+ function center_code() {
+ /* Center the security code inside its red box */
+ const ct = document.getElementById("codetext");
+ const bg = document.getElementById("codebg");
+
+ /* First, find the center of the red box */
+ const r1 = bg.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 hdelta = c1 - c2;
+
+ /* We've measured everything so far in "client rect"
+ * coordinates, because that's the only available measurement
+ * we have for the width of the <text> element after futzing
+ * with its contents. But when we reposition that <text>
+ * element, it will be by adjusting its "x" attribute, and
+ * that attribute uses a different coordinate system than the
+ * client rect does. Specifically, "x" refers to an offset
+ * within the SVG's coordinate system, and the client rect
+ * coordinates are pixels on-screen. To convert between the
+ * two, we can take the "width" attribute of the background
+ * element and compare it to the width of the background
+ * element's client rect. Since the size of the background is
+ * fixed, this should give us a multiplier that turns client recr
+ * distances (what we have) into SVG distances (what we want) */
+ const client_to_svg = parseFloat(bg.getAttribute("width"))/r1.width;
+
+ /* Convert hdelta from client rect to SVG coordinates */
+ const svg_hdelta = hdelta * client_to_svg;
+
+ /* 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")) + svg_hdelta);
+ }