LibGfx: Get glyph ID for codepoint, from the CMAP table.
This commit is contained in:
Srimanta Barua
Andreas Kling
parent
be1586850d
commit
675237180f
Notes:
sideshowbarker
2024-07-19 00:21:16 +09:00
Author: https://github.com/SrimantaBarua Commit: https://github.com/SerenityOS/serenity/commit/675237180f3 Pull-request: https://github.com/SerenityOS/serenity/pull/4631 Issue: https://github.com/SerenityOS/serenity/issues/743 Reviewed-by: https://github.com/alimpfard Reviewed-by: https://github.com/sunverwerth
2 changed files with 351 additions and 40 deletions
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@ -30,6 +30,7 @@
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#include <LibCore/File.h>
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namespace Gfx {
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namespace TTF {
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static u16 be_u16(const u8* ptr)
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{
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@ -51,50 +52,196 @@ static u32 tag_from_str(const char *str)
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return be_u32((const u8*) str);
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}
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u16 TTFHead::units_per_em() const
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u16 Head::units_per_em() const
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{
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return be_u16(m_slice.offset_pointer(18));
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}
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i16 TTFHead::xmin() const
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i16 Head::xmin() const
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{
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return be_i16(m_slice.offset_pointer(36));
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}
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i16 TTFHead::ymin() const
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i16 Head::ymin() const
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{
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return be_i16(m_slice.offset_pointer(38));
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}
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i16 TTFHead::xmax() const
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i16 Head::xmax() const
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{
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return be_i16(m_slice.offset_pointer(40));
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}
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i16 TTFHead::ymax() const
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i16 Head::ymax() const
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{
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return be_i16(m_slice.offset_pointer(42));
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}
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u16 TTFHead::lowest_recommended_ppem() const
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u16 Head::lowest_recommended_ppem() const
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{
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return be_u16(m_slice.offset_pointer(46));
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}
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Result<TTFIndexToLocFormat, i16> TTFHead::index_to_loc_format() const
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Result<IndexToLocFormat, i16> Head::index_to_loc_format() const
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{
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i16 raw = be_i16(m_slice.offset_pointer(50));
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switch (raw) {
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case 0:
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return TTFIndexToLocFormat::Offset16;
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return IndexToLocFormat::Offset16;
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case 1:
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return TTFIndexToLocFormat::Offset32;
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return IndexToLocFormat::Offset32;
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default:
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return raw;
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}
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}
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OwnPtr<TTFont> TTFont::load_from_file(const StringView& path, unsigned index)
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u16 Hhea::number_of_h_metrics() const
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{
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return be_u16(m_slice.offset_pointer(34));
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}
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u16 Maxp::num_glyphs() const
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{
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return be_u16(m_slice.offset_pointer(4));
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}
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GlyphHorizontalMetrics Hmtx::get_glyph_horizontal_metrics(u32 glyph_id) const
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{
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ASSERT(glyph_id < m_num_glyphs);
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auto offset = glyph_id * 2;
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i16 left_side_bearing = be_i16(m_slice.offset_pointer(offset + 2));
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if (glyph_id < m_number_of_h_metrics) {
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u16 advance_width = be_u16(m_slice.offset_pointer(offset));
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return GlyphHorizontalMetrics {
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.advance_width = advance_width,
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.left_side_bearing = left_side_bearing,
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};
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} else {
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u16 advance_width = be_u16(m_slice.offset_pointer((m_number_of_h_metrics - 1) * 2));
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return GlyphHorizontalMetrics {
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.advance_width = advance_width,
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.left_side_bearing = left_side_bearing,
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};
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}
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}
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CmapSubtablePlatform CmapSubtable::platform_id() const
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{
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switch (m_raw_platform_id) {
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case 0: return CmapSubtablePlatform::Unicode;
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case 1: return CmapSubtablePlatform::Macintosh;
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case 3: return CmapSubtablePlatform::Windows;
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case 4: return CmapSubtablePlatform::Custom;
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default: ASSERT_NOT_REACHED();
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}
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}
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CmapSubtableFormat CmapSubtable::format() const
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{
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switch (be_u16(m_slice.offset_pointer(0))) {
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case 0: return CmapSubtableFormat::ByteEncoding;
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case 2: return CmapSubtableFormat::HighByte;
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case 4: return CmapSubtableFormat::SegmentToDelta;
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case 6: return CmapSubtableFormat::TrimmedTable;
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case 8: return CmapSubtableFormat::Mixed16And32;
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case 10: return CmapSubtableFormat::TrimmedArray;
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case 12: return CmapSubtableFormat::SegmentedCoverage;
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case 13: return CmapSubtableFormat::ManyToOneRange;
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case 14: return CmapSubtableFormat::UnicodeVariationSequences;
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default: ASSERT_NOT_REACHED();
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}
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}
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u32 Cmap::num_subtables() const
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{
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return be_u16(m_slice.offset_pointer(2));
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}
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Optional<CmapSubtable> Cmap::subtable(u32 index) const
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{
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if (index >= num_subtables()) {
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return {};
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}
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u32 record_offset = 4 + index * 8;
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u16 platform_id = be_u16(m_slice.offset_pointer(record_offset));
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u16 encoding_id = be_u16(m_slice.offset_pointer(record_offset + 2));
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u32 subtable_offset = be_u32(m_slice.offset_pointer(record_offset + 4));
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ASSERT(subtable_offset < m_slice.size());
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auto subtable_slice = ByteBuffer::wrap(m_slice.offset_pointer(subtable_offset), m_slice.size() - subtable_offset);
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return CmapSubtable(move(subtable_slice), platform_id, encoding_id);
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}
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// FIXME: This only handles formats 4 (SegmentToDelta) and 12 (SegmentedCoverage) for now.
