/*
* Copyright 2011 Google Inc. All Rights Reserved.
*
* Licensed under the Apache License, Version 2.0 (the "License");
* you may not use this file except in compliance with the License.
* You may obtain a copy of the License at
*
* http://www.apache.org/licenses/LICENSE-2.0
*
* Unless required by applicable law or agreed to in writing, software
* distributed under the License is distributed on an "AS IS" BASIS,
* WITHOUT WARRANTIES OR CONDITIONS OF ANY KIND, either express or implied.
* See the License for the specific language governing permissions and
* limitations under the License.
*/
#include "subsetter_impl.h"
#include <string.h>
#include <algorithm>
#include <iterator>
#include <map>
#include <set>
#include "sfntly/table/bitmap/eblc_table.h"
#include "sfntly/table/bitmap/ebdt_table.h"
#include "sfntly/table/bitmap/index_sub_table.h"
#include "sfntly/table/bitmap/index_sub_table_format1.h"
#include "sfntly/table/bitmap/index_sub_table_format2.h"
#include "sfntly/table/bitmap/index_sub_table_format3.h"
#include "sfntly/table/bitmap/index_sub_table_format4.h"
#include "sfntly/table/bitmap/index_sub_table_format5.h"
#include "sfntly/table/core/name_table.h"
#include "sfntly/tag.h"
#include "sfntly/data/memory_byte_array.h"
#include "sfntly/port/memory_input_stream.h"
#include "sfntly/port/memory_output_stream.h"
#if defined U_USING_ICU_NAMESPACE
U_NAMESPACE_USE
#endif
namespace {
using namespace sfntly;
// The bitmap tables must be greater than 16KB to trigger bitmap subsetter.
static const int BITMAP_SIZE_THRESHOLD = 16384;
void ConstructName(UChar* name_part, UnicodeString* name, int32_t name_id) {
switch (name_id) {
case NameId::kFullFontName:
*name = name_part;
break;
case NameId::kFontFamilyName:
case NameId::kPreferredFamily:
case NameId::kWWSFamilyName: {
UnicodeString original = *name;
*name = name_part;
*name += original;
break;
}
case NameId::kFontSubfamilyName:
case NameId::kPreferredSubfamily:
case NameId::kWWSSubfamilyName:
*name += name_part;
break;
default:
// This name part is not used to construct font name (e.g. copyright).
// Simply ignore it.
break;
}
}
int32_t HashCode(int32_t platform_id, int32_t encoding_id, int32_t language_id,
int32_t name_id) {
int32_t result = platform_id << 24 | encoding_id << 16 | language_id << 8;
if (name_id == NameId::kFullFontName) {
result |= 0xff;
} else if (name_id == NameId::kPreferredFamily ||
name_id == NameId::kPreferredSubfamily) {
result |= 0xf;
} else if (name_id == NameId::kWWSFamilyName ||
name_id == NameId::kWWSSubfamilyName) {
result |= 1;
}
return result;
}
bool HasName(const char* font_name, Font* font) {
UnicodeString font_string = UnicodeString::fromUTF8(font_name);
if (font_string.isEmpty())
return false;
UnicodeString regular_suffix = UnicodeString::fromUTF8(" Regular");
UnicodeString alt_font_string = font_string;
alt_font_string += regular_suffix;
typedef std::map<int32_t, UnicodeString> NameMap;
NameMap names;
NameTablePtr name_table = down_cast<NameTable*>(font->GetTable(Tag::name));
if (name_table == NULL) {
return false;
}
for (int32_t i = 0; i < name_table->NameCount(); ++i) {
switch (name_table->NameId(i)) {
case NameId::kFontFamilyName:
case NameId::kFontSubfamilyName:
case NameId::kFullFontName:
case NameId::kPreferredFamily:
case NameId::kPreferredSubfamily:
case NameId::kWWSFamilyName:
case NameId::kWWSSubfamilyName: {
UChar* name_part = name_table->Name(i);
if (name_part == NULL) {
continue;
}
int32_t hash_code = HashCode(name_table->PlatformId(i),
name_table->EncodingId(i),
name_table->LanguageId(i),
name_table->NameId(i));
ConstructName(name_part, &(names[hash_code]), name_table->NameId(i));
delete[] name_part;
break;
}
default:
break;
}
}
if (!names.empty()) {
for (NameMap::iterator i = names.begin(), e = names.end(); i != e; ++i) {
if (i->second.caseCompare(font_string, 0) == 0 ||
i->second.caseCompare(alt_font_string, 0) == 0) {
return true;
}
}
}
return false;
}
Font* FindFont(const char* font_name, const FontArray& font_array) {
if (font_array.empty() || font_array[0] == NULL) {
return NULL;
}
if (font_name && strlen(font_name)) {
for (FontArray::const_iterator i = font_array.begin(), e = font_array.end();
i != e; ++i) {
if (HasName(font_name, i->p_)) {
return i->p_;
}
}
}
return font_array[0].p_;
}
bool ResolveCompositeGlyphs(GlyphTable* glyph_table,
LocaTable* loca_table,
const unsigned int* glyph_ids,
size_t glyph_count,
IntegerSet* glyph_id_processed) {
if (glyph_table == NULL || loca_table == NULL ||
glyph_ids == NULL || glyph_count == 0 || glyph_id_processed == NULL) {
return false;
}
// Sort and uniquify glyph ids.
