| |
| /* |
| * Copyright 2006 The Android Open Source Project |
| * |
| * Use of this source code is governed by a BSD-style license that can be |
| * found in the LICENSE file. |
| */ |
| |
| |
| #include "SkBlurMask.h" |
| #include "SkMath.h" |
| #include "SkTemplates.h" |
| #include "SkEndian.h" |
| |
| |
| SkScalar SkBlurMask::ConvertRadiusToSigma(SkScalar radius) { |
| // This constant approximates the scaling done in the software path's |
| // "high quality" mode, in SkBlurMask::Blur() (1 / sqrt(3)). |
| // IMHO, it actually should be 1: we blur "less" than we should do |
| // according to the CSS and canvas specs, simply because Safari does the same. |
| // Firefox used to do the same too, until 4.0 where they fixed it. So at some |
| // point we should probably get rid of these scaling constants and rebaseline |
| // all the blur tests. |
| static const SkScalar kBLUR_SIGMA_SCALE = 0.57735f; |
| |
| return radius ? kBLUR_SIGMA_SCALE * radius + 0.5f : 0.0f; |
| } |
| |
| #define UNROLL_SEPARABLE_LOOPS |
| |
| /** |
| * This function performs a box blur in X, of the given radius. If the |
| * "transpose" parameter is true, it will transpose the pixels on write, |
| * such that X and Y are swapped. Reads are always performed from contiguous |
| * memory in X, for speed. The destination buffer (dst) must be at least |
| * (width + leftRadius + rightRadius) * height bytes in size. |
| * |
| * This is what the inner loop looks like before unrolling, and with the two |
| * cases broken out separately (width < diameter, width >= diameter): |
| * |
| * if (width < diameter) { |
| * for (int x = 0; x < width; ++x) { |
| * sum += *right++; |
| * *dptr = (sum * scale + half) >> 24; |
| * dptr += dst_x_stride; |
| * } |
| * for (int x = width; x < diameter; ++x) { |
| * *dptr = (sum * scale + half) >> 24; |
| * dptr += dst_x_stride; |
| * } |
| * for (int x = 0; x < width; ++x) { |
| * *dptr = (sum * scale + half) >> 24; |
| * sum -= *left++; |
| * dptr += dst_x_stride; |
| * } |
| * } else { |
| * for (int x = 0; x < diameter; ++x) { |
| * sum += *right++; |
| * *dptr = (sum * scale + half) >> 24; |
| * dptr += dst_x_stride; |
| * } |
| * for (int x = diameter; x < width; ++x) { |
| * sum += *right++; |
| * *dptr = (sum * scale + half) >> 24; |
| * sum -= *left++; |
| * dptr += dst_x_stride; |
| * } |
| * for (int x = 0; x < diameter; ++x) { |
| * *dptr = (sum * scale + half) >> 24; |
| * sum -= *left++; |
| * dptr += dst_x_stride; |
| * } |
| * } |
| */ |
| static int boxBlur(const uint8_t* src, int src_y_stride, uint8_t* dst, |
| int leftRadius, int rightRadius, int width, int height, |
| bool transpose) |
| { |
| int diameter = leftRadius + rightRadius; |
| int kernelSize = diameter + 1; |
| int border = SkMin32(width, diameter); |
| uint32_t scale = (1 << 24) / kernelSize; |
| int new_width = width + SkMax32(leftRadius, rightRadius) * 2; |
| int dst_x_stride = transpose ? height : 1; |
| int dst_y_stride = transpose ? 1 : new_width; |
| uint32_t half = 1 << 23; |
| for (int y = 0; y < height; ++y) { |
| uint32_t sum = 0; |
| uint8_t* dptr = dst + y * dst_y_stride; |
| const uint8_t* right = src + y * src_y_stride; |
| const uint8_t* left = right; |
| for (int x = 0; x < rightRadius - leftRadius; x++) { |
| *dptr = 0; |
| dptr += dst_x_stride; |
| } |
| #define LEFT_BORDER_ITER \ |
| sum += *right++; \ |
| *dptr = (sum * scale + half) >> 24; \ |
| dptr += dst_x_stride; |
| |
| int x = 0; |
| #ifdef UNROLL_SEPARABLE_LOOPS |
| for (; x < border - 16; x += 16) { |
| LEFT_BORDER_ITER |
| LEFT_BORDER_ITER |
| LEFT_BORDER_ITER |
| LEFT_BORDER_ITER |
| LEFT_BORDER_ITER |
| LEFT_BORDER_ITER |
| LEFT_BORDER_ITER |
| LEFT_BORDER_ITER |
| LEFT_BORDER_ITER |
| LEFT_BORDER_ITER |
| LEFT_BORDER_ITER |
| LEFT_BORDER_ITER |
