I’m creating a single page application to help sell some electronics and other goodies I’ve collected over the years. Rather than the traditional rectangular display of photos, I wanted to try something different. I wanted the photos to be round. However, I didn’t want to create a bunch of round images.

Enter SVG:

<svg width="220" height="220">
                    <mask id="m1"><ellipse cx="110" cy="110" rx="98" ry="98" style="fill:white;stroke-width:0;fill-opacity: 1.0"></ellipse></mask>
                    <g>
                        <ellipse cx="110" cy="110" rx="100" ry="100" style="stroke-width:10;stroke:#222"></ellipse>
                        <image href="img/sales/lenovo/IMG_0468.jpg" x="-25%" y="-25%" height="150%" width="150%" style="mask: url(#m1)"></image></g></svg>

The original images aren’t square, so I tweaked the size and position of each so that it would completely fill the ellipse (150% and -25% for size and location).  As a fall back, I’m going to add the CSS property and value “display:none” to a standard HTML img element that will be optionally displayed if the browser can’t do SVG (like IE8 and lower for example). I don’t want to lose a potential sale to images not showing up! I’ll use modernizr for SVG detection.

And although the code above doesn’t demonstrate the technique, you can use CSS to decorate the SVG. Check this demo out that I created:

(Click image below to try it.)

At the bottom of the file from the previous post, I’ve added the following:

    <text id="currentValueAsText" x="300" y="300" 
        style="text-anchor: middle;alignment-baseline:middle" 
        fill="#FFFFFF" font-family="'Arial'" font-size="96" opacity=".6">0</text>

It’s a new text node. It’s set to centered both horizontally and vertically (using the text-anchor and alignment-baseline style properties respectively) at 300,300.

Setting the content is simple as well:

(function () {
    window.onload = loaded;
    function loaded() {
        var colorTemp = document.getElementById("color-temp");
        var reading = document.getElementById('current-reading');
        var currentVal = document.getElementById("currentValueAsText");
        var currentAngle = 0;
        var fill;

        var direction = 1;
        setInterval(function () {
            currentAngle += direction;
            if (currentAngle >= 120 || currentAngle <= -120) {
                direction *= -1;
            } else if (currentAngle === 0) {
                fill = direction === 1 ? "#BE1E2D" : "#10A2DC";
                colorTemp.setAttribute("fill", fill);
            }
            // adjust the opacity
            colorTemp.setAttribute("opacity", Math.abs(currentAngle) / 120.0);
            reading.setAttribute("transform", "rotate(" + currentAngle + ")");
            currentValueAsText.textContent = currentAngle.toString();

        }, 25);
    }
})();

Use the textContent property of the SVG text node to set the text.

Done.

Click on the image to launch the demo.

Animating SVG in a modern browser (including IE9) is generally easy enough. This example was slightly more interesting in that I wanted the thicker line to rotate based on the center point of the image, rather than the location of the line itself.

Not what I wanted:

Desired rotation:

The white bar would rotate around the center point (marked by the red arrow above).

I’ve included all of the code at the bottom of the post. (There’s quite a lot of path information).

The JavaScript just used an interval to move the line around the point:

(function () {
    window.onload = loaded;
    function loaded() {
        var colorTemp = document.getElementById("color-temp");
        var reading = document.getElementById('current-reading');
        var currentAngle = 0;
        var fill;

        var direction = 1;
        setInterval(function () {
            currentAngle += direction;
            if (currentAngle >= 120 || currentAngle <= -120) {
                direction *= -1;
            } else if (currentAngle === 0) {
                fill = direction === 1 ? "#BE1E2D" : "#10A2DC";
                colorTemp.setAttribute("fill", fill);
            }
            // adjust the opacity
            colorTemp.setAttribute("opacity", Math.abs(currentAngle) / 120.0);

            reading.setAttribute("transform", "rotate(" + currentAngle + ")");

        }, 25);
    }
})();

The angle is fixed between 120 and –120 degrees. When the angle reaches zero, the fill color is toggled.

As the angle adjusts, the line is updated as well as the opacity of the fill.

The overall size of the SVG drawing is 600×600. Knowing that (and wanting the exact center), I translated a group to an offset of 300x, 300y containing the line:

<g id="temp-transform" transform="translate(300,300)">
        <line id="current-reading" fill="none" stroke="#FFFFFF"
              stroke-width="5" stroke-linecap="round"
              stroke-miterlimit="10" x1="0" y1="-180" x2="0" y2="-120"/>
</g>

This effectively made the rotation now work from the center, once the line coordinates were adjusted to reflect the new translation.