IntegerSet glyph_id_remaining;
glyph_id_remaining.insert(0); // Always include glyph id 0.
for (size_t i = 0; i < glyph_count; ++i) {
glyph_id_remaining.insert(glyph_ids[i]);
}
// Identify if any given glyph id maps to a composite glyph. If so, include
// the glyphs referenced by that composite glyph.
while (!glyph_id_remaining.empty()) {
IntegerSet comp_glyph_id;
for (IntegerSet::iterator i = glyph_id_remaining.begin(),
e = glyph_id_remaining.end(); i != e; ++i) {
if (*i < 0 || *i >= loca_table->num_glyphs()) {
// Invalid glyph id, ignore.
continue;
}
int32_t length = loca_table->GlyphLength(*i);
if (length == 0) {
// Empty glyph, ignore.
continue;
}
int32_t offset = loca_table->GlyphOffset(*i);
GlyphPtr glyph;
glyph.Attach(glyph_table->GetGlyph(offset, length));
if (glyph == NULL) {
// Error finding glyph, ignore.
continue;
}
if (glyph->GlyphType() == GlyphType::kComposite) {
Ptr<GlyphTable::CompositeGlyph> comp_glyph =
down_cast<GlyphTable::CompositeGlyph*>(glyph.p_);
for (int32_t j = 0; j < comp_glyph->NumGlyphs(); ++j) {
int32_t glyph_id = comp_glyph->GlyphIndex(j);
if (glyph_id_processed->find(glyph_id) == glyph_id_processed->end() &&
glyph_id_remaining.find(glyph_id) == glyph_id_remaining.end()) {
comp_glyph_id.insert(comp_glyph->GlyphIndex(j));
}
}
}
glyph_id_processed->insert(*i);
}
glyph_id_remaining.clear();
glyph_id_remaining = comp_glyph_id;
}
return true;
}
bool SetupGlyfBuilders(Font::Builder* font_builder,
GlyphTable* glyph_table,
LocaTable* loca_table,
const IntegerSet& glyph_ids) {
if (!font_builder || !glyph_table || !loca_table) {
return false;
}
GlyphTableBuilderPtr glyph_table_builder =
down_cast<GlyphTable::Builder*>(font_builder->NewTableBuilder(Tag::glyf));
LocaTableBuilderPtr loca_table_builder =
down_cast<LocaTable::Builder*>(font_builder->NewTableBuilder(Tag::loca));
if (glyph_table_builder == NULL || loca_table_builder == NULL) {
// Out of memory.
return false;
}
// Extract glyphs and setup loca list.
IntegerList loca_list;
loca_list.resize(loca_table->num_glyphs());
loca_list.push_back(0);
int32_t last_glyph_id = 0;
int32_t last_offset = 0;
GlyphTable::GlyphBuilderList* glyph_builders =
glyph_table_builder->GlyphBuilders();
for (IntegerSet::const_iterator i = glyph_ids.begin(), e = glyph_ids.end();
i != e; ++i) {
int32_t length = loca_table->GlyphLength(*i);
int32_t offset = loca_table->GlyphOffset(*i);
GlyphPtr glyph;
glyph.Attach(glyph_table->GetGlyph(offset, length));
// Add glyph to new glyf table.
