XFA - Add <a> element in button when an url is detected (bug 1716758)

- it aims to fix https://bugzilla.mozilla.org/show_bug.cgi?id=1716758;
  - some buttons have a JS action with the pattern `app.launchURL(...)` (or similar) so extract when it's possible the url and generate a <a> element with the href equals to the found url;
  - pdf.js already had some code to handle that so this patch slightly refactor that.

src/core/catalog.js

@@ -17,6 +17,7 @@ import {
   addDefaultProtocolToUrl,
   collectActions,
   MissingDataException,
+  recoverJsURL,
   toRomanNumerals,
   tryConvertUrlEncoding,
 } from "./core_utils.js";
@@ -1399,29 +1400,12 @@ class Catalog {
             js = jsAction;
           }
 
-          if (js) {
-            // Attempt to recover valid URLs from `JS` entries with certain
-            // white-listed formats:
-            //  - window.open('http://example.com')
-            //  - app.launchURL('http://example.com', true)
-            const URL_OPEN_METHODS = ["app.launchURL", "window.open"];
-            const regex = new RegExp(
-              "^\\s*(" +
-                URL_OPEN_METHODS.join("|").split(".").join("\\.") +
-                ")\\((?:'|\")([^'\"]*)(?:'|\")(?:,\\s*(\\w+)\\)|\\))",
-              "i"
-            );
-
-            const jsUrl = regex.exec(stringToPDFString(js));
-            if (jsUrl && jsUrl[2]) {
-              url = jsUrl[2];
-
-              if (jsUrl[3] === "true" && jsUrl[1] === "app.launchURL") {
-                resultObj.newWindow = true;
-              }
+          const jsURL = js && recoverJsURL(stringToPDFString(js));
+          if (jsURL) {
+            url = jsURL.url;
+            resultObj.newWindow = jsURL.newWindow;
             break;
           }
-          }
         /* falls through */
         default:
           if (

src/core/core_utils.js

@@ -467,6 +467,34 @@ function tryConvertUrlEncoding(url) {
   }
 }
 
+function recoverJsURL(str) {
+  // Attempt to recover valid URLs from `JS` entries with certain
+  // white-listed formats:
+  //  - window.open('http://example.com')
+  //  - app.launchURL('http://example.com', true)
+  //  - xfa.host.gotoURL('http://example.com')
+  const URL_OPEN_METHODS = ["app.launchURL", "window.open", "xfa.host.gotoURL"];
+  const regex = new RegExp(
+    "^\\s*(" +
+      URL_OPEN_METHODS.join("|").split(".").join("\\.") +
+      ")\\((?:'|\")([^'\"]*)(?:'|\")(?:,\\s*(\\w+)\\)|\\))",
+    "i"
+  );
+
+  const jsUrl = regex.exec(str);
+  if (jsUrl && jsUrl[2]) {
+    const url = jsUrl[2];
+    let newWindow = false;
+
+    if (jsUrl[3] === "true" && jsUrl[1] === "app.launchURL") {
+      newWindow = true;
+    }
+    return { url, newWindow };
+  }
+
+  return null;
+}
+
 export {
   addDefaultProtocolToUrl,
   collectActions,
@@ -483,6 +511,7 @@ export {
   readInt8,
   readUint16,
   readUint32,
+  recoverJsURL,
   toRomanNumerals,
   tryConvertUrlEncoding,
   validateCSSFont,

src/core/xfa/html_utils.js

@@ -26,10 +26,14 @@ import {
   $toStyle,
   XFAObject,
 } from "./xfa_object.js";
+import {
+  addDefaultProtocolToUrl,
+  tryConvertUrlEncoding,
+} from "../core_utils.js";
+import { createValidAbsoluteUrl, warn } from "../../shared/util.js";
 import { getMeasurement, stripQuotes } from "./utils.js";
 import { selectFont } from "./fonts.js";
 import { TextMeasure } from "./text.js";
-import { warn } from "../../shared/util.js";
 
 function measureToString(m) {
   if (typeof m === "string") {
@@ -633,11 +637,24 @@ function setFontFamily(xfaFont, node, fontFinder, style) {
   }
 }
 