| LEFT_BORDER_ITER |
| LEFT_BORDER_ITER |
| LEFT_BORDER_ITER |
| LEFT_BORDER_ITER |
| } |
| #endif |
| for (; x < border; ++x) { |
| LEFT_BORDER_ITER |
| } |
| #undef LEFT_BORDER_ITER |
| #define TRIVIAL_ITER \ |
| *dptr = (sum * scale + half) >> 24; \ |
| dptr += dst_x_stride; |
| x = width; |
| #ifdef UNROLL_SEPARABLE_LOOPS |
| for (; x < diameter - 16; x += 16) { |
| TRIVIAL_ITER |
| TRIVIAL_ITER |
| TRIVIAL_ITER |
| TRIVIAL_ITER |
| TRIVIAL_ITER |
| TRIVIAL_ITER |
| TRIVIAL_ITER |
| TRIVIAL_ITER |
| TRIVIAL_ITER |
| TRIVIAL_ITER |
| TRIVIAL_ITER |
| TRIVIAL_ITER |
| TRIVIAL_ITER |
| TRIVIAL_ITER |
| TRIVIAL_ITER |
| TRIVIAL_ITER |
| } |
| #endif |
| for (; x < diameter; ++x) { |
| TRIVIAL_ITER |
| } |
| #undef TRIVIAL_ITER |
| #define CENTER_ITER \ |
| sum += *right++; \ |
| *dptr = (sum * scale + half) >> 24; \ |
| sum -= *left++; \ |
| dptr += dst_x_stride; |
| |
| x = diameter; |
| #ifdef UNROLL_SEPARABLE_LOOPS |
| for (; x < width - 16; x += 16) { |
| CENTER_ITER |
| CENTER_ITER |
| CENTER_ITER |
| CENTER_ITER |
| CENTER_ITER |
| CENTER_ITER |
| CENTER_ITER |
| CENTER_ITER |
| CENTER_ITER |
| CENTER_ITER |
| CENTER_ITER |
| CENTER_ITER |
| CENTER_ITER |
| CENTER_ITER |
| CENTER_ITER |
| CENTER_ITER |
| } |
| #endif |
| for (; x < width; ++x) { |
| CENTER_ITER |
| } |
| #undef CENTER_ITER |
| #define RIGHT_BORDER_ITER \ |
| *dptr = (sum * scale + half) >> 24; \ |
| sum -= *left++; \ |
| dptr += dst_x_stride; |
| |
| x = 0; |
| #ifdef UNROLL_SEPARABLE_LOOPS |
| for (; x < border - 16; x += 16) { |
| RIGHT_BORDER_ITER |
| RIGHT_BORDER_ITER |
| RIGHT_BORDER_ITER |
| RIGHT_BORDER_ITER |
| RIGHT_BORDER_ITER |
| RIGHT_BORDER_ITER |
| RIGHT_BORDER_ITER |
| RIGHT_BORDER_ITER |
| RIGHT_BORDER_ITER |
| RIGHT_BORDER_ITER |
| RIGHT_BORDER_ITER |
| RIGHT_BORDER_ITER |
| RIGHT_BORDER_ITER |
| RIGHT_BORDER_ITER |
| RIGHT_BORDER_ITER |
| RIGHT_BORDER_ITER |
| } |
| #endif |
| for (; x < border; ++x) { |
| RIGHT_BORDER_ITER |
| } |
| #undef RIGHT_BORDER_ITER |
| for (int x = 0; x < leftRadius - rightRadius; ++x) { |
| *dptr = 0; |
| dptr += dst_x_stride; |
| } |
| SkASSERT(sum == 0); |
| } |
| return new_width; |
| } |
| |
| /** |
| * This variant of the box blur handles blurring of non-integer radii. It |
| * keeps two running sums: an outer sum for the rounded-up kernel radius, and |
| * an inner sum for the rounded-down kernel radius. For each pixel, it linearly |
| * interpolates between them. In float this would be: |
| * outer_weight * outer_sum / kernelSize + |
| * (1.0 - outer_weight) * innerSum / (kernelSize - 2) |
| * |
| * This is what the inner loop looks like before unrolling, and with the two |
| * cases broken out separately (width < diameter, width >= diameter): |
| * |
| * if (width < diameter) { |
| * for (int x = 0; x < width; x++) { |
| * inner_sum = outer_sum; |
| * outer_sum += *right++; |
| * *dptr = (outer_sum * outer_scale + inner_sum * inner_scale + half) >> 24; |
| * dptr += dst_x_stride; |
| * } |
| * for (int x = width; x < diameter; ++x) { |
| * *dptr = (outer_sum * outer_scale + inner_sum * inner_scale + half) >> 24; |
| * dptr += dst_x_stride; |
| * } |
| * for (int x = 0; x < width; x++) { |
| * inner_sum = outer_sum - *left++; |
| * *dptr = (outer_sum * outer_scale + inner_sum * inner_scale + half) >> 24; |
| * dptr += dst_x_stride; |
| * outer_sum = inner_sum; |
| * } |
| * } else { |
| * for (int x = 0; x < diameter; x++) { |
| * inner_sum = outer_sum; |
| * outer_sum += *right++; |
| * *dptr = (outer_sum * outer_scale + inner_sum * inner_scale + half) >> 24; |
| * dptr += dst_x_stride; |
| * } |
| * for (int x = diameter; x < width; ++x) { |
| * inner_sum = outer_sum - *left; |
| * outer_sum += *right++; |
| * *dptr = (outer_sum * outer_scale + inner_sum * inner_scale + half) >> 24; |
