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skia2/src/effects/SkBlurMask.cpp
robertphillips d8982d7e92 Revert of Have GrRectBlurEffect use Linear filtering (rather than Nearest Neighbor) (patchset #2 id:20001 of https://codereview.chromium.org/1378023004/ ) 
Reason for revert:
Trial run confirmed layout test expectations - will reland after suppressions

Original issue's description:
> Have GrRectBlurEffect use Linear filtering (rather than Nearest Neighbor)
>
> Committed: https://skia.googlesource.com/skia/+/2d70bcccc9ba8f3898a7ae506ba7410ed8e9c9db
>
> Committed: https://skia.googlesource.com/skia/+/5175b9563055926b4969d57f06e4ae49b86e055b

TBR=bsalomon@google.com
NOPRESUBMIT=true
NOTREECHECKS=true
NOTRY=true

Review URL: https://codereview.chromium.org/1378813004
2015-10-04 12:21:33 -07:00

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/*
* 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"
// 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;
SkScalar SkBlurMask::ConvertRadiusToSigma(SkScalar radius) {
return radius > 0 ? kBLUR_SIGMA_SCALE * radius + 0.5f : 0.0f;
}
SkScalar SkBlurMask::ConvertSigmaToRadius(SkScalar sigma) {
return sigma > 0.5f ? (sigma - 0.5f) / kBLUR_SIGMA_SCALE : 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,
SkBlurStyle style) {
int x;
while (--sh >= 0) {
switch (style) {
case kSolid_SkBlurStyle:
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 kOuter_SkBlurStyle:
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::BoxBlur(SkMask* dst, const SkMask& src,
SkScalar sigma, SkBlurStyle style, SkBlurQuality quality,
SkIPoint* margin, bool force_quality) {
if (src.fFormat != SkMask::kA8_Format) {
return false;
}
// Force high quality off for small radii (performance)
if (!force_quality && sigma <= SkIntToScalar(2)) {
quality = kLow_SkBlurQuality;
}
SkScalar passRadius;
if (kHigh_SkBlurQuality == 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_SkBlurQuality == 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 = nullptr;
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_SkBlurQuality == 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_SkBlurQuality == 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_SkBlurStyle) {
// 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_SkBlurStyle) {
clamp_with_orig(dp + passCount * (rx + ry * dst->fRowBytes),
dst->fRowBytes, sp, src.fRowBytes, sw, sh, style);
}
(void)autoCall.detach();
}
if (style == kInner_SkBlurStyle) {
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);
}
/* ComputeBlurProfile 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.
*/
uint8_t* SkBlurMask::ComputeBlurProfile(SkScalar sigma) {
int size = SkScalarCeilToInt(6*sigma);
int center = size >> 1;
uint8_t* profile = new uint8_t[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);
}
return 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/
uint8_t SkBlurMask::ProfileLookup(const uint8_t *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];
}
void SkBlurMask::ComputeBlurredScanline(uint8_t *pixels, const uint8_t *profile,
unsigned int width, SkScalar sigma) {
unsigned int profile_size = SkScalarCeilToInt(6*sigma);
SkAutoTMalloc<uint8_t> horizontalScanline(width);
unsigned int sw = width - profile_size;
// 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;
for (unsigned int x = 0 ; x < width ; ++x) {
if (profile_size <= sw) {
pixels[x] = ProfileLookup(profile, x, width, w);
} else {
float span = float(sw)/(2*sigma);
float giX = 1.5f - (x+.5f)/(2*sigma);
pixels[x] = (uint8_t) (255 * (gaussianIntegral(giX) - gaussianIntegral(giX + span)));
}
}
}
bool SkBlurMask::BlurRect(SkScalar sigma, SkMask *dst,
const SkRect &src, SkBlurStyle 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 = nullptr;
int sw = SkScalarFloorToInt(src.width());
int sh = SkScalarFloorToInt(src.height());
if (createMode == SkMask::kJustComputeBounds_CreateMode) {
if (style == kInner_SkBlurStyle) {
dst->fBounds.set(SkScalarRoundToInt(src.fLeft),
SkScalarRoundToInt(src.fTop),
SkScalarRoundToInt(src.fRight),
SkScalarRoundToInt(src.fBottom)); // restore trimmed bounds
dst->fRowBytes = sw;
}
return true;
}
SkAutoTDeleteArray<uint8_t> profile(ComputeBlurProfile(sigma));
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();
uint8_t *outptr = dp;
SkAutoTMalloc<uint8_t> horizontalScanline(dstWidth);
SkAutoTMalloc<uint8_t> verticalScanline(dstHeight);
ComputeBlurredScanline(horizontalScanline, profile.get(), dstWidth, sigma);
ComputeBlurredScanline(verticalScanline, profile.get(), dstHeight, sigma);
for (int y = 0 ; y < dstHeight ; ++y) {
for (int x = 0 ; x < dstWidth ; x++) {
unsigned int maskval = SkMulDiv255Round(horizontalScanline[x], verticalScanline[y]);
*(outptr++) = maskval;
}
}
if (style == kInner_SkBlurStyle) {
// 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_SkBlurStyle) {
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_SkBlurStyle) {
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::BlurRRect(SkScalar sigma, SkMask *dst,
const SkRRect &src, SkBlurStyle style,
SkIPoint *margin, SkMask::CreateMode createMode) {
// Temporary for now -- always fail, should cause caller to fall back
// to old path. Plumbing just to land API and parallelize effort.
return false;
}
// 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,
SkBlurStyle 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 = nullptr;
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_SkBlurStyle) {
// 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_SkBlurStyle) {
clamp_with_orig(dstPixels + pad*dst->fRowBytes + pad,
dst->fRowBytes, srcPixels, src.fRowBytes, srcWidth, srcHeight, style);
}
(void)autoCall.detach();
}
if (style == kInner_SkBlurStyle) {
dst->fBounds = src.fBounds; // restore trimmed bounds
dst->fRowBytes = src.fRowBytes;
}
return true;
}
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