diff options
| -rw-r--r-- | src/core/SkBlurImageFilter.cpp | 393 | ||||
| -rw-r--r-- | tests/ImageFilterTest.cpp | 10 |
2 files changed, 24 insertions, 379 deletions
diff --git a/src/core/SkBlurImageFilter.cpp b/src/core/SkBlurImageFilter.cpp index e9682ff301..5d9a1cf33a 100644 --- a/src/core/SkBlurImageFilter.cpp +++ b/src/core/SkBlurImageFilter.cpp @@ -7,16 +7,11 @@ #include "SkBlurImageFilter.h" -#include <algorithm> - -#include "SkArenaAlloc.h" #include "SkAutoPixmapStorage.h" -#include "SkBitmap.h" #include "SkColorData.h" #include "SkColorSpaceXformer.h" #include "SkTFitsIn.h" #include "SkGpuBlurUtils.h" -#include "SkNx.h" #include "SkOpts.h" #include "SkReadBuffer.h" #include "SkSpecialImage.h" @@ -28,18 +23,13 @@ #include "SkGr.h" #endif -// The value where the three pass window calculation results in a zero window. -// N[Solve[sigma*3*Sqrt[2 Pi]/4 == 1/2, sigma], 16] -static constexpr double kZeroWindow = 0.26596152026762; -static constexpr double kPi = 3.14159265358979323846264338327950288; - class SkBlurImageFilterImpl final : public SkImageFilter { public: SkBlurImageFilterImpl(SkScalar sigmaX, - SkScalar sigmaY, - sk_sp<SkImageFilter> input, - const CropRect* cropRect, - SkBlurImageFilter::TileMode tileMode); + SkScalar sigmaY, + sk_sp<SkImageFilter> input, + const CropRect* cropRect, + SkBlurImageFilter::TileMode tileMode); SkRect computeFastBounds(const SkRect&) const override; @@ -172,342 +162,6 @@ static void get_box3_params(SkScalar s, int *kernelSize, int* kernelSize3, int * } } -#if !defined(SK_SUPPORT_LEGACY_BLUR_IMAGE) - -// This is defined by the SVG spec: -// https://drafts.fxtf.org/filter-effects/#feGaussianBlurElement -static int calculate_window(double sigma) { - // NB 136 is the largest sigma that will not cause a buffer full of 255 mask values to overflow - // using the Gauss filter. It also limits the size of buffers used hold intermediate values. - // Explanation of maximums: - // sum0 = window * 255 - // sum1 = window * sum0 -> window * window * 255 - // sum2 = window * sum1 -> window * window * window * 255 -> window^3 * 255 - // - // The value window^3 * 255 must fit in a uint32_t. So, - // window^3 < 2^32. window = 255. - // - // window = floor(sigma * 3 * sqrt(2 * kPi) / 4 + 0.5) - // For window <= 255, the largest value for sigma is 136. - sigma = SkTPin(sigma, 0.0, 136.0); - auto possibleWindow = static_cast<int>(floor(sigma * 3 * sqrt(2 * kPi) / 4 + 0.5)); - return std::max(1, possibleWindow); -} - -// Calculating the border is tricky. The border is the distance in pixels between the first dst -// pixel and the first src pixel (or the last src pixel and the last dst pixel). -// I will go through the odd case which is simpler, and then through the even case. Given a -// stack of filters seven wide for the odd case of three passes. -// -// S -// aaaAaaa -// bbbBbbb -// cccCccc -// D -// -// The furthest changed pixel is when the filters are in the following configuration. -// -// S -// aaaAaaa -// bbbBbbb -// cccCccc -// D -// -// The A pixel is calculated using the value S, the B uses A, and the C uses B, and -// finally D is C. So, with a window size of seven the border is nine. In the odd case, the -// border is 3*((window - 1)/2). -// -// For even cases the filter stack is more complicated. The spec specifies two passes -// of even filters and a final pass of odd filters. A stack for a width of six looks like -// this. -// -// S -// aaaAaa -// bbBbbb -// cccCccc -// D -// -// The furthest pixel looks like this. -// -// S -// aaaAaa -// bbBbbb -// cccCccc -// D -// -// For a window of six, the border value is eight. In the even case the border is 3 * -// (window/2) - 1. -static int calculate_border(int window) { - return (window & 1) == 1 ? 