| * dptr += dst_x_stride; |
| * outer_sum -= *left++; |
| * } |
| * for (int x = 0; x < diameter; x++) { |
| * inner_sum = outer_sum - *left++; |
| * *dptr = (outer_sum * outer_scale + inner_sum * inner_scale + half) >> 24; |
| * dptr += dst_x_stride; |
| * outer_sum = inner_sum; |
| * } |
| * } |
| * } |
| * return new_width; |
| */ |
| |
| static int boxBlurInterp(const uint8_t* src, int src_y_stride, uint8_t* dst, |
| int radius, int width, int height, |
| bool transpose, uint8_t outer_weight) |
| { |
| int diameter = radius * 2; |
| int kernelSize = diameter + 1; |
| int border = SkMin32(width, diameter); |
| int inner_weight = 255 - outer_weight; |
| outer_weight += outer_weight >> 7; |
| inner_weight += inner_weight >> 7; |
| uint32_t outer_scale = (outer_weight << 16) / kernelSize; |
| uint32_t inner_scale = (inner_weight << 16) / (kernelSize - 2); |
| uint32_t half = 1 << 23; |
| int new_width = width + diameter; |
| int dst_x_stride = transpose ? height : 1; |
| int dst_y_stride = transpose ? 1 : new_width; |
| for (int y = 0; y < height; ++y) { |
| uint32_t outer_sum = 0, inner_sum = 0; |
| uint8_t* dptr = dst + y * dst_y_stride; |
| const uint8_t* right = src + y * src_y_stride; |
| const uint8_t* left = right; |
| int x = 0; |
| |
| #define LEFT_BORDER_ITER \ |
| inner_sum = outer_sum; \ |
| outer_sum += *right++; \ |
| *dptr = (outer_sum * outer_scale + inner_sum * inner_scale + half) >> 24; \ |
| dptr += dst_x_stride; |
| |
| #ifdef UNROLL_SEPARABLE_LOOPS |
| for (;x < border - 16; x += 16) { |
| LEFT_BORDER_ITER |
| LEFT_BORDER_ITER |
| LEFT_BORDER_ITER |
| LEFT_BORDER_ITER |
| LEFT_BORDER_ITER |
| LEFT_BORDER_ITER |
| LEFT_BORDER_ITER |
| LEFT_BORDER_ITER |
| LEFT_BORDER_ITER |
| LEFT_BORDER_ITER |
| LEFT_BORDER_ITER |
| LEFT_BORDER_ITER |
| LEFT_BORDER_ITER |
| LEFT_BORDER_ITER |
| LEFT_BORDER_ITER |
| LEFT_BORDER_ITER |
| } |
| #endif |
| |
| for (;x < border; ++x) { |
| LEFT_BORDER_ITER |
| } |
| #undef LEFT_BORDER_ITER |
| for (int x = width; x < diameter; ++x) { |
| *dptr = (outer_sum * outer_scale + inner_sum * inner_scale + half) >> 24; |
| dptr += dst_x_stride; |
| } |
| x = diameter; |
| |
| #define CENTER_ITER \ |
| inner_sum = outer_sum - *left; \ |
| outer_sum += *right++; \ |
| *dptr = (outer_sum * outer_scale + inner_sum * inner_scale + half) >> 24; \ |
| dptr += dst_x_stride; \ |
| outer_sum -= *left++; |
| |
| #ifdef UNROLL_SEPARABLE_LOOPS |
| for (; x < width - 16; x += 16) { |
| CENTER_ITER |
| CENTER_ITER |
| CENTER_ITER |
| CENTER_ITER |
| CENTER_ITER |
| CENTER_ITER |
| CENTER_ITER |
| CENTER_ITER |
| CENTER_ITER |
| CENTER_ITER |
| CENTER_ITER |
| CENTER_ITER |
| CENTER_ITER |
| CENTER_ITER |
| CENTER_ITER |
| CENTER_ITER |
| } |
| #endif |
| for (; x < width; ++x) { |
| CENTER_ITER |
| } |
| #undef CENTER_ITER |
| |
| #define RIGHT_BORDER_ITER \ |
| inner_sum = outer_sum - *left++; \ |
| *dptr = (outer_sum * outer_scale + inner_sum * inner_scale + half) >> 24; \ |
| dptr += dst_x_stride; \ |
| outer_sum = inner_sum; |
| |
| x = 0; |
| #ifdef UNROLL_SEPARABLE_LOOPS |
| for (; x < border - 16; x += 16) { |
| RIGHT_BORDER_ITER |
| RIGHT_BORDER_ITER |
| RIGHT_BORDER_ITER |
| RIGHT_BORDER_ITER |
| RIGHT_BORDER_ITER |
| RIGHT_BORDER_ITER |
| RIGHT_BORDER_ITER |
| RIGHT_BORDER_ITER |
| RIGHT_BORDER_ITER |
| RIGHT_BORDER_ITER |
| RIGHT_BORDER_ITER |
| RIGHT_BORDER_ITER |
| RIGHT_BORDER_ITER |
| RIGHT_BORDER_ITER |
| RIGHT_BORDER_ITER |
| RIGHT_BORDER_ITER |
| } |
| #endif |
| for (; x < border; ++x) { |
| RIGHT_BORDER_ITER |
| } |
| #undef RIGHT_BORDER_ITER |
| SkASSERT(outer_sum == 0 && inner_sum == 0); |
| } |
| return new_width; |
| } |
| |
| static void get_adjusted_radii(SkScalar passRadius, int *loRadius, int *hiRadius) |
| { |
