Revert "Revert "Revert "Add an average mode for sigma < 2"""

This reverts commit f6975ea5fb178c572cf4c1cd255e5fe623418d45.

Reason for revert:
Did not take into account there are layout test problems too. Adding a legacy flag.

Original change's description:
> Revert "Revert "Add an average mode for sigma < 2""
> 
> We are going to have the google3 auto roller build the CL,
> and add the fixes to the failing tests to that CL. Because
> these are scuba changes, this should be simpler.
> 
> This reverts commit 8e7503195c40492df6a9c072d3303c9df9ec32dc.
> 
> Reason for revert: <INSERT REASONING HERE>
> 
> Original change's description:
> > Revert "Add an average mode for sigma < 2"
> > 
> > This reverts commit ba8275148ab8b10393b053e2586b852796c4afc2.
> > 
> > Reason for revert: layout tests, Google3 equivalent failing.
> > 
> > Original change's description:
> > > Add an average mode for sigma < 2
> > > 
> > > 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>
> > 
> > TBR=mtklein@chromium.org,mtklein@google.com,herb@google.com
> > 
> > Change-Id: Ie8f38b042acec42260913cb7bed5538a2c957e9b
> > No-Presubmit: true
> > No-Tree-Checks: true
> > No-Try: true
> > Bug: chromium:745290
> > Reviewed-on: https://skia-review.googlesource.com/34640
> > Reviewed-by: Mike Klein <mtklein@google.com>
> > Commit-Queue: Mike Klein <mtklein@google.com>
> 
> TBR=mtklein@chromium.org,mtklein@google.com,herb@google.com
> 
> Change-Id: I5f7b706a2f8c8d52b3576c638ecddf12a1652031
> No-Presubmit: true
> No-Tree-Checks: true
> No-Try: true
> Bug: chromium:745290
> Reviewed-on: https://skia-review.googlesource.com/34641
> Reviewed-by: Herb Derby <herb@google.com>
> Commit-Queue: Herb Derby <herb@google.com>

TBR=mtklein@chromium.org,mtklein@google.com,herb@google.com

Change-Id: I9064f8494e5a1a4a78dd545697e22f52985c0fa1
No-Presubmit: true
No-Tree-Checks: true
No-Try: true
Bug: chromium:745290
Reviewed-on: https://skia-review.googlesource.com/34623
Reviewed-by: Herb Derby <herb@google.com>
Commit-Queue: Herb Derby <herb@google.com>

1 files changed, 4 insertions, 99 deletions

diff --git a/src/core/SkMaskBlurFilter.cpp b/src/core/SkMaskBlurFilter.cpp
index 7eba2dab8d..42837f79a9 100644
--- a/src/core/SkMaskBlurFilter.cpp
+++ b/src/core/SkMaskBlurFilter.cpp
@@ -25,36 +25,22 @@ static uint64_t weight_from_diameter(uint32_t d) {
 }
 
 static uint32_t filter_window(double sigma) {
-    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));
+    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)
-    : 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);
-}
+    : fFilterWindow{filter_window(sigma)}
+    , fScaledWeight{(static_cast<uint64_t>(1) << 32) / weight_from_diameter(fFilterWindow)} {}
 
 uint64_t SkMaskBlurFilter::FilterInfo::weight() const {
-    return fWeight;
+    return weight_from_diameter(fFilterWindow);
 
 }
 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);
 }
 
@@ -77,10 +63,6 @@ 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))}
@@ -186,83 +168,6 @@ 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 {
 
     auto buffer0Begin = &fBuffer0[0];
     auto buffer1Begin = &fBuffer1[0];