3 * ((window - 1) / 2) : 3 * (window / 2) - 1; -} - -static int calculate_buffer(int window) { - int bufferSize = window - 1; - return (window & 1) == 1 ? 3 * bufferSize : 3 * bufferSize + 1; -} - -// blur_one_direction implements the common three pass box filter approximation of Gaussian blur, -// but combines all three passes into a single pass. This approach is facilitated by three circular -// buffers the width of the window which track values for trailing edges of each of the three -// passes. This allows the algorithm to use more precision in the calculation because the values -// are not rounded each pass. And this implementation also avoids a trap that's easy to fall -// into resulting in blending in too many zeroes near the edge. -// -// In general, a window sum has the form: -// sum_n+1 = sum_n + leading_edge - trailing_edge. -// If instead we do the subtraction at the end of the previous iteration, we can just -// calculate the sums instead of having to do the subtractions too. -// -// In previous iteration: -// sum_n+1 = sum_n - trailing_edge. -// -// In this iteration: -// sum_n+1 = sum_n + leading_edge. -// -// Now we can stack all three sums and do them at once. Sum0 gets its leading edge from the -// actual data. Sum1's leading edge is just Sum0, and Sum2's leading edge is Sum1. So, doing the -// three passes at the same time has the form: -// -// sum0_n+1 = sum0_n + leading edge -// sum1_n+1 = sum1_n + sum0_n+1 -// sum2_n+1 = sum2_n + sum1_n+1 -// -// sum2_n+1 / window^3 is the new value of the destination pixel. -// -// Reduce the sums by the trailing edges which were stored in the circular buffers, -// for the next go around. This is the case for odd sized windows, even windows the the third -// circular buffer is one larger then the first two circular buffers. -// -// sum2_n+2 = sum2_n+1 - buffer2[i]; -// buffer2[i] = sum1; -// sum1_n+2 = sum1_n+1 - buffer1[i]; -// buffer1[i] = sum0; -// sum0_n+2 = sum0_n+1 - buffer0[i]; -// buffer0[i] = leading edge -// -// This is all encapsulated in the processValue function below. -// -using Pass0And1 = Sk4u[2]; -// The would be dLeft parameter is assumed to be 0. -static void blur_one_direction(Sk4u* buffer, int window, - int srcLeft, int srcRight, int dstRight, - const uint32_t* src, int srcXStride, int srcYStride, int srcH, - uint32_t* dst, int dstXStride, int dstYStride) { - - // The circular buffers are one less than the window. - auto pass0Count = window - 1, - pass1Count = window - 1, - pass2Count = (window & 1) == 1 ? window - 1 : window; - - Pass0And1* buffer01Start = (Pass0And1*)buffer; - Sk4u* buffer2Start = buffer + pass0Count + pass1Count; - Pass0And1* buffer01End = (Pass0And1*)buffer2Start; - Sk4u* buffer2End = buffer2Start + pass2Count; - - // If the window is odd then the divisor is just window ^ 3 otherwise, - // it is window * window * (window + 1) = window ^ 3 + window ^ 2; - auto window2 = window * window; - auto window3 = window2 * window; - auto divisor = (window & 1) == 1 ? window3 : window3 + window2; - - // NB the sums in the blur code use the following technique to avoid - // adding 1/2 to round the divide. - // - // Sum/d + 1/2 == (Sum + h) / d - // Sum + d(1/2) == Sum + h - // h == (1/2)d - // - // But the d/2 it self should be rounded. - // h == d/2 + 1/2 == (d + 1) / 2 - // - // weight = 1 / d * 2 ^ 32 - auto weight = static_cast<uint32_t>(round(1.0 / divisor * (1ull << 32))); - auto half = static_cast<uint32_t>((divisor + 1) / 2); - - auto border = calculate_border(window); - - // Calculate the start