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Always check all Kids nodes, in Catalog.getPageDict, to avoid getting stuck in an empty node further down in the Pages tree (issue 8088)

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As discussed on IRC, we need to check all nodes at the *bottom* of the tree to ensure that we find the correct `Page` dict.
Furthermore, this patch also gets rid of the caching present in a previous version, since it's not clear if that really helps.

Note that this patch purposely adds an `eq` test, using a reduced test-case, so that we can be sure that the algorithm actually finds the correct `Page` dict for each `pageIndex`.

Fixes 8088.
This commit is contained in:
Jonas Jenwald 2017-02-23 13:28:50 +01:00
parent cada411af4
commit 1ce295541c
4 changed files with 182 additions and 25 deletions
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34
src/core/obj.js
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@ -452,7 +452,6 @@ var Catalog = (function CatalogClosure() {
var nodesToVisit = [this.catDict.getRaw('Pages')];
var currentPageIndex = 0;
var xref = this.xref;
var checkAllKids = false;
function next() {
while (nodesToVisit.length) {
@ -476,16 +475,10 @@ var Catalog = (function CatalogClosure() {
}
// Must be a child page dictionary.
assert(
isDict(currentNode),
'page dictionary kid reference points to wrong type of object'
);
assert(isDict(currentNode),
'page dictionary kid reference points to wrong type of object');
var count = currentNode.get('Count');
// If the current node doesn't have any children, avoid getting stuck
// in an empty node further down in the tree (see issue5644.pdf).
if (count === 0) {
checkAllKids = true;
}
// Skip nodes where the page can't be.
if (currentPageIndex + count <= pageIndex) {
currentPageIndex += count;
@ -494,21 +487,12 @@ var Catalog = (function CatalogClosure() {
var kids = currentNode.get('Kids');
assert(isArray(kids), 'page dictionary kids object is not an array');
if (!checkAllKids && count === kids.length) {
// Nodes that don't have the page have been skipped and this is the
// bottom of the tree which means the page requested must be a
// descendant of this pages node. Ideally we would just resolve the
// promise with the page ref here, but there is the case where more
// pages nodes could link to single a page (see issue 3666 pdf). To
// handle this push it back on the queue so if it is a pages node it
// will be descended into.
nodesToVisit = [kids[pageIndex - currentPageIndex]];
currentPageIndex = pageIndex;
continue;
} else {
for (var last = kids.length - 1; last >= 0; last--) {
nodesToVisit.push(kids[last]);
}
// Always check all `Kids` nodes, to avoid getting stuck in an empty
// node further down in the tree (see issue5644.pdf, issue8088.pdf),
// and to ensure that we actually find the correct `Page` dict.
for (var last = kids.length - 1; last >= 0; last--) {
nodesToVisit.push(kids[last]);
}
}
capability.reject('Page index ' + pageIndex + ' not found.');