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u32 CmapSubtable::glyph_id_for_codepoint(u32 codepoint) const
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{
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switch (format()) {
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case CmapSubtableFormat::SegmentToDelta:
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return glyph_id_for_codepoint_table_4(codepoint);
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case CmapSubtableFormat::SegmentedCoverage:
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return glyph_id_for_codepoint_table_12(codepoint);
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default:
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return 0;
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}
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}
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u32 CmapSubtable::glyph_id_for_codepoint_table_4(u32 codepoint) const
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{
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u32 segcount_x2 = be_u16(m_slice.offset_pointer(6));
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if (m_slice.size() < segcount_x2 * 4 + 16) {
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return 0;
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}
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for (u32 offset = 0; offset < segcount_x2; offset += 2) {
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u32 end_codepoint = be_u16(m_slice.offset_pointer(14 + offset));
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if (codepoint > end_codepoint) {
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continue;
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}
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u32 start_codepoint = be_u16(m_slice.offset_pointer(16 + segcount_x2 + offset));
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if (codepoint < start_codepoint) {
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break;
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}
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u32 delta = be_u16(m_slice.offset_pointer(16 + segcount_x2 * 2 + offset));
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u32 range = be_u16(m_slice.offset_pointer(16 + segcount_x2 * 3 + offset));
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if (range == 0) {
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return (codepoint + delta) & 0xffff;
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} else {
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u32 glyph_offset = 16 + segcount_x2 * 3 + offset + range + (codepoint - start_codepoint) * 2;
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ASSERT(glyph_offset + 2 <= m_slice.size());
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return (be_u16(m_slice.offset_pointer(glyph_offset)) + delta) & 0xffff;
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}
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}
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return 0;
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}
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u32 CmapSubtable::glyph_id_for_codepoint_table_12(u32 codepoint) const
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{
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u32 num_groups = be_u32(m_slice.offset_pointer(12));
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ASSERT(m_slice.size() >= 16 + 12 * num_groups);
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for (u32 offset = 0; offset < num_groups * 12; offset += 12) {
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u32 start_codepoint = be_u32(m_slice.offset_pointer(16 + offset));
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if (codepoint < start_codepoint) {
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break;
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}
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u32 end_codepoint = be_u32(m_slice.offset_pointer(20 + offset));
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if (codepoint > end_codepoint) {
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continue;
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}
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u32 glyph_offset = be_u32(m_slice.offset_pointer(24 + offset));
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return codepoint - start_codepoint + glyph_offset;
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}
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return 0;
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}
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u32 Cmap::glyph_id_for_codepoint(u32 codepoint) const
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{
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auto opt_subtable = subtable(m_active_index);
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if (!opt_subtable.has_value()) {
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return 0;
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}
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auto subtable = opt_subtable.value();
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return subtable.glyph_id_for_codepoint(codepoint);
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}
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OwnPtr<Font> Font::load_from_file(const StringView& path, unsigned index)
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{
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dbg() << "path: " << path << " | index: " << index;
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auto file_or_error = Core::File::open(String(path), Core::IODevice::ReadOnly);
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@ -120,23 +267,27 @@ OwnPtr<TTFont> TTFont::load_from_file(const StringView& path, unsigned index)
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return nullptr;
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}
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u32 offset = be_u32(buffer.offset_pointer(12 + 4 * index));
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return OwnPtr(new TTFont(move(buffer), offset));
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return OwnPtr(new Font(move(buffer), offset));
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} else if (tag == tag_from_str("OTTO")) {
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dbg() << "CFF fonts not supported yet";
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return nullptr;
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} else if (tag != 0x00010000) {
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dbg() << "Not a valid TTF font";
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dbg() << "Not a valid font";
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return nullptr;
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} else {
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return OwnPtr(new TTFont(move(buffer), 0));
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return OwnPtr(new Font(move(buffer), 0));
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}
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}
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TTFont::TTFont(AK::ByteBuffer&& buffer, u32 offset)
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Font::Font(AK::ByteBuffer&& buffer, u32 offset)
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: m_buffer(move(buffer))
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{
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ASSERT(m_buffer.size() >= offset + 12);
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bool head_has_been_initialized = false;
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Optional<ByteBuffer> head_slice = {};
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Optional<ByteBuffer> hhea_slice = {};
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Optional<ByteBuffer> maxp_slice = {};
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Optional<ByteBuffer> hmtx_slice = {};
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Optional<ByteBuffer> cmap_slice = {};
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//auto sfnt_version = be_u32(data + offset);
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auto num_tables = be_u16(m_buffer.offset_pointer(offset + 4));
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@ -148,16 +299,58 @@ TTFont::TTFont(AK::ByteBuffer&& buffer, u32 offset)
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u32 table_offset = be_u32(m_buffer.offset_pointer(record_offset + 8));
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u32 table_length = be_u32(m_buffer.offset_pointer(record_offset + 12));
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ASSERT(m_buffer.size() >= table_offset + table_length);
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auto buffer = ByteBuffer::wrap(m_buffer.offset_pointer(table_offset), table_length);
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// Get the tables we need
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// Get the table offsets we need.
