These were removed in PR 9170, since they were unused in the browsers that we'll support in PDF.js version `2.0`.
However looking at the output of Travis, where a subset of the unit-tests are run using Node.js, there's warnings about `btoa` being undefined. This doesn't appear to cause any errors, which probably explains why we didn't notice this before (despite PR 9201).
Implement a serialization "generator" for `DOMElement` in domutils.js
that yields the serialization of the SVG element. This method is used by
a newly added `ReadableSVGStream` class, which can be used like any
other readable stream in Node.js.
This reduces the memory requirements. Now, it is not needed to require
the serialization to fully fit in memory.
Note: The implementation of the serializer is a state machine in ES5
since the rest of the file is also in ES5. Its functionality is
equivalent to:
```
function* serializeSVGElement(elem) {
yield '<' + elem.nodeName;
if (elem.nodeName === 'svg:svg') {
yield ' xmlns:xlink="http://www.w3.org/1999/xlink"' +
' xmlns:svg="http://www.w3.org/2000/svg"';
}
for (let i in elem.attributes) {
yield ' ' + i + '="' + xmlEncode(elem.attributes[i]) + '"';
}
yield '>';
if (elem.nodeName === 'svg:tspan' || elem.nodeName === 'svg:style') {
yield xmlEncode(elem.textContent);
} else {
for (let childNode of elem.childNodes) {
yield* serializeSVGElement(childNode);
}
}
yield '</' + elem.nodeName + '>';
}
```
- Mark the test as async, and don't swallow exceptions.
- Fix the DOMElement polyfill to behave closer to the actual getAttributeNS
method, which excludes the namespace prefix.
Do not directly export to global. Instead, export all stubs in domstubs.js and
add a method setStubs to assign all exported stubs to a namespace. Then replace
the import domstubs with an explicit call to this setStubs method. Also added
unsetStubs for undoing the changes. This is done to allow unit testing of the
SVG backend without namespace pollution.
Test case:
Using the PDF file from https://github.com/mozilla/pdf.js/issues/8534
node --max_old_space_size=200 examples/node/pdf2svg.js /tmp/FatalProcessOutOfMemory.pdf
Before this patch:
Node.js crashes due to OOM after processing 10 pages.
After this patch:
Node.js crashes due to OOM after processing 19 pages.
