Introduce support for relative position adjustments [1]:
- plumb dx, dy attributes
- extend ScopedPosResolver to also handle the new attributes
- introduce ShapeBuffer to store both utf8 text and position
adjustments for shaping (replaces prev 'filtered' array).
- position adjustments are cumulative (relative adjustments affect
all following characters)
- utf8 encoding is variable length; for simplicity, ensure that the
pos adjustment array and the utf8 array are always the same size by
repeating the pos adjustment times number of utf8 bytes
- introduce a temporary buffer for retrieving utf8 cluster information
from SkShaper
- post-shaping, use the utf8 cluster info to map back to character
indices and apply the associated position adjutment
[1] https://www.w3.org/TR/SVG11/text.html#TSpanElementDXAttribute
Bug: skia:10840
Change-Id: Ia9f227f91723400711ff2b5d260976290da1e2e5
Reviewed-on: https://skia-review.googlesource.com/c/skia/+/346636
Commit-Queue: Florin Malita <fmalita@google.com>
Reviewed-by: Tyler Denniston <tdenniston@google.com>
735ac97eb4