1 /*
2  * Copyright 2017 Google Inc.
3  *
4  * Use of this source code is governed by a BSD-style license that can be
5  * found in the LICENSE file.
6  */
7 
8 #ifndef SkMaskBlurFilter_DEFINED
9 #define SkMaskBlurFilter_DEFINED
10 
11 #include <algorithm>
12 #include <memory>
13 #include <tuple>
14 
15 #include "SkMask.h"
16 #include "SkTypes.h"
17 
18 // Implement a single channel Gaussian blur. The specifics for implementation are taken from:
19 // https://drafts.fxtf.org/filters/#feGaussianBlurElement
20 class SkMaskBlurFilter {
21 public:
22     // Create an object suitable for filtering an SkMask using a filter with width sigmaW and
23     // height sigmaH.
24     SkMaskBlurFilter(double sigmaW, double sigmaH);
25 
26     // returns true iff the sigmas will result in an identity mask (no blurring)
27     bool hasNoBlur() const;
28 
29     // Given a src SkMask, generate dst SkMask returning the border width and height.
30     SkIPoint blur(const SkMask& src, SkMask* dst) const;
31 
32 private:
33     const double fSigmaW;
34     const double fSigmaH;
35 };
36 
37 #endif  // SkBlurMaskFilter_DEFINED
38