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// Copyright 2024 The Chromium Authors
// Use of this source code is governed by a BSD-style license that can be
// found in the LICENSE file.
#include "third_party/blink/renderer/platform/fonts/shaping/glyph_data_range.h"
#include "third_party/blink/renderer/platform/fonts/shaping/shape_result_run.h"
namespace blink {
GlyphDataRange::GlyphDataRange(const ShapeResultRun& run)
: run_(&run), size_(run.glyph_data_.size()) {}
GlyphDataRange::GlyphDataRange(const GlyphDataRange& range,
const_iterator begin_glyph,
const_iterator end_glyph)
: run_(range.run_) {
DCHECK(run_);
CHECK_GE(begin_glyph, run_->glyph_data_.begin());
index_ = begin_glyph - run_->glyph_data_.begin();
DCHECK_GE(index_, range.index_);
CHECK_LE(index_, run_->NumGlyphs());
CHECK_GE(end_glyph, begin_glyph);
size_ = end_glyph - begin_glyph;
CHECK_LE(size_, run_->NumGlyphs() - index_);
}
base::span<const HarfBuzzRunGlyphData> GlyphDataRange::Glyphs() const {
return run_ ? base::span{run_->glyph_data_}.subspan(index_, size_)
: base::span<const HarfBuzzRunGlyphData>{};
}
GlyphDataRange::const_iterator GlyphDataRange::begin() const {
return run_ ? UNSAFE_TODO(run_->glyph_data_.begin() + index_) : nullptr;
}
GlyphDataRange::const_iterator GlyphDataRange::end() const {
return run_ ? UNSAFE_TODO(run_->glyph_data_.begin() + index_ + size_)
: nullptr;
}
bool GlyphDataRange::HasOffsets() const {
return run_ && run_->glyph_data_.HasNonZeroOffsets();
}
base::span<const GlyphOffset> GlyphDataRange::Offsets() const {
if (HasOffsets()) [[unlikely]] {
return run_->glyph_data_.Offsets().subspan(index_, size_);
}
return base::span<const GlyphOffset>{};
}
// Find the range of HarfBuzzRunGlyphData for the specified character index
// range. This function uses binary search twice, hence O(2 log n).
GlyphDataRange GlyphDataRange::FindGlyphDataRange(
bool is_rtl,
unsigned start_character_index,
unsigned end_character_index) const {
const auto comparer = [](const HarfBuzzRunGlyphData& glyph_data,
unsigned index) {
return glyph_data.character_index < index;
};
if (!is_rtl) {
const HarfBuzzRunGlyphData* start_glyph =
std::lower_bound(begin(), end(), start_character_index, comparer);
if (start_glyph == end()) [[unlikely]] {
return GlyphDataRange();
}
const HarfBuzzRunGlyphData* end_glyph =
std::lower_bound(start_glyph, end(), end_character_index, comparer);
return {*this, start_glyph, end_glyph};
}
// RTL needs to use reverse iterators because there maybe multiple glyphs
// for a character, and we want to find the first one in the logical order.
const auto rbegin = std::reverse_iterator<const HarfBuzzRunGlyphData*>(end());
const auto rend = std::reverse_iterator<const HarfBuzzRunGlyphData*>(begin());
const auto start_glyph_it =
std::lower_bound(rbegin, rend, start_character_index, comparer);
if (start_glyph_it == rend) [[unlikely]] {
return GlyphDataRange();
}
const auto end_glyph_it =
std::lower_bound(start_glyph_it, rend, end_character_index, comparer);
// Convert reverse iterators to pointers. Then increment to make |begin|
// inclusive and |end| exclusive.
const HarfBuzzRunGlyphData* start_glyph = UNSAFE_TODO(&*end_glyph_it + 1);
const HarfBuzzRunGlyphData* end_glyph = UNSAFE_TODO(&*start_glyph_it + 1);
return {*this, start_glyph, end_glyph};
}
void GlyphDataRange::Trace(Visitor* visitor) const {
visitor->Trace(run_);
}
} // namespace blink
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