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Diffstat (limited to 'gfx/2d/Blur.h')
| -rw-r--r-- | gfx/2d/Blur.h | 186 |
1 files changed, 186 insertions, 0 deletions
diff --git a/gfx/2d/Blur.h b/gfx/2d/Blur.h new file mode 100644 index 000000000..8464a57fe --- /dev/null +++ b/gfx/2d/Blur.h @@ -0,0 +1,186 @@ +/* -*- 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 +{ +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(); + + /** + * Return the size, in pixels, of the 8-bit alpha surface we'd use. + */ + IntSize GetSize(); + + /** + * Return the stride, in bytes, of the 8-bit alpha surface we'd use. + */ + int32_t GetStride(); + + /** + * Returns the device-space rectangle the 8-bit alpha surface covers. + */ + IntRect GetRect(); + + /** + * Return a pointer to a dirty rect, as passed in to the constructor, or nullptr + * if none was passed in. + */ + Rect* GetDirtyRect(); + + /** + * 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); + + /** + * 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); + +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); + void BoxBlur_SSE2(uint8_t* aData, + int32_t aLeftLobe, int32_t aRightLobe, int32_t aTopLobe, + int32_t aBottomLobe, uint32_t *aIntegralImage, size_t aIntegralImageStride); +#ifdef BUILD_ARM_NEON + void BoxBlur_NEON(uint8_t* aData, + int32_t aLeftLobe, int32_t aRightLobe, int32_t aTopLobe, + int32_t aBottomLobe, uint32_t *aIntegralImage, size_t aIntegralImageStride); +#endif +#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); +#endif + + static CheckedInt<int32_t> RoundUpToMultipleOf4(int32_t aVal); + + /** + * A rect indicating the area where blurring is unnecessary, and the blur + * algorithm should skip over it. + */ + 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_ */ |