c8ee7b1384
This is a reland of commite6f23f98deOriginal change's description: > Reland "Add anisotropic option to SkSamplingOptions." > > This is a reland of commit9be2d572d4> > Original change's description: > > Add anisotropic option to SkSamplingOptions. > > > > Implement on GPU. > > > > Bug: skia:13036 > > Change-Id: I35d760596c4f8faaec27fccf284b70802fcf3f9b > > Reviewed-on: https://skia-review.googlesource.com/c/skia/+/524757 > > Commit-Queue: Brian Salomon <bsalomon@google.com> > > Reviewed-by: Brian Osman <brianosman@google.com> > > Reviewed-by: Michael Ludwig <michaelludwig@google.com> > > Bug: skia:13036 > Change-Id: I3e411aae389dc880ce32bba78852705059fb88b0 > Reviewed-on: https://skia-review.googlesource.com/c/skia/+/535197 > Reviewed-by: Brian Osman <brianosman@google.com> > Commit-Queue: Brian Salomon <bsalomon@google.com> Bug: skia:13036 Change-Id: Icb2513cea6c4ec4cec934f78c66071081c232960 Reviewed-on: https://skia-review.googlesource.com/c/skia/+/535437 Reviewed-by: Brian Osman <brianosman@google.com> Commit-Queue: Brian Salomon <bsalomon@google.com>
104 lines
3.1 KiB
C++
104 lines
3.1 KiB
C++
/*
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* Copyright 2020 Google Inc.
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*
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* Use of this source code is governed by a BSD-style license that can be
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* found in the LICENSE file.
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*/
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#ifndef SkImageSampling_DEFINED
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#define SkImageSampling_DEFINED
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#include "include/core/SkTypes.h"
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#include <algorithm>
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#include <new>
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enum class SkFilterMode {
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kNearest, // single sample point (nearest neighbor)
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kLinear, // interporate between 2x2 sample points (bilinear interpolation)
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kLast = kLinear,
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};
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enum class SkMipmapMode {
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kNone, // ignore mipmap levels, sample from the "base"
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kNearest, // sample from the nearest level
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kLinear, // interpolate between the two nearest levels
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kLast = kLinear,
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};
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/*
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* Specify B and C (each between 0...1) to create a shader that applies the corresponding
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* cubic reconstruction filter to the image.
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*
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* Example values:
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* B = 1/3, C = 1/3 "Mitchell" filter
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* B = 0, C = 1/2 "Catmull-Rom" filter
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*
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* See "Reconstruction Filters in Computer Graphics"
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* Don P. Mitchell
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* Arun N. Netravali
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* 1988
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* https://www.cs.utexas.edu/~fussell/courses/cs384g-fall2013/lectures/mitchell/Mitchell.pdf
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*
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* Desmos worksheet https://www.desmos.com/calculator/aghdpicrvr
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* Nice overview https://entropymine.com/imageworsener/bicubic/
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*/
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struct SkCubicResampler {
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float B, C;
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// Historic default for kHigh_SkFilterQuality
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static constexpr SkCubicResampler Mitchell() { return {1/3.0f, 1/3.0f}; }
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static constexpr SkCubicResampler CatmullRom() { return {0.0f, 1/2.0f}; }
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};
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struct SK_API SkSamplingOptions {
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const int maxAniso = 0;
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const bool useCubic = false;
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const SkCubicResampler cubic = {0, 0};
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const SkFilterMode filter = SkFilterMode::kNearest;
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const SkMipmapMode mipmap = SkMipmapMode::kNone;
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SkSamplingOptions() = default;
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SkSamplingOptions(const SkSamplingOptions&) = default;
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SkSamplingOptions& operator=(const SkSamplingOptions& that) {
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this->~SkSamplingOptions(); // A pedantic no-op.
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new (this) SkSamplingOptions(that);
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return *this;
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}
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SkSamplingOptions(SkFilterMode fm, SkMipmapMode mm)
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: filter(fm)
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, mipmap(mm) {}
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explicit SkSamplingOptions(SkFilterMode fm)
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: filter(fm)
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, mipmap(SkMipmapMode::kNone) {}
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explicit SkSamplingOptions(const SkCubicResampler& c)
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: useCubic(true)
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, cubic(c) {}
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static SkSamplingOptions Aniso(int maxAniso) {
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return SkSamplingOptions{std::max(maxAniso, 1)};
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}
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bool operator==(const SkSamplingOptions& other) const {
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return maxAniso == other.maxAniso
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&& useCubic == other.useCubic
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&& cubic.B == other.cubic.B
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&& cubic.C == other.cubic.C
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&& filter == other.filter
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&& mipmap == other.mipmap;
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}
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bool operator!=(const SkSamplingOptions& other) const { return !(*this == other); }
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bool isAniso() const { return maxAniso != 0; }
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private:
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SkSamplingOptions(int maxAniso) : maxAniso(maxAniso) {}
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};
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#endif
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