making sure bbox is there

js/misc.js

@@ -124,8 +124,20 @@ export async function loadText(path) {
   return (await fetch(path)).text();
 }
 
+function getBBox(elem) {
+  if (elem.getBoundingClientRect) {
+    return elem.getBoundingClientRect();
+  }
+  return {
+    left: elem.offsetLeft,
+    top: elem.offsetTop,
+    width: elem.offsetWidth,
+    height: elem.offsetHeight,
+  };
+}
+
 export function convertMousePosition(canvas, measures, snap, e) {
-  const rect = canvas.getBoundingClientRect();
+  const rect = getBBox(canvas);
   const pixelX = ((e.clientX - rect.left) / rect.width) * measures.width;
   const pixelY = ((e.clientY - rect.top) / rect.height) * measures.height;
   const halfW = measures.width * 0.5;
@@ -145,7 +157,7 @@ export function convertMousePosition(canvas, measures, snap, e) {
 export function convertTouchPosition(canvas, measures, snap, e) {
   const [x, y, w] = [...e.touches].reduce(
     (p, t) => {
-      const weight = t.force;
+      const weight = Number.isFinite(+t.force) ? t.force : 1;
       return [
         p[0] + t.clientX * weight,
         p[1] + t.clientY * weight,
@@ -155,8 +167,8 @@ export function convertTouchPosition(canvas, measures, snap, e) {
     [0, 0, 0],
   );
   return convertMousePosition(canvas, measures, snap, {
-    clientX: x / w,
-    clientY: y / w,
+    clientX: w > 0 ? x / w : x,
+    clientY: w > 0 ? y / w : y,
   });
 }