| *loRadius = *hiRadius = SkScalarCeilToInt(passRadius); |
| if (SkIntToScalar(*hiRadius) - passRadius > 0.5f) { |
| *loRadius = *hiRadius - 1; |
| } |
| } |
| |
| #include "SkColorPriv.h" |
| |
| static void merge_src_with_blur(uint8_t dst[], int dstRB, |
| const uint8_t src[], int srcRB, |
| const uint8_t blur[], int blurRB, |
| int sw, int sh) { |
| dstRB -= sw; |
| srcRB -= sw; |
| blurRB -= sw; |
| while (--sh >= 0) { |
| for (int x = sw - 1; x >= 0; --x) { |
| *dst = SkToU8(SkAlphaMul(*blur, SkAlpha255To256(*src))); |
| dst += 1; |
| src += 1; |
| blur += 1; |
| } |
| dst += dstRB; |
| src += srcRB; |
| blur += blurRB; |
| } |
| } |
| |
| static void clamp_with_orig(uint8_t dst[], int dstRowBytes, |
| const uint8_t src[], int srcRowBytes, |
| int sw, int sh, |
| SkBlurMask::Style style) { |
| int x; |
| while (--sh >= 0) { |
| switch (style) { |
| case SkBlurMask::kSolid_Style: |
| for (x = sw - 1; x >= 0; --x) { |
| int s = *src; |
| int d = *dst; |
| *dst = SkToU8(s + d - SkMulDiv255Round(s, d)); |
| dst += 1; |
| src += 1; |
| } |
| break; |
| case SkBlurMask::kOuter_Style: |
| for (x = sw - 1; x >= 0; --x) { |
| if (*src) { |
| *dst = SkToU8(SkAlphaMul(*dst, SkAlpha255To256(255 - *src))); |
| } |
| dst += 1; |
| src += 1; |
| } |
| break; |
| default: |
| SkDEBUGFAIL("Unexpected blur style here"); |
| break; |
| } |
| dst += dstRowBytes - sw; |
| src += srcRowBytes - sw; |
| } |
| } |
| |
| /////////////////////////////////////////////////////////////////////////////// |
| |
| // we use a local function to wrap the class static method to work around |
| // a bug in gcc98 |
| void SkMask_FreeImage(uint8_t* image); |
| void SkMask_FreeImage(uint8_t* image) { |
| SkMask::FreeImage(image); |
| } |
| |
| bool SkBlurMask::Blur(SkMask* dst, const SkMask& src, |
| SkScalar radius, Style style, Quality quality, |
| SkIPoint* margin) { |
| return SkBlurMask::BoxBlur(dst, src, |
| SkBlurMask::ConvertRadiusToSigma(radius), |
| style, quality, margin); |
| } |
| |
| bool SkBlurMask::BoxBlur(SkMask* dst, const SkMask& src, |
| SkScalar sigma, Style style, Quality quality, |
| SkIPoint* margin) { |
| |
| if (src.fFormat != SkMask::kA8_Format) { |
| return false; |
| } |
| |
| // Force high quality off for small radii (performance) |
| if (sigma <= SkIntToScalar(2)) { |
| quality = kLow_Quality; |
| } |
| |
| SkScalar passRadius; |
| if (kHigh_Quality == quality) { |
| // For the high quality path the 3 pass box blur kernel width is |
| // 6*rad+1 while the full Gaussian width is 6*sigma. |
| passRadius = sigma - (1/6.0f); |
| } else { |
| // For the low quality path we only attempt to cover 3*sigma of the |
| // Gaussian blur area (1.5*sigma on each side). The single pass box |
| // blur's kernel size is 2*rad+1. |
| passRadius = 1.5f*sigma - 0.5f; |
| } |
| |
| // highQuality: use three box blur passes as a cheap way |
| // to approximate a Gaussian blur |
| int passCount = (kHigh_Quality == quality) ? 3 : 1; |
| |
| int rx = SkScalarCeilToInt(passRadius); |
| int outerWeight = 255 - SkScalarRoundToInt((SkIntToScalar(rx) - passRadius) * 255); |
| |
| SkASSERT(rx >= 0); |
| SkASSERT((unsigned)outerWeight <= 255); |
| if (rx <= 0) { |
| return false; |
| } |
| |
| int ry = rx; // only do square blur for now |
| |
| int padx = passCount * rx; |
| int pady = passCount * ry; |
| |
| if (margin) { |
| margin->set(padx, pady); |
| } |
| dst->fBounds.set(src.fBounds.fLeft - padx, src.fBounds.fTop - pady, |
| src.fBounds.fRight + padx, src.fBounds.fBottom + pady); |
| |
| dst->fRowBytes = dst->fBounds.width(); |
| dst->fFormat = SkMask::kA8_Format; |
| dst->fImage = NULL; |
| |
| if (src.fImage) { |
| size_t dstSize = dst->computeImageSize(); |
| if (0 == dstSize) { |
| return false; // too big to allocate, abort |
| } |
| |
