Details
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Improvement
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Status: Closed
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Minor
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Resolution: Fixed
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2.0.27, 3.0.0 PDFBox
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None
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None
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Patch
Description
I ran the PDFBox tests with a profiler and saw that LZWFilter used quite a bunch of time, so I thought I might look at the code. I just looked at it totally out of context and tried to understand what is done there and what could be changed without altering results.
- made the private mehtods static
- changed the variable/method parameter 'earlyChange' from integer to boolean because I thought tha would be more readable
- some minor tweaks
- it looks like codeTable is initialized quite often and everytime, 256 length 1 byte arrays are created, so I pre-allocate those byte arrays so that they can be shared by all code tables. tilman I assumed the contents of the codeTable entries will not be changed, and my analysis of the code seems to prove that (also the passing unit tests). Just please have a look at this so I don't break anything.
- it took me some time to fully understand what findPatternCode() does and why it checks the codeTable in reverse order. I more or less recreated that method from scratch and I think it should now always be faster: for patterns of length 1 no iteration is done, and for longer patterns iteration stops once the correct entry is found. As this is the most notable change, please take a closer look. Unit tests pass.