ReadableFontDataPtr data = glyph->ReadFontData();
WritableFontDataPtr copy_data;
copy_data.Attach(WritableFontData::CreateWritableFontData(data->Length()));
data->CopyTo(copy_data);
GlyphBuilderPtr glyph_builder;
glyph_builder.Attach(glyph_table_builder->GlyphBuilder(copy_data));
glyph_builders->push_back(glyph_builder);
// Configure loca list.
for (int32_t j = last_glyph_id + 1; j <= *i; ++j) {
loca_list[j] = last_offset;
}
last_offset += length;
loca_list[*i + 1] = last_offset;
last_glyph_id = *i;
}
for (int32_t j = last_glyph_id + 1; j <= loca_table->num_glyphs(); ++j) {
loca_list[j] = last_offset;
}
loca_table_builder->SetLocaList(&loca_list);
return true;
}
bool HasOverlap(int32_t range_begin, int32_t range_end,
const IntegerSet& glyph_ids) {
if (range_begin == range_end) {
return glyph_ids.find(range_begin) != glyph_ids.end();
} else if (range_end > range_begin) {
IntegerSet::const_iterator left = glyph_ids.lower_bound(range_begin);
IntegerSet::const_iterator right = glyph_ids.lower_bound(range_end);
return right != left;
}
return false;
}
// Initialize builder, returns false if glyph_id subset is not covered.
// Not thread-safe, caller to ensure object life-time.
bool InitializeBitmapBuilder(EbdtTable::Builder* ebdt, EblcTable::Builder* eblc,
const IntegerSet& glyph_ids) {
BitmapLocaList loca_list;
BitmapSizeTableBuilderList* strikes = eblc->BitmapSizeBuilders();
// Note: Do not call eblc_builder->GenerateLocaList(&loca_list) and then
// ebdt_builder->SetLoca(loca_list). For fonts like SimSun, there are
// >28K glyphs inside, where a typical usage will be <1K glyphs. Doing
// the calls improperly will result in creation of >100K objects that
// will be destroyed immediately, inducing significant slowness.
IntegerList removed_strikes;
for (size_t i = 0; i < strikes->size(); i++) {
if (!HasOverlap((*strikes)[i]->StartGlyphIndex(),
(*strikes)[i]->EndGlyphIndex(), glyph_ids)) {
removed_strikes.push_back(i);
continue;
}
IndexSubTableBuilderList* index_builders =
(*strikes)[i]->IndexSubTableBuilders();
IntegerList removed_indexes;
BitmapGlyphInfoMap info_map;
for (size_t j = 0; j < index_builders->size(); ++j) {
if ((*index_builders)[j] == NULL) {
// Subtable is malformed, let's just skip it.
removed_indexes.push_back(j);
continue;
}
int32_t first_glyph_id = (*index_builders)[j]->first_glyph_index();
int32_t last_glyph_id = (*index_builders)[j]->last_glyph_index();
if (!HasOverlap(first_glyph_id, last_glyph_id, glyph_ids)) {
removed_indexes.push_back(j);
continue;
}
for (IntegerSet::const_iterator gid = glyph_ids.begin(),
gid_end = glyph_ids.end();
gid != gid_end; gid++) {
if (*gid < first_glyph_id) {
continue;
}
if (*gid > last_glyph_id) {
break;
}
BitmapGlyphInfoPtr info;
info.Attach((*index_builders)[j]->GlyphInfo(*gid));
if (info && info->length()) { // Do not include gid without bitmap
info_map[*gid] = info;
}
}
}
if (!info_map.empty()) {
loca_list.push_back(info_map);
} else {
removed_strikes.push_back(i); // Detected null entries.
