pat pat - 1 month ago 34
Javascript Question

JavaScript createElement and SVG

I want to create inline SVG graphics using Javascript.

However, it seems like createElementNS function applies some normalization and transforms all tags to lowercase. That is fine for HTML but not for XML/SVG. The NS I used is http://www.w3.org/2000/svg.

In particular I have problems creating a element. As it will be appended as an thus will not work.

I did some search but could not find a solution yet.

Does anybody know a solution?

Thanks a lot!

document.createElementNS("http://www.w3.org/2000/svg","textPath");


results in

<textpath></textpath>

Answer

I hope, the following example will help you:

<head>
    <style>
        #svgContainer {
            width: 400px;
            height: 400px;
            background-color: #a0a0a0;
        }
    </style>
    <script>
        function CreateSVG () {
            var xmlns = "http://www.w3.org/2000/svg";
            var boxWidth = 300;
            var boxHeight = 300;

            var svgElem = document.createElementNS (xmlns, "svg");
            svgElem.setAttributeNS (null, "viewBox", "0 0 " + boxWidth + " " + boxHeight);
            svgElem.setAttributeNS (null, "width", boxWidth);
            svgElem.setAttributeNS (null, "height", boxHeight);
            svgElem.style.display = "block";

            var g = document.createElementNS (xmlns, "g");
            svgElem.appendChild (g);
            g.setAttributeNS (null, 'transform', 'matrix(1,0,0,-1,0,300)');

                // draw linear gradient
            var defs = document.createElementNS (xmlns, "defs");
            var grad = document.createElementNS (xmlns, "linearGradient");
            grad.setAttributeNS (null, "id", "gradient");
            grad.setAttributeNS (null, "x1", "0%");
            grad.setAttributeNS (null, "x2", "0%");
            grad.setAttributeNS (null, "y1", "100%");
            grad.setAttributeNS (null, "y2", "0%");
            var stopTop = document.createElementNS (xmlns, "stop");
            stopTop.setAttributeNS (null, "offset", "0%");
            stopTop.setAttributeNS (null, "stop-color", "#ff0000");
            grad.appendChild (stopTop);
            var stopBottom = document.createElementNS (xmlns, "stop");
            stopBottom.setAttributeNS (null, "offset", "100%");
            stopBottom.setAttributeNS (null, "stop-color", "#0000ff");
            grad.appendChild (stopBottom);
            defs.appendChild (grad);
            g.appendChild (defs);

                // draw borders
            var coords = "M 0, 0";
            coords += " l 0, 300";
            coords += " l 300, 0";
            coords += " l 0, -300";
            coords += " l -300, 0";

            var path = document.createElementNS (xmlns, "path");
            path.setAttributeNS (null, 'stroke', "#000000");
            path.setAttributeNS (null, 'stroke-width', 10);
            path.setAttributeNS (null, 'stroke-linejoin', "round");
            path.setAttributeNS (null, 'd', coords);
            path.setAttributeNS (null, 'fill', "url(#gradient)");
            path.setAttributeNS (null, 'opacity', 1.0);
            g.appendChild (path);

            var svgContainer = document.getElementById ("svgContainer");
            svgContainer.appendChild (svgElem);         
        }

    </script>
</head>
<body onload="CreateSVG ()">
    <div id="svgContainer"></div>
</body>