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// Copyright 2019 The Chromium Authors
// Use of this source code is governed by a BSD-style license that can be
// found in the LICENSE file.
#include "components/paint_preview/common/subset_font.h"
// clang-format off
#include <hb.h>
#include <hb-subset.h>
#include <hb-cplusplus.hh>
// clang-format on
#include <memory>
#include <utility>
#include <vector>
#include "base/functional/bind.h"
#include "base/functional/callback.h"
#include "base/numerics/safe_conversions.h"
#include "components/crash/core/common/crash_key.h"
#include "skia/ext/font_utils.h"
#include "third_party/skia/include/core/SkFontMgr.h"
#include "third_party/skia/include/core/SkStream.h"
#include "third_party/skia/include/core/SkTypeface.h"
namespace paint_preview {
namespace {
// Converts and SkStream to an SkData object without copy if possible or
// falls back to a copy.
sk_sp<SkData> StreamToData(std::unique_ptr<SkStreamAsset> stream) {
DCHECK(stream);
bool rewind = stream->rewind();
DCHECK(rewind);
DCHECK(stream->hasLength());
size_t size = stream->getLength();
// TODO: Replace with const SkData* = SkStreamAsset::getData() when Skia
// adds such a method.
if (const void* base = stream->getMemoryBase()) {
SkData::ReleaseProc proc = [](const void*, void* ctx) {
delete static_cast<SkStreamAsset*>(ctx);
};
return SkData::MakeWithProc(base, size, proc, stream.release());
}
return SkData::MakeFromStream(stream.get(), size);
}
// Converts SkData to a hb_blob_t.
hb::unique_ptr<hb_blob_t> MakeBlob(sk_sp<SkData> data) {
if (!data ||
!base::IsValueInRangeForNumericType<unsigned int, size_t>(data->size()))
return hb::unique_ptr<hb_blob_t>(nullptr);
return hb::unique_ptr<hb_blob_t>(
hb_blob_create(static_cast<const char*>(data->data()),
static_cast<unsigned int>(data->size()),
HB_MEMORY_MODE_READONLY, nullptr, nullptr));
}
// Adds |glyph_id| to the set of glyphs to be retained.
void AddGlyphs(hb_set_t* glyph_id_set, uint16_t glyph_id) {
hb_set_add(glyph_id_set, glyph_id);
}
} // namespace
// Implementation based on SkPDFSubsetFont() using harfbuzz.
sk_sp<SkData> SubsetFont(SkTypeface* typeface, const GlyphUsage& usage) {
static crash_reporter::CrashKeyString<128> crash_key(
"PaintPreview-SubsetFont");
SkString family_name;
typeface->getFamilyName(&family_name);
crash_reporter::ScopedCrashKeyString auto_clear(&crash_key,
family_name.c_str());
int ttc_index = 0;
sk_sp<SkData> data = StreamToData(typeface->openStream(&ttc_index));
hb::unique_ptr<hb_face_t> face(
hb_face_create(MakeBlob(data).get(), ttc_index));
hb::unique_ptr<hb_subset_input_t> input(hb_subset_input_create_or_fail());
if (!face || !input) {
return nullptr;
}
hb_set_t* glyphs =
hb_subset_input_glyph_set(input.get()); // Owned by |input|.
usage.ForEach(base::BindRepeating(&AddGlyphs, base::Unretained(glyphs)));
hb_subset_input_set_flags(input.get(), HB_SUBSET_FLAGS_RETAIN_GIDS);
// Retain all variation information for OpenType variation fonts. See:
// https://docs.microsoft.com/en-us/typography/opentype/spec/otvaroverview
hb_set_t* skip_subset =
hb_subset_input_set(input.get(), HB_SUBSET_SETS_NO_SUBSET_TABLE_TAG);
hb_set_add(skip_subset, HB_TAG('a', 'v', 'a', 'r'));
hb_set_add(skip_subset, HB_TAG('c', 'v', 'a', 'r'));
hb_set_add(skip_subset, HB_TAG('f', 'v', 'a', 'r'));
hb_set_add(skip_subset, HB_TAG('M', 'V', 'A', 'R'));
// Normally harfbuzz would subset these variation tables, but they are needed
// for variation fonts.
hb_set_add(skip_subset, HB_TAG('g', 'v', 'a', 'r'));
hb_set_add(skip_subset, HB_TAG('H', 'V', 'A', 'R'));
hb_set_add(skip_subset, HB_TAG('V', 'V', 'A', 'R'));
// Also retain layout information which is important for non-latin characters.
hb_set_add(skip_subset, HB_TAG('G', 'D', 'E', 'F'));
hb_set_add(skip_subset, HB_TAG('G', 'S', 'U', 'B'));
hb_set_add(skip_subset, HB_TAG('G', 'P', 'O', 'S'));
hb::unique_ptr<hb_face_t> subset_face(
hb_subset_or_fail(face.get(), input.get()));
if (!subset_face) {
return nullptr;
}
// Store the correct collection index for the subsetted font.
const int final_ttc_index = hb_face_get_index(subset_face.get());
hb::unique_ptr<hb_blob_t> subset_blob(
hb_face_reference_blob(subset_face.get()));
if (!subset_blob) {
return nullptr;
}
unsigned int length = 0;
const char* subset_data = hb_blob_get_data(subset_blob.get(), &length);
if (!subset_data || !length) {
return nullptr;
}
auto sk_data = SkData::MakeWithProc(
subset_data, static_cast<size_t>(length),
[](const void*, void* ctx) { hb_blob_destroy((hb_blob_t*)ctx); },
subset_blob.release());
if (!sk_data) {
return nullptr;
}
// Ensure the data is in SkTypeface format so it will deserialize when
// embedded in an SkPicture. This is *not* a validation/sanitation and the
// inner workings may vary by platform.
sk_sp<SkFontMgr> mgr = skia::DefaultFontMgr();
sk_sp<SkTypeface> sk_subset_typeface =
mgr->makeFromData(sk_data, final_ttc_index);
if (!sk_subset_typeface) {
return nullptr;
}
// For fonts with variations we need to force the right variant of SkTypeface
// post subset.
const int axis_count = typeface->getVariationDesignPosition({});
if (axis_count > 0) {
std::vector<SkFontArguments::VariationPosition::Coordinate> typeface_axis;
typeface_axis.resize(axis_count);
if (typeface->getVariationDesignPosition(typeface_axis) > 0) {
SkFontArguments::VariationPosition variation;
variation.coordinates = typeface_axis.data();
variation.coordinateCount = typeface_axis.size();
SkFontArguments args;
args.setVariationDesignPosition(variation);
args.setCollectionIndex(final_ttc_index);
sk_subset_typeface = sk_subset_typeface->makeClone(args);
}
}
// TODO(crbug.com/40197502): Even after forcing the right variation,
// `sk_subset_typeface` may have the wrong SkFontStyle as there is no way to
// manipulate the style while loading the font from data.
return sk_subset_typeface->serialize(
SkTypeface::SerializeBehavior::kDoIncludeData);
}
} // namespace paint_preview
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