| int sw = src.fBounds.width(); |
| int sh = src.fBounds.height(); |
| const uint8_t* sp = src.fImage; |
| uint8_t* dp = SkMask::AllocImage(dstSize); |
| SkAutoTCallVProc<uint8_t, SkMask_FreeImage> autoCall(dp); |
| |
| // build the blurry destination |
| SkAutoTMalloc<uint8_t> tmpBuffer(dstSize); |
| uint8_t* tp = tmpBuffer.get(); |
| int w = sw, h = sh; |
| |
| if (outerWeight == 255) { |
| int loRadius, hiRadius; |
| get_adjusted_radii(passRadius, &loRadius, &hiRadius); |
| if (kHigh_Quality == quality) { |
| // Do three X blurs, with a transpose on the final one. |
| w = boxBlur(sp, src.fRowBytes, tp, loRadius, hiRadius, w, h, false); |
| w = boxBlur(tp, w, dp, hiRadius, loRadius, w, h, false); |
| w = boxBlur(dp, w, tp, hiRadius, hiRadius, w, h, true); |
| // Do three Y blurs, with a transpose on the final one. |
| h = boxBlur(tp, h, dp, loRadius, hiRadius, h, w, false); |
| h = boxBlur(dp, h, tp, hiRadius, loRadius, h, w, false); |
| h = boxBlur(tp, h, dp, hiRadius, hiRadius, h, w, true); |
| } else { |
| w = boxBlur(sp, src.fRowBytes, tp, rx, rx, w, h, true); |
| h = boxBlur(tp, h, dp, ry, ry, h, w, true); |
| } |
| } else { |
| if (kHigh_Quality == quality) { |
| // Do three X blurs, with a transpose on the final one. |
| w = boxBlurInterp(sp, src.fRowBytes, tp, rx, w, h, false, outerWeight); |
| w = boxBlurInterp(tp, w, dp, rx, w, h, false, outerWeight); |
| w = boxBlurInterp(dp, w, tp, rx, w, h, true, outerWeight); |
| // Do three Y blurs, with a transpose on the final one. |
| h = boxBlurInterp(tp, h, dp, ry, h, w, false, outerWeight); |
| h = boxBlurInterp(dp, h, tp, ry, h, w, false, outerWeight); |
| h = boxBlurInterp(tp, h, dp, ry, h, w, true, outerWeight); |
| } else { |
| w = boxBlurInterp(sp, src.fRowBytes, tp, rx, w, h, true, outerWeight); |
| h = boxBlurInterp(tp, h, dp, ry, h, w, true, outerWeight); |
| } |
| } |
| |
| dst->fImage = dp; |
| // if need be, alloc the "real" dst (same size as src) and copy/merge |
| // the blur into it (applying the src) |
| if (style == kInner_Style) { |
| // now we allocate the "real" dst, mirror the size of src |
| size_t srcSize = src.computeImageSize(); |
| if (0 == srcSize) { |
| return false; // too big to allocate, abort |
| } |
| dst->fImage = SkMask::AllocImage(srcSize); |
| merge_src_with_blur(dst->fImage, src.fRowBytes, |
| sp, src.fRowBytes, |
| dp + passCount * (rx + ry * dst->fRowBytes), |
| dst->fRowBytes, sw, sh); |
| SkMask::FreeImage(dp); |
| } else if (style != kNormal_Style) { |
| clamp_with_orig(dp + passCount * (rx + ry * dst->fRowBytes), |
| dst->fRowBytes, sp, src.fRowBytes, sw, sh, style); |
| } |
| (void)autoCall.detach(); |
| } |
| |
| if (style == kInner_Style) { |
| dst->fBounds = src.fBounds; // restore trimmed bounds |
| dst->fRowBytes = src.fRowBytes; |
| } |
| |
| return true; |
| } |
| |
| /* Convolving a box with itself three times results in a piecewise |
| quadratic function: |
| |
| 0 x <= -1.5 |
| 9/8 + 3/2 x + 1/2 x^2 -1.5 < x <= -.5 |
| 3/4 - x^2 -.5 < x <= .5 |
| 9/8 - 3/2 x + 1/2 x^2 0.5 < x <= 1.5 |
| 0 1.5 < x |
| |
| Mathematica: |
| |
| g[x_] := Piecewise [ { |
| {9/8 + 3/2 x + 1/2 x^2 , -1.5 < x <= -.5}, |
| {3/4 - x^2 , -.5 < x <= .5}, |
| {9/8 - 3/2 x + 1/2 x^2 , 0.5 < x <= 1.5} |
| }, 0] |
| |
| To get the profile curve of the blurred step function at the rectangle |
| edge, we evaluate the indefinite integral, which is piecewise cubic: |
| |
| 0 x <= -1.5 |
| 9/16 + 9/8 x + 3/4 x^2 + 1/6 x^3 -1.5 < x <= -0.5 |
| 1/2 + 3/4 x - 1/3 x^3 -.5 < x <= .5 |
| 7/16 + 9/8 x - 3/4 x^2 + 1/6 x^3 .5 < x <= 1.5 |
| 1 1.5 < x |
| |
| in Mathematica code: |
| |
| gi[x_] := Piecewise[ { |
| { 0 , x <= -1.5 }, |
| { 9/16 + 9/8 x + 3/4 x^2 + 1/6 x^3, -1.5 < x <= -0.5 }, |
| { 1/2 + 3/4 x - 1/3 x^3 , -.5 < x <= .5}, |
