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      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 
     26 namespace android {
     27 namespace uirenderer {
     28 
     29 /**
     30  * Utility methods for accessing data within SkPaint, and providing defaults
     31  * with optional SkPaint pointers.
     32  */
     33 class PaintUtils {
     34 public:
     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