Notify when SkFontMetrics bounds are bogus.
OpenType and many other font formats have the concept of pre-computed
metrics for the union of all glyph bounding boxes. This allows for fast
though course quick rejecting of bounds, since the glyphs themselves may
potentially be quite a bit larger than the EM. With the introduction of
variable fonts OpenType does not vary these bounds, so the bounds are
only valid for the default non-varied font.
As a result the fTop, fBottom, fXMax, and fXMin reported in
SkFontMetrics may be bogus. Since simply always setting them to empty
zeros may be disruptive, provide a way forward for new users to check if
the bounds are valid.
This is a continuation which implements this in the DirectWrite and
CoreText ports.
Change-Id: I50812e78f31ee06fedf8ab1f005837d673a8f2ad
Reviewed-on: https://skia-review.googlesource.com/c/skia/+/311976
Reviewed-by: Herb Derby <herb@google.com>
Reviewed-by: Mike Klein <mtklein@google.com>
Commit-Queue: Ben Wagner <bungeman@google.com>
3 files changed