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Mypal/gfx/2d/Blur.cpp

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/* -*- Mode: C++; tab-width: 8; indent-tabs-mode: nil; c-basic-offset: 2 -*- */
/* 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/. */
#include "Blur.h"
#include <algorithm>
#include <math.h>
#include <string.h>
#include "mozilla/CheckedInt.h"
#include "2D.h"
#include "DataSurfaceHelpers.h"
#include "Tools.h"
#ifdef BUILD_ARM_NEON
#include "mozilla/arm.h"
#endif
using namespace std;
namespace mozilla {
namespace gfx {
/**
* Box blur involves looking at one pixel, and setting its value to the average
* of its neighbouring pixels.
* @param aInput The input buffer.
* @param aOutput The output buffer.
* @param aLeftLobe The number of pixels to blend on the left.
* @param aRightLobe The number of pixels to blend on the right.
* @param aWidth The number of columns in the buffers.
* @param aRows The number of rows in the buffers.
* @param aSkipRect An area to skip blurring in.
* XXX shouldn't we pass stride in separately here?
*/
static void
BoxBlurHorizontal(unsigned char* aInput,
unsigned char* aOutput,
int32_t aLeftLobe,
int32_t aRightLobe,
int32_t aWidth,
int32_t aRows,
const IntRect& aSkipRect)
{
MOZ_ASSERT(aWidth > 0);
int32_t boxSize = aLeftLobe + aRightLobe + 1;
bool skipRectCoversWholeRow = 0 >= aSkipRect.x &&
aWidth <= aSkipRect.XMost();
if (boxSize == 1) {
memcpy(aOutput, aInput, aWidth*aRows);
return;
}
uint32_t reciprocal = uint32_t((uint64_t(1) << 32) / boxSize);
for (int32_t y = 0; y < aRows; y++) {
// Check whether the skip rect intersects this row. If the skip
// rect covers the whole surface in this row, we can avoid
// this row entirely (and any others along the skip rect).
bool inSkipRectY = y >= aSkipRect.y &&
y < aSkipRect.YMost();
if (inSkipRectY && skipRectCoversWholeRow) {
y = aSkipRect.YMost() - 1;
continue;
}
uint32_t alphaSum = 0;
for (int32_t i = 0; i < boxSize; i++) {
int32_t pos = i - aLeftLobe;
// See assertion above; if aWidth is zero, then we would have no
// valid position to clamp to.
pos = max(pos, 0);
pos = min(pos, aWidth - 1);
alphaSum += aInput[aWidth * y + pos];
}
for (int32_t x = 0; x < aWidth; x++) {
// Check whether we are within the skip rect. If so, go
// to the next point outside the skip rect.
if (inSkipRectY && x >= aSkipRect.x &&
x < aSkipRect.XMost()) {
x = aSkipRect.XMost();
if (x >= aWidth)
break;
// Recalculate the neighbouring alpha values for
// our new point on the surface.
alphaSum = 0;
for (int32_t i = 0; i < boxSize; i++) {
int32_t pos = x + i - aLeftLobe;
// See assertion above; if aWidth is zero, then we would have no
// valid position to clamp to.
pos = max(pos, 0);
pos = min(pos, aWidth - 1);
alphaSum += aInput[aWidth * y + pos];
}
}
int32_t tmp = x - aLeftLobe;
int32_t last = max(tmp, 0);
int32_t next = min(tmp + boxSize, aWidth - 1);
aOutput[aWidth * y + x] = (uint64_t(alphaSum) * reciprocal) >> 32;
alphaSum += aInput[aWidth * y + next] -
aInput[aWidth * y + last];
}
}
}
/**
* Identical to BoxBlurHorizontal, except it blurs top and bottom instead of
* left and right.
* XXX shouldn't we pass stride in separately here?
