XFA - Add a layer to display XFA forms

  - add an option to enable XFA rendering if any;
  - for now, let the canvas layer: it could be useful to implement XFAF forms (embedded pdf in xml stream for the background and xfa form for the foreground);
  - ui elements in template DOM are pretty close to their html counterpart so we generate a fake html DOM from template one:
    - it makes easier to translate template properties to html ones;
    - it makes faster the creation of the html element in the main thread.

Author: calixteman

src/core/document.js

@@ -15,6 +15,7 @@
 
 import {
   assert,
+  bytesToString,
   FormatError,
   info,
   InvalidPDFException,
@@ -28,6 +29,7 @@ import {
   shadow,
   stringToBytes,
   stringToPDFString,
+  stringToUTF8String,
   unreachable,
   Util,
   warn,
@@ -56,6 +58,7 @@ import { calculateMD5 } from "./crypto.js";
 import { Linearization } from "./parser.js";
 import { OperatorList } from "./operator_list.js";
 import { PartialEvaluator } from "./evaluator.js";
+import { XFAFactory } from "./xfa/factory.js";
 
 const DEFAULT_USER_UNIT = 1.0;
 const LETTER_SIZE_MEDIABOX = [0, 0, 612, 792];
@@ -79,6 +82,7 @@ class Page {
     builtInCMapCache,
     globalImageCache,
     nonBlendModesSet,
+    xfaFactory,
   }) {
     this.pdfManager = pdfManager;
     this.pageIndex = pageIndex;
@@ -91,6 +95,7 @@ class Page {
     this.nonBlendModesSet = nonBlendModesSet;
     this.evaluatorOptions = pdfManager.evaluatorOptions;
     this.resourcesPromise = null;
+    this.xfaFactory = xfaFactory;
 
     const idCounters = {
       obj: 0,
@@ -137,6 +142,11 @@ class Page {
   }
 
   _getBoundingBox(name) {
+    if (this.xfaData) {
+      const { width, height } = this.xfaData.attributes.style;
+      return [0, 0, parseInt(width), parseInt(height)];
+    }
+
     const box = this._getInheritableProperty(name, /* getArray = */ true);
 
     if (Array.isArray(box) && box.length === 4) {
@@ -231,6 +241,13 @@ class Page {
     return stream;
   }
 
+  get xfaData() {
+    if (this.xfaFactory) {
+      return shadow(this, "xfaData", this.xfaFactory.getPage(this.pageIndex));
+    }
+    return shadow(this, "xfaData", null);
+  }
+
   save(handler, task, annotationStorage) {
     const partialEvaluator = new PartialEvaluator({
       xref: this.xref,
@@ -695,6 +712,9 @@ class PDFDocument {
   }
 
   get numPages() {
+    if (this.xfaFactory) {
+      return shadow(this, "numPages", this.xfaFactory.numberPages);
+    }
     const linearization = this.linearization;
     const num = linearization ? linearization.numPages : this.catalog.numPages;
     return shadow(this, "numPages", num);
@@ -732,6 +752,80 @@ class PDFDocument {
     });
   }
 
+  get xfaData() {
+    const acroForm = this.catalog.acroForm;
+    if (!acroForm) {
+      return null;
+    }
+
+    const xfa = acroForm.get("XFA");
+    const entries = {
+      "xdp:xdp": "",
+      template: "",
+      datasets: "",
+      config: "",
+      connectionSet: "",
+      localeSet: "",
+      stylesheet: "",
+      "/xdp:xdp": "",
+    };
+    if (isStream(xfa) && !xfa.isEmpty) {
+      try {
+        entries["xdp:xdp"] = stringToUTF8String(bytesToString(xfa.getBytes()));
+        return entries;
+      } catch (_) {
+        warn("XFA - Invalid utf-8 string.");
+        return null;
+      }
+    }
+
+    if (!Array.isArray(xfa) || xfa.length === 0) {
+      return null;
+    }
+
+    for (let i = 0, ii = xfa.length; i < ii; i += 2) {
+      let name;
+      if (i === 0) {
+        name = "xdp:xdp";
+      } else if (i === ii - 2) {
+        name = "/xdp:xdp";
+      } else {
+        name = xfa[i];
+      }
+
+      if (!entries.hasOwnProperty(name)) {
+        continue;
+      }
+      const data = this.xref.fetchIfRef(xfa[i + 1]);
+      if (!isStream(data) || data.isEmpty) {
+        continue;
+      }
+      try {
+        entries[name] = stringToUTF8String(bytesToString(data.getBytes()));
+      } catch (_) {
+        warn("XFA - Invalid utf-8 string.");
+        return null;
+      }
+    }
+    return entries;
+  }
+
+  get xfaFactory() {
+    if (
+      this.pdfManager.enableXfa &&
+      this.formInfo.hasXfa &&
+      !this.formInfo.hasAcroForm
+    ) {
+      const data = this.xfaData;
+      return shadow(this, "xfaFactory", data ? new XFAFactory(data) : null);
+    }
+    return shadow(this, "xfaFaxtory", null);
+  }
+
+  get isPureXfa() {
+    return this.xfaFactory !== null;
+  }
+
   get formInfo() {
     const formInfo = { hasFields: false, hasAcroForm: false, hasXfa: false };
     const acroForm = this.catalog.acroForm;
@@ -918,6 +1012,24 @@ class PDFDocument {
     }
     const { catalog, linearization } = this;
 
