Can an SVG background be interactive?

Question

I have an SVG image that I created. It is a rectangle with a circle inside it. The circle follows the users mouse using JavaScript. The image is represented by the following code:

<svg xmlns="http://www.w3.org/2000/svg" version="1.1" xmlns:xlink="http://www.w3.org/1999/xlink" xmlspace="preserve" preserveAspectRatio="xMidYMin slic">
<style>
    * { vector-effect:non-scaling-stroke }
    rect { fill: blue; }
    circle { fill:orange; opacity:0.75; }
</style>
<rect cx="50%" cy="0" width="720" height="1278" id="origin" />
<circle cx="50%" cy="116" r="72" id="dot"    />
<script>
    var svg  = document.documentElement,
        pt   = svg.createSVGPoint(),
        dot  = document.querySelector('#dot');

    svg.addEventListener('mousemove',function(evt){
      var loc = cursorPoint(evt);
        dot.setAttribute('cx',loc.x);
        dot.setAttribute('cy',loc.y);
    },false);

    function rotateElement(el,originX,originY,towardsX,towardsY){
        var degrees = Math.atan2(towardsY-originY,towardsX-originX)*180/Math.PI + 90;
        el.setAttribute(
            'transform',
            'translate('+originX+','+originY+') translate('+(-originX)+','+(-originY)+')'
        );
    }

    // Get point in global SVG space
    function cursorPoint(evt){
      pt.x = evt.clientX; pt.y = evt.clientY;
      return pt.matrixTransform(svg.getScreenCTM().inverse());
    }
</script> 
</svg>

What I would like to do with this image is use it as a CSS background. If I use CSS to set the image as a background {background: url("image.svg");} then the JavaScript no longer works, i.e. the circle no longer follows the cursor. I believe this is due to the fact that when the image is a background, it has other elements stacked on top of it.

So how can I have the image be a background and also remain interactive? Any suggestions would be greatly appreciated.

Answer 1

One of the way to get a scripted background SVG working, is to use CSS4 element(). It's currently only implemented in Firefox 4+ via -moz-element().

An example:

<div id="bg" style="width: 400px; height: 400px;">
    <svg width="400" height="400" viewPort="0 0 400 400">
        <!-- force correct 0,0 coordinates -->
        <rect x="0" y="0" width="1" height="1" fill="transparent" />
        <rect x="0" y="0" id="animable1" width="120" height="120" fill="blue" />
        <rect x="0" y="0" id="animable2" width="60" height="60" fill="red" />
    </svg>
</div>

<div id="target" style="border: 4px dashed black; height: 400px; width: 400px; background: gray -moz-element(#bg); background-size: 20%;"></div>

<script type="text/javascript">
    var divTarget = document.getElementById("target");
    var animable1 = document.getElementById("animable1");
    var animable2 = document.getElementById("animable2");
    document.addEventListener("mousemove", function(event){
        var rotation = Math.atan2(event.clientY, event.clientX);
        animable1.setAttribute("transform", "translate(140 140) rotate(" + (rotation / Math.PI * 360) + " 60 60)");
        animable2.setAttribute("transform", "translate(170 170) rotate(" + (360 - rotation / Math.PI * 360) + " 30 30)");
    }, false);
    animable1.setAttribute("transform", "translate(140 140) rotate(0 60 60)");
    animable2.setAttribute("transform", "translate(170 170) rotate(0 30 30)");
</script>

Answer 2

You should create two files one of the .css file and the other one is Of course, better to have separate files, because it is actually a part of the container is html. SVG within this container,'s JavaScripts. This divide-and-conquer simplification or incident. For this reason, the external file is actually being held as JavaScripts. This is a great way to will not loose in the code.

SVG defining:

<div><object id="circle-svg" width="400" height="300" type="image/svg+xml" data="moving_circle.svg"></object></div>

Here, the part of the data you describe your own SVG

for example, canvas:

            canvas = d3.select("#circle-svg")
                    .on("mouseover", mouseover)
                    .on("mousemove", mousemove)
                    .on("mouseout", mouseout);

Part1: Take a look at this code (html based)

<head>
<title>Controlling an SVG with Javascript</title>
<script type='text/javascript' src='svg-interaction.js'></script>
   <script type="text/javascript" src="http://mbostock.github.com/d3/d3.js"></script>

           <style type="text/css">
            div.tooltip {
                    position: absolute;
                      text-align: center;
                    z-index: 10;
                      width: 140px;
                      height: auto;
                    padding: 8px;
                    font: 24px sans-serif;
                    background: red;
                    color: white;
                    border: solid 1px #aaa;
                    border-radius: 8px;
                    opacity: 0;
            }
    </style>
     <head>

    <body>
    <h2>Controlling SVG with Javascript</h2>
     <div class="page-content">
      <div><object id="circle-svg" width="400" height="300" type="image/svg+xml" data="moving_circle.svg"></object></div>

You can define your scripts over there

Then you continue to the second phase (Your SVG study)

<svg viewBox="0 0 400 400" preserveAspectRatio="none"
 xmlns="http://www.w3.org/2000/svg"
 xmlns:xlink="http://www.w3.org/1999/xlink"
 xmlns:a3="http://ns.adobe.com/AdobeSVGViewerExtensions/3.0/"
 a3:scriptImplementation="Adobe"
 onload="init(evt)"
 onzoom="updateTracker(evt)"
 onscroll="updateTracker(evt)"
 onresize="updateTracker(evt)">
<script type="text/ecmascript" a3:scriptImplementation="Adobe"><![CDATA[
    /*****
    *
    *   Globals
    *
    *****/
    var elems = {
        tracker: false,
        cursor:  false,
        trans:   true,
        scale:   true,
        mx:      true,
        my:      true,
        ux:      true,
        uy:      true
    };
    var frame = {
        x_trans: 0,
        y_trans: 0,
        zoom   : 1,
        x_scale: 1,
        y_scale: 1
    };