*/
static void
BoxBlurVertical(unsigned char* aInput,
unsigned char* aOutput,
int32_t aTopLobe,
int32_t aBottomLobe,
int32_t aWidth,
int32_t aRows,
const IntRect& aSkipRect)
{
MOZ_ASSERT(aRows > 0);
int32_t boxSize = aTopLobe + aBottomLobe + 1;
bool skipRectCoversWholeColumn = 0 >= aSkipRect.y &&
aRows <= aSkipRect.YMost();
if (boxSize == 1) {
memcpy(aOutput, aInput, aWidth*aRows);
return;
}
uint32_t reciprocal = uint32_t((uint64_t(1) << 32) / boxSize);
for (int32_t x = 0; x < aWidth; x++) {
bool inSkipRectX = x >= aSkipRect.x &&
x < aSkipRect.XMost();
if (inSkipRectX && skipRectCoversWholeColumn) {
x = aSkipRect.XMost() - 1;
continue;
}
uint32_t alphaSum = 0;
for (int32_t i = 0; i < boxSize; i++) {
int32_t pos = i - aTopLobe;
// See assertion above; if aRows is zero, then we would have no
// valid position to clamp to.
pos = max(pos, 0);
pos = min(pos, aRows - 1);
alphaSum += aInput[aWidth * pos + x];
}
for (int32_t y = 0; y < aRows; y++) {
if (inSkipRectX && y >= aSkipRect.y &&
y < aSkipRect.YMost()) {
y = aSkipRect.YMost();
if (y >= aRows)
break;
alphaSum = 0;
for (int32_t i = 0; i < boxSize; i++) {
int32_t pos = y + i - aTopLobe;
// See assertion above; if aRows is zero, then we would have no
// valid position to clamp to.
pos = max(pos, 0);
pos = min(pos, aRows - 1);
alphaSum += aInput[aWidth * pos + x];
}
}
int32_t tmp = y - aTopLobe;
int32_t last = max(tmp, 0);
int32_t next = min(tmp + boxSize, aRows - 1);
aOutput[aWidth * y + x] = (uint64_t(alphaSum) * reciprocal) >> 32;
alphaSum += aInput[aWidth * next + x] -
aInput[aWidth * last + x];
}
}
}
static void ComputeLobes(int32_t aRadius, int32_t aLobes[3][2])
{
int32_t major, minor, final;
/* See http://www.w3.org/TR/SVG/filters.html#feGaussianBlur for
* some notes about approximating the Gaussian blur with box-blurs.
* The comments below are in the terminology of that page.
*/
int32_t z = aRadius / 3;
switch (aRadius % 3) {
case 0:
// aRadius = z*3; choose d = 2*z + 1
major = minor = final = z;
break;
case 1:
// aRadius = z*3 + 1
// This is a tricky case since there is no value of d which will
// yield a radius of exactly aRadius. If d is odd, i.e. d=2*k + 1
// for some integer k, then the radius will be 3*k. If d is even,
// i.e. d=2*k, then the radius will be 3*k - 1.
// So we have to choose values that don't match the standard
// algorithm.
major = z + 1;
minor = final = z;
break;
case 2:
// aRadius = z*3 + 2; choose d = 2*z + 2
major = final = z + 1;
minor = z;
break;
default:
// Mathematical impossibility!
MOZ_ASSERT(false);
major = minor = final = 0;
}
MOZ_ASSERT(major + minor + final == aRadius);
aLobes[0][0] = major;
aLobes[0][1] = minor;
aLobes[1][0] = minor;
aLobes[1][1] = major;
aLobes[2][0] = final;
aLobes[2][1] = final;
}
static void
SpreadHorizontal(unsigned char* aInput,
unsigned char* aOutput,
int32_t aRadius,
int32_t aWidth,
int32_t aRows,
int32_t aStride,
const IntRect& aSkipRect)
{
if (aRadius == 0) {
memcpy(aOutput, aInput, aStride * aRows);
return;
}
bool skipRectCoversWholeRow = 0 >= aSkipRect.x &&
aWidth <= aSkipRect.XMost();
for (int32_t y = 0; y < aRows; y++) {
// Check whether the skip rect intersects this row. If the skip
// rect covers the whole surface in this row, we can avoid
// this row entirely (and any others along the skip rect).
