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// Copyright 2013 The Flutter Authors. All rights reserved.
// Use of this source code is governed by a BSD-style license that can be
// found in the LICENSE file.
#include <hb-subset.h>
#include <cstdlib>
#include <fstream>
#include <iostream>
#include <limits>
#include <set>
#include <string>
#include "hb_wrappers.h"
hb_codepoint_t ParseCodepoint(std::string_view arg, bool& optional) {
constexpr std::string_view kOptionalPrefix = "optional:";
if (arg.substr(0, kOptionalPrefix.length()) == kOptionalPrefix) {
optional = true;
arg = arg.substr(kOptionalPrefix.length());
} else {
optional = false;
}
uint64_t value = 0;
// Check for \u123, u123, otherwise let strtoul work it out.
if (arg[0] == 'u') {
value = strtoul(arg.data() + 1, nullptr, 16);
} else if (arg[0] == '\\' && arg[1] == 'u') {
value = strtoul(arg.data() + 2, nullptr, 16);
} else {
value = strtoul(arg.data(), nullptr, 0);
}
if (value == 0 || value > std::numeric_limits<hb_codepoint_t>::max()) {
std::cerr << "The value '" << arg << "' (" << value
<< ") could not be parsed as a valid unicode codepoint; aborting."
<< std::endl;
exit(-1);
}
return value;
}
void Usage() {
std::cout << "Usage:" << std::endl;
std::cout << "font-subset <output.ttf> <input.ttf>" << std::endl;
std::cout << std::endl;
std::cout << "The output.ttf file will be overwritten if it exists already "
"and the subsetting operation succeeds."
<< std::endl;
std::cout << "Codepoints should be specified on stdin, separated by spaces, "
"and must be input as decimal numbers (123), hexadecimal "
"numbers (0x7B), or unicode hexadecimal characters (\\u7B)."
<< std::endl;
std::cout << "Codepoints can be prefixed by the string \"optional:\" to "
"specify that the codepoint can be omitted if it isn't found "
"in the input font file."
<< std::endl;
std::cout << "Input terminates with a newline." << std::endl;
std::cout
<< "This program will de-duplicate codepoints if the same codepoint is "
"specified multiple times, e.g. '123 123' will be treated as '123'."
<< std::endl;
}
template <typename...>
using void_t = void;
template <typename T, typename = void>
struct HarfBuzzSubset {
// This is the HarfBuzz 3.0 interface.
static HarfbuzzWrappers::HbFacePtr Make(hb_face_t* face, T input) {
// The prior version of harfbuzz automatically dropped layout tables,
// but in the new version they are kept by default. So re-add them to the
// drop list to retain the same behaviour.
if (!hb_ot_var_has_data(face) || hb_ot_var_get_axis_count(face) == 0) {
// we can only drop GSUB/GPOS/GDEF for non variable fonts, they may be
// needed for variable fonts (guessing we need to keep all of these, but
// in Material Symbols Icon variable fonts if we drop the GSUB table (they
// do not have GPOS/DEF) then the Fill=1,Weight=100 variation is rendered
// incorrect. (and other variations are probably less noticibly
// incorrect))
hb_set_add(hb_subset_input_set(input, HB_SUBSET_SETS_DROP_TABLE_TAG),
HB_TAG('G', 'S', 'U', 'B'));
hb_set_add(hb_subset_input_set(input, HB_SUBSET_SETS_DROP_TABLE_TAG),
HB_TAG('G', 'P', 'O', 'S'));
hb_set_add(hb_subset_input_set(input, HB_SUBSET_SETS_DROP_TABLE_TAG),
HB_TAG('G', 'D', 'E', 'F'));
}
return HarfbuzzWrappers::HbFacePtr(hb_subset_or_fail(face, input));
}
};
int main(int argc, char** argv) {
if (argc != 3) {
Usage();
return -1;
}
std::string output_file_path(argv[1]);
std::string input_file_path(argv[2]);
std::cout << "Using output file: " << output_file_path << std::endl;
std::cout << "Using source file: " << input_file_path << std::endl;
HarfbuzzWrappers::HbBlobPtr font_blob(
hb_blob_create_from_file(input_file_path.c_str()));
if (!hb_blob_get_length(font_blob.get())) {
std::cerr << "Failed to load input font " << input_file_path
<< "; aborting. This error indicates that the font is invalid or "
"the current version of Harfbuzz is unable to process it."
<< std::endl;
return -1;
}
HarfbuzzWrappers::HbFacePtr font_face(hb_face_create(font_blob.get(), 0));
if (font_face.get() == hb_face_get_empty()) {
std::cerr << "Failed to load input font face " << input_file_path
<< "; aborting. This error indicates that the font is invalid or "
"the current version of Harfbuzz is unable to process it."
<< std::endl;
return -1;
}
HarfbuzzWrappers::HbSubsetInputPtr input(hb_subset_input_create_or_fail());
{
hb_set_t* desired_codepoints = hb_subset_input_unicode_set(input.get());
HarfbuzzWrappers::HbSetPtr actual_codepoints(hb_set_create());
hb_face_collect_unicodes(font_face.get(), actual_codepoints.get());
std::string raw_codepoint;
while (std::cin >> raw_codepoint) {
bool optional = false;
auto codepoint =
ParseCodepoint(std::string_view(raw_codepoint), optional);
if (!codepoint) {
std::cerr << "Invalid codepoint for " << raw_codepoint << "; exiting."
<< std::endl;
return -1;
}
if (!hb_set_has(actual_codepoints.get(), codepoint)) {
if (optional) {
// Code point is optional, so omit it.
continue;
}
std::cerr << "Codepoint " << raw_codepoint
<< " not found in font, aborting." << std::endl;
return -1;
}
hb_set_add(desired_codepoints, codepoint);
}
if (hb_set_is_empty(desired_codepoints)) {
std::cerr << "No codepoints specified, exiting." << std::endl;
return -1;
}
}
HarfbuzzWrappers::HbFacePtr new_face =
HarfBuzzSubset<hb_subset_input_t*>::Make(font_face.get(), input.get());
if (!new_face || new_face.get() == hb_face_get_empty()) {
std::cerr
<< "Failed to subset font; aborting. This error normally indicates "
"the current version of Harfbuzz is unable to process it."
<< std::endl;
return -1;
}
HarfbuzzWrappers::HbBlobPtr result(hb_face_reference_blob(new_face.get()));
if (!hb_blob_get_length(result.get())) {
std::cerr << "Failed get new font bytes; aborting. This error may indicate "
"low availability of memory or a bug in Harfbuzz."
<< std::endl;
return -1;
}
unsigned int data_length;
const char* data = hb_blob_get_data(result.get(), &data_length);
std::ofstream output_font_file;
output_font_file.open(output_file_path,
std::ios::out | std::ios::trunc | std::ios::binary);
if (!output_font_file.is_open()) {
std::cerr << "Failed to open output file '" << output_file_path
<< "'. The parent directory may not exist, or the user does not "
"have permission to create this file."
<< std::endl;
return -1;
}
output_font_file.write(data, data_length);
output_font_file.flush();
output_font_file.close();
std::cout << "Wrote " << data_length << " bytes to " << output_file_path
<< std::endl;
return 0;
}