[svg] Text rotate support
Implement support for text 'rotate' attribute:
https://www.w3.org/TR/SVG11/text.html#TSpanElementRotateAttribute.
Unlike other character-positioning attributes (x/y/dx/dy), rotate
- is not cumulative
- only applies to its respective node scope (does not affect other
fragments in the current chunk)
- has different padding semantics: if there are fewer rotate
values than characters, the remaining characters use the last
specified value from the closest ancestor
To the last point, we now have to discriminate three states:
- unspecified (default -> 0)
- explicit value for the given character index
- implicit value (last value in the closest ancestor)
Local implicit values override implicit ancestor values -- but not
explicit ancestor values.
High level changes:
- plumb 'rotate' attribute
- expand per-character position info (ShapeBuffer) to include rotation
- expand per-glyph position info (RunRec) to include rotation
- expand PosAttrs to include rotation and add specific inheritance
rules (see above)
- pass computed rotation values to RSX blob buffers
Bug: skia:10840
Change-Id: Ia19ec5e8bb6fea06d49a9bd72ace575c2ffd100e
Reviewed-on: https://skia-review.googlesource.com/c/skia/+/348877
Commit-Queue: Florin Malita <fmalita@google.com>
Reviewed-by: Tyler Denniston <tdenniston@google.com>
5 files changed