/* * Copyright (c) 2020, Srimanta Barua * * SPDX-License-Identifier: BSD-2-Clause */ #include "AK/ByteBuffer.h" #include #include #include #include #include #include #include #include #include #include namespace TTF { u16 be_u16(const u8* ptr); u32 be_u32(const u8* ptr); i16 be_i16(const u8* ptr); float be_fword(const u8* ptr); u32 tag_from_str(const char* str); u16 be_u16(const u8* ptr) { return (((u16)ptr[0]) << 8) | ((u16)ptr[1]); } u32 be_u32(const u8* ptr) { return (((u32)ptr[0]) << 24) | (((u32)ptr[1]) << 16) | (((u32)ptr[2]) << 8) | ((u32)ptr[3]); } i16 be_i16(const u8* ptr) { return (((i16)ptr[0]) << 8) | ((i16)ptr[1]); } float be_fword(const u8* ptr) { return (float)be_i16(ptr) / (float)(1 << 14); } u32 tag_from_str(const char* str) { return be_u32((const u8*)str); } Optional Head::from_slice(const ReadonlyBytes& slice) { if (slice.size() < (size_t)Sizes::Table) { return {}; } return Head(slice); } u16 Head::units_per_em() const { return be_u16(m_slice.offset_pointer((u32)Offsets::UnitsPerEM)); } i16 Head::xmin() const { return be_i16(m_slice.offset_pointer((u32)Offsets::XMin)); } i16 Head::ymin() const { return be_i16(m_slice.offset_pointer((u32)Offsets::YMin)); } i16 Head::xmax() const { return be_i16(m_slice.offset_pointer((u32)Offsets::XMax)); } i16 Head::ymax() const { return be_i16(m_slice.offset_pointer((u32)Offsets::YMax)); } u16 Head::lowest_recommended_ppem() const { return be_u16(m_slice.offset_pointer((u32)Offsets::LowestRecPPEM)); } IndexToLocFormat Head::index_to_loc_format() const { i16 raw = be_i16(m_slice.offset_pointer((u32)Offsets::IndexToLocFormat)); switch (raw) { case 0: return IndexToLocFormat::Offset16; case 1: return IndexToLocFormat::Offset32; default: VERIFY_NOT_REACHED(); } } Optional Hhea::from_slice(const ReadonlyBytes& slice) { if (slice.size() < (size_t)Sizes::Table) { return {}; } return Hhea(slice); } i16 Hhea::ascender() const { return be_i16(m_slice.offset_pointer((u32)Offsets::Ascender)); } i16 Hhea::descender() const { return be_i16(m_slice.offset_pointer((u32)Offsets::Descender)); } i16 Hhea::line_gap() const { return be_i16(m_slice.offset_pointer((u32)Offsets::LineGap)); } u16 Hhea::advance_width_max() const { return be_u16(m_slice.offset_pointer((u32)Offsets::AdvanceWidthMax)); } u16 Hhea::number_of_h_metrics() const { return be_u16(m_slice.offset_pointer((u32)Offsets::NumberOfHMetrics)); } Optional Maxp::from_slice(const ReadonlyBytes& slice) { if (slice.size() < (size_t)Sizes::TableV0p5) { return {}; } return Maxp(slice); } u16 Maxp::num_glyphs() const { return be_u16(m_slice.offset_pointer((u32)Offsets::NumGlyphs)); } Optional Hmtx::from_slice(const ReadonlyBytes& slice, u32 num_glyphs, u32 number_of_h_metrics) { if (slice.size() < number_of_h_metrics * (u32)Sizes::LongHorMetric + (num_glyphs - number_of_h_metrics) * (u32)Sizes::LeftSideBearing) { return {}; } return Hmtx(slice, num_glyphs, number_of_h_metrics); } Optional Name::from_slice(const ReadonlyBytes& slice) { return Name(slice); } String Name::string_for_id(NameId id) const { auto num_entries = be_u16(m_slice.offset_pointer(2)); auto string_offset = be_u16(m_slice.offset_pointer(4)); for (int i = 0; i < num_entries; ++i) { auto this_id = be_u16(m_slice.offset_pointer(6 + i * 12 + 6)); if (this_id != (u16)id) continue; auto platform = be_u16(m_slice.offset_pointer(6 + i * 12 + 0)); auto length = be_u16(m_slice.offset_pointer(6 + i * 12 + 8)); auto offset = be_u16(m_slice.offset_pointer(6 + i * 12 + 10)); if (platform == (u16)Platform::Windows) { static auto& decoder = *TextCodec::decoder_for("utf-16be"); return decoder.to_utf8(StringView { (const char*)m_slice.offset_pointer(string_offset + offset), length }); } return String((const char*)m_slice.offset_pointer(string_offset + offset), length); } return String::empty(); } GlyphHorizontalMetrics Hmtx::get_glyph_horizontal_metrics(u32 glyph_id) const { VERIFY(glyph_id < m_num_glyphs); if (glyph_id < m_number_of_h_metrics) { auto offset = glyph_id * (u32)Sizes::LongHorMetric; u16 advance_width = be_u16(m_slice.offset_pointer(offset)); i16 left_side_bearing = be_i16(m_slice.offset_pointer(offset + 2)); return GlyphHorizontalMetrics { .advance_width = advance_width, .left_side_bearing = left_side_bearing, }; } auto offset = m_number_of_h_metrics * (u32)Sizes::LongHorMetric + (glyph_id - m_number_of_h_metrics) * (u32)Sizes::LeftSideBearing; u16 advance_width = be_u16(m_slice.offset_pointer((m_number_of_h_metrics - 1) * (u32)Sizes::LongHorMetric)); i16 left_side_bearing = be_i16(m_slice.offset_pointer(offset)); return GlyphHorizontalMetrics { .advance_width = advance_width, .left_side_bearing = left_side_bearing, }; } RefPtr Font::load_from_file(String path, unsigned index) { auto file_or_error = Core::File::open(move(path), Core::IODevice::ReadOnly); if (file_or_error.is_error()) { dbgln("Could not open file: {}", file_or_error.error()); return nullptr; } auto file = file_or_error.value(); if (!file->open(Core::IODevice::ReadOnly)) { dbgln("Could not open file"); return nullptr; } auto buffer = file->read_all(); return load_from_memory(buffer, index); } RefPtr Font::load_from_memory(ByteBuffer& buffer, unsigned index) { if (buffer.size() < 4) { dbgln("Font file too small"); return nullptr; } u32 tag = be_u32(buffer.data()); if (tag == tag_from_str("ttcf")) { // It's a font collection if (buffer.size() < (u32)Sizes::TTCHeaderV1 + sizeof(u32) * (index + 1)) { dbgln("Font file too small"); return nullptr; } u32 offset = be_u32(buffer.offset_pointer((u32)Sizes::TTCHeaderV1 + sizeof(u32) * index)); return load_from_offset(move(buffer), offset); } if (tag == tag_from_str("OTTO")) { dbgln("CFF fonts not supported yet"); return nullptr; } if (tag != 0x00010000) { dbgln("Not a valid font"); return nullptr; } return load_from_offset(move(buffer), 0); } // FIXME: "loca" and "glyf" are not available for CFF fonts. RefPtr Font::load_from_offset(ByteBuffer&& buffer, u32 offset) { if (Checked::addition_would_overflow(offset, (u32)Sizes::OffsetTable)) { dbgln("Invalid offset in font header"); return nullptr; } if (buffer.size() < offset + (u32)Sizes::OffsetTable) { dbgln("Font file too small"); return nullptr; } Optional opt_head_slice = {}; Optional opt_name_slice = {}; Optional opt_hhea_slice = {}; Optional opt_maxp_slice = {}; Optional opt_hmtx_slice = {}; Optional opt_cmap_slice = {}; Optional opt_loca_slice = {}; Optional opt_glyf_slice = {}; Optional opt_head = {}; Optional opt_name = {}; Optional opt_hhea = {}; Optional opt_maxp = {}; Optional opt_hmtx = {}; Optional opt_cmap = {}; Optional opt_loca = {}; auto num_tables = be_u16(buffer.offset_pointer(offset + (u32)Offsets::NumTables)); if (buffer.size() < offset + (u32)Sizes::OffsetTable + num_tables * (u32)Sizes::TableRecord) { dbgln("Font file too small"); return nullptr; } for (auto i = 0; i < num_tables; i++) { u32 record_offset = offset + (u32)Sizes::OffsetTable + i * (u32)Sizes::TableRecord; u32 tag = be_u32(buffer.offset_pointer(record_offset)); u32 table_offset = be_u32(buffer.offset_pointer(record_offset + (u32)Offsets::TableRecord_Offset)); u32 table_length = be_u32(buffer.offset_pointer(record_offset + (u32)Offsets::TableRecord_Length)); if (Checked::addition_would_overflow(table_offset, table_length)) { dbgln("Invalid table offset/length in font."); return nullptr; } if (buffer.size() < table_offset + table_length) { dbgln("Font file too small"); return nullptr; } auto buffer_here = ReadonlyBytes(buffer.offset_pointer(table_offset), table_length); // Get the table offsets we