+    if (this.xfaFactory) {
+      return Promise.resolve(
+        new Page({
+          pdfManager: this.pdfManager,
+          xref: this.xref,
+          pageIndex,
+          pageDict: Dict.empty,
+          ref: null,
+          globalIdFactory: this._globalIdFactory,
+          fontCache: catalog.fontCache,
+          builtInCMapCache: catalog.builtInCMapCache,
+          globalImageCache: catalog.globalImageCache,
+          nonBlendModesSet: catalog.nonBlendModesSet,
+          xfaFactory: this.xfaFactory,
+        })
+      );
+    }
+
     const promise =
       linearization && linearization.pageFirst === pageIndex
         ? this._getLinearizationPage(pageIndex)
@@ -935,6 +1047,7 @@ class PDFDocument {
         builtInCMapCache: catalog.builtInCMapCache,
         globalImageCache: catalog.globalImageCache,
         nonBlendModesSet: catalog.nonBlendModesSet,
+        xfaFactory: null,
       });
     }));
   }

src/core/pdf_manager.js

@@ -106,13 +106,14 @@ class BasePdfManager {
 }
 
 class LocalPdfManager extends BasePdfManager {
-  constructor(docId, data, password, evaluatorOptions, docBaseUrl) {
+  constructor(docId, data, password, evaluatorOptions, enableXfa, docBaseUrl) {
     super();
 
     this._docId = docId;
     this._password = password;
     this._docBaseUrl = docBaseUrl;
     this.evaluatorOptions = evaluatorOptions;
+    this.enableXfa = enableXfa;
 
     const stream = new Stream(data);
     this.pdfDocument = new PDFDocument(this, stream);
@@ -141,14 +142,22 @@ class LocalPdfManager extends BasePdfManager {
 }
 
 class NetworkPdfManager extends BasePdfManager {
-  constructor(docId, pdfNetworkStream, args, evaluatorOptions, docBaseUrl) {
+  constructor(
+    docId,
+    pdfNetworkStream,
+    args,
+    evaluatorOptions,
+    enableXfa,
+    docBaseUrl
+  ) {
     super();
 
     this._docId = docId;
     this._password = args.password;
     this._docBaseUrl = docBaseUrl;
     this.msgHandler = args.msgHandler;
     this.evaluatorOptions = evaluatorOptions;
+    this.enableXfa = enableXfa;
 
     this.streamManager = new ChunkedStreamManager(pdfNetworkStream, {
       msgHandler: args.msgHandler,

src/core/worker.js

@@ -188,14 +188,15 @@ class WorkerMessageHandler {
         await pdfManager.ensureDoc("checkFirstPage");
       }
 
-      const [numPages, fingerprint] = await Promise.all([
+      const [numPages, fingerprint, isPureXfa] = await Promise.all([
         pdfManager.ensureDoc("numPages"),
         pdfManager.ensureDoc("fingerprint"),
+        pdfManager.ensureDoc("isPureXfa"),
       ]);
-      return { numPages, fingerprint };
+      return { numPages, fingerprint, isPureXfa };
     }
 
-    function getPdfManager(data, evaluatorOptions) {
+    function getPdfManager(data, evaluatorOptions, enableXfa) {
       var pdfManagerCapability = createPromiseCapability();
       let newPdfManager;
 
