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105 lines
2.7 KiB
C++
105 lines
2.7 KiB
C++
/*
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* Copyright (c) 2021, Idan Horowitz <idan.horowitz@serenityos.org>
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*
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* SPDX-License-Identifier: BSD-2-Clause
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*/
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#pragma once
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#include <AK/Array.h>
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#include <AK/Utf32View.h>
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#include <AK/Vector.h>
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namespace Gfx {
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enum class BidirectionalClass {
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STRONG_LTR,
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STRONG_RTL,
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WEAK_NUMBERS,
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WEAK_SEPARATORS,
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NEUTRAL,
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};
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extern Array<BidirectionalClass, 0x1F000> const char_bidi_class_lookup_table;
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constexpr BidirectionalClass get_char_bidi_class(u32 ch)
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{
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if (ch >= char_bidi_class_lookup_table.size())
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return BidirectionalClass::STRONG_LTR;
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return char_bidi_class_lookup_table[ch];
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}
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// FIXME: These should be parsed from the official BidiMirroring.txt that specifies the mirroring character for each character (this function doesn't take into account a large amount of characters)
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constexpr u32 get_mirror_char(u32 ch)
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{
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if (ch == 0x28)
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return 0x29;
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if (ch == 0x29)
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return 0x28;
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if (ch == 0x3C)
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return 0x3E;
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if (ch == 0x3E)
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return 0x3C;
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if (ch == 0x5B)
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return 0x5D;
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if (ch == 0x7B)
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return 0x7D;
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if (ch == 0x7D)
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return 0x7B;
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if (ch == 0xAB)
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return 0xBB;
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if (ch == 0xBB)
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return 0xAB;
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if (ch == 0x2039)
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return 0x203A;
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if (ch == 0x203A)
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return 0x2039;
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return ch;
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}
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enum class TextDirection {
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LTR,
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RTL,
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};
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constexpr TextDirection bidi_class_to_direction(BidirectionalClass class_)
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{
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VERIFY(class_ != BidirectionalClass::NEUTRAL);
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if (class_ == BidirectionalClass::STRONG_LTR || class_ == BidirectionalClass::WEAK_NUMBERS || class_ == BidirectionalClass::WEAK_SEPARATORS)
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return TextDirection::LTR;
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return TextDirection::RTL;
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}
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// Assumes the text has a homogeneous direction
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template<typename TextType>
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constexpr TextDirection get_text_direction(TextType text)
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{
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for (u32 code_point : text) {
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auto char_direction = get_char_bidi_class(code_point);
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if (char_direction != BidirectionalClass::NEUTRAL)
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return bidi_class_to_direction(char_direction);
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}
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return TextDirection::LTR;
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}
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class DirectionalRun {
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public:
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DirectionalRun(Vector<u32> code_points, u8 embedding_level)
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: m_code_points(move(code_points))
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, m_embedding_level(embedding_level)
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{
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}
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[[nodiscard]] Utf32View text() const { return { m_code_points.data(), m_code_points.size() }; }
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[[nodiscard]] u8 embedding_level() const { return m_embedding_level; }
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[[nodiscard]] TextDirection direction() const { return (m_embedding_level % 2) == 0 ? TextDirection::LTR : TextDirection::RTL; }
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Vector<u32>& code_points() { return m_code_points; }
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private:
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Vector<u32> m_code_points;
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u8 m_embedding_level;
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};
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}
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