Source/WebCore/rendering/style/TextDecorationThickness.h

/*
 * Copyright (C) 2018-2020 Apple Inc. All rights reserved.
 *
 * Redistribution and use in source and binary forms, with or without
 * modification, are permitted provided that the following conditions
 * are met:
 * 1. Redistributions of source code must retain the above copyright
 *    notice, this list of conditions and the following disclaimer.
 * 2. Redistributions in binary form must reproduce the above copyright
 *    notice, this list of conditions and the following disclaimer in the
 *    documentation and/or other materials provided with the distribution.
 *
 * THIS SOFTWARE IS PROVIDED BY APPLE INC. AND ITS CONTRIBUTORS ``AS IS''
 * AND ANY EXPRESS OR IMPLIED WARRANTIES, INCLUDING, BUT NOT LIMITED TO,
 * THE IMPLIED WARRANTIES OF MERCHANTABILITY AND FITNESS FOR A PARTICULAR
 * PURPOSE ARE DISCLAIMED. IN NO EVENT SHALL APPLE INC. OR ITS CONTRIBUTORS
 * BE LIABLE FOR ANY DIRECT, INDIRECT, INCIDENTAL, SPECIAL, EXEMPLARY, OR
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 */

#pragma once

#include "FontMetrics.h"
#include "Length.h"
#include <wtf/text/TextStream.h>

namespace WebCore {

class TextDecorationThickness {
public:
    static TextDecorationThickness createWithAuto()
    {
        return TextDecorationThickness(Type::Auto);
    }
    static TextDecorationThickness createFromFont()
    {
        return TextDecorationThickness(Type::FromFont);
    }
    static TextDecorationThickness createWithLength(float length)
    {
        TextDecorationThickness result(Type::Length);
        result.setLengthValue(length);
        return result;
    }

    bool isAuto() const
    {
        return m_type == Type::Auto;
    }

    bool isFromFont() const
    {
        return m_type == Type::FromFont;
    }

    bool isLength() const
    {
        return m_type == Type::Length;
    }

    void setLengthValue(float length)
    {
        ASSERT(isLength());
        m_length = length;
    }

    float lengthValue() const
    {
        ASSERT(isLength());
        return m_length;
    }

    float resolve(float fontSize, const FontMetrics& metrics) const
    {
        if (isAuto()) {
            const float textDecorationBaseFontSize = 16;
            return fontSize / textDecorationBaseFontSize;
        }
        if (isFromFont())
            return metrics.underlineThickness();
        ASSERT(isLength());
        return m_length;
    }

    bool operator==(const TextDecorationThickness& other) const
    {
        switch (m_type) {
        case Type::Auto:
        case Type::FromFont:
            return m_type == other.m_type;
        case Type::Length:
            return m_type == other.m_type && m_length == other.m_length;
        default:
            ASSERT_NOT_REACHED();
            return true;
        }
    }

    bool operator!=(const TextDecorationThickness& other) const
    {
        return !(*this == other);
    }

private:
    enum class Type : uint8_t {
        Auto,
        FromFont,
        Length
    };

    TextDecorationThickness(Type type)
        : m_type { type }
    {
    }

    Type m_type;
    float m_length { 0 };
};

inline TextStream& operator<<(TextStream& ts, const TextDecorationThickness& thickness)
{
    if (thickness.isAuto())
        ts << "auto";
    else if (thickness.isFromFont())
        ts << "from-font";
    else
        ts << TextStream::FormatNumberRespectingIntegers(thickness.lengthValue());
    return ts;
}

} // namespace WebCore