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 <SkData.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 <log/log.h>
28 #include <utils/Trace.h>
29
30 namespace android {
31 namespace renderengine {
32 namespace skia {
33
createMixEffect()34 static sk_sp<SkRuntimeEffect> createMixEffect() {
35 SkString mixString(R"(
36 uniform shader blurredInput;
37 uniform shader originalInput;
38 uniform float mixFactor;
39
40 half4 main(float2 xy) {
41 return half4(mix(originalInput.eval(xy), blurredInput.eval(xy), mixFactor)).rgb1;
42 }
43 )");
44
45 auto [mixEffect, mixError] = SkRuntimeEffect::MakeForShader(mixString);
46 if (!mixEffect) {
47 LOG_ALWAYS_FATAL("RuntimeShader error: %s", mixError.c_str());
48 }
49 return mixEffect;
50 }
51
getShaderTransform(const SkCanvas * canvas,const SkRect & blurRect,const float scale)52 static SkMatrix getShaderTransform(const SkCanvas* canvas, const SkRect& blurRect,
53 const float scale) {
54 // 1. Apply the blur shader matrix, which scales up the blurred surface to its real size
55 auto matrix = SkMatrix::Scale(scale, scale);
56 // 2. Since the blurred surface has the size of the layer, we align it with the
57 // top left corner of the layer position.
58 matrix.postConcat(SkMatrix::Translate(blurRect.fLeft, blurRect.fTop));
59 // 3. Finally, apply the inverse canvas matrix. The snapshot made in the BlurFilter is in the
60 // original surface orientation. The inverse matrix has to be applied to align the blur
61 // surface with the current orientation/position of the canvas.
62 SkMatrix drawInverse;
63 if (canvas != nullptr && canvas->getTotalMatrix().invert(&drawInverse)) {
64 matrix.postConcat(drawInverse);
65 }
66 return matrix;
67 }
68
BlurFilter(const float maxCrossFadeRadius)69 BlurFilter::BlurFilter(const float maxCrossFadeRadius)
70 : mMaxCrossFadeRadius(maxCrossFadeRadius),
71 mMixEffect(maxCrossFadeRadius > 0 ? createMixEffect() : nullptr) {}
72
getMaxCrossFadeRadius() const73 float BlurFilter::getMaxCrossFadeRadius() const {
74 return mMaxCrossFadeRadius;
75 }
76
drawBlurRegion(SkCanvas * canvas,const SkRRect & effectRegion,const uint32_t blurRadius,const float blurAlpha,const SkRect & blurRect,sk_sp<SkImage> blurredImage,sk_sp<SkImage> input)77 void BlurFilter::drawBlurRegion(SkCanvas* canvas, const SkRRect& effectRegion,
78 const uint32_t blurRadius, const float blurAlpha,
79 const SkRect& blurRect, sk_sp<SkImage> blurredImage,
80 sk_sp<SkImage> input) {
81 ATRACE_CALL();
82
83 SkPaint paint;
84 paint.setAlphaf(blurAlpha);
85
86 const auto blurMatrix = getShaderTransform(canvas, blurRect, kInverseInputScale);
87 SkSamplingOptions linearSampling(SkFilterMode::kLinear, SkMipmapMode::kNone);
88 const auto blurShader = blurredImage->makeShader(SkTileMode::kClamp, SkTileMode::kClamp,
89 linearSampling, &blurMatrix);
90
91 if (blurRadius < mMaxCrossFadeRadius) {
92 // For sampling Skia's API expects the inverse of what logically seems appropriate. In this
93 // case you might expect the matrix to simply be the canvas matrix.
94 SkMatrix inputMatrix;
95 if (!canvas->getTotalMatrix().invert(&inputMatrix)) {
96 ALOGE("matrix was unable to be inverted");
97 }
98
99 SkRuntimeShaderBuilder blurBuilder(mMixEffect);
100 blurBuilder.child("blurredInput") = blurShader;
101 blurBuilder.child("originalInput") =
102 input->makeShader(SkTileMode::kClamp, SkTileMode::kClamp, linearSampling,
103 inputMatrix);
104 blurBuilder.uniform("mixFactor") = blurRadius / mMaxCrossFadeRadius;
105
106 paint.setShader(blurBuilder.makeShader());
107 } else {
108 paint.setShader(blurShader);
109 }
110
111 if (effectRegion.isRect()) {
112 if (blurAlpha == 1.0f) {
113 paint.setBlendMode(SkBlendMode::kSrc);
114 }
115 canvas->drawRect(effectRegion.rect(), paint);
116 } else {
117 paint.setAntiAlias(true);
118 canvas->drawRRect(effectRegion, paint);
119 }
120 }
121
122 } // namespace skia
123 } // namespace renderengine
124 } // namespace android
125