Categories
Vector Graphics for the Web

Vector Graphics for the Web – Introduction

When working on the web, there are two types of image formats that you can use:

  1. Raster Graphics: They are made up of pixels. The more pixels you have the higher the resolution you get.
  2. Vector Graphics: They use mathematical equations to create a two dimensional image. The graphics data is described by mathematical formula.

This article will look at vector graphics and how to work with them using JavaScript.

Vector graphics can be drawn by writing code to create them. Programs such as Inkscape and Illustrator also use them in their default formats.

Take for example the map of Africa shown above. It is a composite shape made up of individual paths that each represents a country. With this knowledge, we can apply a transformation to the individual countries to any size. Provided we do the transformations uniformly, we can size or resize the image without distortion.

The SVG Specification

SVG is a language for describing vector graphics in XML. SVG is a W3C specification and works well with HTML, CSS and JavaScript.

Below is a basic skeleton of an SVG document. xlmns specifies the namespace for the document.

<svg xmlns="http://www.w3.org/2000/svg"> 
 
</svg>

To draw a circle, we specify the properties of the circle in the document. So our document becomes:

<svg xmlns="http://www.w3.org/2000/svg"> 
	<circle cx="40" cy="40" r="30" stroke="#000" stroke-width="1" fill="#FFF" />
</svg>

Saving the above in a circle.svg document and viewing in a browser will draw the circle shown below:

Circle in SVG

SVG Advantages

Resolution Independence

Vector Graphics are Resolution Independent
Vector Graphics are Resolution Independent

Scalable Vector Graphics (SVG) do not lose their resolution regardless of how they are resized.

Interactivity

You can add hyperlinks and animation to SVG by styling and scripting. SVG has a navigable DOM which allows for the creation of interactive elements.

SEO Friendly

SVG is made up of XML text files. As a result, you can add keyword descriptions and links making content more recognisable for search engines.

Adding SVG to Your Web Pages

Using the Image Tag

An SVG document can be embedded in the image tag like a regular image in HTML. An example is shown below:

<img src="circle.svg" alt="A simple circle" width="100" height="100" />

The disadvantage of this method is that the SVG will not be interactive.

Using the Object Tag

This is the best option if you intend to make the SVG interactive. The code to do so is shown below:

<object type="image/svg+xml" data="circle.svg"></object>

Using inline SVG

In this method, the code to generate the svg is placed between the body tags of the web pages.

Browser Adoption

Browser Support for SVG
Browser Support for SVG

On the Can I Use website, most modern browsers have great support for SVG with the exception of Internet Explorer.

JavaScript Tools for Working with SVG

RaphaelJS

RaphaelJS is a JavaScript library that allows you to work with vector graphics using JavaScript. It acts like an interface for creating SVG without having to write code in SVG.

Think of it like jQuery. Without a wrapper like jQuery providing a layer of abstraction for JavaScript, you would have to write raw JavaScript to do anything on the web. If you think of how tedious writing JavaScript is and multiply that by 10, you will have an idea of the difficulty of SVG.

RaphaelJS is a vector graphics library which is used to draw objects in the browser. It enables SVG support for IE8 and below.

JustGage

JustGage is a handy JavaScript plugin for generating and animating nice & clean gauges. It is based on RaphaelJS library for vector drawing, so it’s completely resolution independent and self-adjusting.

Oh yes, since it’s pure SVG, it works in almost any browser –
IE6+, Chrome, Firefox, Safari, Opera, Android, etc.

Snap.svg

Snap.svg was developed by the creator of the RaphaelJS library. Unlike RaphaelJS which supports IE8 and below, Snap.svg was designed for modern browsers and therefore supports the newest SVG features like masking, clipping, patterns, full gradients, groups, and more.

D3.js

D3.js is a JavaScript library for manipulating documents based on data. D3helps you bring data to life using HTML, SVG, and CSS. D3’s emphasis on web standards gives you the full capabilities of modern browsers without tying yourself to a proprietary framework, combining powerful visualization components and a data-driven approach to DOM manipulation.

Conclusion

In the world of front end web development, there are a plethora of tools that are used to create interactive web applications. This tools involve working with HTML5, CSS3, SVG and WebGL.

The main advantage of SVG is that it allows you create graphics without the loss of resolution when they are resized. This might not seem like much to you but in a world of responsive design, it represents a big opportunity.

Leave a Reply

Your email address will not be published. Required fields are marked *