In b5b94a4af3, i.e. PR #4259, we stopped using cidmaps.js. Despite that, it's still included when PDF.js is built. At almost 0.5 MB (and approx. 7000 lines), this is currently the single largest file in the codebase.
Including such a large file in the builds, when it is not actually used, seems extremely wasteful; hence this patch.
I have a large PDF where this function is called 1.6 million times
during loading. Minimizing the string concatenations reduces the
cumulative allocations done by Firefox within this function from 113 MB
to 48 MB.
In the referenced issue, there is a PDF which uses a fill pattern which does not
have a matrix defined. This causes singularValueDecompose2dScale to fail with
undefined property error when accessing elements of that matrix.
This fix will only use the matrix when it is defined. The output for the PDF in
question now looks identical to chrome and preview with respect to the gradient
fill pattern.
QueueOptimizer is really hard to read. Enough so that it's blocking my
efforts to streamline the representation used for operator lists.
This patch improves its readability in the following ways.
- More descriptive variable names make the sequence checking much clearer,
as do additional comments.
- The addState() functions now return the index of the first op past the
sequence, instead of setting context.currentOperation to the last op of
the sequence.
- The loop in optimize() is clearer.
- The array modification in the fourth addState() function is much clearer
-- we're just removing trios of ops.
- All four |addState| functions are now more consistent with each other.
I used some debug printfs to find documents where these optimizations are
used and then checked that the number of optimized ops was the same before
and after my changes.
DecodeStream currently initializes its |buffer| field to |null|, which
is reasonable, because lots of DecodeStreams never need to instantiate a
buffer. But this requires various special cases in the code.
This patch change it so DecodeStreamClosure has a single empty
Uint8Array which gets shared between all buffers upon initialization.
This avoids the special cases.
DecodeStream.prototype.ensureBuffer() is really hot, and this removes a
test from the fast path. For one 226 page scanned document this sped up
rendering by about 2%.
