1 /*
2 * Copyright 2021 The Android Open Source Project
3 *
4 * Licensed under the Apache License, Version 2.0 (the "License");
5 * you may not use this file except in compliance with the License.
6 * You may obtain a copy of the License at
7 *
8 * http://www.apache.org/licenses/LICENSE-2.0
9 *
10 * Unless required by applicable law or agreed to in writing, software
11 * distributed under the License is distributed on an "AS IS" BASIS,
12 * WITHOUT WARRANTIES OR CONDITIONS OF ANY KIND, either express or implied.
13 * See the License for the specific language governing permissions and
14 * limitations under the License.
15 */
16
17 #define ATRACE_TAG ATRACE_TAG_GRAPHICS
18 #include "BlurFilter.h"
19 #include <SkBlendMode.h>
20 #include <SkCanvas.h>
21 #include <SkPaint.h>
22 #include <SkRRect.h>
23 #include <SkRuntimeEffect.h>
24 #include <SkSize.h>
25 #include <SkString.h>
26 #include <SkSurface.h>
27 #include <SkTileMode.h>
28 #include <log/log.h>
29 #include <utils/Trace.h>
30
31 namespace android {
32 namespace renderengine {
33 namespace skia {
34
createMixEffect()35 static sk_sp<SkRuntimeEffect> createMixEffect() {
36 SkString mixString(R"(
37 uniform shader blurredInput;
38 uniform shader originalInput;
39 uniform float mixFactor;
40
41 half4 main(float2 xy) {
42 return half4(mix(originalInput.eval(xy), blurredInput.eval(xy), mixFactor)).rgb1;
43 }
44 )");
45
46 auto [mixEffect, mixError] = SkRuntimeEffect::MakeForShader(mixString);
47 if (!mixEffect) {
48 LOG_ALWAYS_FATAL("RuntimeShader error: %s", mixError.c_str());
49 }
50 return mixEffect;
51 }
52
getShaderTransform(const SkCanvas * canvas,const SkRect & blurRect,const float scale)53 static SkMatrix getShaderTransform(const SkCanvas* canvas, const SkRect& blurRect,
54 const float scale) {
55 // 1. Apply the blur shader matrix, which scales up the blurred surface to its real size
56 auto matrix = SkMatrix::Scale(scale, scale);
57 // 2. Since the blurred surface has the size of the layer, we align it with the
58 // top left corner of the layer position.
59 matrix.postConcat(SkMatrix::Translate(blurRect.fLeft, blurRect.fTop));
60 // 3. Finally, apply the inverse canvas matrix. The snapshot made in the BlurFilter is in the
61 // original surface orientation. The inverse matrix has to be applied to align the blur
62 // surface with the current orientation/position of the canvas.
63 SkMatrix drawInverse;
64 if (canvas != nullptr && canvas->getTotalMatrix().invert(&drawInverse)) {
65 matrix.postConcat(drawInverse);
66 }
67 return matrix;
68 }
69
BlurFilter(const float maxCrossFadeRadius)70 BlurFilter::BlurFilter(const float maxCrossFadeRadius)
71 : mMaxCrossFadeRadius(maxCrossFadeRadius),
72 mMixEffect(maxCrossFadeRadius > 0 ? createMixEffect() : nullptr) {}
73
getMaxCrossFadeRadius() const74 float BlurFilter::getMaxCrossFadeRadius() const {
75 return mMaxCrossFadeRadius;
76 }
77
drawBlurRegion(SkCanvas * canvas,const SkRRect & effectRegion,const uint32_t blurRadius,const float blurAlpha,const SkRect & blurRect,sk_sp<SkImage> blurredImage,sk_sp<SkImage> input)78 void BlurFilter::drawBlurRegion(SkCanvas* canvas, const SkRRect& effectRegion,
79 const uint32_t blurRadius, const float blurAlpha,
80 const SkRect& blurRect, sk_sp<SkImage> blurredImage,
81 sk_sp<SkImage> input) {
82 ATRACE_CALL();
83
84 SkPaint paint;
85 paint.setAlphaf(blurAlpha);
86
87 const auto blurMatrix = getShaderTransform(canvas, blurRect, kInverseInputScale);
88 SkSamplingOptions linearSampling(SkFilterMode::kLinear, SkMipmapMode::kNone);
89 const auto blurShader = blurredImage->makeShader(SkTileMode::kClamp, SkTileMode::kClamp,
90 linearSampling, &blurMatrix);
91
92 if (blurRadius < mMaxCrossFadeRadius) {
93 // For sampling Skia's API expects the inverse of what logically seems appropriate. In this
94 // case you might expect the matrix to simply be the canvas matrix.
95 SkMatrix inputMatrix;
96 if (!canvas->getTotalMatrix().invert(&inputMatrix)) {
97 ALOGE("matrix was unable to be inverted");
98 }
99
100 SkRuntimeShaderBuilder blurBuilder(mMixEffect);
101 blurBuilder.child("blurredInput") = blurShader;
102 blurBuilder.child("originalInput") =
103 input->makeShader(SkTileMode::kClamp, SkTileMode::kClamp, linearSampling,
104 inputMatrix);
105 blurBuilder.uniform("mixFactor") = blurRadius / mMaxCrossFadeRadius;
106
107 paint.setShader(blurBuilder.makeShader());
108 } else {
109 paint.setShader(blurShader);
110 }
111
112 if (effectRegion.isRect()) {
113 if (blurAlpha == 1.0f) {
114 paint.setBlendMode(SkBlendMode::kSrc);
115 }
116 canvas->drawRect(effectRegion.rect(), paint);
117 } else {
118 paint.setAntiAlias(true);
119 canvas->drawRRect(effectRegion, paint);
120 }
121 }
122
123 } // namespace skia
124 } // namespace renderengine
125 } // namespace android
126