PaintUtils.h revision ea508588e9c4a9d87f36b0e74de4d9420c2af06d 
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 <SkXfermode.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   /**
36     * Safely retrieves the mode from the specified xfermode. If the specified
37     * xfermode is null, the mode is assumed to be SkXfermode::kSrcOver_Mode.
38     */
39    static inline SkXfermode::Mode getXfermode(SkXfermode* mode) {
40        SkXfermode::Mode resultMode;
41        if (!SkXfermode::AsMode(mode, &resultMode)) {
42            resultMode = SkXfermode::kSrcOver_Mode;
43        }
44        return resultMode;
45    }
46
47    static inline GLenum getFilter(const SkPaint* paint) {
48        if (!paint || paint->getFilterQuality() != kNone_SkFilterQuality) {
49            return GL_LINEAR;
50        }
51        return GL_NEAREST;
52    }
53
54    // TODO: move to a method on android:Paint? replace with SkPaint::nothingToDraw()?
55    static inline bool paintWillNotDraw(const SkPaint& paint) {
56        return paint.getAlpha() == 0
57                && !paint.getColorFilter()
58                && getXfermode(paint.getXfermode()) == SkXfermode::kSrcOver_Mode;
59    }
60
61    // TODO: move to a method on android:Paint? replace with SkPaint::nothingToDraw()?
62    static inline bool paintWillNotDrawText(const SkPaint& paint) {
63        return paint.getAlpha() == 0
64                && paint.getLooper() == nullptr
65                && !paint.getColorFilter()
66                && getXfermode(paint.getXfermode()) == SkXfermode::kSrcOver_Mode;
67    }
68
69    static bool isBlendedShader(const SkShader* shader) {
70        if (shader == nullptr) {
71            return false;
72        }
73        return !shader->isOpaque();
74    }
75
76    static bool isBlendedColorFilter(const SkColorFilter* filter) {
77        if (filter == nullptr) {
78            return false;
79        }
80        return (filter->getFlags() & SkColorFilter::kAlphaUnchanged_Flag) == 0;
81    }
82
83    struct TextShadow {
84        SkScalar radius;
85        float dx;
86        float dy;
87        SkColor color;
88    };
89
90    static inline bool getTextShadow(const SkPaint* paint, TextShadow* textShadow) {
91        SkDrawLooper::BlurShadowRec blur;
92        if (paint && paint->getLooper() && paint->getLooper()->asABlurShadow(&blur)) {
93            if (textShadow) {
94                textShadow->radius = Blur::convertSigmaToRadius(blur.fSigma);
95                textShadow->dx = blur.fOffset.fX;
96                textShadow->dy = blur.fOffset.fY;
97                textShadow->color = blur.fColor;
98            }
99            return true;
100        }
101        return false;
102    }
103
104    static inline bool hasTextShadow(const SkPaint* paint) {
105        return getTextShadow(paint, nullptr);
106    }
107
108    static inline SkXfermode::Mode getXfermodeDirect(const SkPaint* paint) {
109        return paint ? getXfermode(paint->getXfermode()) : SkXfermode::kSrcOver_Mode;
110    }
111
112    static inline int getAlphaDirect(const SkPaint* paint) {
113        return paint ? paint->getAlpha() : 255;
114    }
115
116}; // class PaintUtils
117
118} /* namespace uirenderer */
119} /* namespace android */
120
121#endif /* PAINT_UTILS_H */
122