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/*
* Copyright (C) 2004, 2005, 2006, 2007 Nikolas Zimmermann <zimmermann@kde.org>
* Copyright (C) 2004, 2005 Rob Buis <buis@kde.org>
* Copyright (C) 2005 Eric Seidel <eric@webkit.org>
* Copyright (C) 2009 Dirk Schulze <krit@webkit.org>
* Copyright (C) 2010 Igalia, S.L.
* Copyright (C) Research In Motion Limited 2010. All rights reserved.
* Copyright (C) 2013 Google Inc. All rights reserved.
*
* This library is free software; you can redistribute it and/or
* modify it under the terms of the GNU Library General Public
* License as published by the Free Software Foundation; either
* version 2 of the License, or (at your option) any later version.
*
* This library is distributed in the hope that it will be useful,
* but WITHOUT ANY WARRANTY; without even the implied warranty of
* MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE. See the GNU
* Library General Public License for more details.
*
* You should have received a copy of the GNU Library General Public License
* along with this library; see the file COPYING.LIB. If not, write to
* the Free Software Foundation, Inc., 51 Franklin Street, Fifth Floor,
* Boston, MA 02110-1301, USA.
*/
#include "third_party/blink/renderer/platform/graphics/filters/fe_gaussian_blur.h"
#include "third_party/blink/renderer/platform/graphics/filters/filter.h"
#include "third_party/blink/renderer/platform/graphics/filters/paint_filter_builder.h"
#include "third_party/blink/renderer/platform/wtf/text/text_stream.h"
namespace blink {
namespace {
inline unsigned ApproximateBoxWidth(float s) {
return static_cast<unsigned>(
floorf(s * (3 / 4.f * sqrtf(kTwoPiFloat)) + 0.5f));
}
IntSize CalculateKernelSize(const FloatSize& std) {
DCHECK(std.Width() >= 0 && std.Height() >= 0);
IntSize kernel_size;
if (std.Width()) {
int size = std::max<unsigned>(2, ApproximateBoxWidth(std.Width()));
kernel_size.SetWidth(size);
}
if (std.Height()) {
int size = std::max<unsigned>(2, ApproximateBoxWidth(std.Height()));
kernel_size.SetHeight(size);
}
return kernel_size;
}
}
FEGaussianBlur::FEGaussianBlur(Filter* filter, float x, float y)
: FilterEffect(filter), std_x_(x), std_y_(y) {}
FloatRect FEGaussianBlur::MapEffect(const FloatSize& std_deviation,
const FloatRect& rect) {
IntSize kernel_size = CalculateKernelSize(std_deviation);
// We take the half kernel size and multiply it by three, because we run box
// blur three times.
FloatRect result = rect;
result.InflateX(3.0f * kernel_size.Width() * 0.5f);
result.InflateY(3.0f * kernel_size.Height() * 0.5f);
return result;
}
FloatRect FEGaussianBlur::MapEffect(const FloatRect& rect) const {
FloatSize std_error(GetFilter()->ApplyHorizontalScale(std_x_),
GetFilter()->ApplyVerticalScale(std_y_));
return MapEffect(std_error, rect);
}
sk_sp<PaintFilter> FEGaussianBlur::CreateImageFilter() {
sk_sp<PaintFilter> input(paint_filter_builder::Build(
InputEffect(0), OperatingInterpolationSpace()));
float std_x = GetFilter()->ApplyHorizontalScale(std_x_);
float std_y = GetFilter()->ApplyVerticalScale(std_y_);
base::Optional<PaintFilter::CropRect> crop_rect = GetCropRect();
return sk_make_sp<BlurPaintFilter>(
SkFloatToScalar(std_x), SkFloatToScalar(std_y), SkTileMode::kDecal,
std::move(input), base::OptionalOrNullptr(crop_rect));
}
WTF::TextStream& FEGaussianBlur::ExternalRepresentation(WTF::TextStream& ts,
int indent) const {
WriteIndent(ts, indent);
ts << "[feGaussianBlur";
FilterEffect::ExternalRepresentation(ts);
ts << " stdDeviation=\"" << std_x_ << ", " << std_y_ << "\"]\n";
InputEffect(0)->ExternalRepresentation(ts, indent + 1);
return ts;
}
} // namespace blink
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