+
+ /***********************************************/
+ /* First, center the ticket within the browser */
+ /***********************************************/
+
+ function center_ticket() {
+ /* We're relying on the SVG being the full height of the
+ * viewport already, and on the aspect ratio being
+ * preserved. First, find the center of the ticket. */
+ const r = document.getElementById("ticket").getBoundingClientRect();
+ const c = r.left + (r.width / 2);
+
+ /* That's the center-line of the ticket. We want to move it to
+ * the center-line of the viewport. */
+ const vc = document.documentElement.clientWidth / 2;
+
+ /* This is how much we need to translate the SVG */
+ const delta = vc - c;
+
+ /* But before we can set the absolute left-coordinate of the
+ * SVG, we need to know where it is now. Note: without the
+ * "px" this doesn't default to pixels like CSS does. */
+ const svg = document.querySelector("svg");
+ svg.style.left = (svg.getBoundingClientRect().left + delta) + "px";
+ }
+
+ /* Re-center it when the window is resized */
+ window.addEventListener("resize", center_ticket);
+
+ /* Center it once when the page has loaded, too */
+ window.addEventListener("load", center_ticket);
+
+
+ /*************************/
+ /* Set the security code */
+ /*************************/
+
+ /* All <text> elements produced by inkscape contain a single <tspan>
+ * that itself contains the actual text. This does something real
+ * sneaky, and actually OVERWRITES that tspan with our own text
+ * content. This turns out to be what we need anyway because trying
+ * to center a (display: inline) tspan is a pain in the butt. */
+ const ct = document.getElementById("codetext");
+
+ /* Get the "code" from the querystring if it's there */
+ let params = new URLSearchParams(document.location.search);
+ if (params.get("code")) {
+ ct.textContent = params.get("code");
+ }
+ else {
+ /* Otherwise, use a random code */
+ const bucket = ["0","1","2","3","4","5","6","7","8","9",
+ "A","B","C","D","E","F","G","H","I","J",
+ "K","L","M","N","O","P","Q","R","S","T",
+ "U","V","W","X","Y","Z"];
+
+ /* Two random ints between 0 and 35 */
+ const i1 = Math.floor(Math.random() * 36);
+ const i2 = Math.floor(Math.random() * 36);
+ const d1 = bucket[i1];
+ const d2 = bucket[i2];
+ ct.textContent = d1 + d2;
+ }
+
+ /* Now center the security code inside its red box */
+ /* First, find the center of the red box */
+ const r1 = document.getElementById("codebg").getBoundingClientRect();
+ const c1 = r1.left + (r1.width / 2);
+
+ /* Now the center of the code text */
+ const r2 = ct.getBoundingClientRect();
+ const c2 = r2.left + (r2.width / 2);
+
+ /* What do we add to c2 to make it equal to c1? */
+ const code_delta = c1 - c2;
+
+ /* Since this <text> element has an "x" attribute it's easier for us
+ * to shift that than it is to mess with the "left" style. */
+ ct.setAttribute("x", parseFloat(ct.getAttribute("x")) + code_delta);
+
+
+ /*****************************************/
+ /* Next, set up the ticket date and time */
+ /*****************************************/