| /* |
| * Copyright 2024 Google LLC |
| * |
| * Use of this source code is governed by a BSD-style license that can be |
| * found in the LICENSE file. |
| */ |
| |
| #ifndef SkMatrixConvolutionImageFilter_DEFINED |
| #define SkMatrixConvolutionImageFilter_DEFINED |
| |
| namespace MatrixConvolutionImageFilter { |
| |
| // The matrix convolution image filter applies the convolution naively, it does not use any DFT to |
| // convert the input images into the frequency domain. As such, kernels can quickly become too |
| // slow to run in a reasonable amount of time (and anyone using a giant kernel should not be |
| // relying on Skia to perform the calculations). 256 as a limit on the kernel size is somewhat |
| // arbitrary but should, hopefully, not cause existing clients/websites to fail when historically |
| // there was no upper limit. |
| // Note: SkSL balks (w/ a "program is too large" error) whenever the number of kernel values |
| // is >= 2048 (e.g., 8x256, 16x128, ...) so that should be a pretty good upper limit for what |
| // is being seen in the wild. |
| static constexpr int kLargeKernelSize = 256; |
| |
| // The texture-based implementation has two levels: a small size version and one at the |
| // maximum kernel size. In either case, the texture is a 1D array that can hold any |
| // width/height combination that fits within it. |
| static constexpr int kSmallKernelSize = 64; |
| |
| // The uniform-based kernel shader can store 28 values in any order layout (28x1, 1x25, 5x5, and |
| // smaller orders like 3x3 or 5x4, etc.), but must be a multiple of 4 for better packing in std140. |
| static constexpr int kMaxUniformKernelSize = 28; |
| |
| } // namespace MatrixConvolutionImageFilter |
| |
| #endif // SkMatrixConvolutionImageFilter_DEFINED |
