| /* |
| * Copyright 2026 Google LLC |
| * |
| * Use of this source code is governed by a BSD-style license that can be |
| * found in the LICENSE file. |
| */ |
| |
| #ifndef skgpu_GradientBitmap_DEFINED |
| #define skgpu_GradientBitmap_DEFINED |
| |
| #include "include/core/SkBitmap.h" |
| #include "src/core/SkColorData.h" |
| |
| namespace skgpu { |
| |
| // Gradient stop offsets / interval thresholds live in [0, 1] but lose too much |
| // precision when rounded to half floats directly. Encoding them as the |
| // (mantissa, exponent) pair returned by frexp preserves the value across an F16 |
| // texture; the shader recovers it with ldexp(mantissa, exponent). |
| // |
| // On success, writes the mantissa and exponent and returns true. Returns false |
| // if the exponent does not round-trip through F16, in which case the caller must |
| // not use the texture encoding. |
| bool EncodeGradientStopToHalf(float offset, float* mantissa, float* exponent); |
| |
| // Builds the F16 texture both Ganesh and Graphite upload for many-stop |
| // gradients. The bitmap is `numStops` wide and 2 tall: row 0 holds the premul |
| // colors and row 1 holds each stop offset encoded as (mantissa, exponent, 0, 1) |
| // via EncodeGradientStopToHalf. The shader binary-searches the offset row and |
| // mixes the two adjacent colors. If `offsets` is null the stops are assumed to |
| // be evenly spaced. Returns an empty bitmap if allocation or offset encoding |
| // fails. |
| SkBitmap CreateGradientColorAndOffsetBitmap(int numStops, |
| const SkPMColor4f* colors, |
| const float* offsets); |
| |
| } // namespace skgpu |
| |
| #endif // skgpu_GradientBitmap_DEFINED |