| { 7/16 + 9/8 x - 3/4 x^2 + 1/6 x^3, .5 < x <= 1.5} |
| },1] |
| */ |
| |
| static float gaussianIntegral(float x) { |
| if (x > 1.5f) { |
| return 0.0f; |
| } |
| if (x < -1.5f) { |
| return 1.0f; |
| } |
| |
| float x2 = x*x; |
| float x3 = x2*x; |
| |
| if ( x > 0.5f ) { |
| return 0.5625f - (x3 / 6.0f - 3.0f * x2 * 0.25f + 1.125f * x); |
| } |
| if ( x > -0.5f ) { |
| return 0.5f - (0.75f * x - x3 / 3.0f); |
| } |
| return 0.4375f + (-x3 / 6.0f - 3.0f * x2 * 0.25f - 1.125f * x); |
| } |
| |
| /* compute_profile allocates and fills in an array of floating |
| point values between 0 and 255 for the profile signature of |
| a blurred half-plane with the given blur radius. Since we're |
| going to be doing screened multiplications (i.e., 1 - (1-x)(1-y)) |
| all the time, we actually fill in the profile pre-inverted |
| (already done 255-x). |
| |
| It's the responsibility of the caller to delete the |
| memory returned in profile_out. |
| */ |
| |
| static void compute_profile(SkScalar sigma, unsigned int **profile_out) { |
| int size = SkScalarCeilToInt(6*sigma); |
| |
| int center = size >> 1; |
| unsigned int *profile = SkNEW_ARRAY(unsigned int, size); |
| |
| float invr = 1.f/(2*sigma); |
| |
| profile[0] = 255; |
| for (int x = 1 ; x < size ; ++x) { |
| float scaled_x = (center - x - .5f) * invr; |
| float gi = gaussianIntegral(scaled_x); |
| profile[x] = 255 - (uint8_t) (255.f * gi); |
| } |
| |
| *profile_out = profile; |
| } |
| |
| // TODO MAYBE: Maintain a profile cache to avoid recomputing this for |
| // commonly used radii. Consider baking some of the most common blur radii |
| // directly in as static data? |
| |
| // Implementation adapted from Michael Herf's approach: |
| // http://stereopsis.com/shadowrect/ |
| |
| static inline unsigned int profile_lookup( unsigned int *profile, int loc, int blurred_width, int sharp_width ) { |
| int dx = SkAbs32(((loc << 1) + 1) - blurred_width) - sharp_width; // how far are we from the original edge? |
| int ox = dx >> 1; |
| if (ox < 0) { |
| ox = 0; |
| } |
| |
| return profile[ox]; |
| } |
| |
| bool SkBlurMask::BlurRect(SkMask *dst, const SkRect &src, |
| SkScalar radius, Style style, |
| SkIPoint *margin, SkMask::CreateMode createMode) { |
| return SkBlurMask::BlurRect(SkBlurMask::ConvertRadiusToSigma(radius), |
| dst, src, |
| style, margin, createMode); |
| } |
| |
| bool SkBlurMask::BlurRect(SkScalar sigma, SkMask *dst, |
| const SkRect &src, Style style, |
| SkIPoint *margin, SkMask::CreateMode createMode) { |
| int profile_size = SkScalarCeilToInt(6*sigma); |
| |
| int pad = profile_size/2; |
| if (margin) { |
| margin->set( pad, pad ); |
| } |
| |
| dst->fBounds.set(SkScalarRoundToInt(src.fLeft - pad), |
| SkScalarRoundToInt(src.fTop - pad), |
| SkScalarRoundToInt(src.fRight + pad), |
| SkScalarRoundToInt(src.fBottom + pad)); |
| |
| dst->fRowBytes = dst->fBounds.width(); |
| dst->fFormat = SkMask::kA8_Format; |
| dst->fImage = NULL; |
| |
| int sw = SkScalarFloorToInt(src.width()); |
| int sh = SkScalarFloorToInt(src.height()); |
| |
| if (createMode == SkMask::kJustComputeBounds_CreateMode) { |
| if (style == kInner_Style) { |
| dst->fBounds.set(SkScalarRoundToInt(src.fLeft), |
| SkScalarRoundToInt(src.fTop), |
| SkScalarRoundToInt(src.fRight), |
| SkScalarRoundToInt(src.fBottom)); // restore trimmed bounds |
| dst->fRowBytes = sw; |
| } |
| return true; |
| } |
| unsigned int *profile = NULL; |
| |
| compute_profile(sigma, &profile); |
| SkAutoTDeleteArray<unsigned int> ada(profile); |
| |
| size_t dstSize = dst->computeImageSize(); |
| if (0 == dstSize) { |
| return false; // too big to allocate, abort |
| } |
| |
| uint8_t* dp = SkMask::AllocImage(dstSize); |
| |
| dst->fImage = dp; |
| |
| int dstHeight = dst->fBounds.height(); |
