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ladybird/Userland/Libraries/LibTTF/Font.cpp

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/*
* Copyright (c) 2020, Srimanta Barua <srimanta.barua1@gmail.com>
* Copyright (c) 2021, Andreas Kling <kling@serenityos.org>
*
* SPDX-License-Identifier: BSD-2-Clause
*/
#include <AK/Checked.h>
#include <AK/MappedFile.h>
#include <AK/Utf32View.h>
#include <AK/Utf8View.h>
#include <LibCore/File.h>
#include <LibTTF/Cmap.h>
#include <LibTTF/Font.h>
#include <LibTTF/Glyf.h>
#include <LibTTF/Tables.h>
#include <LibTextCodec/Decoder.h>
#include <math.h>
#include <sys/mman.h>
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> 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> 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> 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> 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> 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));
Vector<int> valid_ids;
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)
valid_ids.append(i);
}
if (valid_ids.is_empty())
return String::empty();
auto it = valid_ids.find_if([this](auto const& i) {
// check if font has naming table for en-US language id
auto platform = be_u16(m_slice.offset_pointer(6 + i * 12 + 0));
auto language_id = be_u16(m_slice.offset_pointer(6 + i * 12 + 4));
return (platform == (u16)Platform::Macintosh && language_id == (u16)MacintoshLanguage::English)
|| (platform == (u16)Platform::Windows && language_id == (u16)WindowsLanguage::EnglishUnitedStates);
});
auto i = it != valid_ids.end() ? *it : valid_ids.first();
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);
}
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,
};
}
Result<NonnullRefPtr<Font>, String> Font::try_load_from_file(String path, unsigned index)
{
auto file_or_error = MappedFile::map(path);
if (file_or_error.is_error())
return String { file_or_error.error().string() };
auto& file = *file_or_error.value();
auto result = try_load_from_externally_owned_memory(file.bytes(), index);
if (result.is_error())
return result.error();
auto& font = *result.value();
font.m_mapped_file = file_or_error.release_value();
return result;
}
Result<NonnullRefPtr<Font>, String> Font::try_load_from_externally_owned_memory(ReadonlyBytes buffer, unsigned index)
{
if (buffer.size() < 4)
return String { "Font file too small" };
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))
return String { "Font file too small" };
u32 offset = be_u32(buffer.offset_pointer((u32)Sizes::TTCHeaderV1 + sizeof(u32) * index));
return try_load_from_offset(move(buffer), offset);
}
if (tag == tag_from_str("OTTO"))
return String { "CFF fonts not supported yet" };
if (tag != 0x00010000)
return String { "Not a valid font" };
return try_load_from_offset(move(buffer), 0);
}
// FIXME: "loca" and "glyf" are not available for CFF fonts.
Result<NonnullRefPtr<Font>, String> Font::try_load_from_offset(ReadonlyBytes buffer, u32 offset)
{
if (Checked<u32>::addition_would_overflow(offset, (u32)Sizes::OffsetTable))
return String { "Invalid offset in font header" };
if (buffer.size() < offset + (u32)Sizes::OffsetTable)
return String { "Font file too small" };
Optional<ReadonlyBytes> opt_head_slice = {};
Optional<ReadonlyBytes> opt_name_slice = {};
Optional<ReadonlyBytes> opt_hhea_slice = {};
Optional<ReadonlyBytes> opt_maxp_slice = {};
Optional<ReadonlyBytes> opt_hmtx_slice = {};
Optional<ReadonlyBytes> opt_cmap_slice = {};
Optional<ReadonlyBytes> opt_loca_slice = {};
Optional<ReadonlyBytes> opt_glyf_slice = {};
Optional<Head> opt_head = {};
Optional<Name> opt_name = {};
Optional<Hhea> opt_hhea = {};
Optional<Maxp> opt_maxp = {};
Optional<Hmtx> opt_hmtx = {};
Optional<Cmap> opt_cmap = {};
Optional<Loca> 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)
return String { "Font file too small" };
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<u32>::addition_would_overflow(table_offset, table_length))
return String { "Invalid table offset/length in font." };
if (buffer.size() < table_offset + table_length)
return String { "Font file too small" };
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())
return String { "Could not load Head" };
auto head = opt_head.value();
if (!opt_name_slice.has_value() || !(opt_name = Name::from_slice(opt_name_slice.value())).has_value())
return String { "Could not load Name" };
auto name = opt_name.value();
if (!opt_hhea_slice.has_value() || !(opt_hhea = Hhea::from_slice(opt_hhea_slice.value())).has_value())
return String { "Could not load Hhea" };
auto hhea = opt_hhea.value();
if (!opt_maxp_slice.has_value() || !(opt_maxp = Maxp::from_slice(opt_maxp_slice.value())).has_value())
return String { "Could not load Maxp" };
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())
return String { "Could not load Hmtx" };
auto hmtx = opt_hmtx.value();
if (!opt_cmap_slice.has_value() || !(opt_cmap = Cmap::from_slice(opt_cmap_slice.value())).has_value())
return String { "Could not load Cmap" };
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())
return String { "Could not load Loca" };
auto loca = opt_loca.value();
if (!opt_glyf_slice.has_value())
return String { "Could not load Glyf" };
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<Gfx::Bitmap> 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_code_point('.'), 1, 1).advance_width == glyph_metrics(glyph_id_for_code_point('X'), 1, 1).advance_width;
}
int ScaledFont::width(StringView const& view) const { return unicode_view_width(Utf8View(view)); }
int ScaledFont::width(Utf8View const& view) const { return unicode_view_width(view); }
int ScaledFont::width(Utf32View const& view) const { return unicode_view_width(view); }
template<typename T>
ALWAYS_INLINE int ScaledFont::unicode_view_width(T const& view) const
{
if (view.is_empty())
return 0;
int width = 0;
int longest_width = 0;
for (auto code_point : view) {
if (code_point == '\n' || code_point == '\r') {
longest_width = max(width, longest_width);
width = 0;
continue;
}
u32 glyph_id = glyph_id_for_code_point(code_point);
auto metrics = glyph_metrics(glyph_id);
width += metrics.advance_width;
}
longest_width = max(width, longest_width);
return longest_width;
}
RefPtr<Gfx::Bitmap> 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_code_point(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_code_point(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_code_point(code_point);
auto metrics = glyph_metrics(id);
return metrics.advance_width;
}
u8 ScaledFont::glyph_fixed_width() const
{
return glyph_metrics(glyph_id_for_code_point(' ')).advance_width;
}
}
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