1.1 --- /dev/null Thu Jan 01 00:00:00 1970 +0000
1.2 +++ b/gfx/2d/Blur.h Wed Dec 31 06:09:35 2014 +0100
1.3 @@ -0,0 +1,176 @@
1.4 +/* -*- Mode: C++; tab-width: 8; indent-tabs-mode: nil; c-basic-offset: 2 -*- */
1.5 +/* vim: set ts=8 sts=2 et sw=2 tw=80: */
1.6 +/* This Source Code Form is subject to the terms of the Mozilla Public
1.7 + * License, v. 2.0. If a copy of the MPL was not distributed with this
1.8 + * file, You can obtain one at http://mozilla.org/MPL/2.0/. */
1.9 +
1.10 +#ifndef MOZILLA_GFX_BLUR_H_
1.11 +#define MOZILLA_GFX_BLUR_H_
1.12 +
1.13 +#include "mozilla/gfx/Rect.h"
1.14 +#include "mozilla/gfx/Point.h"
1.15 +#include "mozilla/CheckedInt.h"
1.16 +
1.17 +namespace mozilla {
1.18 +namespace gfx {
1.19 +
1.20 +#ifdef _MSC_VER
1.21 +#pragma warning( disable : 4251 )
1.22 +#endif
1.23 +
1.24 +/**
1.25 + * Implementation of a triple box blur approximation of a Gaussian blur.
1.26 + *
1.27 + * A Gaussian blur is good for blurring because, when done independently
1.28 + * in the horizontal and vertical directions, it matches the result that
1.29 + * would be obtained using a different (rotated) set of axes. A triple
1.30 + * box blur is a very close approximation of a Gaussian.
1.31 + *
1.32 + * This is a "service" class; the constructors set up all the information
1.33 + * based on the values and compute the minimum size for an 8-bit alpha
1.34 + * channel context.
1.35 + * The callers are responsible for creating and managing the backing surface
1.36 + * and passing the pointer to the data to the Blur() method. This class does
1.37 + * not retain the pointer to the data outside of the Blur() call.
1.38 + *
1.39 + * A spread N makes each output pixel the maximum value of all source
1.40 + * pixels within a square of side length 2N+1 centered on the output pixel.
1.41 + */
1.42 +class GFX2D_API AlphaBoxBlur
1.43 +{
1.44 +public:
1.45 +
1.46 + /** Constructs a box blur and computes the backing surface size.
1.47 + *
1.48 + * @param aRect The coordinates of the surface to create in device units.
1.49 + *
1.50 + * @param aBlurRadius The blur radius in pixels. This is the radius of the
1.51 + * entire (triple) kernel function. Each individual box blur has radius
1.52 + * approximately 1/3 this value, or diameter approximately 2/3 this value.
1.53 + * This parameter should nearly always be computed using CalculateBlurRadius,
1.54 + * below.
1.55 + *
1.56 + * @param aDirtyRect A pointer to a dirty rect, measured in device units, if
1.57 + * available. This will be used for optimizing the blur operation. It is
1.58 + * safe to pass nullptr here.
1.59 + *
1.60 + * @param aSkipRect A pointer to a rect, measured in device units, that
1.61 + * represents an area where blurring is unnecessary and shouldn't be done for
1.62 + * speed reasons. It is safe to pass nullptr here.
1.63 + */
1.64 + AlphaBoxBlur(const Rect& aRect,
1.65 + const IntSize& aSpreadRadius,
1.66 + const IntSize& aBlurRadius,
1.67 + const Rect* aDirtyRect,
1.68 + const Rect* aSkipRect);
1.69 +
1.70 + AlphaBoxBlur(const Rect& aRect,
1.71 + int32_t aStride,
1.72 + float aSigmaX,
1.73 + float aSigmaY);
1.74 +
1.75 + ~AlphaBoxBlur();
1.76 +
1.77 + /**
1.78 + * Return the size, in pixels, of the 8-bit alpha surface we'd use.
