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#include <SkXfermode.h>
25
26namespace android {
27namespace uirenderer {
28
29/**
30 * Utility methods for accessing data within SkPaint, and providing defaults
31 * with optional SkPaint pointers.
32 */
33class PaintUtils {
34public:
35
36   /**
37     * Safely retrieves the mode from the specified xfermode. If the specified
38     * xfermode is null, the mode is assumed to be SkXfermode::kSrcOver_Mode.
39     */
40    static inline SkXfermode::Mode getXfermode(SkXfermode* mode) {
41        SkXfermode::Mode resultMode;
42        if (!SkXfermode::AsMode(mode, &resultMode)) {
43            resultMode = SkXfermode::kSrcOver_Mode;
44        }
45        return resultMode;
46    }
47
48    static inline GLenum getFilter(const SkPaint* paint) {
49        if (!paint || paint->getFilterQuality() != kNone_SkFilterQuality) {
50            return GL_LINEAR;
51        }
52        return GL_NEAREST;
53    }
54
55    // TODO: move to a method on android:Paint? replace with SkPaint::nothingToDraw()?
56    static inline bool paintWillNotDraw(const SkPaint& paint) {
57        return paint.getAlpha() == 0
58                && !paint.getColorFilter()
59                && getXfermode(paint.getXfermode()) == SkXfermode::kSrcOver_Mode;
60    }
61
62    // TODO: move to a method on android:Paint? replace with SkPaint::nothingToDraw()?
63    static inline bool paintWillNotDrawText(const SkPaint& paint) {
64        return paint.getAlpha() == 0
65                && paint.getLooper() == nullptr
66                && !paint.getColorFilter()
67                && getXfermode(paint.getXfermode()) == SkXfermode::kSrcOver_Mode;
68    }
69
70    static bool isOpaquePaint(const SkPaint* paint) {
71        if (!paint) return true; // default (paintless) behavior is SrcOver, black
72
73        if (paint->getAlpha() != 0xFF
74                || PaintUtils::isBlendedShader(paint->getShader())
75                || PaintUtils::isBlendedColorFilter(paint->getColorFilter())) {
76            return false;
77        }
78
79        // Only let simple srcOver / src blending modes declare opaque, since behavior is clear.
80        SkXfermode::Mode mode = getXfermode(paint->getXfermode());
81        return mode == SkXfermode::Mode::kSrcOver_Mode
82                || mode == SkXfermode::Mode::kSrc_Mode;
83    }
84
85    static bool isBlendedShader(const SkShader* shader) {
86        if (shader == nullptr) {
87            return false;
88        }
89        return !shader->isOpaque();
90    }
91
92    static bool isBlendedColorFilter(const SkColorFilter* filter) {
93        if (filter == nullptr) {
94            return false;
95        }
96        return (filter->getFlags() & SkColorFilter::kAlphaUnchanged_Flag) == 0;
97    }
98
99    struct TextShadow {
100        SkScalar radius;
101        float dx;
102        float dy;
103        SkColor color;
104    };
105
106    static inline bool getTextShadow(const SkPaint* paint, TextShadow* textShadow) {
107        SkDrawLooper::BlurShadowRec blur;
108        if (paint && paint->getLooper() && paint->getLooper()->asABlurShadow(&blur)) {
109            if (textShadow) {
110                textShadow->radius = Blur::convertSigmaToRadius(blur.fSigma);
111                textShadow->dx = blur.fOffset.fX;
112                textShadow->dy = blur.fOffset.fY;
113                textShadow->color = blur.fColor;
114            }
115            return true;
116        }
117        return false;
118    }
119
120    static inline bool hasTextShadow(const SkPaint* paint) {
121        return getTextShadow(paint, nullptr);
122    }
123
124    static inline SkXfermode::Mode getXfermodeDirect(const SkPaint* paint) {
125        return paint ? getXfermode(paint->getXfermode()) : SkXfermode::kSrcOver_Mode;
126    }
127
128    static inline int getAlphaDirect(const SkPaint* paint) {
129        return paint ? paint->getAlpha() : 255;
130    }
131
132}; // class PaintUtils
133
134} /* namespace uirenderer */
135} /* namespace android */
136
137#endif /* PAINT_UTILS_H */
138