bool inSkipRectY = y >= aSkipRect.y &&
y < aSkipRect.YMost();
if (inSkipRectY && skipRectCoversWholeRow) {
y = aSkipRect.YMost() - 1;
continue;
}
for (int32_t x = 0; x < aWidth; x++) {
// Check whether we are within the skip rect. If so, go
// to the next point outside the skip rect.
if (inSkipRectY && x >= aSkipRect.x &&
x < aSkipRect.XMost()) {
x = aSkipRect.XMost();
if (x >= aWidth)
break;
}
int32_t sMin = max(x - aRadius, 0);
int32_t sMax = min(x + aRadius, aWidth - 1);
int32_t v = 0;
for (int32_t s = sMin; s <= sMax; ++s) {
v = max<int32_t>(v, aInput[aStride * y + s]);
}
aOutput[aStride * y + x] = v;
}
}
}
static void
SpreadVertical(unsigned char* aInput,
unsigned char* aOutput,
int32_t aRadius,
int32_t aWidth,
int32_t aRows,
int32_t aStride,
const IntRect& aSkipRect)
{
if (aRadius == 0) {
memcpy(aOutput, aInput, aStride * aRows);
return;
}
bool skipRectCoversWholeColumn = 0 >= aSkipRect.y &&
aRows <= aSkipRect.YMost();
for (int32_t x = 0; x < aWidth; x++) {
bool inSkipRectX = x >= aSkipRect.x &&
x < aSkipRect.XMost();
if (inSkipRectX && skipRectCoversWholeColumn) {
x = aSkipRect.XMost() - 1;
continue;
}
for (int32_t y = 0; y < aRows; y++) {
// Check whether we are within the skip rect. If so, go
// to the next point outside the skip rect.
if (inSkipRectX && y >= aSkipRect.y &&
y < aSkipRect.YMost()) {
y = aSkipRect.YMost();
if (y >= aRows)
break;
}
int32_t sMin = max(y - aRadius, 0);
int32_t sMax = min(y + aRadius, aRows - 1);
int32_t v = 0;
for (int32_t s = sMin; s <= sMax; ++s) {
v = max<int32_t>(v, aInput[aStride * s + x]);
}
aOutput[aStride * y + x] = v;
}
}
}
CheckedInt<int32_t>
AlphaBoxBlur::RoundUpToMultipleOf4(int32_t aVal)
{
CheckedInt<int32_t> val(aVal);
val += 3;
val /= 4;
val *= 4;
return val;
}
AlphaBoxBlur::AlphaBoxBlur(const Rect& aRect,
const IntSize& aSpreadRadius,
const IntSize& aBlurRadius,
const Rect* aDirtyRect,
const Rect* aSkipRect)
: mSpreadRadius(aSpreadRadius),
mBlurRadius(aBlurRadius),
mSurfaceAllocationSize(0)
{
Rect rect(aRect);
rect.Inflate(Size(aBlurRadius + aSpreadRadius));
rect.RoundOut();
if (aDirtyRect) {
// If we get passed a dirty rect from layout, we can minimize the
// shadow size and make painting faster.
mHasDirtyRect = true;
mDirtyRect = *aDirtyRect;
Rect requiredBlurArea = mDirtyRect.Intersect(rect);
requiredBlurArea.Inflate(Size(aBlurRadius + aSpreadRadius));
rect = requiredBlurArea.Intersect(rect);
} else {
mHasDirtyRect = false;
}
mRect = IntRect(int32_t(rect.x), int32_t(rect.y),
int32_t(rect.width), int32_t(rect.height));
if (mRect.IsEmpty()) {
return;
}
if (aSkipRect) {
// If we get passed a skip rect, we can lower the amount of
// blurring/spreading we need to do. We convert it to IntRect to avoid
// expensive int<->float conversions if we were to use Rect instead.
