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/*
* Copyright (c) 2020, Srimanta Barua <srimanta.barua1@gmail.com>
* All rights reserved.
*
* Redistribution and use in source and binary forms, with or without
* modification, are permitted provided that the following conditions are met:
*
* 1. Redistributions of source code must retain the above copyright notice, this
* list of conditions and the following disclaimer.
*
* 2. Redistributions in binary form must reproduce the above copyright notice,
* this list of conditions and the following disclaimer in the documentation
* and/or other materials provided with the distribution.
*
* THIS SOFTWARE IS PROVIDED BY THE COPYRIGHT HOLDERS AND CONTRIBUTORS "AS IS"
* AND ANY EXPRESS OR IMPLIED WARRANTIES, INCLUDING, BUT NOT LIMITED TO, THE
* IMPLIED WARRANTIES OF MERCHANTABILITY AND FITNESS FOR A PARTICULAR PURPOSE ARE
* DISCLAIMED. IN NO EVENT SHALL THE COPYRIGHT HOLDER OR CONTRIBUTORS BE LIABLE
* FOR ANY DIRECT, INDIRECT, INCIDENTAL, SPECIAL, EXEMPLARY, OR CONSEQUENTIAL
* DAMAGES (INCLUDING, BUT NOT LIMITED TO, PROCUREMENT OF SUBSTITUTE GOODS OR
* SERVICES; LOSS OF USE, DATA, OR PROFITS; OR BUSINESS INTERRUPTION) HOWEVER
* CAUSED AND ON ANY THEORY OF LIABILITY, WHETHER IN CONTRACT, STRICT LIABILITY,
* OR TORT (INCLUDING NEGLIGENCE OR OTHERWISE) ARISING IN ANY WAY OUT OF THE USE
* OF THIS SOFTWARE, EVEN IF ADVISED OF THE POSSIBILITY OF SUCH DAMAGE.
*/
#include <AK/Optional.h>
#include <LibTTF/Cmap.h>
namespace TTF {
extern u16 be_u16(const u8* ptr);
extern u32 be_u32(const u8* ptr);
extern i16 be_i16(const u8* ptr);
Cmap::Subtable::Platform Cmap::Subtable::platform_id() const
{
switch (m_raw_platform_id) {
case 0:
return Platform::Unicode;
case 1:
return Platform::Macintosh;
case 3:
return Platform::Windows;
case 4:
return Platform::Custom;
default:
ASSERT_NOT_REACHED();
}
}
Cmap::Subtable::Format Cmap::Subtable::format() const
{
switch (be_u16(m_slice.offset_pointer(0))) {
case 0:
return Format::ByteEncoding;
case 2:
return Format::HighByte;
case 4:
return Format::SegmentToDelta;
case 6:
return Format::TrimmedTable;
case 8:
return Format::Mixed16And32;
case 10:
return Format::TrimmedArray;
case 12:
return Format::SegmentedCoverage;
case 13:
return Format::ManyToOneRange;
case 14:
return Format::UnicodeVariationSequences;
default:
ASSERT_NOT_REACHED();
}
}
u32 Cmap::num_subtables() const
{
return be_u16(m_slice.offset_pointer((u32)Offsets::NumTables));
}
Optional<Cmap::Subtable> Cmap::subtable(u32 index) const
{
if (index >= num_subtables()) {
return {};
}
u32 record_offset = (u32)Sizes::TableHeader + index * (u32)Sizes::EncodingRecord;
u16 platform_id = be_u16(m_slice.offset_pointer(record_offset));
u16 encoding_id = be_u16(m_slice.offset_pointer(record_offset + (u32)Offsets::EncodingRecord_EncodingID));
u32 subtable_offset = be_u32(m_slice.offset_pointer(record_offset + (u32)Offsets::EncodingRecord_Offset));
ASSERT(subtable_offset < m_slice.size());
auto subtable_slice = ReadonlyBytes(m_slice.offset_pointer(subtable_offset), m_slice.size() - subtable_offset);
return Subtable(subtable_slice, platform_id, encoding_id);
}
// FIXME: This only handles formats 4 (SegmentToDelta) and 12 (SegmentedCoverage) for now.
u32 Cmap::Subtable::glyph_id_for_codepoint(u32 codepoint) const
{
switch (format()) {
case Format::SegmentToDelta:
return glyph_id_for_codepoint_table_4(codepoint);
case Format::SegmentedCoverage:
return glyph_id_for_codepoint_table_12(codepoint);
default:
return 0;
}
}
u32 Cmap::Subtable::glyph_id_for_codepoint_table_4(u32 codepoint) const
{
u32 segcount_x2 = be_u16(m_slice.offset_pointer((u32)Table4Offsets::SegCountX2));
if (m_slice.size() < segcount_x2 * (u32)Table4Sizes::NonConstMultiplier + (u32)Table4Sizes::Constant) {
return 0;
}
for (u32 offset = 0; offset < segcount_x2; offset += 2) {
u32 end_codepoint = be_u16(m_slice.offset_pointer((u32)Table4Offsets::EndConstBase + offset));
if (codepoint > end_codepoint) {
continue;
}
u32 start_codepoint = be_u16(m_slice.offset_pointer((u32)Table4Offsets::StartConstBase + segcount_x2 + offset));
if (codepoint < start_codepoint) {
break;
}
u32 delta = be_u16(m_slice.offset_pointer((u32)Table4Offsets::DeltaConstBase + segcount_x2 * 2 + offset));
u32 range = be_u16(m_slice.offset_pointer((u32)Table4Offsets::RangeConstBase + segcount_x2 * 3 + offset));
if (range == 0) {
return (codepoint + delta) & 0xffff;
}
u32 glyph_offset = (u32)Table4Offsets::GlyphOffsetConstBase + segcount_x2 * 3 + offset + range + (codepoint - start_codepoint) * 2;
ASSERT(glyph_offset + 2 <= m_slice.size());
return (be_u16(m_slice.offset_pointer(glyph_offset)) + delta) & 0xffff;
}
return 0;
}
u32 Cmap::Subtable::glyph_id_for_codepoint_table_12(u32 codepoint) const
{
u32 num_groups = be_u32(m_slice.offset_pointer((u32)Table12Offsets::NumGroups));
ASSERT(m_slice.size() >= (u32)Table12Sizes::Header + (u32)Table12Sizes::Record * num_groups);
for (u32 offset = 0; offset < num_groups * (u32)Table12Sizes::Record; offset += (u32)Table12Sizes::Record) {
u32 start_codepoint = be_u32(m_slice.offset_pointer((u32)Table12Offsets::Record_StartCode + offset));
if (codepoint < start_codepoint) {
break;
}
u32 end_codepoint = be_u32(m_slice.offset_pointer((u32)Table12Offsets::Record_EndCode + offset));
if (codepoint > end_codepoint) {
continue;
}
u32 glyph_offset = be_u32(m_slice.offset_pointer((u32)Table12Offsets::Record_StartGlyph + offset));
return codepoint - start_codepoint + glyph_offset;
}
return 0;
}
u32 Cmap::glyph_id_for_codepoint(u32 codepoint) const
{
auto opt_subtable = subtable(m_active_index);
if (!opt_subtable.has_value()) {
return 0;
}
auto subtable = opt_subtable.value();
return subtable.glyph_id_for_codepoint(codepoint);
}
Optional<Cmap> Cmap::from_slice(const ReadonlyBytes& slice)
{
if (slice.size() < (size_t)Sizes::TableHeader) {
return {};
}
return Cmap(slice);
}
}
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