libs/hwui/utils/PaintUtils.h

/*
 * Copyright (C) 2014 The Android Open Source Project
 *
 * Licensed under the Apache License, Version 2.0 (the "License");
 * you may not use this file except in compliance with the License.
 * You may obtain a copy of the License at
 *
 *      http://www.apache.org/licenses/LICENSE-2.0
 *
 * Unless required by applicable law or agreed to in writing, software
 * distributed under the License is distributed on an "AS IS" BASIS,
 * WITHOUT WARRANTIES OR CONDITIONS OF ANY KIND, either express or implied.
 * See the License for the specific language governing permissions and
 * limitations under the License.
 */
#ifndef PAINT_UTILS_H
#define PAINT_UTILS_H

#include <GLES2/gl2.h>
#include <utils/Blur.h>

#include <SkColorFilter.h>
#include <SkDrawLooper.h>
#include <SkPaint.h>
#include <SkShader.h>

namespace android {
namespace uirenderer {

/**
 * Utility methods for accessing data within SkPaint, and providing defaults
 * with optional SkPaint pointers.
 */
class PaintUtils {
public:
    static inline GLenum getFilter(const SkPaint* paint) {
        if (!paint || paint->getFilterQuality() != kNone_SkFilterQuality) {
            return GL_LINEAR;
        }
        return GL_NEAREST;
    }

    static bool isOpaquePaint(const SkPaint* paint) {
        if (!paint) return true;  // default (paintless) behavior is SrcOver, black

        if (paint->getAlpha() != 0xFF || PaintUtils::isBlendedShader(paint->getShader()) ||
            PaintUtils::isBlendedColorFilter(paint->getColorFilter())) {
            return false;
        }

        // Only let simple srcOver / src blending modes declare opaque, since behavior is clear.
        SkBlendMode mode = paint->getBlendMode();
        return mode == SkBlendMode::kSrcOver || mode == SkBlendMode::kSrc;
    }

    static bool isBlendedShader(const SkShader* shader) {
        if (shader == nullptr) {
            return false;
        }
        return !shader->isOpaque();
    }

    static bool isBlendedColorFilter(const SkColorFilter* filter) {
        if (filter == nullptr) {
            return false;
        }
        return (filter->getFlags() & SkColorFilter::kAlphaUnchanged_Flag) == 0;
    }

    static inline SkBlendMode getBlendModeDirect(const SkPaint* paint) {
        return paint ? paint->getBlendMode() : SkBlendMode::kSrcOver;
    }

    static inline int getAlphaDirect(const SkPaint* paint) {
        return paint ? paint->getAlpha() : 255;
    }

};  // class PaintUtils

} /* namespace uirenderer */
} /* namespace android */

#endif /* PAINT_UTILS_H */