| int dstWidth = dst->fBounds.width(); |
| |
| // nearest odd number less than the profile size represents the center |
| // of the (2x scaled) profile |
| int center = ( profile_size & ~1 ) - 1; |
| |
| int w = sw - center; |
| int h = sh - center; |
| |
| uint8_t *outptr = dp; |
| |
| SkAutoTMalloc<uint8_t> horizontalScanline(dstWidth); |
| |
| for (int x = 0 ; x < dstWidth ; ++x) { |
| if (profile_size <= sw) { |
| horizontalScanline[x] = profile_lookup(profile, x, dstWidth, w); |
| } else { |
| float span = float(sw)/(2*sigma); |
| float giX = 1.5f - (x+.5f)/(2*sigma); |
| horizontalScanline[x] = (uint8_t) (255 * (gaussianIntegral(giX) - gaussianIntegral(giX + span))); |
| } |
| } |
| |
| for (int y = 0 ; y < dstHeight ; ++y) { |
| unsigned int profile_y; |
| if (profile_size <= sh) { |
| profile_y = profile_lookup(profile, y, dstHeight, h); |
| } else { |
| float span = float(sh)/(2*sigma); |
| float giY = 1.5f - (y+.5f)/(2*sigma); |
| profile_y = (uint8_t) (255 * (gaussianIntegral(giY) - gaussianIntegral(giY + span))); |
| } |
| |
| for (int x = 0 ; x < dstWidth ; x++) { |
| unsigned int maskval = SkMulDiv255Round(horizontalScanline[x], profile_y); |
| *(outptr++) = maskval; |
| } |
| } |
| |
| if (style == kInner_Style) { |
| // now we allocate the "real" dst, mirror the size of src |
| size_t srcSize = (size_t)(src.width() * src.height()); |
| if (0 == srcSize) { |
| return false; // too big to allocate, abort |
| } |
| dst->fImage = SkMask::AllocImage(srcSize); |
| for (int y = 0 ; y < sh ; y++) { |
| uint8_t *blur_scanline = dp + (y+pad)*dstWidth + pad; |
| uint8_t *inner_scanline = dst->fImage + y*sw; |
| memcpy(inner_scanline, blur_scanline, sw); |
| } |
| SkMask::FreeImage(dp); |
| |
| dst->fBounds.set(SkScalarRoundToInt(src.fLeft), |
| SkScalarRoundToInt(src.fTop), |
| SkScalarRoundToInt(src.fRight), |
| SkScalarRoundToInt(src.fBottom)); // restore trimmed bounds |
| dst->fRowBytes = sw; |
| |
| } else if (style == kOuter_Style) { |
| for (int y = pad ; y < dstHeight-pad ; y++) { |
| uint8_t *dst_scanline = dp + y*dstWidth + pad; |
| memset(dst_scanline, 0, sw); |
| } |
| } else if (style == kSolid_Style) { |
| for (int y = pad ; y < dstHeight-pad ; y++) { |
| uint8_t *dst_scanline = dp + y*dstWidth + pad; |
| memset(dst_scanline, 0xff, sw); |
| } |
| } |
| // normal and solid styles are the same for analytic rect blurs, so don't |
| // need to handle solid specially. |
| |
| return true; |
| } |
| |
| bool SkBlurMask::BlurGroundTruth(SkMask* dst, const SkMask& src, SkScalar radius, |
| Style style, SkIPoint* margin) { |
| return BlurGroundTruth(ConvertRadiusToSigma(radius), dst, src, style, margin); |
| } |
| // The "simple" blur is a direct implementation of separable convolution with a discrete |
| // gaussian kernel. It's "ground truth" in a sense; too slow to be used, but very |
| // useful for correctness comparisons. |
| |
| bool SkBlurMask::BlurGroundTruth(SkScalar sigma, SkMask* dst, const SkMask& src, |
| Style style, SkIPoint* margin) { |
| |
| if (src.fFormat != SkMask::kA8_Format) { |
| return false; |
| } |
| |
| float variance = sigma * sigma; |
| |
| int windowSize = SkScalarCeilToInt(sigma*6); |
| // round window size up to nearest odd number |
| windowSize |= 1; |
| |
| SkAutoTMalloc<float> gaussWindow(windowSize); |
| |
| int halfWindow = windowSize >> 1; |
| |
| gaussWindow[halfWindow] = 1; |
| |
| float windowSum = 1; |
| for (int x = 1 ; x <= halfWindow ; ++x) { |
| float gaussian = expf(-x*x / (2*variance)); |
| gaussWindow[halfWindow + x] = gaussWindow[halfWindow-x] = gaussian; |
| windowSum += 2*gaussian; |
| } |
| |
| // leave the filter un-normalized for now; we will divide by the normalization |
| // sum later; |
| |
| int pad = halfWindow; |
| if (margin) { |