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if (tag == tag_from_str("head")) {
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auto buffer = ByteBuffer::wrap(m_buffer.offset_pointer(table_offset), table_length);
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m_head = TTFHead(move(buffer));
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head_has_been_initialized = true;
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head_slice = move(buffer);
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} else if (tag == tag_from_str("hhea")) {
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hhea_slice = move(buffer);
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} else if (tag == tag_from_str("maxp")) {
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maxp_slice = move(buffer);
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} else if (tag == tag_from_str("hmtx")) {
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hmtx_slice = move(buffer);
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} else if (tag == tag_from_str("cmap")) {
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cmap_slice = move(buffer);
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}
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}
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// Check that we've got everything we need
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ASSERT(head_has_been_initialized);
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// Check that we've got everything we need.
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ASSERT(head_slice.has_value());
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ASSERT(hhea_slice.has_value());
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ASSERT(maxp_slice.has_value());
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ASSERT(hmtx_slice.has_value());
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ASSERT(cmap_slice.has_value());
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// Load the tables.
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m_head = Head(move(head_slice.value()));
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m_hhea = Hhea(move(hhea_slice.value()));
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m_maxp = Maxp(move(maxp_slice.value()));
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m_hmtx = Hmtx(move(hmtx_slice.value()), m_maxp.num_glyphs(), m_hhea.number_of_h_metrics());
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m_cmap = Cmap(move(cmap_slice.value()));
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// Select cmap table. FIXME: Do this better. Right now, just looks for platform "Windows"
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// and corresponding encoding "Unicode full repertoire", or failing that, "Unicode BMP"
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for (u32 i = 0; i < m_cmap.num_subtables(); i++) {
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auto opt_subtable = m_cmap.subtable(i);
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if (!opt_subtable.has_value()) {
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continue;
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}
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auto subtable = opt_subtable.value();
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if (subtable.platform_id() == CmapSubtablePlatform::Windows) {
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if (subtable.encoding_id() == 10) {
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m_cmap.set_active_index(i);
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break;
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}
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if (subtable.encoding_id() == 1) {
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m_cmap.set_active_index(i);
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break;
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}
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}
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}
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dbg() << "Glyph ID for 'A': " << m_cmap.glyph_id_for_codepoint('A');
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dbg() << "Glyph ID for 'B': " << m_cmap.glyph_id_for_codepoint('B');
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}
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}
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}
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@ -32,28 +32,22 @@
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#include <AK/StringView.h>
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namespace Gfx {
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namespace TTF {
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class TTFont;
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class Font;
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enum class TTFIndexToLocFormat {
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enum class IndexToLocFormat {
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Offset16,
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Offset32,
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};
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class TTFHead {
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class Head {
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private:
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TTFHead() {}
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TTFHead(ByteBuffer&& slice)
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Head() {}
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Head(ByteBuffer&& slice)
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: m_slice(move(slice))
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{
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ASSERT(m_slice.size() >= 54);
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dbg() << "HEAD:"
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<< "\n units_per_em: " << units_per_em()
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<< "\n xmin: " << xmin()
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<< "\n ymin: " << ymin()
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<< "\n xmax: " << xmax()
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<< "\n ymax: " << ymax()
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<< "\n lowest_recommended_ppem: " << lowest_recommended_ppem();
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}
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u16 units_per_em() const;
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i16 xmin() const;
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@ -61,23 +55,147 @@ private:
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i16 xmax() const;
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i16 ymax() const;
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u16 lowest_recommended_ppem() const;
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Result<TTFIndexToLocFormat, i16> index_to_loc_format() const;
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Result<IndexToLocFormat, i16> index_to_loc_format() const;