}
// Remove unused index sub tables
for (IntegerList::reverse_iterator j = removed_indexes.rbegin(),
e = removed_indexes.rend();
j != e; j++) {
index_builders->erase(index_builders->begin() + *j);
}
}
if (removed_strikes.size() == strikes->size() || loca_list.empty()) {
return false;
}
for (IntegerList::reverse_iterator i = removed_strikes.rbegin(),
e = removed_strikes.rend(); i != e; i++) {
strikes->erase(strikes->begin() + *i);
}
if (strikes->empty()) { // no glyph covered, can safely drop the builders.
return false;
}
ebdt->SetLoca(&loca_list);
ebdt->GlyphBuilders(); // Initialize the builder.
return true;
}
void CopyBigGlyphMetrics(BigGlyphMetrics::Builder* source,
BigGlyphMetrics::Builder* target) {
target->SetHeight(static_cast<byte_t>(source->Height()));
target->SetWidth(static_cast<byte_t>(source->Width()));
target->SetHoriBearingX(static_cast<byte_t>(source->HoriBearingX()));
target->SetHoriBearingY(static_cast<byte_t>(source->HoriBearingY()));
target->SetHoriAdvance(static_cast<byte_t>(source->HoriAdvance()));
target->SetVertBearingX(static_cast<byte_t>(source->VertBearingX()));
target->SetVertBearingY(static_cast<byte_t>(source->VertBearingY()));
target->SetVertAdvance(static_cast<byte_t>(source->VertAdvance()));
}
CALLER_ATTACH IndexSubTable::Builder*
ConstructIndexFormat4(IndexSubTable::Builder* b, const BitmapGlyphInfoMap& loca,
int32_t* image_data_offset) {
IndexSubTableFormat4BuilderPtr builder4;
builder4.Attach(IndexSubTableFormat4::Builder::CreateBuilder());
CodeOffsetPairBuilderList offset_pairs;
size_t offset = 0;
int32_t lower_bound = b->first_glyph_index();
int32_t upper_bound = b->last_glyph_index();
int32_t last_gid = -1;
BitmapGlyphInfoMap::const_iterator i = loca.lower_bound(lower_bound);
BitmapGlyphInfoMap::const_iterator end = loca.end();
if (i != end) {
last_gid = i->first;
builder4->set_first_glyph_index(last_gid);
builder4->set_image_format(b->image_format());
builder4->set_image_data_offset(*image_data_offset);
}
for (; i != end; i++) {
int32_t gid = i->first;
if (gid > upper_bound) {
break;
}
offset_pairs.push_back(
IndexSubTableFormat4::CodeOffsetPairBuilder(gid, offset));
offset += i->second->length();
last_gid = gid;
}
offset_pairs.push_back(
IndexSubTableFormat4::CodeOffsetPairBuilder(-1, offset));
builder4->set_last_glyph_index(last_gid);
*image_data_offset += offset;
builder4->SetOffsetArray(offset_pairs);
return builder4.Detach();
}
CALLER_ATTACH IndexSubTable::Builder*
ConstructIndexFormat5(IndexSubTable::Builder* b, const BitmapGlyphInfoMap& loca,
int32_t* image_data_offset) {
IndexSubTableFormat5BuilderPtr new_builder;
new_builder.Attach(IndexSubTableFormat5::Builder::CreateBuilder());
// Copy BigMetrics
int32_t image_size = 0;
if (b->index_format() == IndexSubTable::Format::FORMAT_2) {
IndexSubTableFormat2BuilderPtr builder2 =
down_cast<IndexSubTableFormat2::Builder*>(b);
CopyBigGlyphMetrics(builder2->BigMetrics(), new_builder->BigMetrics());
image_size = builder2->ImageSize();
} else {
IndexSubTableFormat5BuilderPtr builder5 =
down_cast<IndexSubTableFormat5::Builder*>(b);
BigGlyphMetricsBuilderPtr metrics_builder;
CopyBigGlyphMetrics(builder5->BigMetrics(), new_builder->BigMetrics());
image_size = builder5->ImageSize();
}
IntegerList* glyph_array = new_builder->GlyphArray();
size_t offset = 0;
int32_t lower_bound = b->first_glyph_index();
int32_t upper_bound = b->last_glyph_index();
int32_t last_gid = -1;
BitmapGlyphInfoMap::const_iterator i = loca.lower_bound(lower_bound);
