Merge pull request #5351 from timvandermeij/destinations

Require destinations when they are needed and do not fetch all of them in advance

src/core/obj.js

@@ -457,6 +457,38 @@ var Catalog = (function CatalogClosure() {
       }
       return shadow(this, 'destinations', dests);
     },
+    getDestination: function Catalog_getDestination(destinationId) {
+      function fetchDestination(dest) {
+        return isDict(dest) ? dest.get('D') : dest;
+      }
+
+      var xref = this.xref;
+      var dest, nameTreeRef, nameDictionaryRef;
+      var obj = this.catDict.get('Names');
+      if (obj && obj.has('Dests')) {
+        nameTreeRef = obj.getRaw('Dests');
+      } else if (this.catDict.has('Dests')) {
+        nameDictionaryRef = this.catDict.get('Dests');
+      }
+
+      if (nameDictionaryRef) {
+        // reading simple destination dictionary
+        obj = nameDictionaryRef;
+        obj.forEach(function catalogForEach(key, value) {
+          if (!value) {
+            return;
+          }
+          if (key === destinationId) {
+            dest = fetchDestination(value);
+          }
+        });
+      }
+      if (nameTreeRef) {
+        var nameTree = new NameTree(nameTreeRef, xref);
+        dest = fetchDestination(nameTree.get(destinationId));
+      }
+      return dest;
+    },
     get attachments() {
       var xref = this.xref;
       var attachments = null, nameTreeRef;
@@ -1358,6 +1390,76 @@ var NameTree = (function NameTreeClosure() {
         }
       }
       return dict;
+    },
+
+    get: function NameTree_get(destinationId) {
+      if (!this.root) {
+        return null;
+      }
+
+      var xref = this.xref;
+      var kidsOrNames = xref.fetchIfRef(this.root);
+      var loopCount = 0;
+      var MAX_NAMES_LEVELS = 10;
+      var l, r, m;
+
+      // Perform a binary search to quickly find the entry that
+      // contains the named destination we are looking for.
+      while (kidsOrNames.has('Kids')) {
+        loopCount++;
+        if (loopCount > MAX_NAMES_LEVELS) {
+          warn('Search depth limit for named destionations has been reached.');
+          return null;
+        }
+        
+        var kids = kidsOrNames.get('Kids');
+        if (!isArray(kids)) {
+          return null;
+        }
+
+        l = 0;
+        r = kids.length - 1;
+        while (l <= r) {
+          m = (l + r) >> 1;
+          var kid = xref.fetchIfRef(kids[m]);
+          var limits = kid.get('Limits');
+
+          if (destinationId < limits[0]) {
+            r = m - 1;
+          } else if (destinationId > limits[1]) {
+            l = m + 1;
+          } else {
+            kidsOrNames = xref.fetchIfRef(kids[m]);
+            break;
+          }
+        }
+        if (l > r) {
+          return null;
+        }
+      }
+
+      // If we get here, then we have found the right entry. Now
+      // go through the named destinations in the Named dictionary
+      // until we find the exact destination we're looking for.
+      var names = kidsOrNames.get('Names');
+      if (isArray(names)) {
+        // Perform a binary search to reduce the lookup time.
+        l = 0;
+        r = names.length - 2;
+        while (l <= r) {
+          // Check only even indices (0, 2, 4, ...) because the
+          // odd indices contain the actual D array.
+          m = (l + r) & ~1;
+          if (destinationId < names[m]) {
+            r = m - 2;
+          } else if (destinationId > names[m]) {
+            l = m + 2;
+          } else {
+            return xref.fetchIfRef(names[m + 1]);
+          }
+        }
+      }
+      return null;
     }
   };
   return NameTree;

src/core/worker.js

@@ -325,6 +325,12 @@ var WorkerMessageHandler = PDFJS.WorkerMessageHandler = {
       }
     );
 
+    handler.on('GetDestination',
+      function wphSetupGetDestination(data) {
+        return pdfManager.ensureCatalog('getDestination', [ data.id ]);
+      }
+    );
+
     handler.on('GetAttachments',
       function wphSetupGetAttachments(data) {
         return pdfManager.ensureCatalog('attachments');

src/display/api.js

@@ -293,10 +293,20 @@ var PDFDocumentProxy = (function PDFDocumentProxyClosure() {
     /**
      * @return {Promise} A promise that is resolved with a lookup table for
      * mapping named destinations to reference numbers.
+     *
+     * This can be slow for large documents: use getDestination instead
      */
     getDestinations: function PDFDocumentProxy_getDestinations() {
       return this.transport.getDestinations();
     },
+    /**
+     * @param {string} id The named destination to get.
+     * @return {Promise} A promise that is resolved with all information
+     * of the given named destination.
+     */
+    getDestination: function PDFDocumentProxy_getDestination(id) {
+      return this.transport.getDestination(id);
+    },
     /**
      * @return {Promise} A promise that is resolved with a lookup table for
      * mapping named attachments to their content.
@@ -1128,6 +1138,10 @@ var WorkerTransport = (function WorkerTransportClosure() {
       return this.messageHandler.sendWithPromise('GetDestinations', null);
     },
 
+    getDestination: function WorkerTransport_getDestination(id) {
+      return this.messageHandler.sendWithPromise('GetDestination', { id: id } );
+    },
+
     getAttachments: function WorkerTransport_getAttachments() {
       return this.messageHandler.sendWithPromise('GetAttachments', null);
     },

test/unit/api_spec.js

@@ -123,6 +123,13 @@ describe('api', function() {
                                           0, 841.89, null] });
       });
     });
+    it('gets a destination', function() {
+      var promise = doc.getDestination('chapter1');
+      waitsForPromiseResolved(promise, function(data) {
+        expect(data).toEqual([{ gen: 0, num: 17 }, { name: 'XYZ' },
+                              0, 841.89, null]);
+      });
+    });
     it('gets attachments', function() {
       var promise = doc.getAttachments();
       waitsForPromiseResolved(promise, function (data) {

web/viewer.js

@@ -675,15 +675,19 @@ var PDFViewerApplication = {
       }
     };
 
-    this.destinationsPromise.then(function() {
-      if (typeof dest === 'string') {
-        destString = dest;
-        dest = self.destinations[dest];
-      }
-      if (!(dest instanceof Array)) {
+    var destinationPromise;
+    if (typeof dest === 'string') {
+      destString = dest;
+      destinationPromise = this.pdfDocument.getDestination(dest);
+    } else {
+      destinationPromise = Promise.resolve(dest);
+    }
+    destinationPromise.then(function(destination) {
+      dest = destination;
+      if (!(destination instanceof Array)) {
         return; // invalid destination
       }
-      goToDestination(dest[0]);
+      goToDestination(destination[0]);
     });
   },
 
@@ -984,15 +988,8 @@ var PDFViewerApplication = {
       }
     });
 
-    var destinationsPromise =
-      this.destinationsPromise = pdfDocument.getDestinations();
-    destinationsPromise.then(function(destinations) {
-      self.destinations = destinations;
-    });
-
-    // outline depends on destinations and pagesRefMap
-    var promises = [pagesPromise, destinationsPromise,
-                    this.animationStartedPromise];
+    // outline depends on pagesRefMap
+    var promises = [pagesPromise, this.animationStartedPromise];
     Promise.all(promises).then(function() {
       pdfDocument.getOutline().then(function(outline) {
         var outlineView = document.getElementById('outlineView');