1.79 + */
1.80 + IntSize GetSize();
1.81 +
1.82 + /**
1.83 + * Return the stride, in bytes, of the 8-bit alpha surface we'd use.
1.84 + */
1.85 + int32_t GetStride();
1.86 +
1.87 + /**
1.88 + * Returns the device-space rectangle the 8-bit alpha surface covers.
1.89 + */
1.90 + IntRect GetRect();
1.91 +
1.92 + /**
1.93 + * Return a pointer to a dirty rect, as passed in to the constructor, or nullptr
1.94 + * if none was passed in.
1.95 + */
1.96 + Rect* GetDirtyRect();
1.97 +
1.98 + /**
1.99 + * Return the minimum buffer size that should be given to Blur() method. If
1.100 + * zero, the class is not properly setup for blurring. Note that this
1.101 + * includes the extra three bytes on top of the stride*width, where something
1.102 + * like gfxImageSurface::GetDataSize() would report without it, even if it
1.103 + * happens to have the extra bytes.
1.104 + */
1.105 + size_t GetSurfaceAllocationSize() const;
1.106 +
1.107 + /**
1.108 + * Perform the blur in-place on the surface backed by specified 8-bit
1.109 + * alpha surface data. The size must be at least that returned by
1.110 + * GetSurfaceAllocationSize() or bad things will happen.
1.111 + */
1.112 + void Blur(uint8_t* aData);
1.113 +
1.114 + /**
1.115 + * Calculates a blur radius that, when used with box blur, approximates a
1.116 + * Gaussian blur with the given standard deviation. The result of this
1.117 + * function should be used as the aBlurRadius parameter to AlphaBoxBlur's
1.118 + * constructor, above.
1.119 + */
1.120 + static IntSize CalculateBlurRadius(const Point& aStandardDeviation);
1.121 +
1.122 +private:
1.123 +
1.124 + void BoxBlur_C(uint8_t* aData,
1.125 + int32_t aLeftLobe, int32_t aRightLobe, int32_t aTopLobe,
1.126 + int32_t aBottomLobe, uint32_t *aIntegralImage, size_t aIntegralImageStride);
1.127 + void BoxBlur_SSE2(uint8_t* aData,
1.128 + int32_t aLeftLobe, int32_t aRightLobe, int32_t aTopLobe,
1.129 + int32_t aBottomLobe, uint32_t *aIntegralImage, size_t aIntegralImageStride);
1.130 +
1.131 + static CheckedInt<int32_t> RoundUpToMultipleOf4(int32_t aVal);
1.132 +
1.133 + /**
1.134 + * A rect indicating the area where blurring is unnecessary, and the blur
1.135 + * algorithm should skip over it.
1.136 + */
1.137 + IntRect mSkipRect;
1.138 +
1.139 + /**
1.140 + * The device-space rectangle the the backing 8-bit alpha surface covers.
1.141 + */
1.142 + IntRect mRect;
1.143 +
1.144 + /**
1.145 + * A copy of the dirty rect passed to the constructor. This will only be valid if
1.146 + * mHasDirtyRect is true.
1.147 + */
1.148 + Rect mDirtyRect;
1.149 +
1.150 + /**
1.151 + * The spread radius, in pixels.
1.152 + */
1.153 + IntSize mSpreadRadius;
1.154 +
1.155 + /**
1.156 + * The blur radius, in pixels.
1.157 + */
1.158 + IntSize mBlurRadius;
1.159 +
1.160 + /**
1.161 + * The stride of the data passed to Blur()
1.162 + */
1.163 + int32_t mStride;
1.164 +
1.165 + /**
1.166 + * The minimum size of the buffer needed for the Blur() operation.
1.167 + */
1.168 + size_t mSurfaceAllocationSize;
1.169 +
1.170 + /**
1.171 + * Whether mDirtyRect contains valid data.
1.172 + */
1.173 + bool mHasDirtyRect;
1.174 +};
1.175 +
1.176 +}
1.177 +}
1.178 +
1.179 +#endif /* MOZILLA_GFX_BLUR_H_ */