+function fixURL(str) {
+  if (typeof str === "string") {
+    let url = addDefaultProtocolToUrl(str);
+    url = tryConvertUrlEncoding(url);
+    const absoluteUrl = createValidAbsoluteUrl(url);
+    if (absoluteUrl) {
+      return absoluteUrl.href;
+    }
+  }
+  return null;
+}
+
 export {
   computeBbox,
   createWrapper,
   fixDimensions,
   fixTextIndent,
+  fixURL,
   isPrintOnly,
   layoutClass,
   layoutNode,

src/core/xfa/template.js

@@ -76,6 +76,7 @@ import {
   createWrapper,
   fixDimensions,
   fixTextIndent,
+  fixURL,
   isPrintOnly,
   layoutClass,
   layoutNode,
@@ -100,6 +101,7 @@ import {
 } from "./utils.js";
 import { stringToBytes, Util, warn } from "../../shared/util.js";
 import { getMetrics } from "./fonts.js";
+import { recoverJsURL } from "../core_utils.js";
 import { searchNode } from "./som.js";
 
 const TEMPLATE_NS_ID = NamespaceIds.template.id;
@@ -1066,7 +1068,10 @@ class Button extends XFAObject {
 
   [$toHTML](availableSpace) {
     // TODO: highlight.
-    return HTMLResult.success({
+
+    const parent = this[$getParent]();
+    const grandpa = parent[$getParent]();
+    const htmlButton = {
       name: "button",
       attributes: {
         id: this[$uid],
@@ -1074,8 +1079,39 @@ class Button extends XFAObject {
         style: {},
       },
       children: [],
+    };
+
+    for (const event of grandpa.event.children) {
+      // if (true) break;
+      if (event.activity !== "click" || !event.script) {
+        continue;
+      }
+      const jsURL = recoverJsURL(event.script[$content]);
+      if (!jsURL) {
+        continue;
+      }
+      const href = fixURL(jsURL.url);
+      if (!href) {
+        continue;
+      }
+      const target = jsURL.newWindow ? "_blank" : undefined;
+
+      // we've an url so generate a <a>
+      htmlButton.children.push({
+        name: "a",
+        attributes: {
+          id: "link" + this[$uid],
+          href,
+          target,
+          class: ["xfaLink"],
+          style: {},
+        },
+        children: [],
       });
     }
+
+    return HTMLResult.success(htmlButton);
+  }
 }
 
 class Calculate extends XFAObject {
@@ -2897,7 +2933,12 @@ class Field extends XFAObject {
       ui.attributes.style = Object.create(null);
     }
 
+    let aElement = null;
+
     if (this.ui.button) {
+      if (ui.children.length === 1) {
+        [aElement] = ui.children.splice(0, 1);
+      }
       Object.assign(ui.attributes.style, borderStyle);
     } else {
       Object.assign(style, borderStyle);
@@ -2955,6 +2996,10 @@ class Field extends XFAObject {
       }
     }
 
+    if (aElement) {
+      ui.children.push(aElement);
+    }
+
     if (!caption) {
       if (ui.attributes.class) {
         // Even if no caption this class will help to center the ui.

src/core/xfa/xhtml.js

@@ -30,12 +30,12 @@ import {
 } from "./xfa_object.js";
 import { $buildXFAObject, NamespaceIds } from "./namespaces.js";
 import {
-  addDefaultProtocolToUrl,
-  tryConvertUrlEncoding,
-} from "../core_utils.js";
-import { fixTextIndent, measureToString, setFontFamily } from "./html_utils.js";
+  fixTextIndent,
+  fixURL,
+  measureToString,
+  setFontFamily,
+} from "./html_utils.js";
 import { getMeasurement, HTMLResult, stripQuotes } from "./utils.js";
-import { createValidAbsoluteUrl } from "../../shared/util.js";
 
 const XHTML_NS_ID = NamespaceIds.xhtml.id;
 
