index.html.in: center the security code in its container

[charm-bypass.git] / index.html.in

diff --git a/index.html.in b/index.html.in
index 13a10e350010e8622ba9885abff4f83fbda8bb81..f600950306a38c7ca893d6bb186c23a282cfbbbc 100644 (file)
--- a/index.html.in
+++ b/index.html.in
@@ -262,6 +262,54 @@
       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 */
       /*****************************************/