LibGfx: Move other font-related files to LibGfx/Font/

1 files changed, 89 insertions, 0 deletions

diff --git a/Userland/Libraries/LibGfx/Font/Emoji.cpp b/Userland/Libraries/LibGfx/Font/Emoji.cpp
new file mode 100644
index 0000000000..1d2099f066
--- /dev/null
+++ b/Userland/Libraries/LibGfx/Font/Emoji.cpp
@@ -0,0 +1,89 @@
+/*
+ * Copyright (c) 2019-2020, Sergey Bugaev <bugaevc@serenityos.org>
+ * Copyright (c) 2022, Linus Groh <linusg@serenityos.org>
+ *
+ * SPDX-License-Identifier: BSD-2-Clause
+ */
+
+#include <AK/HashMap.h>
+#include <AK/Span.h>
+#include <AK/String.h>
+#include <AK/Utf8View.h>
+#include <LibGfx/Bitmap.h>
+#include <LibGfx/Font/Emoji.h>
+
+namespace Gfx {
+
+// https://unicode.org/reports/tr51/
+// https://unicode.org/emoji/charts/emoji-list.html
+// https://unicode.org/emoji/charts/emoji-zwj-sequences.html
+
+static HashMap<Span<u32>, RefPtr<Gfx::Bitmap>> s_emojis;
+
+Bitmap const* Emoji::emoji_for_code_point(u32 code_point)
+{
+    return emoji_for_code_points(Array { code_point });
+}
+
+Bitmap const* Emoji::emoji_for_code_points(Span<u32> const& code_points)
+{
+    auto it = s_emojis.find(code_points);
+    if (it != s_emojis.end())
+        return (*it).value.ptr();
+
+    auto basename = String::join('_', code_points, "U+{:X}");
+    auto bitmap_or_error = Bitmap::try_load_from_file(String::formatted("/res/emoji/{}.png", basename));
+    if (bitmap_or_error.is_error()) {
+        s_emojis.set(code_points, nullptr);
+        return nullptr;
+    }
+    auto bitmap = bitmap_or_error.release_value();
+    s_emojis.set(code_points, bitmap);
+    return bitmap.ptr();
+}
+
+Bitmap const* Emoji::emoji_for_code_point_iterator(Utf8CodePointIterator& it)
+{
+    // NOTE: I'm sure this could be more efficient, e.g. by checking if each code point falls
+    // into a certain range in the loop below (emojis, modifiers, variation selectors, ZWJ),
+    // and bailing out early if not. Current worst case is 10 file lookups for any sequence of
+    // code points (if the first glyph isn't part of the font in regular text rendering).
+
+    constexpr size_t max_emoji_code_point_sequence_length = 10;
+
+    Vector<u32, max_emoji_code_point_sequence_length> code_points;
+
+    struct EmojiAndCodePoints {
+        Bitmap const* emoji;
+        Span<u32> code_points;
+    };
+    Vector<EmojiAndCodePoints, max_emoji_code_point_sequence_length> possible_emojis;
+
+    // Determine all existing emojis for the longest possible ZWJ emoji sequence,
+    // or until we run out of code points in the iterator.
+    for (size_t i = 0; i < max_emoji_code_point_sequence_length; ++i) {
+        auto code_point = it.peek(i);
+        if (!code_point.has_value())
+            break;
+        code_points.append(*code_point);
+        if (auto const* emoji = emoji_for_code_points(code_points))
+            possible_emojis.empend(emoji, code_points);
+    }
+
+    if (possible_emojis.is_empty())
+        return nullptr;
+
+    // If we found one or more matches, return the longest, i.e. last. For example:
+    // U+1F3F3 - white flag
+    // U+1F3F3 U+FE0F U+200D U+1F308 - rainbow flag
+    auto& [emoji, emoji_code_points] = possible_emojis.last();
+
+    // Advance the iterator, so it's on the last code point of our found emoji and
+    // whoever is iterating will advance to the next new code point.
+    for (size_t i = 0; i < emoji_code_points.size() - 1; ++i)
+        ++it;
+
+    return emoji;
+}
+
+}