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/*
* Copyright 2017 Google Inc.
*
* Use of this source code is governed by a BSD-style license that can be
* found in the LICENSE file.
*/
#ifndef SkGaussFilter_DEFINED
#define SkGaussFilter_DEFINED
#include <cstddef>
// Define gaussian filters for values of sigma < 2. Produce values good to 1 part in 1,000,000.
// Gaussian produces values as defined in the SVG 1.1 spec:
// https://www.w3.org/TR/SVG/filters.html#feGaussianBlurElement
// Bessel produces values as defined in "Scale-Space for Discrete Signals" by Tony Lindeberg
class SkGaussFilter {
public:
static constexpr int kGaussArrayMax = 6;
enum class Type : bool {
Gaussian,
Bessel
};
// Type selects which method is used to calculate the gaussian factors.
SkGaussFilter(double sigma, Type type);
size_t size() const { return fN; }
int radius() const { return fN - 1; }
int width() const { return 2 * this->radius() + 1; }
// Allow a filter to be used in a C++ ranged-for loop.
const double* begin() const { return &fBasis[0]; }
const double* end() const { return &fBasis[fN]; }
private:
double fBasis[kGaussArrayMax];
int fN;
};
#endif // SkGaussFilter_DEFINED
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