| margin->set( pad, pad ); |
| } |
| |
| dst->fBounds = src.fBounds; |
| dst->fBounds.outset(pad, pad); |
| |
| dst->fRowBytes = dst->fBounds.width(); |
| dst->fFormat = SkMask::kA8_Format; |
| dst->fImage = NULL; |
| |
| if (src.fImage) { |
| |
| size_t dstSize = dst->computeImageSize(); |
| if (0 == dstSize) { |
| return false; // too big to allocate, abort |
| } |
| |
| int srcWidth = src.fBounds.width(); |
| int srcHeight = src.fBounds.height(); |
| int dstWidth = dst->fBounds.width(); |
| |
| const uint8_t* srcPixels = src.fImage; |
| uint8_t* dstPixels = SkMask::AllocImage(dstSize); |
| SkAutoTCallVProc<uint8_t, SkMask_FreeImage> autoCall(dstPixels); |
| |
| // do the actual blur. First, make a padded copy of the source. |
| // use double pad so we never have to check if we're outside anything |
| |
| int padWidth = srcWidth + 4*pad; |
| int padHeight = srcHeight; |
| int padSize = padWidth * padHeight; |
| |
| SkAutoTMalloc<uint8_t> padPixels(padSize); |
| memset(padPixels, 0, padSize); |
| |
| for (int y = 0 ; y < srcHeight; ++y) { |
| uint8_t* padptr = padPixels + y * padWidth + 2*pad; |
| const uint8_t* srcptr = srcPixels + y * srcWidth; |
| memcpy(padptr, srcptr, srcWidth); |
| } |
| |
| // blur in X, transposing the result into a temporary floating point buffer. |
| // also double-pad the intermediate result so that the second blur doesn't |
| // have to do extra conditionals. |
| |
| int tmpWidth = padHeight + 4*pad; |
| int tmpHeight = padWidth - 2*pad; |
| int tmpSize = tmpWidth * tmpHeight; |
| |
| SkAutoTMalloc<float> tmpImage(tmpSize); |
| memset(tmpImage, 0, tmpSize*sizeof(tmpImage[0])); |
| |
| for (int y = 0 ; y < padHeight ; ++y) { |
| uint8_t *srcScanline = padPixels + y*padWidth; |
| for (int x = pad ; x < padWidth - pad ; ++x) { |
| float *outPixel = tmpImage + (x-pad)*tmpWidth + y + 2*pad; // transposed output |
| uint8_t *windowCenter = srcScanline + x; |
| for (int i = -pad ; i <= pad ; ++i) { |
| *outPixel += gaussWindow[pad+i]*windowCenter[i]; |
| } |
| *outPixel /= windowSum; |
| } |
| } |
| |
| // blur in Y; now filling in the actual desired destination. We have to do |
| // the transpose again; these transposes guarantee that we read memory in |
| // linear order. |
| |
| for (int y = 0 ; y < tmpHeight ; ++y) { |
| float *srcScanline = tmpImage + y*tmpWidth; |
| for (int x = pad ; x < tmpWidth - pad ; ++x) { |
| float *windowCenter = srcScanline + x; |
| float finalValue = 0; |
| for (int i = -pad ; i <= pad ; ++i) { |
| finalValue += gaussWindow[pad+i]*windowCenter[i]; |
| } |
| finalValue /= windowSum; |
| uint8_t *outPixel = dstPixels + (x-pad)*dstWidth + y; // transposed output |
| int integerPixel = int(finalValue + 0.5f); |
| *outPixel = SkClampMax( SkClampPos(integerPixel), 255 ); |
| } |
| } |
| |
| dst->fImage = dstPixels; |
| // if need be, alloc the "real" dst (same size as src) and copy/merge |
| // the blur into it (applying the src) |
| if (style == kInner_Style) { |
| // now we allocate the "real" dst, mirror the size of src |
| size_t srcSize = src.computeImageSize(); |
| if (0 == srcSize) { |
| return false; // too big to allocate, abort |
| } |
| dst->fImage = SkMask::AllocImage(srcSize); |
| merge_src_with_blur(dst->fImage, src.fRowBytes, |
| srcPixels, src.fRowBytes, |
| dstPixels + pad*dst->fRowBytes + pad, |
| dst->fRowBytes, srcWidth, srcHeight); |
| SkMask::FreeImage(dstPixels); |
| } else if (style != kNormal_Style) { |
| clamp_with_orig(dstPixels + pad*dst->fRowBytes + pad, |
| dst->fRowBytes, srcPixels, src.fRowBytes, srcWidth, srcHeight, style); |
| } |
| (void)autoCall.detach(); |
| } |
| |
| if (style == kInner_Style) { |
| dst->fBounds = src.fBounds; // restore trimmed bounds |
| dst->fRowBytes = src.fRowBytes; |
| } |
| |
| return true; |
| } |