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e1eb882b1c
In the common case of text rendering rather than getting the emoji bitmap for a fixed number of code points, we don't know how many code points make one emoji. As far as I can tell, the longest ones are up to ten code points, so we try to consume all of them and do a lookup during each iteration, and return the emoji for the longest chain of code points. Quite basic and definitely room for improvement, but it works!
89 lines
3 KiB
C++
89 lines
3 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/HashMap.h>
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#include <AK/Span.h>
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#include <AK/String.h>
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#include <AK/Utf8View.h>
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#include <LibGfx/Bitmap.h>
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#include <LibGfx/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<Span<u32>, 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(Span<u32> const& code_points)
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{
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auto it = s_emojis.find(code_points);
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if (it != s_emojis.end())
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return (*it).value.ptr();
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auto basename = String::join('_', code_points, "U+{:X}");
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auto bitmap_or_error = Bitmap::try_load_from_file(String::formatted("/res/emoji/{}.png", basename));
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if (bitmap_or_error.is_error()) {
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s_emojis.set(code_points, 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(code_points, 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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};
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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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for (size_t 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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code_points.append(*code_point);
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if (auto const* emoji = emoji_for_code_points(code_points))
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possible_emojis.empend(emoji, code_points);
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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+FE0F U+200D U+1F308 - rainbow flag
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auto& [emoji, emoji_code_points] = 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 (size_t i = 0; i < emoji_code_points.size() - 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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