/* -*- Mode: C++; tab-width: 8; indent-tabs-mode: nil; c-basic-offset: 2 -*- */ /* vim: set ts=8 sts=2 et sw=2 tw=80: */ /* This Source Code Form is subject to the terms of the Mozilla Public * License, v. 2.0. If a copy of the MPL was not distributed with this * file, You can obtain one at http://mozilla.org/MPL/2.0/. */ #ifndef MOZILLA_GFX_BLUR_H_ #define MOZILLA_GFX_BLUR_H_ #include "mozilla/gfx/Rect.h" #include "mozilla/gfx/Point.h" #include "mozilla/CheckedInt.h" namespace mozilla { namespace gfx { #ifdef _MSC_VER # pragma warning(disable : 4251) #endif /** * Implementation of a triple box blur approximation of a Gaussian blur. * * A Gaussian blur is good for blurring because, when done independently * in the horizontal and vertical directions, it matches the result that * would be obtained using a different (rotated) set of axes. A triple * box blur is a very close approximation of a Gaussian. * * This is a "service" class; the constructors set up all the information * based on the values and compute the minimum size for an 8-bit alpha * channel context. * The callers are responsible for creating and managing the backing surface * and passing the pointer to the data to the Blur() method. This class does * not retain the pointer to the data outside of the Blur() call. * * A spread N makes each output pixel the maximum value of all source * pixels within a square of side length 2N+1 centered on the output pixel. */ class GFX2D_API AlphaBoxBlur final { public: /** Constructs a box blur and computes the backing surface size. * * @param aRect The coordinates of the surface to create in device units. * * @param aBlurRadius The blur radius in pixels. This is the radius of the * entire (triple) kernel function. Each individual box blur has radius * approximately 1/3 this value, or diameter approximately 2/3 this value. * This parameter should nearly always be computed using * CalculateBlurRadius, below. * * @param aDirtyRect A pointer to a dirty rect, measured in device units, if * available. This will be used for optimizing the blur operation. It is * safe to pass nullptr here. * * @param aSkipRect A pointer to a rect, measured in device units, that * represents an area where blurring is unnecessary and shouldn't be done * for speed reasons. It is safe to pass nullptr here. */ AlphaBoxBlur(const Rect& aRect, const IntSize& aSpreadRadius, const IntSize& aBlurRadius, const Rect* aDirtyRect, const Rect* aSkipRect); AlphaBoxBlur(const Rect& aRect, int32_t aStride, float aSigmaX, float aSigmaY); AlphaBoxBlur(); void Init(const Rect& aRect, const IntSize& aSpreadRadius, const IntSize& aBlurRadius, const Rect* aDirtyRect, const Rect* aSkipRect); ~AlphaBoxBlur(); /** * Return the size, in pixels, of the 8-bit alpha surface we'd use. */ IntSize GetSize() const; /** * Return the stride, in bytes, of the 8-bit alpha surface we'd use. */ int32_t GetStride() const; /** * Returns the device-space rectangle the 8-bit alpha surface covers. */ IntRect GetRect() const; /** * Return a pointer to a dirty rect, as passed in to the constructor, or * nullptr if none was passed in. */ Rect* GetDirtyRect(); /** * Return the spread radius, in pixels. */ IntSize GetSpreadRadius() const { return mSpreadRadius; } /** * Return the blur radius, in pixels. */ IntSize GetBlurRadius() const { return mBlurRadius; } /** * Return the minimum buffer size that should be given to Blur() method. If * zero, the class is not properly setup for blurring. Note that this * includes the extra three bytes on top of the stride*width, where something * like gfxImageSurface::GetDataSize() would report without it, even if it * happens to have the extra bytes. */ size_t GetSurfaceAllocationSize() const; /** * Perform the blur in-place on the surface backed by specified 8-bit * alpha surface data. The size must be at least that returned by * GetSurfaceAllocationSize() or bad things will happen. */ void Blur(uint8_t* aData) const; /** * Calculates a blur radius that, when used with box blur, approximates a * Gaussian blur with the given standard deviation. The result of this * function should be used as the aBlurRadius parameter to AlphaBoxBlur's * constructor, above. */ static IntSize CalculateBlurRadius(const Point& aStandardDeviation); static Float CalculateBlurSigma(int32_t aBlurRadius); private: void BoxBlur_C(uint8_t* aData, int32_t aLeftLobe, int32_t aRightLobe, int32_t aTopLobe, int32_t aBottomLobe, uint32_t* aIntegralImage, size_t aIntegralImageStride) const; void BoxBlur_SSE2(uint8_t* aData, int32_t aLeftLobe, int32_t aRightLobe, int32_t aTopLobe, int32_t aBottomLobe, uint32_t* aIntegralImage, size_t aIntegralImageStride) const; void BoxBlur_NEON(uint8_t* aData, int32_t aLeftLobe, int32_t aRightLobe, int32_t aTopLobe, int32_t aBottomLobe, uint32_t* aIntegralImage, size_t aIntegralImageStride) const; #ifdef _MIPS_ARCH_LOONGSON3A void BoxBlur_LS3(uint8_t* aData, int32_t aLeftLobe, int32_t aRightLobe, int32_t aTopLobe, int32_t aBottomLobe, uint32_t* aIntegralImage, size_t aIntegralImageStride) const; #endif static CheckedInt RoundUpToMultipleOf4(int32_t aVal); /** * A rect indicating the area where blurring is unnecessary, and the blur * algorithm should skip over it. * * This is guaranteed to be 4-pixel aligned in the x axis. */ IntRect mSkipRect; /** * The device-space rectangle the the backing 8-bit alpha surface covers. */ IntRect mRect; /** * A copy of the dirty rect passed to the constructor. This will only be valid * if mHasDirtyRect is true. */ Rect mDirtyRect; /** * The spread radius, in pixels. */ IntSize mSpreadRadius; /** * The blur radius, in pixels. */ IntSize mBlurRadius; /** * The stride of the data passed to Blur() */ int32_t mStride; /** * The minimum size of the buffer needed for the Blur() operation. */ size_t mSurfaceAllocationSize; /** * Whether mDirtyRect contains valid data. */ bool mHasDirtyRect; }; } // namespace gfx } // namespace mozilla #endif /* MOZILLA_GFX_BLUR_H_ */