1/*
2 * Copyright (C) 2004, 2005, 2006, 2007 Nikolas Zimmermann <zimmermann@kde.org>
3 * Copyright (C) 2004, 2005 Rob Buis <buis@kde.org>
4 * Copyright (C) 2005 Eric Seidel <eric@webkit.org>
5 * Copyright (C) 2013 Google Inc. All rights reserved.
6 *
7 * This library is free software; you can redistribute it and/or
8 * modify it under the terms of the GNU Library General Public
9 * License as published by the Free Software Foundation; either
10 * version 2 of the License, or (at your option) any later version.
11 *
12 * This library is distributed in the hope that it will be useful,
13 * but WITHOUT ANY WARRANTY; without even the implied warranty of
14 * MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE.  See the GNU
15 * Library General Public License for more details.
16 *
17 * You should have received a copy of the GNU Library General Public License
18 * along with this library; see the file COPYING.LIB.  If not, write to
19 * the Free Software Foundation, Inc., 51 Franklin Street, Fifth Floor,
20 * Boston, MA 02110-1301, USA.
21 */
22
23#ifndef FEGaussianBlur_h
24#define FEGaussianBlur_h
25
26#include "platform/graphics/filters/Filter.h"
27#include "platform/graphics/filters/FilterEffect.h"
28
29namespace WebCore {
30
31class PLATFORM_EXPORT FEGaussianBlur : public FilterEffect {
32public:
33    static PassRefPtr<FEGaussianBlur> create(Filter*, float, float);
34
35    float stdDeviationX() const;
36    void setStdDeviationX(float);
37
38    float stdDeviationY() const;
39    void setStdDeviationY(float);
40
41    static float calculateStdDeviation(float);
42
43    virtual void determineAbsolutePaintRect();
44    virtual FloatRect mapRect(const FloatRect&, bool forward = true) OVERRIDE FINAL;
45    static void calculateKernelSize(Filter*, unsigned& kernelSizeX, unsigned& kernelSizeY, float stdX, float stdY);
46    static void calculateUnscaledKernelSize(unsigned& kernelSizeX, unsigned& kernelSizeY, float stdX, float stdY);
47
48    virtual TextStream& externalRepresentation(TextStream&, int indention) const;
49
50private:
51    static const int s_minimalRectDimension = 100 * 100; // Empirical data limit for parallel jobs
52
53    template<typename Type>
54    friend class ParallelJobs;
55
56    struct PlatformApplyParameters {
57        FEGaussianBlur* filter;
58        RefPtr<Uint8ClampedArray> srcPixelArray;
59        RefPtr<Uint8ClampedArray> dstPixelArray;
60        int width;
61        int height;
62        unsigned kernelSizeX;
63        unsigned kernelSizeY;
64    };
65
66    static void platformApplyWorker(PlatformApplyParameters*);
67
68    FEGaussianBlur(Filter*, float, float);
69
70    virtual void applySoftware() OVERRIDE;
71    virtual bool applySkia() OVERRIDE;
72
73    static inline void kernelPosition(int boxBlur, unsigned& std, int& dLeft, int& dRight);
74    inline void platformApply(Uint8ClampedArray* srcPixelArray, Uint8ClampedArray* tmpPixelArray, unsigned kernelSizeX, unsigned kernelSizeY, IntSize& paintSize);
75
76    inline void platformApplyGeneric(Uint8ClampedArray* srcPixelArray, Uint8ClampedArray* tmpPixelArray, unsigned kernelSizeX, unsigned kernelSizeY, IntSize& paintSize);
77    virtual PassRefPtr<SkImageFilter> createImageFilter(SkiaImageFilterBuilder*) OVERRIDE;
78
79    float m_stdX;
80    float m_stdY;
81};
82
83inline void FEGaussianBlur::kernelPosition(int boxBlur, unsigned& std, int& dLeft, int& dRight)
84{
85    // check http://www.w3.org/TR/SVG/filters.html#feGaussianBlurElement for details
86    switch (boxBlur) {
87    case 0:
88        if (!(std % 2)) {
89            dLeft = std / 2 - 1;
90            dRight = std - dLeft;
91        } else {
92            dLeft = std / 2;
93            dRight = std - dLeft;
94        }
95        break;
96    case 1:
97        if (!(std % 2)) {
98            dLeft++;
99            dRight--;
100        }
101        break;
102    case 2:
103        if (!(std % 2)) {
104            dRight++;
105            std++;
106        }
107        break;
108    }
109}
110
111} // namespace WebCore
112
113#endif // FEGaussianBlur_h
114