Fixes issue #340

[msueyoshi-m]

The vhea table can now be read properly. As a result, the vmtx table information can also be taken correctly and the advanceHeight can be obtained. I have confirmed that there are no problems with Japanese fonts.

[blikblum]

Can you provide a test that fails before the PR and passes after?

[Harbs]

The change doesn't even look correct. Version should be two uint16 values and not a single int32.

https://learn.microsoft.com/en-us/typography/opentype/spec/vhea

[Harbs]

The other change does seem correct. advanceHeightMax is a UFWORD which is a uint16.

https://learn.microsoft.com/en-us/typography/opentype/spec/otff

[Harbs]

IMO, the first change should be:

  version:                r.fixed32,  // Version number of the Vertical Header Table

[msueyoshi-m]

Since hhea and vhea have the same structure, I believed it would be clearer to present them consistently in the program, even though they are described differently in the specification.
The maxp table version is specified as Version16Dot16 in the Document, but the structure is defined as int32 in the program. Therefore, I determined that defining Version16Dot16 as int32 would be better.

For testing, use test/data/NotoSansCJK/NotoSansCJKkr-Regular.otf. Any font that includes a vhea table will work. Before the PR, vhea.numberOfMetrics is set to 0, which causes the Glyph object's advanceHeight to be 0 for all glyphs.

[Harbs]

I'm pretty sure you will get the wrong version.

The version should resolve to a string: major.minor. Defining it as an int32 should cause it to resolve to a non-sensical number.

[Harbs]

That doesn't change the parsing of the rest of the table, but the version should be read correctly.

[msueyoshi-m]

Thank you for the feedback. I’ve made the requested changes.

[Harbs]

Cool.

To be clear: I'm just some random guy who happens to like this project saying things as I understand them. 😄 I have no control over accepting the PR.

If you have a way of adding tests for this fix, it'll probably make it easier for those who can accept it to merge the PR.

[msueyoshi-m]

My child has caught a cold, so I am unable to respond immediately. However, I believe I will be able to add the test code to the test folder within a few days.

[msueyoshi-m]

@blikblum
Added a test in vhea.js to verify the bug fix for issue #340. The test fails before the PR and passes after the PR.

[blikblum]

LGTM

@devongovett can you look at this?