@@ -207,6 +208,7 @@ class WorkerMessageHandler {
             source.data,
             source.password,
             evaluatorOptions,
+            enableXfa,
             docBaseUrl
           );
           pdfManagerCapability.resolve(newPdfManager);
@@ -246,6 +248,7 @@ class WorkerMessageHandler {
               rangeChunkSize: source.rangeChunkSize,
             },
             evaluatorOptions,
+            enableXfa,
             docBaseUrl
           );
           // There may be a chance that `newPdfManager` is not initialized for
@@ -277,6 +280,7 @@ class WorkerMessageHandler {
             pdfFile,
             source.password,
             evaluatorOptions,
+            enableXfa,
             docBaseUrl
           );
           pdfManagerCapability.resolve(newPdfManager);
@@ -399,7 +403,7 @@ class WorkerMessageHandler {
         fontExtraProperties: data.fontExtraProperties,
       };
 
-      getPdfManager(data, evaluatorOptions)
+      getPdfManager(data, evaluatorOptions, data.enableXfa)
         .then(function (newPdfManager) {
           if (terminated) {
             // We were in a process of setting up the manager, but it got
@@ -487,6 +491,16 @@ class WorkerMessageHandler {
       });
     });
 
+    handler.on("GetPageXfa", function wphSetupGetXfa({ pageIndex }) {
+      return pdfManager.getPage(pageIndex).then(function (page) {
+        return page.xfaData;
+      });
+    });
+
+    handler.on("GetIsPureXfa", function wphSetupGetIsPureXfa(data) {
+      return pdfManager.ensureDoc("isPureXfa");
+    });
+
     handler.on("GetOutline", function wphSetupGetOutline(data) {
       return pdfManager.ensureCatalog("documentOutline");
     });

src/core/xfa/factory.js

@@ -13,13 +13,27 @@
  * limitations under the License.
  */
 
+import { $toHTML } from "./xfa_object.js";
 import { Binder } from "./bind.js";
 import { XFAParser } from "./parser.js";
 
 class XFAFactory {
   constructor(data) {
-    this.root = new XFAParser().parse(XFAFactory._createDocument(data));
-    this.form = new Binder(this.root).bind();
+    try {
+      this.root = new XFAParser().parse(XFAFactory._createDocument(data));
+      this.form = new Binder(this.root).bind();
+      this.pages = this.form[$toHTML]();
+    } catch (e) {
+      console.log(e);
+    }
+  }
+
+  getPage(pageIndex) {
+    return this.pages.children[pageIndex];
+  }
+
+  get numberPages() {
+    return this.pages.children.length;
   }
 
   static _createDocument(data) {

src/core/xfa/html_utils.js

@@ -0,0 +1,69 @@
+/* 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.
+ */
+
+const converters = {
+  pt: x => x,
+  cm: x => Math.round((x / 2.54) * 72),
+  mm: x => Math.round((x / (10 * 2.54)) * 72),
+  in: x => Math.round(x * 72),
+};
+
+function measureToString(m) {
+  const conv = converters[m.unit];
+  if (conv) {
+    return `${conv(m.value)}px`;
+  }
+  return `${m.value}${m.unit}`;
+}
+
+function setWidthHeight(node, style) {
+  if (node.w) {
+    style.width = measureToString(node.w);
+  } else {
+    if (node.maxW && node.maxW.value > 0) {
+      style.maxWidth = measureToString(node.maxW);
+    }
+    if (node.minW && node.minW.value > 0) {
+      style.minWidth = measureToString(node.minW);
+    }
+  }
+
+  if (node.h) {
+    style.height = measureToString(node.h);
+  } else {
+    if (node.maxH && node.maxH.value > 0) {
+      style.maxHeight = measureToString(node.maxH);
+    }
+    if (node.minH && node.minH.value > 0) {
+      style.minHeight = measureToString(node.minH);
+    }
+  }
+}
+
+function setPosition(node, style) {
+  style.transform = "";
+  if (node.rotate) {
+    style.transform = `rotate(-${node.rotate}deg) `;
+    style.transformOrigin = "top left";
+  }
+
+  if (node.x !== "" || node.y !== "") {
+    style.position = "absolute";
+    style.left = node.x ? measureToString(node.x) : "0pt";
+    style.top = node.y ? measureToString(node.y) : "0pt";
+  }
+}
+
+export { measureToString, setPosition, setWidthHeight };