tiny.filigree.font.names

1const std = @import("std");2const binary = @import("binary.zig");3const model = @import("model.zig");45const FontError = model.FontError;6const Table = binary.Table;7const readU16 = binary.readU16;89pub const NameRecordBytes = struct {10    platform_id: u16,11    encoding_id: u16,12    language_id: u16,13    name_id: u16,14    bytes: []const u8,15};1617pub fn bestNameRecord(data: []const u8, name_table: Table, name_id: u16) FontError!?NameRecordBytes {18    if (name_table.len < 6) return error.InvalidFont;19    const version = try readU16(data, name_table.offset);20    if (version != 0 and version != 1) return error.InvalidFont;21    const count = try readU16(data, name_table.offset + 2);22    const storage_offset = try readU16(data, name_table.offset + 4);23    const records_offset = name_table.offset + 6;24    if (@as(u64, count) * 12 > @as(u64, name_table.len - 6)) return error.InvalidFont;25    if (storage_offset > name_table.len) return error.InvalidFont;2627    var best_score: u16 = 0;28    var best: ?NameRecordBytes = null;29    for (0..count) |record_index| {30        const record_offset = records_offset + record_index * 12;31        const platform_id = try readU16(data, record_offset);32        const encoding_id = try readU16(data, record_offset + 2);33        const language_id = try readU16(data, record_offset + 4);34        const current_name_id = try readU16(data, record_offset + 6);35        if (current_name_id != name_id) continue;36        const len = try readU16(data, record_offset + 8);37        const relative = try readU16(data, record_offset + 10);38        if (!nameRecordIsUtf16(platform_id, encoding_id)) continue;39        if (relative > name_table.len - storage_offset) return error.InvalidFont;40        const storage_start = name_table.offset + storage_offset;41        const start = storage_start + @as(usize, relative);42        const storage_remaining = name_table.len - storage_offset - @as(usize, relative);43        if (@as(usize, len) > storage_remaining) return error.InvalidFont;44        if (len % 2 != 0) return error.InvalidFont;45        const score = nameRecordScore(platform_id, encoding_id, language_id);46        if (score <= best_score) continue;47        best_score = score;48        best = .{49            .platform_id = platform_id,50            .encoding_id = encoding_id,51            .language_id = language_id,52            .name_id = current_name_id,53            .bytes = data[start..][0..len],54        };55    }56    return best;57}5859pub fn utf16BeToUtf8Alloc(allocator: std.mem.Allocator, bytes: []const u8) ![]u8 {60    var utf8_len: usize = 0;61    var read_index: usize = 0;62    while (read_index < bytes.len) {63        const codepoint = try readUtf16BeScalar(bytes, &read_index);64        utf8_len += try std.unicode.utf8CodepointSequenceLength(codepoint);65    }6667    const result = try allocator.alloc(u8, utf8_len);68    errdefer allocator.free(result);69    var write_index: usize = 0;70    read_index = 0;71    while (read_index < bytes.len) {72        const codepoint = try readUtf16BeScalar(bytes, &read_index);73        write_index += try std.unicode.utf8Encode(codepoint, result[write_index..]);74    }75    return result;76}7778fn nameRecordIsUtf16(platform_id: u16, encoding_id: u16) bool {79    return platform_id == 0 or (platform_id == 3 and (encoding_id == 1 or encoding_id == 10));80}8182fn nameRecordScore(platform_id: u16, encoding_id: u16, language_id: u16) u16 {83    if (platform_id == 3 and encoding_id == 10 and language_id == 0x0409) return 500;84    if (platform_id == 3 and encoding_id == 1 and language_id == 0x0409) return 450;85    if (platform_id == 3 and encoding_id == 10) return 400;86    if (platform_id == 3 and encoding_id == 1) return 350;87    if (platform_id == 0) return 300;88    return 0;89}9091fn readUtf16BeScalar(bytes: []const u8, index: *usize) FontError!u21 {92    const unit = try readUtf16BeUnit(bytes, index.*);93    index.* += 2;94    if (unit >= 0xd800 and unit <= 0xdbff) {95        if (index.* >= bytes.len) return error.InvalidFont;96        const low = try readUtf16BeUnit(bytes, index.*);97        if (low < 0xdc00 or low > 0xdfff) return error.InvalidFont;98        index.* += 2;99        return @intCast(0x10000 + (((@as(u32, unit) - 0xd800) << 10) | (@as(u32, low) - 0xdc00)));100    }101    if (unit >= 0xdc00 and unit <= 0xdfff) return error.InvalidFont;102    return @intCast(unit);103}104105fn readUtf16BeUnit(bytes: []const u8, offset: usize) FontError!u16 {106    if (offset > bytes.len or bytes.len - offset < 2) return error.InvalidFont;107    return std.mem.readInt(u16, bytes[offset..][0..2], .big);108}

1pub const names = @import("names.zig");