Move the getXfaHtmlForPrinting helper function to its own file (PR 13411 follow-up)

The `web/ui_utils.js` file should be usable from basically anywhere in the `web/`-folder, hence it should ideally not have any dependecies on its own and particularily *not* onces that pull in entire (large) factories.

web/print_utils.js

@@ -0,0 +1,42 @@
+/* Copyright 2021 Mozilla Foundation
+ *
+ * Licensed under the Apache License, Version 2.0 (the "License");
+ * you may not use this file except in compliance with the License.
+ * You may obtain a copy of the License at
+ *
+ *     http://www.apache.org/licenses/LICENSE-2.0
+ *
+ * Unless required by applicable law or agreed to in writing, software
+ * distributed under the License is distributed on an "AS IS" BASIS,
+ * WITHOUT WARRANTIES OR CONDITIONS OF ANY KIND, either express or implied.
+ * See the License for the specific language governing permissions and
+ * limitations under the License.
+ */
+
+import { CSS_UNITS } from "./ui_utils.js";
+import { DefaultXfaLayerFactory } from "./xfa_layer_builder.js";
+
+function getXfaHtmlForPrinting(printContainer, pdfDocument) {
+  const xfaHtml = pdfDocument.allXfaHtml;
+  const factory = new DefaultXfaLayerFactory();
+  const scale = Math.round(CSS_UNITS * 100) / 100;
+  for (const xfaPage of xfaHtml.children) {
+    const page = document.createElement("div");
+    page.className = "xfaPrintedPage";
+    printContainer.appendChild(page);
+
+    const { width, height } = xfaPage.attributes.style;
+    const viewBox = [0, 0, parseInt(width), parseInt(height)];
+    const viewport = { viewBox, scale, rotation: 0 };
+
+    const builder = factory.createXfaLayerBuilder(
+      /* pageDiv = */ page,
+      /* pdfPage = */ null,
+      /* annotationStorage = */ pdfDocument.annotationStorage,
+      /* xfaHtml = */ xfaPage
+    );
+    builder.render(viewport, "print");
+  }
+}
+
+export { getXfaHtmlForPrinting };