SVG DOM API

The Document Object Model (DOM) is an API for XML documents. It defines the logical structure of documents and the way a document is accessed and manipulated. This page shows how to create an SVG document using the DOM API.

Getting started

The DOM API defines an interface called DOMImplementation , which represents the bootstrap of any DOM implementation. The role of this class is to bootstrap a particular implementation of the DOM by providing a method to create a Document . Then, the concrete Document represents an XML document and also acts like a factory for the various DOM objects such as Element , Attr and Text .

How to get an instance of the DOMImplementation interface depends on the DOM implementation you are using. In Batik, the DOM implementation is located in the package org.apache.batik.dom.svg and the class is named SVGDOMImplementation . The following example shows how to get a concrete DOMImplementation object.

import org.w3c.dom.DOMImplementation;
import org.apache.batik.dom.svg.SVGDOMImplementation;

DOMImplementation impl = SVGDOMImplementation.getDOMImplementation();

Once you have an instance of a DOMImplementation , you are not relying on Batik-specific code any more and ready to use the DOM API.

Creating a Document

Using the DOMImplementation , you are now able to create a Document . The following example illustrates how to create an SVG document. Note that the Batik's DOM implementation can be used to represent either an SVG document fragment or any kind of XML document. Note that by choosing the namespace URI and the local name of the root element of SVG, we are creating an SVG document.

import org.apache.batik.dom.svg.SVGDOMImplementation;
import org.w3c.dom.Document;

// We are using a constant available on the SVGDOMImplementation,
// but we could have used "http://www.w3.org/2000/svg".

String svgNS = SVGDOMImplementation.SVG_NAMESPACE_URI;
DOMImplementation impl = SVGDOMImplementation.getDOMImplementation();
Document doc = impl.createDocument(svgNS, "svg", null);

As we have created an SVG Document , we can cast this document to an SVGDocument (defined in the org.w3c.dom.svg package) if needed.

Building an SVG Document

Finally, using the Document object, we are now able to construct SVG content. Note that the document created before supports both generic XML and SVG. Though the DOM implementation of Batik is an SVG DOM implementation, the SVG-specific methods that rely on the document having been rendered (particularly geometry related methods, such as SVGLocatable.getBBox ) cannot be used at this point.

The document can be built using DOM Level 2 Core methods. The following example shows how to create a red rectangle located at (10, 20), with a size of (100, 50) placed in a (400, 450) SVG canvas:

import org.apache.batik.dom.svg.SVGDOMImplementation;
import org.w3c.dom.Document;
import org.w3c.dom.Element;

DOMImplementation impl = SVGDOMImplementation.getDOMImplementation();
String svgNS = SVGDOMImplementation.SVG_NAMESPACE_URI;
Document doc = impl.createDocument(svgNS, "svg", null);

// Get the root element (the 'svg' element).
Element svgRoot = doc.getDocumentElement();

// Set the width and height attributes on the root 'svg' element.
svgRoot.setAttributeNS(null, "width", "400");
svgRoot.setAttributeNS(null, "height", "450");

// Create the rectangle.
Element rectangle = doc.createElementNS(svgNS, "rect");
rectangle.setAttributeNS(null, "x", "10");
rectangle.setAttributeNS(null, "y", "20");
rectangle.setAttributeNS(null, "width", "100");
rectangle.setAttributeNS(null, "height", "50");
rectangle.setAttributeNS(null, "fill", "red");

// Attach the rectangle to the root 'svg' element.
svgRoot.appendChild(rectangle);