XFA - Convert some template properties into CSS ones (#13082)

- implement few positioning properties: position, width, height, anchor;
  - implement font element;
  - implement fill element (used by font) and its children (linear, radial, ...);
  - font property is inherited from ancestor container (see https://www.pdfa.org/wp-content/uploads/2020/07/XFA-3_3.pdf#page=43) so let CSS handles that stuff;
  - in order to reduce the number of properties to set, only set non default properties and put the default in CSS;
  - set a background to some containers to be able to see them (will be removed in a future commit).

src/core/xfa/utils.js

@@ -13,7 +13,13 @@
  * limitations under the License.
  */
 
-const measurementPattern = /([+-]?)([0-9]+\.?[0-9]*)(.*)/;
+const dimConverters = {
+  pt: x => x,
+  cm: x => (x / 2.54) * 72,
+  mm: x => (x / (10 * 2.54)) * 72,
+  in: x => x * 72,
+};
+const measurementPattern = /([+-]?[0-9]+\.?[0-9]*)(.*)/;
 
 function getInteger({ data, defaultValue, validate }) {
   if (!data) {
@@ -67,15 +73,22 @@ function getMeasurement(str, def = "0") {
   if (!match) {
     return getMeasurement(def);
   }
-  const [, sign, valueStr, unit] = match;
+  const [, valueStr, unit] = match;
   const value = parseFloat(valueStr);
   if (isNaN(value)) {
     return getMeasurement(def);
   }
-  return {
-    value: sign === "-" ? -value : value,
-    unit: unit || "pt",
-  };
+
+  if (value === 0) {
+    return 0;
+  }
+
+  const conv = dimConverters[unit];
+  if (conv) {
+    return conv(value);
+  }
+
+  return value;
 }
 
 function getRatio(data) {
@@ -134,7 +147,7 @@ function getColor(data, def = [0, 0, 0]) {
 }
 
 function getBBox(data) {
-  const def = getMeasurement("-1");
+  const def = -1;
   if (!data) {
     return { x: def, y: def, width: def, height: def };
   }
@@ -142,7 +155,7 @@ function getBBox(data) {
     .trim()
     .split(/\s*,\s*/)
     .map(m => getMeasurement(m, "-1"));
-  if (bbox.length < 4 || bbox[2].value < 0 || bbox[3].value < 0) {
+  if (bbox.length < 4 || bbox[2] < 0 || bbox[3] < 0) {
     return { x: def, y: def, width: def, height: def };
   }