PaintUtils.h revision c2f31df8b3b9a237e9abffc59c61804ad8495073 
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    // TODO: move to a method on android:Paint? replace with SkPaint::nothingToDraw()?
43    static inline bool paintWillNotDraw(const SkPaint& paint) {
44        return paint.getAlpha() == 0
45                && !paint.getColorFilter()
46                && paint.getBlendMode() == SkBlendMode::kSrcOver;
47    }
48
49    // TODO: move to a method on android:Paint? replace with SkPaint::nothingToDraw()?
50    static inline bool paintWillNotDrawText(const SkPaint& paint) {
51        return paint.getAlpha() == 0
52                && paint.getLooper() == nullptr
53                && !paint.getColorFilter()
54                && paint.getBlendMode() == SkBlendMode::kSrcOver;
55    }
56
57    static bool isOpaquePaint(const SkPaint* paint) {
58        if (!paint) return true; // default (paintless) behavior is SrcOver, black
59
60        if (paint->getAlpha() != 0xFF
61                || PaintUtils::isBlendedShader(paint->getShader())
62                || PaintUtils::isBlendedColorFilter(paint->getColorFilter())) {
63            return false;
64        }
65
66        // Only let simple srcOver / src blending modes declare opaque, since behavior is clear.
67        SkBlendMode mode = paint->getBlendMode();
68        return mode == SkBlendMode::kSrcOver
69                || mode == SkBlendMode::kSrc;
70    }
71
72    static bool isBlendedShader(const SkShader* shader) {
73        if (shader == nullptr) {
74            return false;
75        }
76        return !shader->isOpaque();
77    }
78
79    static bool isBlendedColorFilter(const SkColorFilter* filter) {
80        if (filter == nullptr) {
81            return false;
82        }
83        return (filter->getFlags() & SkColorFilter::kAlphaUnchanged_Flag) == 0;
84    }
85
86    struct TextShadow {
87        SkScalar radius;
88        float dx;
89        float dy;
90        SkColor color;
91    };
92
93    static inline bool getTextShadow(const SkPaint* paint, TextShadow* textShadow) {
94        SkDrawLooper::BlurShadowRec blur;
95        if (paint && paint->getLooper() && paint->getLooper()->asABlurShadow(&blur)) {
96            if (textShadow) {
97                textShadow->radius = Blur::convertSigmaToRadius(blur.fSigma);
98                textShadow->dx = blur.fOffset.fX;
99                textShadow->dy = blur.fOffset.fY;
100                textShadow->color = blur.fColor;
101            }
102            return true;
103        }
104        return false;
105    }
106
107    static inline bool hasTextShadow(const SkPaint* paint) {
108        return getTextShadow(paint, nullptr);
109    }
110
111    static inline SkBlendMode getBlendModeDirect(const SkPaint* paint) {
112        return paint ? paint->getBlendMode() : SkBlendMode::kSrcOver;
113    }
114
115    static inline int getAlphaDirect(const SkPaint* paint) {
116        return paint ? paint->getAlpha() : 255;
117    }
118
119}; // class PaintUtils
120
121} /* namespace uirenderer */
122} /* namespace android */
123
124#endif /* PAINT_UTILS_H */
125