133 lines
5.2 KiB
C++
133 lines
5.2 KiB
C++
/*
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* Copyright (c) 2019-2020, Sergey Bugaev <bugaevc@serenityos.org>
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* Copyright (c) 2022, Linus Groh <linusg@serenityos.org>
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*
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* SPDX-License-Identifier: BSD-2-Clause
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*/
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#include <AK/DeprecatedString.h>
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#include <AK/HashMap.h>
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#include <AK/Span.h>
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#include <AK/Utf8View.h>
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#include <LibGfx/Bitmap.h>
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#include <LibGfx/Font/Emoji.h>
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namespace Gfx {
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// https://unicode.org/reports/tr51/
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// https://unicode.org/emoji/charts/emoji-list.html
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// https://unicode.org/emoji/charts/emoji-zwj-sequences.html
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static HashMap<DeprecatedString, RefPtr<Gfx::Bitmap>> s_emojis;
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Bitmap const* Emoji::emoji_for_code_point(u32 code_point)
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{
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return emoji_for_code_points(Array { code_point });
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}
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Bitmap const* Emoji::emoji_for_code_points(ReadonlySpan<u32> const& code_points)
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{
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// FIXME: This function is definitely not fast.
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auto basename = DeprecatedString::join('_', code_points, "U+{:X}"sv);
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auto it = s_emojis.find(basename);
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if (it != s_emojis.end())
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return (*it).value.ptr();
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auto bitmap_or_error = Bitmap::load_from_file(DeprecatedString::formatted("/res/emoji/{}.png", basename));
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if (bitmap_or_error.is_error()) {
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s_emojis.set(basename, nullptr);
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return nullptr;
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}
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auto bitmap = bitmap_or_error.release_value();
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s_emojis.set(basename, bitmap);
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return bitmap.ptr();
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}
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Bitmap const* Emoji::emoji_for_code_point_iterator(Utf8CodePointIterator& it)
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{
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// NOTE: I'm sure this could be more efficient, e.g. by checking if each code point falls
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// into a certain range in the loop below (emojis, modifiers, variation selectors, ZWJ),
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// and bailing out early if not. Current worst case is 10 file lookups for any sequence of
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// code points (if the first glyph isn't part of the font in regular text rendering).
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constexpr size_t max_emoji_code_point_sequence_length = 10;
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Vector<u32, max_emoji_code_point_sequence_length> code_points;
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struct EmojiAndCodePoints {
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Bitmap const* emoji;
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Span<u32> code_points;
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u8 real_codepoint_length;
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};
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Vector<EmojiAndCodePoints, max_emoji_code_point_sequence_length> possible_emojis;
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// Determine all existing emojis for the longest possible ZWJ emoji sequence,
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// or until we run out of code points in the iterator.
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bool last_codepoint_sequence_found = false;
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for (u8 i = 0; i < max_emoji_code_point_sequence_length; ++i) {
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auto code_point = it.peek(i);
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if (!code_point.has_value())
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break;
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// NOTE: The following only applies to emoji presentation, not to other
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// emoji modifiers.
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//
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// For a single emoji core sequence, we assume that emoji presentation
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// is implied, since this function will only be called for characters
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// with default text presentation when either (1) the character is not
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// found in the font, or (2) the character is followed by an explicit
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// emoji presentation selector.
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//
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// For emoji zwj sequences, Serenity chooses to treat minimally-qualified
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// and unqualified emojis the same as fully-qualified emojis (with regards
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// to emoji presentation).
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//
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// From https://unicode.org/reports/tr51/#Emoji_Implementation_Notes:
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// > minimally-qualified or unqualified emoji zwj sequences may be handled
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// > in the same way as their fully-qualified forms; the choice is up to
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// > the implementation.
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//
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// In both cases, whenever an emoji presentation selector (U+FE0F) is found, we
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// just skip it in order to drop fully-qualified emojis down to their
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// minimally-qualified or unqualified forms (with respect to emoji presentation)
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// for doing emoji lookups. This ensures that all forms are treated the same
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// assuming the emoji filenames are named accordingly (with all emoji presentation
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// selector codepoints removed).
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if (code_point.value() == 0xFE0F) {
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// If the last sequence was found, then we can just update
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// its real length.
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if (last_codepoint_sequence_found) {
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possible_emojis.last().real_codepoint_length++;
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}
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// And we can always skip the lookup since the code point sequence
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// will be unchanged since last time.
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continue;
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} else {
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code_points.append(*code_point);
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}
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if (auto const* emoji = emoji_for_code_points(code_points)) {
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u8 real_codepoint_length = i + 1;
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possible_emojis.empend(emoji, code_points, real_codepoint_length);
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last_codepoint_sequence_found = true;
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} else {
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last_codepoint_sequence_found = false;
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}
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}
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if (possible_emojis.is_empty())
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return nullptr;
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// If we found one or more matches, return the longest, i.e. last. For example:
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// U+1F3F3 - white flag
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// U+1F3F3 U+200D U+1F308 - rainbow flag (unqualified form)
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auto& [emoji, emoji_code_points, codepoint_length] = possible_emojis.last();
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// Advance the iterator, so it's on the last code point of our found emoji and
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// whoever is iterating will advance to the next new code point.
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for (u8 i = 0; i < codepoint_length - 1; ++i)
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++it;
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return emoji;
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}
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}
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