need. if (tag == tag_from_str("head")) { opt_head_slice = buffer_here; } else if (tag == tag_from_str("name")) { opt_name_slice = buffer_here; } else if (tag == tag_from_str("hhea")) { opt_hhea_slice = buffer_here; } else if (tag == tag_from_str("maxp")) { opt_maxp_slice = buffer_here; } else if (tag == tag_from_str("hmtx")) { opt_hmtx_slice = buffer_here; } else if (tag == tag_from_str("cmap")) { opt_cmap_slice = buffer_here; } else if (tag == tag_from_str("loca")) { opt_loca_slice = buffer_here; } else if (tag == tag_from_str("glyf")) { opt_glyf_slice = buffer_here; } } if (!opt_head_slice.has_value() || !(opt_head = Head::from_slice(opt_head_slice.value())).has_value()) { dbgln("Could not load Head"); return nullptr; } auto head = opt_head.value(); if (!opt_name_slice.has_value() || !(opt_name = Name::from_slice(opt_name_slice.value())).has_value()) { dbgln("Could not load Name"); return nullptr; } auto name = opt_name.value(); if (!opt_hhea_slice.has_value() || !(opt_hhea = Hhea::from_slice(opt_hhea_slice.value())).has_value()) { dbgln("Could not load Hhea"); return nullptr; } auto hhea = opt_hhea.value(); if (!opt_maxp_slice.has_value() || !(opt_maxp = Maxp::from_slice(opt_maxp_slice.value())).has_value()) { dbgln("Could not load Maxp"); return nullptr; } auto maxp = opt_maxp.value(); if (!opt_hmtx_slice.has_value() || !(opt_hmtx = Hmtx::from_slice(opt_hmtx_slice.value(), maxp.num_glyphs(), hhea.number_of_h_metrics())).has_value()) { dbgln("Could not load Hmtx"); return nullptr; } auto hmtx = opt_hmtx.value(); if (!opt_cmap_slice.has_value() || !(opt_cmap = Cmap::from_slice(opt_cmap_slice.value())).has_value()) { dbgln("Could not load Cmap"); return nullptr; } auto cmap = opt_cmap.value(); if (!opt_loca_slice.has_value() || !(opt_loca = Loca::from_slice(opt_loca_slice.value(), maxp.num_glyphs(), head.index_to_loc_format())).has_value()) { dbgln("Could not load Loca"); return nullptr; } auto loca = opt_loca.value(); if (!opt_glyf_slice.has_value()) { dbgln("Could not load Glyf"); return nullptr; } auto glyf = Glyf(opt_glyf_slice.value()); // Select cmap table. FIXME: Do this better. Right now, just looks for platform "Windows" // and corresponding encoding "Unicode full repertoire", or failing that, "Unicode BMP" for (u32 i = 0; i < cmap.num_subtables(); i++) { auto opt_subtable = cmap.subtable(i); if (!opt_subtable.has_value()) { continue; } auto subtable = opt_subtable.value(); if (subtable.platform_id() == Cmap::Subtable::Platform::Windows) { if (subtable.encoding_id() == (u16)Cmap::Subtable::WindowsEncoding::UnicodeFullRepertoire) { cmap.set_active_index(i); break; } if (subtable.encoding_id() == (u16)Cmap::Subtable::WindowsEncoding::UnicodeBMP) { cmap.set_active_index(i); break; } } } return adopt_ref(*new Font(move(buffer), move(head), move(name), move(hhea), move(maxp), move(hmtx), move(cmap), move(loca), move(glyf))); } ScaledFontMetrics Font::metrics(float x_scale, float y_scale) const { auto ascender = m_hhea.ascender() * y_scale; auto descender = m_hhea.descender() * y_scale; auto line_gap = m_hhea.line_gap() * y_scale; auto advance_width_max = m_hhea.advance_width_max() * x_scale; return ScaledFontMetrics { .ascender = (int)roundf(ascender), .descender = (int)roundf(descender), .line_gap = (int)roundf(line_gap), .advance_width_max = (int)roundf(advance_width_max), }; } // FIXME: "loca" and "glyf" are not available for CFF fonts. ScaledGlyphMetrics Font::glyph_metrics(u32 glyph_id, float x_scale, float y_scale) const { if (glyph_id >= glyph_count()) { glyph_id = 0; } auto horizontal_metrics = m_hmtx.get_glyph_horizontal_metrics(glyph_id); auto glyph_offset = m_loca.get_glyph_offset(glyph_id); auto glyph = m_glyf.glyph(glyph_offset); int ascender = glyph.ascender(); int descender = glyph.descender(); return ScaledGlyphMetrics { .ascender = (int)roundf(ascender * y_scale), .descender = (int)roundf(descender * y_scale), .advance_width = (int)roundf(horizontal_metrics.advance_width * x_scale), .left_side_bearing = (int)roundf(horizontal_metrics.left_side_bearing * x_scale), }; } // FIXME: "loca" and "glyf" are not available for CFF fonts. RefPtr Font::raster_glyph(u32 glyph_id, float x_scale, float y_scale) const { if (glyph_id >= glyph_count()) { glyph_id = 0; } auto glyph_offset = m_loca.get_glyph_offset(glyph_id); auto glyph = m_glyf.glyph(glyph_offset); return glyph.raster(x_scale, y_scale, [&](u16 glyph_id) { if (glyph_id >= glyph_count()) { glyph_id = 0; } auto glyph_offset = m_loca.get_glyph_offset(glyph_id); return m_glyf.glyph(glyph_offset); }); } u32 Font::glyph_count() const { return m_maxp.num_glyphs(); } u16 Font::units_per_em() const { return m_head.units_per_em(); } String Font::family() const { auto string = m_name.typographic_family_name(); if (!string.is_empty()) return string; return m_name.family_name(); } String Font::variant() const { auto string = m_name.typographic_subfamily_name(); if (!string.is_empty()) return string; return m_name.subfamily_name(); } u16 Font::weight() const { // FIXME: This is pretty naive, read weight from the actual font table(s) auto variant_name = variant(); if (variant_name == "Thin") return 100; if (variant_name == "Extra Light") return 200; if (variant_name == "Light") return 300; if (variant_name == "Regular") return 400; if (variant_name == "Medium") return 500; if (variant_name == "Semi Bold") return 600; if (variant_name == "Bold") return 700; if (variant_name == "Extra Bold") return 800; if (variant_name == "Black") return 900; if (variant_name == "Extra Black") return 950; return 400; } bool Font::is_fixed_width() const { // FIXME: Read this information from the font file itself. // FIXME: Although, it appears some application do similar hacks return glyph_metrics(glyph_id_for_codepoint('.'), 1, 1).advance_width == glyph_metrics(glyph_id_for_codepoint('X'), 1, 1).advance_width; } int ScaledFont::width(const StringView& string) const { Utf8View utf8 { string }; return width(utf8); } int ScaledFont::width(const Utf8View& utf8) const { int width = 0; for (u32 codepoint : utf8) { u32 glyph_id = glyph_id_for_codepoint(codepoint); auto metrics = glyph_metrics(glyph_id); width += metrics.advance_width; } return width; } int ScaledFont::width(const Utf32View& utf32) const { int width = 0; for (size_t i = 0; i < utf32.length(); i++) { u32 glyph_id = glyph_id_for_codepoint(utf32.code_points()[i]); auto metrics = glyph_metrics(glyph_id); width += metrics.advance_width; } return width; } RefPtr ScaledFont::raster_glyph(u32 glyph_id) const { auto glyph_iterator = m_cached_glyph_bitmaps.find(glyph_id); if (glyph_iterator != m_cached_glyph_bitmaps.end()) return glyph_iterator->value; auto glyph_bitmap = m_font->raster_glyph(glyph_id, m_x_scale, m_y_scale); m_cached_glyph_bitmaps.set(glyph_id, glyph_bitmap); return glyph_bitmap; } Gfx::Glyph ScaledFont::glyph(u32 code_point) const { auto id = glyph_id_for_codepoint(code_point); auto bitmap = raster_glyph(id); auto metrics = glyph_metrics(id); return Gfx::Glyph(bitmap, metrics.left_side_bearing, metrics.advance_width, metrics.ascender); } u8 ScaledFont::glyph_width(size_t code_point) const { auto id = glyph_id_for_codepoint(code_point); auto metrics = glyph_metrics(id); return metrics.advance_width; } int ScaledFont::glyph_or_emoji_width(u32 code_point) const { auto id = glyph_id_for_codepoint(code_point); auto metrics = glyph_metrics(id); return metrics.advance_width; } u8 ScaledFont::glyph_fixed_width() const { return glyph_metrics(glyph_id_for_codepoint(' ')).advance_width; } }