Returns an SVG linearGradient definition element. The element is provided as a def to svgDoc. A CSS fill property value can refer to the gradient using the specifier url(#id)

• id - the gradient id
• color1 - the start color of the gradient
• color2 - the end color of the gradient

svgShape

Encodes a PostGIS geometry as an SVG shape.

• geom - geometry to encode
• class - [optional] class attribute
• id - [optional] id attribute
• style - [optional] style attribute value
  • see svgStyle
• attr - [optional] additional attributes
• title - [optional] title

svgPolygon

Encodes an array of XY ordinates as an SVG polygon.

• pts - array of X Y ordinates
• class - [optional] class attribute
• id - [optional] id attribute
• style - [optional] style attribute value
  • see svgStyle
• attr - [optional] additional attributes
• title - [optional] title

svgRect

Encodes an array of XY ordinates as an SVG polygon.

• x - X location of bottom-left corner
• y - Y location of bottom-left corner
• width - rectangle width
• height - rectangle height
• class - [optional] class attribute
• id - [optional] id attribute
• style - [optional] style attribute value
  • see svgStyle
• attr - [optional] additional attributes
• title - [optional] title

svgText

Encodes text starting at position loc as an SVG text element.

• loc - Point geometry giving location of text
• content - text value
• class - [optional] class attribute
• id - [optional] id attribute
• style - [optional] style attribute value
• attr - [optional] additional attributes
• title - [optional] title

Relevant style CSS properties include:

• text-anchor - value of start | middle | end | inherit
• font - full font specifier. E.g. 10px Verdana,Helvetica,Arial,sans-serif
• font-style - value of normal | italic | oblique
• font-weight - value of normal | bold | bolder | lighter | <number>

svgStyle

Encodes an array of name,value pairs as a string of SVG CSS name: value; properties

• param ... - list of name/value pairs

Common styling CSS properties are given below. For full list see W3C SVG spec.

• fill - fill color
• fill-opacity - opacity of fill; value in [ 0,1 ]
• stroke - line color
• stroke-dasharray - dashed line specifier, e.g. 2,4,1,4
• stroke-dashoffset - offset of dashes
• stroke-width - line width
• fill-opacity - opacity of stroke; value in [ 0,1 ]

CSS color specifiers include:

• #RRGGBB
• colorname
• hsl(h,s,l) - can use the svgHSL function to create this
• url(#id) - reference to a gradient definition

svgRGB

Encodes Red,Bliue,Green values as a CSS HSL function rgb(R,G,B).

• red - a value in 0..255
• green - a value in 0..255
• blue - a value in 0..255

svgHSL

Encodes Hue,Saturation,Lightness values as a CSS HSL function hsl(H,S,L).

• hue - a hue value in degrees (from 0 through 360, with 0 = red, 120 = green, and 240 = blue)
• saturation - [optional] a percentage, default 100
• lightness - [optional] a percentage, default 50

svgRandInt

Returns a random integer from the range [lo, hi] (inclusive)

svgRandPick

Returns a random item from an array of integers