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 <SkCanvas.h>
20 #include <SkPaint.h>
21 #include <SkRRect.h>
22 #include <SkRuntimeEffect.h>
23 #include <SkSize.h>
24 #include <SkString.h>
25 #include <SkSurface.h>
26 #include <log/log.h>
27 #include <utils/Trace.h>
28
29 namespace android {
30 namespace renderengine {
31 namespace skia {
32
createMixEffect()33 static sk_sp<SkRuntimeEffect> createMixEffect() {
34 SkString mixString(R"(
35 uniform shader blurredInput;
36 uniform shader originalInput;
37 uniform float mixFactor;
38
39 half4 main(float2 xy) {
40 return half4(mix(originalInput.eval(xy), blurredInput.eval(xy), mixFactor)).rgb1;
41 }
42 )");
43
44 auto [mixEffect, mixError] = SkRuntimeEffect::MakeForShader(mixString);
45 if (!mixEffect) {
46 LOG_ALWAYS_FATAL("RuntimeShader error: %s", mixError.c_str());
47 }
48 return mixEffect;
49 }
50
getShaderTransform(const SkCanvas * canvas,const SkRect & blurRect,const float scale)51 static SkMatrix getShaderTransform(const SkCanvas* canvas, const SkRect& blurRect,
52 const float scale) {
53 // 1. Apply the blur shader matrix, which scales up the blurred surface to its real size
54 auto matrix = SkMatrix::Scale(scale, scale);
55 // 2. Since the blurred surface has the size of the layer, we align it with the
56 // top left corner of the layer position.
57 matrix.postConcat(SkMatrix::Translate(blurRect.fLeft, blurRect.fTop));
58 // 3. Finally, apply the inverse canvas matrix. The snapshot made in the BlurFilter is in the
59 // original surface orientation. The inverse matrix has to be applied to align the blur
60 // surface with the current orientation/position of the canvas.
61 SkMatrix drawInverse;
62 if (canvas != nullptr && canvas->getTotalMatrix().invert(&drawInverse)) {
63 matrix.postConcat(drawInverse);
64 }
65 return matrix;
66 }
67
BlurFilter(const float maxCrossFadeRadius)68 BlurFilter::BlurFilter(const float maxCrossFadeRadius)
69 : mMaxCrossFadeRadius(maxCrossFadeRadius),
70 mMixEffect(maxCrossFadeRadius > 0 ? createMixEffect() : nullptr) {}
71
getMaxCrossFadeRadius() const72 float BlurFilter::getMaxCrossFadeRadius() const {
73 return mMaxCrossFadeRadius;
74 }
75
drawBlurRegion(SkCanvas * canvas,const SkRRect & effectRegion,const uint32_t blurRadius,const float blurAlpha,const SkRect & blurRect,sk_sp<SkImage> blurredImage,sk_sp<SkImage> input)76 void BlurFilter::drawBlurRegion(SkCanvas* canvas, const SkRRect& effectRegion,
77 const uint32_t blurRadius, const float blurAlpha,
78 const SkRect& blurRect, sk_sp<SkImage> blurredImage,
79 sk_sp<SkImage> input) {
80 ATRACE_CALL();
81
82 SkPaint paint;
83 paint.setAlphaf(blurAlpha);
84
85 const auto blurMatrix = getShaderTransform(canvas, blurRect, kInverseInputScale);
86 SkSamplingOptions linearSampling(SkFilterMode::kLinear, SkMipmapMode::kNone);
87 const auto blurShader = blurredImage->makeShader(SkTileMode::kClamp, SkTileMode::kClamp,
88 linearSampling, &blurMatrix);
89
90 if (blurRadius < mMaxCrossFadeRadius) {
91 // For sampling Skia's API expects the inverse of what logically seems appropriate. In this
92 // case you might expect the matrix to simply be the canvas matrix.
93 SkMatrix inputMatrix;
94 if (!canvas->getTotalMatrix().invert(&inputMatrix)) {
95 ALOGE("matrix was unable to be inverted");
96 }
97
98 SkRuntimeShaderBuilder blurBuilder(mMixEffect);
99 blurBuilder.child("blurredInput") = blurShader;
100 blurBuilder.child("originalInput") =
101 input->makeShader(SkTileMode::kClamp, SkTileMode::kClamp, linearSampling,
102 inputMatrix);
103 blurBuilder.uniform("mixFactor") = blurRadius / mMaxCrossFadeRadius;
104
105 paint.setShader(blurBuilder.makeShader());
106 } else {
107 paint.setShader(blurShader);
108 }
109
110 if (effectRegion.isRect()) {
111 if (blurAlpha == 1.0f) {
112 paint.setBlendMode(SkBlendMode::kSrc);
113 }
114 canvas->drawRect(effectRegion.rect(), paint);
115 } else {
116 paint.setAntiAlias(true);
117 canvas->drawRRect(effectRegion, paint);
118 }
119 }
120
121 } // namespace skia
122 } // namespace renderengine
123 } // namespace android
124