Rect skipRect = *aSkipRect;
skipRect.RoundIn();
skipRect.Deflate(Size(aBlurRadius + aSpreadRadius));
mSkipRect = IntRect(int32_t(skipRect.x), int32_t(skipRect.y),
int32_t(skipRect.width), int32_t(skipRect.height));
mSkipRect = mSkipRect.Intersect(mRect);
if (mSkipRect.IsEqualInterior(mRect))
return;
mSkipRect -= mRect.TopLeft();
} else {
mSkipRect = IntRect(0, 0, 0, 0);
}
CheckedInt<int32_t> stride = RoundUpToMultipleOf4(mRect.width);
if (stride.isValid()) {
mStride = stride.value();
// We need to leave room for an additional 3 bytes for a potential overrun
// in our blurring code.
size_t size = BufferSizeFromStrideAndHeight(mStride, mRect.height, 3);
if (size != 0) {
mSurfaceAllocationSize = size;
}
}
}
AlphaBoxBlur::AlphaBoxBlur(const Rect& aRect,
int32_t aStride,
float aSigmaX,
float aSigmaY)
: mRect(int32_t(aRect.x), int32_t(aRect.y),
int32_t(aRect.width), int32_t(aRect.height)),
mSpreadRadius(),
mBlurRadius(CalculateBlurRadius(Point(aSigmaX, aSigmaY))),
mStride(aStride),
mSurfaceAllocationSize(0)
{
IntRect intRect;
if (aRect.ToIntRect(&intRect)) {
size_t minDataSize = BufferSizeFromStrideAndHeight(intRect.width, intRect.height);
if (minDataSize != 0) {
mSurfaceAllocationSize = minDataSize;
}
}
}
AlphaBoxBlur::~AlphaBoxBlur()
{
}
IntSize
AlphaBoxBlur::GetSize()
{
IntSize size(mRect.width, mRect.height);
return size;
}
int32_t
AlphaBoxBlur::GetStride()
{
return mStride;
}
IntRect
AlphaBoxBlur::GetRect()
{
return mRect;
}
Rect*
AlphaBoxBlur::GetDirtyRect()
{
if (mHasDirtyRect) {
return &mDirtyRect;
}
return nullptr;
}
size_t
AlphaBoxBlur::GetSurfaceAllocationSize() const
{
return mSurfaceAllocationSize;
}
void
AlphaBoxBlur::Blur(uint8_t* aData)
{
if (!aData) {
return;
}
// no need to do all this if not blurring or spreading
if (mBlurRadius != IntSize(0,0) || mSpreadRadius != IntSize(0,0)) {
int32_t stride = GetStride();
IntSize size = GetSize();
if (mSpreadRadius.width > 0 || mSpreadRadius.height > 0) {
// No need to use CheckedInt here - we have validated it in the constructor.
size_t szB = stride * size.height;
unsigned char* tmpData = new (std::nothrow) uint8_t[szB];
if (!tmpData) {
return;
}
memset(tmpData, 0, szB);
SpreadHorizontal(aData, tmpData, mSpreadRadius.width, GetSize().width, GetSize().height, stride, mSkipRect);
SpreadVertical(tmpData, aData, mSpreadRadius.height, GetSize().width, GetSize().height, stride, mSkipRect);
delete [] tmpData;
}
int32_t horizontalLobes[3][2];
ComputeLobes(mBlurRadius.width, horizontalLobes);
int32_t verticalLobes[3][2];
ComputeLobes(mBlurRadius.height, verticalLobes);
// We want to allow for some extra space on the left for alignment reasons.
int32_t maxLeftLobe = RoundUpToMultipleOf4(horizontalLobes[0][0] + 1).value();
IntSize integralImageSize(size.width + maxLeftLobe + horizontalLobes[1][1],
size.height + verticalLobes[0][0] + verticalLobes[1][1] + 1);
if ((integralImageSize.width * integralImageSize.height) > (1 << 24)) {
// Fallback to old blurring code when the surface is so large it may
// overflow our integral image!
