third_party/skia/src/core/SkPaintPriv.h

/*
 * Copyright 2013 Google Inc.
 *
 * Use of this source code is governed by a BSD-style license that can be
 * found in the LICENSE file.
 */

#ifndef SkPaintPriv_DEFINED
#define SkPaintPriv_DEFINED

#include "include/core/SkPaint.h"

#include <vector>

enum class SkBackend : uint8_t;
class SkPaintParamsKey;
class SkReadBuffer;
class SkShaderCodeDictionary;
class SkWriteBuffer;

class SkPaintPriv {
public:
    enum ShaderOverrideOpacity {
        kNone_ShaderOverrideOpacity,        //!< there is no overriding shader (bitmap or image)
        kOpaque_ShaderOverrideOpacity,      //!< the overriding shader is opaque
        kNotOpaque_ShaderOverrideOpacity,   //!< the overriding shader may not be opaque
    };

    /**
     *  Returns true if drawing with this paint (or nullptr) will ovewrite all affected pixels.
     *
     *  Note: returns conservative true, meaning it may return false even though the paint might
     *        in fact overwrite its pixels.
     */
    static bool Overwrites(const SkPaint* paint, ShaderOverrideOpacity);

    static bool ShouldDither(const SkPaint&, SkColorType, bool shaderOverride=false);

    /*
     * The luminance color is used to determine which Gamma Canonical color to map to.  This is
     * really only used by backends which want to cache glyph masks, and need some way to know if
     * they need to generate new masks based off a given color.
     */
    static SkColor ComputeLuminanceColor(const SkPaint&);

    /** Serializes SkPaint into a buffer. A companion unflatten() call
    can reconstitute the paint at a later time.

    @param buffer  SkWriteBuffer receiving the flattened SkPaint data
    */
    static void Flatten(const SkPaint& paint, SkWriteBuffer& buffer);

    /** Populates SkPaint, typically from a serialized stream, created by calling
        flatten() at an earlier time.
    */
    static SkPaint Unflatten(SkReadBuffer& buffer);

    // If this paint has any color filter, fold it into the shader and/or paint color
    // so that it draws the same but getColorFilter() returns nullptr.
    //
    // Since we may be filtering now, we need to know what color space to filter in,
    // typically the color space of the device we're drawing into.
    static void RemoveColorFilter(SkPaint*, SkColorSpace* dstCS);

    static SkScalar ComputeResScaleForStroking(const SkMatrix&);

    /**
        Return the SkPaintParamsKeys that would be needed to draw the provided paint.

        @param paint      the paint to be decomposed
        @param dictionary dictionary of code fragments available to be used in the SkPaintParamKeys
        @param backend    the backend that would be carrying out the drawing
        @return           the SkPaintParamsKeys that would be needed to draw this paint
    */
    static std::vector<std::unique_ptr<SkPaintParamsKey>> ToKeys(const SkPaint& paint,
                                                                 SkShaderCodeDictionary* dictionary,
                                                                 SkBackend backend);
};

#endif