This works because the contents of the outer group caused the new starting point (origin) to be 300x, 300y rather than the default 0x, 0y. You can see the line is from y –120 to y –180. That’s because I wanted the line to start in the top middle (as the x is set to 0 for the line).

I used Adobe Illustrator CS 5.5 to create the SVG image. Illustrator typically does not always handle fonts well when exporting as SVG. The final text node was this:

<text transform="matrix(1 0 0 1 254.1387 83.3198)" fill="#D1D3D4" font-family="'Arial'"
      font-weight="bold" font-size="29.4616">thermo</text>

To make it work across browsers, I needed to modify the text node below slightly. Note the font name and missing bold attribute. It’s not a hard switch, but it’s annoying if you need to make changes to your SVG multiple times.

<text transform="matrix(1 0 0 1 254.1387 83.3198)" fill="#D1D3D4" 
font-family="'Arial-BoldMT'" font-size="29.4616">thermo</text>

If you have any questions, please leave a comment!

<!DOCTYPE HTML>
<html>
<head>
    <title>Svg Spinner Demo</title>
    <style>
        #demo1 svg {
            width: 300px;
            height: 300px;
        }

    </style>
</head>
<body>

<div id="demo1">
<svg version="1.0" id="Layer_1" xmlns="http://www.w3.org/2000/svg" xmlns:xlink="http://www.w3.org/1999/xlink" x="0px" y="0px"
     width="600px" height="600px" viewBox="0 0 600 600" enable-background="new 0 0 600 600" xml:space="preserve">
<g>
    <radialGradient id="SVGID_1_" cx="298.9106" cy="196.146" r="399.267" gradientUnits="userSpaceOnUse">
        <stop  offset="0" style="stop-color:#D9D9D9"/>
        <stop  offset="1" style="stop-color:#C2C2C2"/>
    </radialGradient>
    <path fill="url(#SVGID_1_)" d="M300.646,595.41c-78.957,0-153.188-30.747-209.02-86.579C35.795,453,5.048,378.77,5.048,299.812
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        c-14.788,34.961-35.958,66.359-62.923,93.324s-58.363,48.135-93.324,62.923c-36.194,15.309-74.644,23.07-114.281,23.07
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        S465.005,2.214,300.646,2.214L300.646,2.214z"/>
</g>
<g>
    <radialGradient id="SVGID_2_" cx="299.0464" cy="204.2632" r="368.0053" gradientUnits="userSpaceOnUse">
        <stop  offset="0" style="stop-color:#141414"/>
        <stop  offset="1" style="stop-color:#080808"/>
    </radialGradient>
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</g>
<g>
    <radialGradient id="SVGID_3_" cx="299.5176" cy="232.4409" r="259.4771" gradientUnits="userSpaceOnUse">
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    </radialGradient>
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</g>
<g opacity="0.8">
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</g>
<g id="temperature-markings">
        <line fill="none" stroke="#C7C8CA" stroke-width="5" stroke-miterlimit="10"
              x1="300.646" y1="123.751" x2="300.646" y2="161.603"/>
        <line fill="none" stroke="#C7C8CA" stroke-width="5" stroke-miterlimit="10"
              x1="422.102" y1="371.971" x2="454.881" y2="390.896"/>
        <line fill="none" stroke="#C7C8CA" stroke-width="5" stroke-miterlimit="10"
              x1="146.41" y1="390.896" x2="179.191" y2="371.97"/>
</g>
<g id="temp-transform" transform="translate(300,300)">
        <line id="current-reading" fill="none" stroke="#FFFFFF"
              stroke-width="5" stroke-linecap="round"
              stroke-miterlimit="10" x1="0" y1="-180" x2="0" y2="-120"/>
</g>
    <text transform="matrix(1 0 0 1 254.1387 83.3198)" fill="#D1D3D4" font-family="'Arial'"
          font-weight="bold" font-size="29.4616">thermo</text>
</svg>


</div>


<script type="text/javascript">

    (function () {

        window.onload = loaded;

        function loaded() {
            var colorTemp = document.getElementById("color-temp");
            var reading = document.getElementById('current-reading');
            var currentAngle = 0;
            var fill;

            var direction = 1;
            setInterval(function () {
                currentAngle += direction;
                if (currentAngle >= 120 || currentAngle <= -120) {
                    direction *= -1;
                } else if (currentAngle === 0) {
                    fill = direction === 1 ? "#BE1E2D" : "#10A2DC";
                    colorTemp.setAttribute("fill", fill);
                }
                // adjust the opacity
                colorTemp.setAttribute("opacity", Math.abs(currentAngle) / 120.0);

                reading.setAttribute("transform", "rotate(" + currentAngle + ")");

            }, 25);
        }
    })();


</script>
</body>
</html>