// No need to use CheckedInt here - we have validated it in the constructor.
size_t szB = stride * size.height;
uint8_t* tmpData = new (std::nothrow) uint8_t[szB];
if (!tmpData) {
return;
}
memset(tmpData, 0, szB);
uint8_t* a = aData;
uint8_t* b = tmpData;
if (mBlurRadius.width > 0) {
BoxBlurHorizontal(a, b, horizontalLobes[0][0], horizontalLobes[0][1], stride, GetSize().height, mSkipRect);
BoxBlurHorizontal(b, a, horizontalLobes[1][0], horizontalLobes[1][1], stride, GetSize().height, mSkipRect);
BoxBlurHorizontal(a, b, horizontalLobes[2][0], horizontalLobes[2][1], stride, GetSize().height, mSkipRect);
} else {
a = tmpData;
b = aData;
}
// The result is in 'b' here.
if (mBlurRadius.height > 0) {
BoxBlurVertical(b, a, verticalLobes[0][0], verticalLobes[0][1], stride, GetSize().height, mSkipRect);
BoxBlurVertical(a, b, verticalLobes[1][0], verticalLobes[1][1], stride, GetSize().height, mSkipRect);
BoxBlurVertical(b, a, verticalLobes[2][0], verticalLobes[2][1], stride, GetSize().height, mSkipRect);
} else {
a = b;
}
// The result is in 'a' here.
if (a == tmpData) {
memcpy(aData, tmpData, szB);
}
delete [] tmpData;
} else {
size_t integralImageStride = GetAlignedStride<16>(integralImageSize.width, 4);
if (integralImageStride == 0) {
return;
}
// We need to leave room for an additional 12 bytes for a maximum overrun
// of 3 pixels in the blurring code.
size_t bufLen = BufferSizeFromStrideAndHeight(integralImageStride, integralImageSize.height, 12);
if (bufLen == 0) {
return;
}
// bufLen is a byte count, but here we want a multiple of 32-bit ints, so
// we divide by 4.
AlignedArray<uint32_t> integralImage((bufLen / 4) + ((bufLen % 4) ? 1 : 0));
if (!integralImage) {
return;
}
#ifdef USE_SSE2
if (Factory::HasSSE2()) {
BoxBlur_SSE2(aData, horizontalLobes[0][0], horizontalLobes[0][1], verticalLobes[0][0],
verticalLobes[0][1], integralImage, integralImageStride);
BoxBlur_SSE2(aData, horizontalLobes[1][0], horizontalLobes[1][1], verticalLobes[1][0],
verticalLobes[1][1], integralImage, integralImageStride);
BoxBlur_SSE2(aData, horizontalLobes[2][0], horizontalLobes[2][1], verticalLobes[2][0],
verticalLobes[2][1], integralImage, integralImageStride);
} else
#endif
#ifdef BUILD_ARM_NEON
if (mozilla::supports_neon()) {
BoxBlur_NEON(aData, horizontalLobes[0][0], horizontalLobes[0][1], verticalLobes[0][0],
verticalLobes[0][1], integralImage, integralImageStride);
BoxBlur_NEON(aData, horizontalLobes[1][0], horizontalLobes[1][1], verticalLobes[1][0],
verticalLobes[1][1], integralImage, integralImageStride);
BoxBlur_NEON(aData, horizontalLobes[2][0], horizontalLobes[2][1], verticalLobes[2][0],
verticalLobes[2][1], integralImage, integralImageStride);
} else
#endif
{
#ifdef _MIPS_ARCH_LOONGSON3A
BoxBlur_LS3(aData, horizontalLobes[0][0], horizontalLobes[0][1], verticalLobes[0][0],
verticalLobes[0][1], integralImage, integralImageStride);
BoxBlur_LS3(aData, horizontalLobes[1][0], horizontalLobes[1][1], verticalLobes[1][0],
verticalLobes[1][1], integralImage, integralImageStride);
BoxBlur_LS3(aData, horizontalLobes[2][0], horizontalLobes[2][1], verticalLobes[2][0],
verticalLobes[2][1], integralImage, integralImageStride);
#else
BoxBlur_C(aData, horizontalLobes[0][0], horizontalLobes[0][1], verticalLobes[0][0],
verticalLobes[0][1], integralImage, integralImageStride);
