PaintUtils.h revision 792fb3252f6460acfd82c4e5d7536ca6b787a0e0 
1/*
2 * Copyright (C) 2014 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#ifndef PAINT_UTILS_H
17#define PAINT_UTILS_H
18
19#include <utils/Blur.h>
20
21#include <SkColorFilter.h>
22#include <SkDrawLooper.h>
23#include <SkShader.h>
24
25namespace android {
26namespace uirenderer {
27
28/**
29 * Utility methods for accessing data within SkPaint, and providing defaults
30 * with optional SkPaint pointers.
31 */
32class PaintUtils {
33public:
34
35    static inline GLenum getFilter(const SkPaint* paint) {
36        if (!paint || paint->getFilterQuality() != kNone_SkFilterQuality) {
37            return GL_LINEAR;
38        }
39        return GL_NEAREST;
40    }
41
42    static bool isOpaquePaint(const SkPaint* paint) {
43        if (!paint) return true; // default (paintless) behavior is SrcOver, black
44
45        if (paint->getAlpha() != 0xFF
46                || PaintUtils::isBlendedShader(paint->getShader())
47                || PaintUtils::isBlendedColorFilter(paint->getColorFilter())) {
48            return false;
49        }
50
51        // Only let simple srcOver / src blending modes declare opaque, since behavior is clear.
52        SkBlendMode mode = paint->getBlendMode();
53        return mode == SkBlendMode::kSrcOver
54                || mode == SkBlendMode::kSrc;
55    }
56
57    static bool isBlendedShader(const SkShader* shader) {
58        if (shader == nullptr) {
59            return false;
60        }
61        return !shader->isOpaque();
62    }
63
64    static bool isBlendedColorFilter(const SkColorFilter* filter) {
65        if (filter == nullptr) {
66            return false;
67        }
68        return (filter->getFlags() & SkColorFilter::kAlphaUnchanged_Flag) == 0;
69    }
70
71    struct TextShadow {
72        SkScalar radius;
73        float dx;
74        float dy;
75        SkColor color;
76    };
77
78    static inline bool getTextShadow(const SkPaint* paint, TextShadow* textShadow) {
79        SkDrawLooper::BlurShadowRec blur;
80        if (paint && paint->getLooper() && paint->getLooper()->asABlurShadow(&blur)) {
81            if (textShadow) {
82                textShadow->radius = Blur::convertSigmaToRadius(blur.fSigma);
83                textShadow->dx = blur.fOffset.fX;
84                textShadow->dy = blur.fOffset.fY;
85                textShadow->color = blur.fColor;
86            }
87            return true;
88        }
89        return false;
90    }
91
92    static inline bool hasTextShadow(const SkPaint* paint) {
93        return getTextShadow(paint, nullptr);
94    }
95
96    static inline SkBlendMode getBlendModeDirect(const SkPaint* paint) {
97        return paint ? paint->getBlendMode() : SkBlendMode::kSrcOver;
98    }
99
100    static inline int getAlphaDirect(const SkPaint* paint) {
101        return paint ? paint->getAlpha() : 255;
102    }
103
104}; // class PaintUtils
105
106} /* namespace uirenderer */
107} /* namespace android */
108
109#endif /* PAINT_UTILS_H */
110