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I am creating charts on the fly as SVGs using d3.js. These charts are dynamically generated based on the selections of authenticated users. Once these charts are generated, the user has the option to download the generated SVG as a PNG or PDF. The current workflow is the following: // JAVASC // get the element containing generated SVG var svg = document.getElementById("chart-container"); // Extract the data as SVG text string var svg_xml = (new XMLSerializer).serializeToString(svg); // Submit the <FORM> to the server. var form = document.getElementById("svgform"); form['output_format'].value = output_format; // can be either "pdf" or "png" form['data'].value = svg_xml ; form.submit(); The FORM element is a hidden form, used to POST the data: <form id="svgform" method="post" action="conversion.php"> <input type="hidden" id="output_format" name="output_format" value=""> <input type="hidden" id="data" name="data" value=""> </form> The PHP file saves the provided SVG data as a temporary file: // check for valid session, etc - omitted for brevity $xmldat = $_POST['data']; // serialized XML representing the SVG element if(simplexml_load_string($xmldat)===FALSE) { die; } // reject invalid XML $fileformat = $_POST['output_format']; // chosen format for output; PNG or PDF if ($fileformat != "pdf" && $fileformat != "png" ){ die; } // limited options for format $fileformat = escapeshellarg($fileformat); // escape shell arguments that might have snuck in // generate temporary file names with tempnam() - omitted for brevity $handle = fopen($infile, "w"); fwrite($handle, $xmldat); fclose($handle); A conversion utility is run which reads the temporary file ($infile) and creates a new file ($outfile) in the specified $fileformat (PDF or PNG). The resulting new file is then returned to the browser, and the temporar

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