and end of the source pixels with respect to the destination start. - auto srcStart = srcLeft - border, - srcEnd = srcRight - border, - dstEnd = dstRight; - - for (auto y = 0; y < srcH; y++) { - auto buffer01Cursor = buffer01Start; - auto buffer2Cursor = buffer2Start; - - Sk4u sum0{0u}; - Sk4u sum1{0u}; - Sk4u sum2{half}; - - sk_bzero(buffer01Start, (buffer2End - (Sk4u *) (buffer01Start)) * sizeof(*buffer2Start)); - - // Given an expanded input pixel, move the window ahead using the leadingEdge value. - auto processValue = [&](const Sk4u& leadingEdge) -> Sk4u { - sum0 += leadingEdge; - sum1 += sum0; - sum2 += sum1; - - Sk4u value = sum2.mulHi(weight); - - sum2 -= *buffer2Cursor; - *buffer2Cursor = sum1; - buffer2Cursor = (buffer2Cursor + 1) < buffer2End ? buffer2Cursor + 1 : buffer2Start; - - sum1 -= (*buffer01Cursor)[1]; - (*buffer01Cursor)[1] = sum0; - sum0 -= (*buffer01Cursor)[0]; - (*buffer01Cursor)[0] = leadingEdge; - buffer01Cursor = - (buffer01Cursor + 1) < buffer01End ? buffer01Cursor + 1 : buffer01Start; - - return value; - }; - - auto srcIdx = srcStart; - auto dstIdx = 0; - const uint32_t* srcCursor = src; - uint32_t* dstCursor = dst; - - // The destination pixels are not effected by the src pixels, - // change to zero as per the spec. - // https://drafts.fxtf.org/filter-effects/#FilterPrimitivesOverviewIntro - while (dstIdx < srcIdx) { - *dstCursor = 0; - dstCursor += dstXStride; - SK_PREFETCH(dstCursor); - dstIdx++; - } - - // The edge of the source is before the edge of the destination. Calculate the sums for - // the pixels before the start of the destination. - while (dstIdx > srcIdx) { - Sk4u leadingEdge = srcIdx < srcEnd ? SkNx_cast<uint32_t>(Sk4b::Load(srcCursor)) : 0; - (void) processValue(leadingEdge); - srcCursor += srcXStride; - srcIdx++; - } - - // The dstIdx and srcIdx are in sync now; the code just uses the dstIdx for both now. - // Consume the source generating pixels to dst. - auto loopEnd = std::min(dstEnd, srcEnd); - while (dstIdx < loopEnd) { - Sk4u leadingEdge = SkNx_cast<uint32_t>(Sk4b::Load(srcCursor)); - SkNx_cast<uint8_t>(processValue(leadingEdge)).store(dstCursor); - srcCursor += srcXStride; - dstCursor += dstXStride; - SK_PREFETCH(dstCursor); - dstIdx++; - } - - // The leading edge is beyond the end of the source. Assume that the pixels - // are now 0x0000 until the end of the destination. - loopEnd = dstEnd; - while (dstIdx < loopEnd) { - SkNx_cast<uint8_t>(processValue(0u)).store(dstCursor); - dstCursor += dstXStride; - SK_PREFETCH(dstCursor); - dstIdx++; - } - - src += srcYStride; - dst += dstYStride; - } -} - -static sk_sp<SkSpecialImage> combined_pass_blur( - SkVector sigma, - SkSpecialImage* source, const sk_sp<SkSpecialImage>& input, - SkIRect inputBounds, SkIRect dstBounds) { - SkBitmap inputBM; - - if (!input->getROPixels(&inputBM)) { - return nullptr; - } - - if (inputBM.colorType() != kN32_SkColorType) { - return nullptr; - } - - SkBitmap src; - inputBM.extractSubset(&src, inputBounds); - - // Make everything relative to the destination bounds. - inputBounds.offset(-dstBounds.x(), -dstBounds.y()); - dstBounds.offset( -dstBounds.x(), -dstBounds.y()); - - auto windowW = calculate_window(sigma.x()), - windowH = calculate_window(sigma.y()); - - auto srcW = inputBounds.width(), - srcH = inputBounds.height(), - dstW = dstBounds.width(), - dstH = dstBounds.height(); - - SkImageInfo dstInfo = SkImageInfo::Make(dstW, dstH, inputBM.colorType(), inputBM.alphaType()); - - SkBitmap dst; - if (!dst.tryAllocPixels(dstInfo)) { - return nullptr; - } - - auto bufferSizeW = calculate_buffer(windowW), - bufferSizeH = calculate_buffer(windowH); - - // The