BitmapGlyphInfoMap::const_iterator end = loca.end();
if (i != end) {
last_gid = i->first;
new_builder->set_first_glyph_index(last_gid);
new_builder->set_image_format(b->image_format());
new_builder->set_image_data_offset(*image_data_offset);
new_builder->SetImageSize(image_size);
}
for (; i != end; i++) {
int32_t gid = i->first;
if (gid > upper_bound) {
break;
}
glyph_array->push_back(gid);
offset += i->second->length();
last_gid = gid;
}
new_builder->set_last_glyph_index(last_gid);
*image_data_offset += offset;
return new_builder.Detach();
}
CALLER_ATTACH IndexSubTable::Builder*
SubsetIndexSubTable(IndexSubTable::Builder* builder,
const BitmapGlyphInfoMap& loca,
int32_t* image_data_offset) {
switch (builder->index_format()) {
case IndexSubTable::Format::FORMAT_1:
case IndexSubTable::Format::FORMAT_3:
case IndexSubTable::Format::FORMAT_4:
return ConstructIndexFormat4(builder, loca, image_data_offset);
case IndexSubTable::Format::FORMAT_2:
case IndexSubTable::Format::FORMAT_5:
return ConstructIndexFormat5(builder, loca, image_data_offset);
default:
assert(false);
break;
}
return NULL;
}
}
namespace sfntly {
// Not thread-safe, caller to ensure object life-time.
void SubsetEBLC(EblcTable::Builder* eblc, const BitmapLocaList& new_loca) {
BitmapSizeTableBuilderList* size_builders = eblc->BitmapSizeBuilders();
if (size_builders == NULL) {
return;
}
int32_t image_data_offset = EbdtTable::Offset::kHeaderLength;
for (size_t strike = 0; strike < size_builders->size(); ++strike) {
IndexSubTableBuilderList* index_builders =
(*size_builders)[strike]->IndexSubTableBuilders();
for (size_t index = 0; index < index_builders->size(); ++index) {
IndexSubTable::Builder* new_builder_raw =
SubsetIndexSubTable((*index_builders)[index], new_loca[strike],
&image_data_offset);
if (NULL != new_builder_raw) {
(*index_builders)[index].Attach(new_builder_raw);
}
}
}
}
// EBLC structure (from stuartg)
// header
// bitmapSizeTable[]
// one per strike
// holds strike metrics - sbitLineMetrics
// holds info about indexSubTableArray
// indexSubTableArray[][]
// one per strike and then one per indexSubTable for that strike
// holds info about the indexSubTable
// the indexSubTable entries pointed to can be of different formats
// indexSubTable
// one per indexSubTableArray entry
// tells how to get the glyphs
// may hold the glyph metrics if they are uniform for all the glyphs in range
// Please note that the structure can also be
// {indexSubTableArray[], indexSubTables[]}[]
// This way is also legal and in fact how Microsoft fonts are laid out.
//
// There is nothing that says that the indexSubTableArray entries and/or the
// indexSubTable items need to be unique. They may be shared between strikes.
//
// EBDT structure:
// header
// glyphs
// amorphous blob of data
// different glyphs that are only able to be figured out from the EBLC table
// may hold metrics - depends on the EBLC entry that pointed to them
// Subsetting EBLC table (from arthurhsu)
// Most pages use only a fraction (hundreds or less) glyphs out of a given font
// (which can have >20K glyphs for CJK). It's safe to assume that the subset
// font will have sparse bitmap glyphs. So we reconstruct the EBLC table as
// format 4 or 5 here.
enum BuildersToRemove {
kRemoveNone,
kRemoveBDAT,
kRemoveBDATAndEBDT,
kRemoveEBDT
};
int SetupBitmapBuilders(Font* font, Font::Builder* font_builder,
const IntegerSet& glyph_ids) {
if (!font || !font_builder) {
return false;
}
// Check if bitmap table exists.