BoxBlur_C(aData, horizontalLobes[1][0], horizontalLobes[1][1], verticalLobes[1][0],
verticalLobes[1][1], integralImage, integralImageStride);
BoxBlur_C(aData, horizontalLobes[2][0], horizontalLobes[2][1], verticalLobes[2][0],
verticalLobes[2][1], integralImage, integralImageStride);
#endif
}
}
}
}
MOZ_ALWAYS_INLINE void
GenerateIntegralRow(uint32_t *aDest, const uint8_t *aSource, uint32_t *aPreviousRow,
const uint32_t &aSourceWidth, const uint32_t &aLeftInflation, const uint32_t &aRightInflation)
{
uint32_t currentRowSum = 0;
uint32_t pixel = aSource[0];
for (uint32_t x = 0; x < aLeftInflation; x++) {
currentRowSum += pixel;
*aDest++ = currentRowSum + *aPreviousRow++;
}
for (uint32_t x = aLeftInflation; x < (aSourceWidth + aLeftInflation); x += 4) {
uint32_t alphaValues = *(uint32_t*)(aSource + (x - aLeftInflation));
#if defined WORDS_BIGENDIAN || defined IS_BIG_ENDIAN || defined __BIG_ENDIAN__
currentRowSum += (alphaValues >> 24) & 0xff;
*aDest++ = *aPreviousRow++ + currentRowSum;
currentRowSum += (alphaValues >> 16) & 0xff;
*aDest++ = *aPreviousRow++ + currentRowSum;
currentRowSum += (alphaValues >> 8) & 0xff;
*aDest++ = *aPreviousRow++ + currentRowSum;
currentRowSum += alphaValues & 0xff;
*aDest++ = *aPreviousRow++ + currentRowSum;
#else
currentRowSum += alphaValues & 0xff;
*aDest++ = *aPreviousRow++ + currentRowSum;
alphaValues >>= 8;
currentRowSum += alphaValues & 0xff;
*aDest++ = *aPreviousRow++ + currentRowSum;
alphaValues >>= 8;
currentRowSum += alphaValues & 0xff;
*aDest++ = *aPreviousRow++ + currentRowSum;
alphaValues >>= 8;
currentRowSum += alphaValues & 0xff;
*aDest++ = *aPreviousRow++ + currentRowSum;
#endif
}
pixel = aSource[aSourceWidth - 1];
for (uint32_t x = (aSourceWidth + aLeftInflation); x < (aSourceWidth + aLeftInflation + aRightInflation); x++) {
currentRowSum += pixel;
*aDest++ = currentRowSum + *aPreviousRow++;
}
}
MOZ_ALWAYS_INLINE void
GenerateIntegralImage_C(int32_t aLeftInflation, int32_t aRightInflation,
int32_t aTopInflation, int32_t aBottomInflation,
uint32_t *aIntegralImage, size_t aIntegralImageStride,
uint8_t *aSource, int32_t aSourceStride, const IntSize &aSize)
{
uint32_t stride32bit = aIntegralImageStride / 4;
IntSize integralImageSize(aSize.width + aLeftInflation + aRightInflation,
aSize.height + aTopInflation + aBottomInflation);
memset(aIntegralImage, 0, aIntegralImageStride);
GenerateIntegralRow(aIntegralImage, aSource, aIntegralImage,
aSize.width, aLeftInflation, aRightInflation);
for (int y = 1; y < aTopInflation + 1; y++) {
GenerateIntegralRow(aIntegralImage + (y * stride32bit), aSource, aIntegralImage + (y - 1) * stride32bit,
aSize.width, aLeftInflation, aRightInflation);
}
for (int y = aTopInflation + 1; y < (aSize.height + aTopInflation); y++) {
GenerateIntegralRow(aIntegralImage + (y * stride32bit), aSource + aSourceStride * (y - aTopInflation),
aIntegralImage + (y - 1) * stride32bit, aSize.width, aLeftInflation, aRightInflation);
}
if (aBottomInflation) {
for (int y = (aSize.height + aTopInflation); y < integralImageSize.height; y++) {
GenerateIntegralRow(aIntegralImage + (y * stride32bit), aSource + ((aSize.height - 1) * aSourceStride),
aIntegralImage + (y - 1) * stride32bit,
aSize.width, aLeftInflation, aRightInflation);
}
}
}
/**
* Attempt to do an in-place box blur using an integral image.