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ByteBuffer m_slice;
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bool m_is_init;
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friend TTFont;
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friend Font;
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};
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class TTFont {
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class Hhea {
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private:
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Hhea() {}
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Hhea(ByteBuffer&& slice)
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: m_slice(move(slice))
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{
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ASSERT(m_slice.size() >= 36);
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}
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u16 number_of_h_metrics() const;
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ByteBuffer m_slice;
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friend Font;
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};
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class Maxp {
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private:
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Maxp() {}
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Maxp(ByteBuffer&& slice)
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: m_slice(move(slice))
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{
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ASSERT(m_slice.size() >= 6);
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}
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u16 num_glyphs() const;
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ByteBuffer m_slice;
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friend Font;
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};
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struct GlyphHorizontalMetrics {
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u16 advance_width;
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i16 left_side_bearing;
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};
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class Hmtx {
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private:
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Hmtx() {}
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Hmtx(ByteBuffer&& slice, u32 num_glyphs, u32 number_of_h_metrics)
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: m_slice(move(slice))
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, m_num_glyphs(num_glyphs)
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, m_number_of_h_metrics(number_of_h_metrics)
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{
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ASSERT(m_slice.size() >= number_of_h_metrics * 2 + num_glyphs * 2);
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}
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GlyphHorizontalMetrics get_glyph_horizontal_metrics(u32 glyph_id) const;
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ByteBuffer m_slice;
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u32 m_num_glyphs;
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u32 m_number_of_h_metrics;
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friend Font;
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};
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enum class CmapSubtablePlatform {
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Unicode,
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Macintosh,
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Windows,
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Custom,
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};
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enum class CmapSubtableFormat {
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ByteEncoding,
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HighByte,
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SegmentToDelta,
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TrimmedTable,
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Mixed16And32,
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TrimmedArray,
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SegmentedCoverage,
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ManyToOneRange,
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UnicodeVariationSequences,
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};
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class Cmap;
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class CmapSubtable {
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public:
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static OwnPtr<TTFont> load_from_file(const StringView& path, unsigned index);
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CmapSubtablePlatform platform_id() const;
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u16 encoding_id() const { return m_encoding_id; }
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CmapSubtableFormat format() const;
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private:
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TTFont(AK::ByteBuffer&& buffer, u32 offset);
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CmapSubtable(ByteBuffer&& slice, u16 platform_id, u16 encoding_id)
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: m_slice(move(slice))
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, m_raw_platform_id(platform_id)
|
||||
, m_encoding_id(encoding_id)
|
||||
{
|
||||
}
|
||||
// Returns 0 if glyph not found. This corresponds to the "missing glyph"
|
||||
u32 glyph_id_for_codepoint(u32 codepoint) const;
|
||||
u32 glyph_id_for_codepoint_table_4(u32 codepoint) const;
|
||||
u32 glyph_id_for_codepoint_table_12(u32 codepoint) const;
|
||||
|
||||
ByteBuffer m_slice;
|
||||
u16 m_raw_platform_id;
|
||||
u16 m_encoding_id;
|
||||
|
||||
friend Cmap;
|
||||
};
|
||||
|
||||
class Cmap {
|
||||
private:
|
||||
Cmap() {}
|
||||
Cmap(ByteBuffer&& slice)
|
||||
: m_slice(move(slice))
|
||||
{
|
||||
ASSERT(m_slice.size() > 4);
|
||||
}
|
||||
u32 num_subtables() const;
|
||||
Optional<CmapSubtable> subtable(u32 index) const;
|
||||
void set_active_index(u32 index) { m_active_index = index; }
|
||||
// Returns 0 if glyph not found. This corresponds to the "missing glyph"
|
||||
u32 glyph_id_for_codepoint(u32 codepoint) const;
|
||||
|
||||
ByteBuffer m_slice;
|
||||
u32 m_active_index { UINT32_MAX };
|
||||
|
||||
friend Font;
|
||||
};
|
||||
|
||||
class Font {
|
||||
public:
|
||||
static OwnPtr<Font> load_from_file(const StringView& path, unsigned index);
|
||||
|
||||
private:
|
||||
Font(AK::ByteBuffer&& buffer, u32 offset);
|
||||
|
||||
AK::ByteBuffer m_buffer;
|
||||
TTFHead m_head;
|
||||
Head m_head;
|
||||
Hhea m_hhea;
|
||||
Maxp m_maxp;
|
||||
Hmtx m_hmtx;
|
||||
Cmap m_cmap;
|
||||
};
|
||||
|
||||
}
|
||||
}
|
||||
|
|
|
|||
Loading…
Add table
Reference in a new issue