EbdtTablePtr ebdt_table = down_cast<EbdtTable*>(font->GetTable(Tag::EBDT));
EblcTablePtr eblc_table = down_cast<EblcTable*>(font->GetTable(Tag::EBLC));
bool use_ebdt = (ebdt_table != NULL && eblc_table != NULL);
if (!use_ebdt) {
ebdt_table = down_cast<EbdtTable*>(font->GetTable(Tag::bdat));
eblc_table = down_cast<EblcTable*>(font->GetTable(Tag::bloc));
if (ebdt_table == NULL || eblc_table == NULL) {
return kRemoveNone;
}
}
// If the bitmap table's size is too small, skip subsetting.
if (ebdt_table->DataLength() + eblc_table->DataLength() <
BITMAP_SIZE_THRESHOLD) {
return use_ebdt ? kRemoveBDAT : kRemoveNone;
}
// Get the builders.
EbdtTableBuilderPtr ebdt_table_builder = down_cast<EbdtTable::Builder*>(
font_builder->NewTableBuilder(use_ebdt ? Tag::EBDT : Tag::bdat,
ebdt_table->ReadFontData()));
EblcTableBuilderPtr eblc_table_builder = down_cast<EblcTable::Builder*>(
font_builder->NewTableBuilder(use_ebdt ? Tag::EBLC : Tag::bloc,
eblc_table->ReadFontData()));
if (ebdt_table_builder == NULL || eblc_table_builder == NULL) {
// Out of memory.
return use_ebdt ? kRemoveBDAT : kRemoveNone;
}
if (!InitializeBitmapBuilder(ebdt_table_builder, eblc_table_builder,
glyph_ids)) {
// Bitmap tables do not cover the glyphs in our subset.
font_builder->RemoveTableBuilder(use_ebdt ? Tag::EBLC : Tag::bloc);
font_builder->RemoveTableBuilder(use_ebdt ? Tag::EBDT : Tag::bdat);
return use_ebdt ? kRemoveBDATAndEBDT : kRemoveEBDT;
}
BitmapLocaList new_loca;
ebdt_table_builder->GenerateLocaList(&new_loca);
SubsetEBLC(eblc_table_builder, new_loca);
return use_ebdt ? kRemoveBDAT : kRemoveNone;
}
SubsetterImpl::SubsetterImpl() {
}
SubsetterImpl::~SubsetterImpl() {
}
bool SubsetterImpl::LoadFont(const char* font_name,
const unsigned char* original_font,
size_t font_size) {
MemoryInputStream mis;
mis.Attach(original_font, font_size);
if (factory_ == NULL) {
factory_.Attach(FontFactory::GetInstance());
}
FontArray font_array;
factory_->LoadFonts(&mis, &font_array);
font_ = FindFont(font_name, font_array);
if (font_ == NULL) {
return false;
}
return true;
}
int SubsetterImpl::SubsetFont(const unsigned int* glyph_ids,
size_t glyph_count,
unsigned char** output_buffer) {
if (factory_ == NULL || font_ == NULL) {
return -1;
}
// Find glyf and loca table.
GlyphTablePtr glyph_table =
down_cast<GlyphTable*>(font_->GetTable(Tag::glyf));
LocaTablePtr loca_table = down_cast<LocaTable*>(font_->GetTable(Tag::loca));
if (glyph_table == NULL || loca_table == NULL) {
// We are not able to subset the font.
return 0;
}
IntegerSet glyph_id_processed;
if (!ResolveCompositeGlyphs(glyph_table, loca_table,
glyph_ids, glyph_count, &glyph_id_processed) ||
glyph_id_processed.empty()) {
return 0;
}
FontPtr new_font;
new_font.Attach(Subset(glyph_id_processed, glyph_table, loca_table));
if (new_font == NULL) {
return 0;
}
MemoryOutputStream output_stream;
factory_->SerializeFont(new_font, &output_stream);
int length = static_cast<int>(output_stream.Size());
if (length > 0) {
*output_buffer = new unsigned char[length];
memcpy(*output_buffer, output_stream.Get(), length);
}
return length;
}
// Long comments regarding TTF tables and PDF (from stuartg)
//
// According to PDF spec 1.4 (section 5.8), the following tables must be
// present:
// head, hhea, loca, maxp, cvt, prep, glyf, hmtx, fpgm
// cmap if font is used with a simple font dict and not a CIDFont dict
//
// Other tables we need to keep for PDF rendering to support zoom in/out:
// bdat, bloc, ebdt, eblc, ebsc, gasp
//
// Special table:
// CFF - if you have this table then you shouldn't have a glyf table and this
// is the table with all the glyphs. Shall skip subsetting completely
// since sfntly is not capable of subsetting it for now.
