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/*
* Copyright 2020 The Android Open Source Project
*
* Licensed under the Apache License, Version 2.0 (the "License");
* you may not use this file except in compliance with the License.
* You may obtain a copy of the License at
*
* http://www.apache.org/licenses/LICENSE-2.0
*
* Unless required by applicable law or agreed to in writing, software
* distributed under the License is distributed on an "AS IS" BASIS,
* WITHOUT WARRANTIES OR CONDITIONS OF ANY KIND, either express or implied.
* See the License for the specific language governing permissions and
* limitations under the License.
*/
#pragma once
#include <SkCanvas.h>
#include <SkImage.h>
#include <SkRuntimeEffect.h>
#include <SkSurface.h>
using namespace std;
namespace android {
namespace renderengine {
namespace skia {
/**
* This is an implementation of a Kawase blur, as described in here:
* https://community.arm.com/cfs-file/__key/communityserver-blogs-components-weblogfiles/
* 00-00-00-20-66/siggraph2015_2D00_mmg_2D00_marius_2D00_notes.pdf
*/
class BlurFilter {
public:
// Downsample FBO to improve performance
static constexpr float kInputScale = 0.25f;
// Downsample scale factor used to improve performance
static constexpr float kInverseInputScale = 1.0f / kInputScale;
// Maximum number of render passes
static constexpr uint32_t kMaxPasses = 4;
// To avoid downscaling artifacts, we interpolate the blurred fbo with the full composited
// image, up to this radius.
static constexpr float kMaxCrossFadeRadius = 30.0f;
explicit BlurFilter();
virtual ~BlurFilter(){};
// Execute blur, saving it to a texture
sk_sp<SkImage> generate(GrRecordingContext* context, const uint32_t radius,
const sk_sp<SkImage> blurInput, const SkRect& blurRect) const;
/**
* Draw the blurred content (from the generate method) into the canvas.
* @param canvas is the destination/output for the blur
* @param effectRegion the RoundRect in canvas coordinates that determines the blur coverage
* @param blurRadius radius of the blur used to determine the intensity of the crossfade effect
* @param blurAlpha alpha value applied to the effectRegion when the blur is drawn
* @param blurRect bounds of the blurredImage translated into canvas coordinates
* @param blurredImage down-sampled blurred content that was produced by the generate() method
* @param input original unblurred input that is used to crossfade with the blurredImage
*/
void drawBlurRegion(SkCanvas* canvas, const SkRRect& effectRegion, const uint32_t blurRadius,
const float blurAlpha, const SkRect& blurRect, sk_sp<SkImage> blurredImage,
sk_sp<SkImage> input);
private:
sk_sp<SkRuntimeEffect> mBlurEffect;
sk_sp<SkRuntimeEffect> mMixEffect;
};
} // namespace skia
} // namespace renderengine
} // namespace android
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