*/
void
AlphaBoxBlur::BoxBlur_C(uint8_t* aData,
int32_t aLeftLobe,
int32_t aRightLobe,
int32_t aTopLobe,
int32_t aBottomLobe,
uint32_t *aIntegralImage,
size_t aIntegralImageStride)
{
IntSize size = GetSize();
MOZ_ASSERT(size.width > 0);
// Our 'left' or 'top' lobe will include the current pixel. i.e. when
// looking at an integral image the value of a pixel at 'x,y' is calculated
// using the value of the integral image values above/below that.
aLeftLobe++;
aTopLobe++;
int32_t boxSize = (aLeftLobe + aRightLobe) * (aTopLobe + aBottomLobe);
MOZ_ASSERT(boxSize > 0);
if (boxSize == 1) {
return;
}
int32_t stride32bit = aIntegralImageStride / 4;
int32_t leftInflation = RoundUpToMultipleOf4(aLeftLobe).value();
GenerateIntegralImage_C(leftInflation, aRightLobe, aTopLobe, aBottomLobe,
aIntegralImage, aIntegralImageStride, aData,
mStride, size);
uint32_t reciprocal = uint32_t((uint64_t(1) << 32) / boxSize);
uint32_t *innerIntegral = aIntegralImage + (aTopLobe * stride32bit) + leftInflation;
// Storing these locally makes this about 30% faster! Presumably the compiler
// can't be sure we're not altering the member variables in this loop.
IntRect skipRect = mSkipRect;
uint8_t *data = aData;
int32_t stride = mStride;
for (int32_t y = 0; y < size.height; y++) {
bool inSkipRectY = y > skipRect.y && y < skipRect.YMost();
uint32_t *topLeftBase = innerIntegral + ((y - aTopLobe) * stride32bit - aLeftLobe);
uint32_t *topRightBase = innerIntegral + ((y - aTopLobe) * stride32bit + aRightLobe);
uint32_t *bottomRightBase = innerIntegral + ((y + aBottomLobe) * stride32bit + aRightLobe);
uint32_t *bottomLeftBase = innerIntegral + ((y + aBottomLobe) * stride32bit - aLeftLobe);
for (int32_t x = 0; x < size.width; x++) {
if (inSkipRectY && x > skipRect.x && x < skipRect.XMost()) {
x = skipRect.XMost() - 1;
// Trigger early jump on coming loop iterations, this will be reset
// next line anyway.
inSkipRectY = false;
continue;
}
int32_t topLeft = topLeftBase[x];
int32_t topRight = topRightBase[x];
int32_t bottomRight = bottomRightBase[x];
int32_t bottomLeft = bottomLeftBase[x];
uint32_t value = bottomRight - topRight - bottomLeft;
value += topLeft;
data[stride * y + x] = (uint64_t(reciprocal) * value + (uint64_t(1) << 31)) >> 32;
}
}
}
/**
* Compute the box blur size (which we're calling the blur radius) from
* the standard deviation.
*
* Much of this, the 3 * sqrt(2 * pi) / 4, is the known value for
* approximating a Gaussian using box blurs. This yields quite a good
* approximation for a Gaussian. Then we multiply this by 1.5 since our
* code wants the radius of the entire triple-box-blur kernel instead of
* the diameter of an individual box blur. For more details, see:
* http://www.w3.org/TR/SVG11/filters.html#feGaussianBlurElement
* https://bugzilla.mozilla.org/show_bug.cgi?id=590039#c19
*/
static const Float GAUSSIAN_SCALE_FACTOR = Float((3 * sqrt(2 * M_PI) / 4) * 1.5);
IntSize
AlphaBoxBlur::CalculateBlurRadius(const Point& aStd)
{
IntSize size(static_cast<int32_t>(floor(aStd.x * GAUSSIAN_SCALE_FACTOR + 0.5f)),
static_cast<int32_t>(floor(aStd.y * GAUSSIAN_SCALE_FACTOR + 0.5f)));
return size;
}
} // namespace gfx
} // namespace mozilla
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