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Cache the "raw" standard font data in the worker-thread (PR 12726 follow-up)

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*This implementation is basically a copy of the pre-existing `builtInCMapCache` implementation.*

For some, badly generated, PDF documents it's possible that we'll end up having to fetch the *same* standard font data over and over (which is obviously inefficient).
While not common, it's certainly possible that a PDF document uses *custom* font names where the actual font then references one of the standard fonts; see e.g. issue 11399 for one such example.

Note that I did suggest adding worker-thread caching of standard font data in PR 12726, however it wasn't deemed necessary at the time. Now that we have a real-world example that benefit from caching, I think that we should simply implement this now.
This commit is contained in:
Jonas Jenwald 2021-06-08 13:58:52 +02:00
parent 6d88d8cdaa
commit a01c599247
4 changed files with 46 additions and 17 deletions
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52
src/core/evaluator.js
View file

@ -207,6 +207,7 @@ class PartialEvaluator {
idFactory,
fontCache,
builtInCMapCache,
standardFontDataCache,
globalImageCache,
options = null,
}) {
@ -216,6 +217,7 @@ class PartialEvaluator {
this.idFactory = idFactory;
this.fontCache = fontCache;
this.builtInCMapCache = builtInCMapCache;
this.standardFontDataCache = standardFontDataCache;
this.globalImageCache = globalImageCache;
this.options = options || DefaultPartialEvaluatorOptions;
this.parsingType3Font = false;
@ -390,8 +392,13 @@ class PartialEvaluator {
}
async fetchStandardFontData(name) {
const cachedData = this.standardFontDataCache.get(name);
if (cachedData) {
return new Stream(cachedData);
}
// The symbol fonts are not consistent across platforms, always load the
// font data for them.
// standard font data for them.
if (
this.options.useSystemFonts &&
name !== "Symbol" &&
@ -399,31 +406,42 @@ class PartialEvaluator {
) {
return null;
}
const standardFontNameToFileName = getFontNameToFileMap();
const filename = standardFontNameToFileName[name];
const standardFontNameToFileName = getFontNameToFileMap(),
filename = standardFontNameToFileName[name];
let data;
if (this.options.standardFontDataUrl !== null) {
const url = `${this.options.standardFontDataUrl}${filename}`;
const response = await fetch(url);
if (!response.ok) {
warn(
`fetchStandardFontData failed to fetch file "${url}" with "${response.statusText}".`
`fetchStandardFontData: failed to fetch file "${url}" with "${response.statusText}".`
);
} else {
data = await response.arrayBuffer();
}
} else {
// Get the data on the main-thread instead.
try {
data = await this.handler.sendWithPromise("FetchStandardFontData", {
filename,
});
} catch (e) {
warn(
`fetchStandardFontData: failed to fetch file "${filename}" with "${e}".`
);
return null;
}
return new Stream(await response.arrayBuffer());
}
// Get the data on the main thread instead.
try {
const data = await this.handler.sendWithPromise("FetchStandardFontData", {
filename,
});
return new Stream(data);
} catch (e) {
warn(
`fetchStandardFontData failed to fetch file "${filename}" with "${e}".`
);
if (!data) {
return null;
}
return null;
// Cache the "raw" standard font data, to avoid fetching it repeateadly
// (see e.g. issue 11399).
this.standardFontDataCache.set(name, data);
return new Stream(data);
}
async buildFormXObject(