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Add an average mode for sigma < 2

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The original code had an optimization when sigma < 2 that averaged
pixels instead of Gaussian bluring them. This CL adds that
behavior back to the new implementat.

BUG=chromium:745290
Change-Id: I35b7de2138a859d546439cc2053b4b599a94ebe1
Reviewed-on: https://skia-review.googlesource.com/34180
Commit-Queue: Herb Derby <herb@google.com>
Reviewed-by: Mike Klein <mtklein@chromium.org>
This commit is contained in:
Herb Derby 2017-08-14 15:35:46 -04:00 committed by Skia Commit-Bot
parent 61d1378857
commit ba8275148a
2 changed files with 112 additions and 4 deletions
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103
src/core/SkMaskBlurFilter.cpp
View File

@ -25,22 +25,36 @@ static uint64_t weight_from_diameter(uint32_t d) {
}
static uint32_t filter_window(double sigma) {
auto possibleWindow = static_cast<uint32_t>(floor(sigma * 3 * sqrt(2*kPi)/4 + 0.5));
if (sigma < 2) {
uint32_t radius = static_cast<uint32_t>(ceil(1.5 * sigma - 0.5));
return 2 * radius + 1;
}
auto possibleWindow = static_cast<uint32_t>(floor(sigma * 3 * sqrt(2 * kPi) / 4 + 0.5));
return std::max(1u, possibleWindow);
}
SkMaskBlurFilter::FilterInfo::FilterInfo(double sigma)
: fFilterWindow{filter_window(sigma)}
, fScaledWeight{(static_cast<uint64_t>(1) << 32) / weight_from_diameter(fFilterWindow)} {}
: fIsSmall{sigma < 2}
, fFilterWindow{filter_window(sigma)}
, fWeight{fIsSmall ? fFilterWindow : weight_from_diameter(fFilterWindow)}
, fScaledWeight{(static_cast<uint64_t>(1) << 32) / fWeight}
{
SkASSERT(sigma >= 0);
}
uint64_t SkMaskBlurFilter::FilterInfo::weight() const {
return weight_from_diameter(fFilterWindow);
return fWeight;
}
uint32_t SkMaskBlurFilter::FilterInfo::borderSize() const {
if (this->isSmall()) {
return (fFilterWindow - 1) / 2;
}
if ((fFilterWindow&1) == 0) {
return 3 * (fFilterWindow / 2) - 1;
}
return 3 * (fFilterWindow / 2);
}
@ -63,6 +77,10 @@ uint64_t SkMaskBlurFilter::FilterInfo::scaledWeight() const {
return fScaledWeight;
}
bool SkMaskBlurFilter::FilterInfo::isSmall() const {
return fIsSmall;
}
SkMaskBlurFilter::SkMaskBlurFilter(double sigmaW, double sigmaH)
: fInfoW{sigmaW}, fInfoH{sigmaH}
, fBuffer0{skstd::make_unique_default<uint32_t[]>(bufferSize(0))}
@ -165,6 +183,83 @@ size_t SkMaskBlurFilter::bufferSize(uint8_t bufferPass) const {
// Blur one horizontal scan into the dst.
void SkMaskBlurFilter::blurOneScan(
FilterInfo info,
const uint8_t* src, size_t srcStride, const uint8_t* srcEnd,
uint8_t* dst, size_t dstStride, uint8_t* dstEnd) const {
// We don't think this is good for quality. It is good for compatibility
// with previous expectations...
if (info.isSmall()) {
this->blurOneScanBox(info, src, srcStride, srcEnd, dst, dstStride, dstEnd);
} else {
this->blurOneScanGauss(info, src, srcStride, srcEnd, dst, dstStride, dstEnd);
}
}
// Blur one horizontal scan into the dst.
void SkMaskBlurFilter::blurOneScanBox(
FilterInfo info,
const uint8_t* src, size_t srcStride, const uint8_t* srcEnd,
uint8_t* dst, size_t dstStride, uint8_t* dstEnd) const {
auto buffer0Begin = &fBuffer0[0];
auto buffer0Cursor = buffer0Begin;
auto buffer0End = &fBuffer0[0] + info.diameter(0) - 1;
std::memset(&fBuffer0[0], 0, (buffer0End - buffer0Begin) * sizeof(fBuffer0[0]));
uint32_t sum0 = 0;
const uint64_t half = static_cast<uint64_t>(1) << 31;
// Consume the source generating pixels.
for (auto srcCursor = src; srcCursor < srcEnd; dst += dstStride, srcCursor += srcStride) {
uint32_t s = *srcCursor;
sum0 += s;
*dst = SkTo<uint8_t>((info.scaledWeight() * sum0 + half) >> 32);
sum0 -= *buffer0Cursor;
*buffer0Cursor = s;
buffer0Cursor = (buffer0Cursor + 1) < buffer0End ? buffer0Cursor + 1 : &fBuffer0[0];
}
// This handles the case when both ends of the box are not between [src, srcEnd), and both
// are zero at that point.
for (auto i = 0; i < static_cast<ptrdiff_t>(2 * info.borderSize()) - (srcEnd - src); i++) {
uint32_t s = 0;
sum0 += s;
*dst = SkTo<uint8_t>((info.scaledWeight() * sum0 + half) >> 32);
sum0 -= *buffer0Cursor;
*buffer0Cursor = s;
buffer0Cursor = (buffer0Cursor + 1) < buffer0End ? buffer0Cursor + 1 : &fBuffer0[0];
dst += dstStride;
}
// Starting from the right, fill in the rest of the buffer.
std::memset(&fBuffer0[0], 0, (buffer0End - &fBuffer0[0]) * sizeof(fBuffer0[0]));
sum0 = 0;
uint8_t* dstCursor = dstEnd;
const uint8_t* srcCursor = srcEnd;
do {
dstCursor -= dstStride;
srcCursor -= srcStride;
uint32_t s = *srcCursor;
sum0 += s;
*dstCursor = SkTo<uint8_t>((info.scaledWeight() * sum0 + half) >> 32);
sum0 -= *buffer0Cursor;
*buffer0Cursor = s;
buffer0Cursor = (buffer0Cursor + 1) < buffer0End ? buffer0Cursor + 1 : &fBuffer0[0];
} while (dstCursor > dst);
}
// Blur one horizontal scan into the dst.
void SkMaskBlurFilter::blurOneScanGauss(
FilterInfo info,
const uint8_t* src, size_t srcStride, const uint8_t* srcEnd,
uint8_t* dst, size_t dstStride, uint8_t* dstEnd) const {

13
src/core/SkMaskBlurFilter.h
View File

@ -37,8 +37,13 @@ public:
// A factor used to simulate division using multiplication and shift.
uint64_t scaledWeight() const;
// Returned when sigma < 2.
bool isSmall() const;
private:
const bool fIsSmall;
const uint32_t fFilterWindow;
const uint64_t fWeight;
const uint64_t fScaledWeight;
};
@ -59,6 +64,14 @@ private:
const uint8_t* src, size_t srcStride, const uint8_t* srcEnd,
uint8_t* dst, size_t dstStride, uint8_t* dstEnd) const;
void blurOneScanBox(FilterInfo gen,
const uint8_t* src, size_t srcStride, const uint8_t* srcEnd,
uint8_t* dst, size_t dstStride, uint8_t* dstEnd) const;
void blurOneScanGauss(FilterInfo gen,
const uint8_t* src, size_t srcStride, const uint8_t* srcEnd,
uint8_t* dst, size_t dstStride, uint8_t* dstEnd) const;
const FilterInfo fInfoW,
fInfoH;