// post - extra info here for printing on PostScript printers but maybe not
// enough to outweigh the space taken by the names
//
// Tables to break apart:
// name - could throw away all but one language and one platform strings/ might
// throw away some of the name entries
// cmap - could strip out non-needed cmap subtables
// - format 4 subtable can be subsetted as well using sfntly
//
// Graphite tables:
// silf, glat, gloc, feat - should be okay to strip out
//
// Tables that can be discarded:
// OS/2 - everything here is for layout and description of the font that is
// elsewhere (some in the PDF objects)
// BASE, GDEF, GSUB, GPOS, JSTF - all used for layout
// kern - old style layout
// DSIG - this will be invalid after subsetting
// hdmx - layout
// PCLT - metadata that's not needed
// vmtx - layout
// vhea - layout
// VDMX
// VORG - not used by TT/OT - used by CFF
// hsty - would be surprised to see one of these - used on the Newton
// AAT tables - mort, morx, feat, acnt, bsin, just, lcar, fdsc, fmtx, prop,
// Zapf, opbd, trak, fvar, gvar, avar, cvar
// - these are all layout tables and once layout happens are not
// needed anymore
// LTSH - layout
CALLER_ATTACH
Font* SubsetterImpl::Subset(const IntegerSet& glyph_ids, GlyphTable* glyf,
LocaTable* loca) {
// The const is initialized here to workaround VC bug of rendering all Tag::*
// as 0. These tags represents the TTF tables that we will embed in subset
// font.
const int32_t TABLES_IN_SUBSET[] = {
Tag::head, Tag::hhea, Tag::loca, Tag::maxp, Tag::cvt,
Tag::prep, Tag::glyf, Tag::hmtx, Tag::fpgm, Tag::EBDT,
Tag::EBLC, Tag::EBSC, Tag::bdat, Tag::bloc, Tag::bhed,
Tag::cmap, // Keep here for future tagged PDF development.
Tag::name, // Keep here due to legal concerns: copyright info inside.
};
// Setup font builders we need.
FontBuilderPtr font_builder;
font_builder.Attach(factory_->NewFontBuilder());
IntegerSet remove_tags;
if (SetupGlyfBuilders(font_builder, glyf, loca, glyph_ids)) {
remove_tags.insert(Tag::glyf);
remove_tags.insert(Tag::loca);
}
// For old Apple bitmap fonts, they have only bdats and bhed is identical
// to head. As a result, we can't remove bdat tables for those fonts.
int setup_result = SetupBitmapBuilders(font_, font_builder, glyph_ids);
if (setup_result == kRemoveBDATAndEBDT || setup_result == kRemoveEBDT) {
remove_tags.insert(Tag::EBDT);
remove_tags.insert(Tag::EBLC);
remove_tags.insert(Tag::EBSC);
}
if (setup_result == kRemoveBDAT || setup_result == kRemoveBDATAndEBDT) {
remove_tags.insert(Tag::bdat);
remove_tags.insert(Tag::bloc);
remove_tags.insert(Tag::bhed);
}
IntegerSet allowed_tags;
for (size_t i = 0; i < sizeof(TABLES_IN_SUBSET) / sizeof(int32_t); ++i) {
allowed_tags.insert(TABLES_IN_SUBSET[i]);
}
IntegerSet result;
std::set_difference(allowed_tags.begin(), allowed_tags.end(),
remove_tags.begin(), remove_tags.end(),
std::inserter(result, result.end()));
allowed_tags = result;
// Setup remaining builders.
for (IntegerSet::iterator i = allowed_tags.begin(), e = allowed_tags.end();
i != e; ++i) {
Table* table = font_->GetTable(*i);
if (table) {
font_builder->NewTableBuilder(*i, table->ReadFontData());
}
}
return font_builder->Build();
}
} // namespace sfntly