Add read support for fvar table #183
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This adds the `fvar` table. Support for the variable size `InstanceRecord` is handled similarly to `ValueRecord` using `ComputedArray` and a custom implementation `FontReadWithArgs` along with custom traversal stuff. Contains tests for reading axes and instances as well as computing normalized coordinates.
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| //! An fvar InstanceRecord | |||
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| use super::InstanceRecord; | |||
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any reason not to define the type in this file?
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Oh, I think I had done everything in fvar.rs before I noticed the pattern you used with ValueRecord and just didn't copy the base type over. I'll update it.
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Turns out the fields on that type weren't pub either, so I'm glad you called this out :)
| axis_count: u16, | ||
| /// The size in bytes of each VariationAxisRecord — set to 20 (0x0014) for this version. | ||
| #[compile(20)] | ||
| axis_size: u16, |
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in theory, I imagine we want to be using this value to determine the stride length during parsing, or else we risk incorrect results with some future spec bump. There's a similar issue in STAT, where it is also not resolved; I'm okay with leaving it as-is for now, but we should definitely open an issue.
I have a half-written patch for STAT somewhere, so hopefully the pattern I use there will also be appropriate here.
aside: the idea of a record that may change size in the future is nasty, I feel like this should really just be a table with a version number. :/
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I agree, and I think the spec is completely broken here. I honestly don't see how they can change either of the sizes in this table without breaking just about every implementation in the wild.
I'll keep this as-is and let you carry over whatever pattern you're considering for STAT when compilation comes up for this table.
Also make the fields public
This adds the
fvartable. Support for the variable sizeInstanceRecordis handled similarly toValueRecordusingComputedArrayand a custom implementationFontReadWithArgsalong with traversal stuff.Also adds otexplorer support for fvar and avar.
Contains tests for reading axes and instances as well as computing normalized coordinates.