@@ -326,16 +326,7 @@ class XhtmlObject extends XmlObject {
 class A extends XhtmlObject {
   constructor(attributes) {
     super(attributes, "a");
-    let href = "";
-    if (typeof attributes.href === "string") {
-      let url = addDefaultProtocolToUrl(attributes.href);
-      url = tryConvertUrlEncoding(url);
-      const absoluteUrl = createValidAbsoluteUrl(url);
-      if (absoluteUrl) {
-        href = absoluteUrl.href;
-      }
-    }
-    this.href = href;
+    this.href = fixURL(attributes.href) || "";
   }
 }
 

test/unit/annotation_spec.js

@@ -1108,7 +1108,7 @@ describe("annotation", function () {
           jsEntry: "window.open('http://www.example.com/test.pdf')",
           expectedUrl: new URL("http://www.example.com/test.pdf").href,
           expectedUnsafeUrl: "http://www.example.com/test.pdf",
-          expectedNewWindow: undefined,
+          expectedNewWindow: false,
         });
 
         // Check that we accept a white-listed {Stream} 'JS' entry.

test/unit/xfa_tohtml_spec.js

@@ -17,18 +17,20 @@ import { isNodeJS } from "../../src/shared/is_node.js";
 import { XFAFactory } from "../../src/core/xfa/factory.js";
 
 describe("XFAFactory", function () {
-  function searchHtmlNode(root, name, value, byAttributes = false) {
+  function searchHtmlNode(root, name, value, byAttributes = false, nth = [0]) {
     if (
       (!byAttributes && root[name] === value) ||
       (byAttributes && root.attributes && root.attributes[name] === value)
     ) {
+      if (nth[0]-- === 0) {
         return root;
       }
+    }
     if (!root.children) {
       return null;
     }
     for (const child of root.children) {
-      const node = searchHtmlNode(child, name, value, byAttributes);
+      const node = searchHtmlNode(child, name, value, byAttributes, nth);
       if (node) {
         return node;
       }
@@ -588,4 +590,60 @@ describe("XFAFactory", function () {
     expect(a.value).toEqual("qwerty/");
     expect(a.attributes.href).toEqual("");
   });
+
+  it("should replace button with an URL by a link", function () {
+    const xml = `
+<?xml version="1.0"?>
+<xdp:xdp xmlns:xdp="http://ns.adobe.com/xdp/">
+  <template xmlns="http://www.xfa.org/schema/xfa-template/3.3">
+    <subform name="root" mergeMode="matchTemplate">
+      <pageSet>
+        <pageArea>
+          <contentArea x="123pt" w="456pt" h="789pt"/>
+          <medium stock="default" short="456pt" long="789pt"/>
+        </pageArea>
+      </pageSet>
+      <subform name="first">
+        <field y="1pt" w="11pt" h="22pt" x="2pt">
+          <ui>
+            <button/>
+          </ui>
+          <event activity="click" name="event__click">
+            <script contentType="application/x-javascript">
+              app.launchURL("https://github.com/mozilla/pdf.js", true);
+            </script>
+          </event>
+        </field>
+        <field y="1pt" w="11pt" h="22pt" x="2pt">
+          <ui>
+            <button/>
+          </ui>
+          <event activity="click" name="event__click">
+            <script contentType="application/x-javascript">
+              xfa.host.gotoURL("https://github.com/allizom/pdf.js");
+            </script>
+          </event>
+        </field>
+      </subform>
+    </subform>
+  </template>
+  <xfa:datasets xmlns:xfa="http://www.xfa.org/schema/xfa-data/1.0/">
+    <xfa:data>
+    </xfa:data>
+  </xfa:datasets>
+</xdp:xdp>
+    `;
+    const factory = new XFAFactory({ "xdp:xdp": xml });
+
+    expect(factory.numberPages).toEqual(1);
+
+    const pages = factory.getPages();
+    let a = searchHtmlNode(pages, "name", "a");
+    expect(a.attributes.href).toEqual("https://github.com/mozilla/pdf.js");
+    expect(a.attributes.target).toEqual("_blank");
+
+    a = searchHtmlNode(pages, "name", "a", false, [1]);
+    expect(a.attributes.href).toEqual("https://github.com/allizom/pdf.js");
+    expect(a.attributes.target).toBe(undefined);
+  });
 });

web/xfa_layer_builder.css

@@ -220,6 +220,11 @@
   text-align: center;
 }
 
+.xfaLink {
+  width: 100%;
+  height: 100%;
+}
+
 .xfaCheckbox,
 .xfaRadio {
   width: 100%;