Implement an explicit binary search-based analytic gradient colorizer
Provides a reasonably flexible fragment processor that defines another
colorizer implementation for gradients. It can support up to 8
interpolation intervals (which is 16 colors if every stop is a hard stop
or 9 colors if every stop is a smooth transition). It
supports mixtures of hard and smooth stops. It is conditionally compiled
into versions specific to the interval count (so it can produce up to
8 shader variants).
The GrGradientShader controller does not remove the single and dual
interval colorizers, which are useful specializations of this explicit
binary search colorizer. Similarly, since it can only handle up to 8
intervals, the texture colorizer is still used as a fallback.
Currently it does not employ capabilities detection to determine if the
hardware can support the number of required uniforms, which can become
substantial for the larger gradient configurations.
Bug: chromium:796479, chromium:729727, chromium:696603, chromium:543625, chromium:414254
Change-Id: Ia1f735a5019766ae4796cc22964b2913db34b95b
Reviewed-on: https://skia-review.googlesource.com/155080
Commit-Queue: Michael Ludwig <michaelludwig@google.com>
Reviewed-by: Brian Osman <brianosman@google.com>
9 files changed