LibGfx: Read OpenType table directory using structs and streams
This commit is contained in:
Sam Atkins
Andreas Kling
parent
5455ecf650
commit
1ab03ff963
Notes:
sideshowbarker
2024-07-17 06:40:35 +09:00
Author: https://github.com/AtkinsSJ Commit: https://github.com/SerenityOS/serenity/commit/1ab03ff963 Pull-request: https://github.com/SerenityOS/serenity/pull/21744
3 changed files with 40 additions and 43 deletions
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@ -3,6 +3,7 @@
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* Copyright (c) 2021-2023, Andreas Kling <kling@serenityos.org>
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* Copyright (c) 2022, Jelle Raaijmakers <jelle@gmta.nl>
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* Copyright (c) 2023, Lukas Affolter <git@lukasach.dev>
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* Copyright (c) 2023, Sam Atkins <atkinssj@serenityos.org>
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*
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* SPDX-License-Identifier: BSD-2-Clause
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*/
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@ -111,11 +112,9 @@ ErrorOr<NonnullRefPtr<Font>> Font::try_load_from_externally_owned_memory(Readonl
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// FIXME: "loca" and "glyf" are not available for CFF fonts.
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ErrorOr<NonnullRefPtr<Font>> Font::try_load_from_offset(ReadonlyBytes buffer, u32 offset)
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{
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if (Checked<u32>::addition_would_overflow(offset, (u32)Sizes::OffsetTable))
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return Error::from_string_literal("Invalid offset in font header");
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if (buffer.size() <= offset + (u32)Sizes::OffsetTable)
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return Error::from_string_literal("Font file too small");
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FixedMemoryStream stream { buffer };
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TRY(stream.seek(offset, AK::SeekMode::SetPosition));
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auto& table_directory = *TRY(stream.read_in_place<TableDirectory const>());
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Optional<ReadonlyBytes> opt_head_slice = {};
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Optional<ReadonlyBytes> opt_name_slice = {};
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@ -144,54 +143,47 @@ ErrorOr<NonnullRefPtr<Font>> Font::try_load_from_offset(ReadonlyBytes buffer, u3
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Optional<CBDT> cbdt;
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Optional<GPOS> gpos;
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auto num_tables = be_u16(buffer.offset(offset + (u32)Offsets::NumTables));
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if (buffer.size() <= offset + (u32)Sizes::OffsetTable + num_tables * (u32)Sizes::TableRecord)
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return Error::from_string_literal("Font file too small");
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for (auto i = 0; i < table_directory.num_tables; i++) {
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auto& table_record = *TRY(stream.read_in_place<TableRecord const>());
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for (auto i = 0; i < num_tables; i++) {
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u32 record_offset = offset + (u32)Sizes::OffsetTable + i * (u32)Sizes::TableRecord;
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u32 tag = be_u32(buffer.offset(record_offset));
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u32 table_offset = be_u32(buffer.offset(record_offset + (u32)Offsets::TableRecord_Offset));
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u32 table_length = be_u32(buffer.offset(record_offset + (u32)Offsets::TableRecord_Length));
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if (table_length == 0 || Checked<u32>::addition_would_overflow(table_offset, table_length))
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if (table_record.length == 0 || Checked<u32>::addition_would_overflow(static_cast<u32>(table_record.offset), static_cast<u32>(table_record.length)))
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return Error::from_string_literal("Invalid table offset or length in font");
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if (buffer.size() < table_offset + table_length)
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if (buffer.size() < table_record.offset + table_record.length)
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return Error::from_string_literal("Font file too small");
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auto buffer_here = ReadonlyBytes(buffer.offset(table_offset), table_length);
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auto buffer_here = buffer.slice(table_record.offset, table_record.length);
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// Get the table offsets we need.
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if (tag == tag_from_str("head")) {
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if (table_record.table_tag == tag_from_str("head")) {
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opt_head_slice = buffer_here;
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} else if (tag == tag_from_str("name")) {
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} else if (table_record.table_tag == tag_from_str("name")) {
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opt_name_slice = buffer_here;
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} else if (tag == tag_from_str("hhea")) {
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} else if (table_record.table_tag == tag_from_str("hhea")) {
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opt_hhea_slice = buffer_here;
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} else if (tag == tag_from_str("maxp")) {
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} else if (table_record.table_tag == tag_from_str("maxp")) {
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opt_maxp_slice = buffer_here;
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} else if (tag == tag_from_str("hmtx")) {
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} else if (table_record.table_tag == tag_from_str("hmtx")) {
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opt_hmtx_slice = buffer_here;
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} else if (tag == tag_from_str("cmap")) {
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} else if (table_record.table_tag == tag_from_str("cmap")) {
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opt_cmap_slice = buffer_here;
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} else if (tag == tag_from_str("loca")) {
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} else if (table_record.table_tag == tag_from_str("loca")) {
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opt_loca_slice = buffer_here;
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} else if (tag == tag_from_str("glyf")) {
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} else if (table_record.table_tag == tag_from_str("glyf")) {
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opt_glyf_slice = buffer_here;
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} else if (tag == tag_from_str("OS/2")) {
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} else if (table_record.table_tag == tag_from_str("OS/2")) {
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opt_os2_slice = buffer_here;
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} else if (tag == tag_from_str("kern")) {
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} else if (table_record.table_tag == tag_from_str("kern")) {
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opt_kern_slice = buffer_here;
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} else if (tag == tag_from_str("fpgm")) {
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} else if (table_record.table_tag == tag_from_str("fpgm")) {
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opt_fpgm_slice = buffer_here;
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} else if (tag == tag_from_str("prep")) {
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} else if (table_record.table_tag == tag_from_str("prep")) {
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opt_prep_slice = buffer_here;
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} else if (tag == tag_from_str("CBLC")) {
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} else if (table_record.table_tag == tag_from_str("CBLC")) {
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cblc = TRY(CBLC::from_slice(buffer_here));
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} else if (tag == tag_from_str("CBDT")) {
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} else if (table_record.table_tag == tag_from_str("CBDT")) {
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cbdt = TRY(CBDT::from_slice(buffer_here));
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} else if (tag == tag_from_str("GPOS")) {
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} else if (table_record.table_tag == tag_from_str("GPOS")) {
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gpos = TRY(GPOS::from_slice(buffer_here));
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}
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}
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@ -68,17 +68,6 @@ private:
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EmbeddedBitmapData embedded_bitmap_data_for_glyph(u32 glyph_id) const;
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enum class Offsets {
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NumTables = 4,
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TableRecord_Offset = 8,
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TableRecord_Length = 12,
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};
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enum class Sizes {
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TTCHeaderV1 = 12,
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OffsetTable = 12,
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TableRecord = 16,
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};
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static ErrorOr<NonnullRefPtr<Font>> try_load_from_offset(ReadonlyBytes, unsigned index = 0);
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Font(
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@ -67,6 +67,22 @@ struct [[gnu::packed]] TableRecord {
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};
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static_assert(AssertSize<TableRecord, 16>());
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}
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template<>
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class AK::Traits<OpenType::TableDirectory const> : public GenericTraits<OpenType::TableDirectory const> {
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public:
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static constexpr bool is_trivially_serializable() { return true; }
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};
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template<>
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class AK::Traits<OpenType::TableRecord const> : public GenericTraits<OpenType::TableRecord const> {
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public:
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static constexpr bool is_trivially_serializable() { return true; }
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};
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namespace OpenType {
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// https://learn.microsoft.com/en-us/typography/opentype/spec/head
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// head: Font Header Table
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class Head {
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