Precision issues with high dpis and drawquad #6
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On some platforms (eg, GCC x86_64), long means 32 bit. This is a problem in pdfpos00, because calculations such as `uh * 1000 * 72` (in pdfunit) are likely to overlow, causing important bugs. This is especially the case when using high dpi values, such as 720000.
The magic formula was wrong, so the circles looked slightly off.
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Hi, rather than replacing long by doubles, I changed it to long long. |
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Hello,
This pull request includes 2 commits very useful when using high DPIs (7200 is enough to trigger bugs).
The first makes drawquad more aligned with what a true circle quadrant should like using Bézier curves. Moreover, when using high DPIs, the calculations would overflow (especially the sign test). To fix overflow and precision issues, replacing long's by double's is enough.
The second commit fixes pdfpos and pdfunit. For similar reasons, these 2 functions concentrated much of the overflows of neatpdf. Replacing 32-bit integers by 64-bit might have been enough, but the calculations used to simulate decimal numbers are the source of many rounding errors, which are problematic when precision is needed (eg, when using grap). Replacing the long's by double's is, here too, sufficient.
Thanks for the work you put in your very fine pieces of code,
Regards,
Elie Le Vaillant