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Attempt to cache fonts that are direct objects (i.e. Dicts), as opposed to Refs, to prevent re-rendering after cleanup from breaking (issue 7403 and issue 7402)

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Fonts that are not referenced by `Ref`s are very uncommon in practice, but it can unfortunately happen. In this case, we're currently not caching them in the usual way, i.e. by `Ref`, which leads to failures when a page is rendered after `cleanup` has run.
The simplest solution would have been to remove the `font.translated` workaround, but since this would have meant loading these kind of fonts over and over, the patch attempts to be a bit clever about this situation.

Note that if we instead loaded fonts per *page*, instead of per document, this issue wouldn't have existed.
This commit is contained in:
Jonas Jenwald 2016-06-11 14:28:59 +02:00
parent 4fe891c5e7
commit 390c02a3e9
1 changed files with 17 additions and 4 deletions
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21
src/core/evaluator.js
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@ -706,17 +706,30 @@ var PartialEvaluator = (function PartialEvaluatorClosure() {
// Workaround for bad PDF generators that reference fonts incorrectly,
// where `fontRef` is a `Dict` rather than a `Ref` (fixes bug946506.pdf).
// In this case we cannot cache the font, since it's not possible to use
// a `Dict` as a key in `this.fontCache` (since it's a `RefSetCache`).
// Furthermore, if the `fontID` is undefined, we instead reference
// the font by `fontName` in `font.loadedName` below.
// In this case we should not put the font into `this.fontCache` (which is
// a `RefSetCache`), since it's not meaningful to use a `Dict` as a key.
//
// However, if we don't cache the font it's not possible to remove it
// when `cleanup` is triggered from the API, which causes issues on
// subsequent rendering operations (see issue7403.pdf).
// A simple workaround would be to just not hold `font.translated`
// references in this case, but this would force us to unnecessarily load
// the same fonts over and over.
//
// Instead, we cheat a bit by attempting to use a modified `fontID` as a
// key in `this.fontCache`, to allow the font to be cached.
// NOTE: This works because `RefSetCache` calls `toString()` on provided
// keys. Also, since `fontRef` is used when getting cached fonts,
// we'll not accidentally match fonts cached with the `fontID`.
if (fontRefIsRef) {
this.fontCache.put(fontRef, fontCapability.promise);
} else {
if (!fontID) {
fontID = (this.uniquePrefix || 'F_') + (++this.idCounters.obj);
}
this.fontCache.put('id_' + fontID, fontCapability.promise);
}
assert(fontID, 'The "fontID" must be defined.');
// Keep track of each font we translated so the caller can
// load them asynchronously before calling display on a page.