amount 1024 is enough for buffers up to 10 sigma. The tmp bitmap will be - // allocated on the heap. - SkSTArenaAlloc<1024> alloc; - Sk4u* buffer = alloc.makeArrayDefault<Sk4u>(std::max(bufferSizeW, bufferSizeH)); - - if (windowW > 1 && windowH > 1) { - // Blur both directions. - - auto tmpW = srcH, - tmpH = dstW; - - auto tmp = alloc.makeArrayDefault<uint32_t>(tmpW * tmpH); - - // Blur horizontally, and transpose. - blur_one_direction( - buffer, windowW, - inputBounds.left(), inputBounds.right(), dstBounds.right(), - static_cast<uint32_t*>(src.getPixels()), 1, src.rowBytesAsPixels(), srcH, - tmp, tmpW, 1); - - // Blur vertically (scan in memory order because of the transposition), - // and transpose back to the original orientation. - blur_one_direction( - buffer, windowH, - inputBounds.top(), inputBounds.bottom(), dstBounds.bottom(), - tmp, 1, tmpW, tmpH, - static_cast<uint32_t*>(dst.getPixels()), dst.rowBytesAsPixels(), 1); - } else if (windowW > 1) { - // Blur only horizontally. - - blur_one_direction( - buffer, windowW, - inputBounds.left(), inputBounds.right(), dstBounds.right(), - static_cast<uint32_t*>(src.getPixels()), 1, src.rowBytesAsPixels(), srcH, - static_cast<uint32_t*>(dst.getPixels()), 1, dst.rowBytesAsPixels()); - } else if (windowH > 1) { - // Blur only vertically. - - blur_one_direction( - buffer, windowH, - inputBounds.top(), inputBounds.bottom(), dstBounds.bottom(), - static_cast<uint32_t*>(src.getPixels()), src.rowBytesAsPixels(), 1, srcW, - static_cast<uint32_t*>(dst.getPixels()), dst.rowBytesAsPixels(), 1); - } else { - // Nothing to do. - - return input->makeSubset(inputBounds); - } - - return SkSpecialImage::MakeFromRaster(SkIRect::MakeWH(dstBounds.width(), - dstBounds.height()), - dst, &source->props()); -} -#endif - sk_sp<SkSpecialImage> SkBlurImageFilterImpl::onFilterImage(SkSpecialImage* source, const Context& ctx, SkIPoint* offset) const { @@ -553,16 +207,12 @@ sk_sp<SkSpecialImage> SkBlurImageFilterImpl::onFilterImage(SkSpecialImage* sourc } else #endif { - // If both sigmas will result in a zero width window, there is nothing to do. - if (sigma.x() < kZeroWindow && sigma.y() < kZeroWindow) { - result = input->makeSubset(inputBounds); - } else { - #if defined(SK_SUPPORT_LEGACY_BLUR_IMAGE) - result = this->cpuFilter(source, sigma, input, inputBounds, dstBounds); - #else - result = combined_pass_blur(sigma, source, input, inputBounds, dstBounds); - #endif - } + #if defined(SK_SUPPORT_LEGACY_BLUR_IMAGE) + result = this->cpuFilter(source, sigma, input, inputBounds, dstBounds); + #else + // The new code will go here. + result = this->cpuFilter(source, sigma, input, inputBounds, dstBounds); + #endif } // Return the resultOffset if the blur succeeded. @@ -585,8 +235,8 @@ sk_sp<SkSpecialImage> SkBlurImageFilterImpl::gpuFilter( // The raw cross arm value c = E^-s // The normalized cross arm value = c/n // N[Solve[{c/n == 1/2048, sigma > 0}, sigma], 16] - static constexpr double kZeroWindowGPU = 0.2561130112451658; - if (sigma.x() < kZeroWindowGPU && sigma.y() < kZeroWindowGPU) { + static constexpr double kCrossTooSmall = 0.2561130112451658; + if (sigma.x() < kCrossTooSmall && sigma.y() < kCrossTooSmall) { return input->makeSubset(inputBounds); } @@ -630,6 +280,13 @@ sk_sp<SkSpecialImage> SkBlurImageFilterImpl::cpuFilter( SkVector sigma, const sk_sp<SkSpecialImage> &input, SkIRect inputBounds, SkIRect dstBounds) const { + // If both sigmas will result in a zero width window, there is nothing to do. + // N[Solve[sigma*3*Sqrt[2 Pi]/4 == 1/2, sigma], 16] + static constexpr double kZeroWindow = 0.2659615202676218; + if (sigma.x() < kZeroWindow && sigma.y() < kZeroWindow) { + return input->makeSubset(inputBounds); + } + int kernelSizeX, kernelSizeX3, lowOffsetX, highOffsetX; int kernelSizeY, kernelSizeY3, lowOffsetY, highOffsetY; get_box3_params(sigma.x(), &kernelSizeX, &kernelSizeX3, &lowOffsetX, &highOffsetX); @@ -719,26 +376,14 @@ const { SkRect SkBlurImageFilterImpl::computeFastBounds(const SkRect& src) const { SkRect bounds = this->getInput(0) ? this->getInput(0)->computeFastBounds(src) : src; -#if defined(SK_SUPPORT_LEGACY_BLUR_IMAGE) bounds.outset(fSigma.width() * 3, fSigma.height() * 3); -#else - auto borderW = calculate_border(calculate_window(fSigma.width())), - borderH = calculate_border(calculate_window(fSigma.height())); - bounds.outset(borderW, borderH); -#endif return bounds; } SkIRect SkBlurImageFilterImpl::onFilterNodeBounds(const SkIRect& src, const SkMatrix& ctm, MapDirection) const { SkVector sigma = map_sigma(fSigma, ctm); -#if defined(SK_SUPPORT_LEGACY_BLUR_IMAGE) return src.makeOutset(SkScalarCeilToInt(sigma.x() * 3), SkScalarCeilToInt(sigma.y() * 3)); -#else - auto borderW = calculate_border(calculate_window(sigma.x())), - borderH = calculate_border(calculate_window(sigma.y())); - return src.makeOutset(borderW, borderH); -#endif } #ifndef SK_IGNORE_TO_STRING diff --git a/tests/ImageFilterTest.cpp b/tests/ImageFilterTest.cpp index 0b8d0d0fec..ac847ce7cf 100644 --- a/tests/ImageFilterTest.cpp +++ b/tests/ImageFilterTest.cpp @@ -855,7 +855,7 @@ DEF_TEST(ImageFilterBlurThenShadowBounds, reporter) { sk_sp<SkImageFilter> filter2(make_drop_shadow(std::move(filter1))); SkIRect bounds = SkIRect::MakeXYWH(0, 0, 100, 100); - SkIRect expectedBounds = SkIRect::MakeXYWH(-132, -132, 234, 234); + SkIRect expectedBounds = SkIRect::MakeXYWH(-133, -133, 236, 236); bounds = filter2->filterBounds(bounds, SkMatrix::I()); REPORTER_ASSERT(reporter, bounds == expectedBounds); @@ -866,7 +866,7 @@ DEF_TEST(ImageFilterShadowThenBlurBounds, reporter) { sk_sp<SkImageFilter> filter2(make_blur(std::move(filter1))); SkIRect bounds = SkIRect::MakeXYWH(0, 0, 100, 100); - SkIRect expectedBounds = SkIRect::MakeXYWH(-132, -132, 234, 234); + SkIRect expectedBounds = SkIRect::MakeXYWH(-133, -133, 236, 236); bounds = filter2->filterBounds(bounds, SkMatrix::I()); REPORTER_ASSERT(reporter, bounds == expectedBounds); @@ -895,7 +895,7 @@ DEF_TEST(ImageFilterScaledBlurRadius, reporter) { scaleMatrix.setScale(2, 2); SkIRect bounds = SkIRect::MakeLTRB(0, 0, 200, 200); - SkIRect expectedBlurBounds = SkIRect::MakeLTRB(-5, -5, 205, 205); + SkIRect expectedBlurBounds = SkIRect::MakeLTRB(-6, -6, 206, 206); SkIRect blurBounds = blur->filterBounds( bounds, scaleMatrix, SkImageFilter::kForward_MapDirection); REPORTER_ASSERT(reporter, blurBounds == expectedBlurBounds); @@ -920,7 +920,7 @@ DEF_TEST(ImageFilterScaledBlurRadius, reporter) { scaleMatrix.setScale(1, -1); SkIRect bounds = SkIRect::MakeLTRB(0, -100, 100, 0); - SkIRect expectedBlurBounds = SkIRect::MakeLTRB(-2, -102, 102, 2); + SkIRect expectedBlurBounds = SkIRect::MakeLTRB(-3, -103, 103, 3); SkIRect blurBounds = blur->filterBounds( bounds, scaleMatrix, SkImageFilter::kForward_MapDirection); REPORTER_ASSERT(reporter, blurBounds == expectedBlurBounds); @@ -949,7 +949,7 @@ DEF_TEST(ImageFilterComposedBlurFastBounds, reporter) { SkRect boundsSrc = SkRect::MakeWH(SkIntToScalar(100), SkIntToScalar(100)); SkRect expectedBounds = SkRect::MakeXYWH( - SkIntToScalar(-4), SkIntToScalar(-4), SkIntToScalar(108), SkIntToScalar(108)); + SkIntToScalar(-6), SkIntToScalar(-6), SkIntToScalar(112), SkIntToScalar(112)); SkRect boundsDst = composedFilter->computeFastBounds(boundsSrc); REPORTER_ASSERT(reporter, boundsDst == expectedBounds); |