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chromium / chromium / src / ad2fcd6e0a36a7282b1b7140f258e7e071a5e753 / . / third_party / blink / renderer / platform / fonts / shaping / shape_result.cc
blob: 0e7fc972f743793a4dbe0caf73826a1cdfcda8e9 [file] [log] [blame]
/*
* Copyright (c) 2012 Google Inc. All rights reserved.
* Copyright (C) 2013 BlackBerry Limited. All rights reserved.
*
* Redistribution and use in source and binary forms, with or without
* modification, are permitted provided that the following conditions are
* met:
*
* * Redistributions of source code must retain the above copyright
* notice, this list of conditions and the following disclaimer.
* * 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.
* * Neither the name of Google Inc. nor the names of its
* contributors may be used to endorse or promote products derived from
* this software without specific prior written permission.
*
* 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
* OWNER 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 "third_party/blink/renderer/platform/fonts/shaping/shape_result.h"
#include <hb.h>
#include <algorithm>
#include <limits>
#include <memory>
#include <utility>
#include "base/containers/adapters.h"
#include "base/memory/ptr_util.h"
#include "third_party/blink/renderer/platform/fonts/character_range.h"
#include "third_party/blink/renderer/platform/fonts/font.h"
#include "third_party/blink/renderer/platform/fonts/shaping/shape_result_buffer.h"
#include "third_party/blink/renderer/platform/fonts/shaping/shape_result_inline_headers.h"
#include "third_party/blink/renderer/platform/fonts/shaping/shape_result_spacing.h"
#include "third_party/blink/renderer/platform/text/text_break_iterator.h"
#include "third_party/blink/renderer/platform/wtf/text/string_builder.h"
namespace blink {
constexpr unsigned HarfBuzzRunGlyphData::kMaxCharacterIndex;
unsigned ShapeResult::RunInfo::NextSafeToBreakOffset(unsigned offset) const {
DCHECK_LE(offset, num_characters_);
if (!Rtl()) {
for (const auto& glyph_data : glyph_data_) {
if (glyph_data.safe_to_break_before &&
glyph_data.character_index >= offset)
return glyph_data.character_index;
}
} else {
for (const auto& glyph_data : base::Reversed(glyph_data_)) {
if (glyph_data.safe_to_break_before &&
glyph_data.character_index >= offset)
return glyph_data.character_index;
}
}
// Next safe break is at the end of the run.
return num_characters_;
}
unsigned ShapeResult::RunInfo::PreviousSafeToBreakOffset(
unsigned offset) const {
if (offset >= num_characters_)
return num_characters_;
if (!Rtl()) {
for (const auto& glyph_data : base::Reversed(glyph_data_)) {
if (glyph_data.safe_to_break_before &&
glyph_data.character_index <= offset)
return glyph_data.character_index;
}
} else {
for (const auto& glyph_data : glyph_data_) {
if (glyph_data.safe_to_break_before &&
glyph_data.character_index <= offset)
return glyph_data.character_index;
}
}
// Next safe break is at the start of the run.
return 0;
}
float ShapeResult::RunInfo::XPositionForVisualOffset(
unsigned offset,
AdjustMidCluster adjust_mid_cluster) const {
DCHECK_LT(offset, num_characters_);
if (Rtl())
offset = num_characters_ - offset - 1;
return XPositionForOffset(offset, adjust_mid_cluster);
}
unsigned ShapeResult::RunInfo::NumGraphemes(unsigned start,
unsigned end) const {
if (graphemes_.size() == 0 || start >= num_characters_)
return 0;
DCHECK_LT(start, end);
DCHECK_LE(end, num_characters_);
return graphemes_[end - 1] - graphemes_[start] + 1;
}
void ShapeResult::EnsureGraphemes(const StringView& text) const {
DCHECK_EQ(NumCharacters(), text.length());
bool is_computed = !runs_.front()->graphemes_.IsEmpty();
#if DCHECK_IS_ON()
for (const auto& run : runs_)
DCHECK_EQ(is_computed, !run->graphemes_.IsEmpty());
#endif
if (is_computed)
return;
unsigned result_start_index = StartIndexForResult();
for (const auto& run : runs_) {
if (!run)
continue;
DCHECK_GE(run->start_index_, result_start_index);
GraphemesClusterList(
StringView(text, run->start_index_ - result_start_index,
run->num_characters_),
&run->graphemes_);
}
}
// XPositionForOffset returns the X position (in layout space) from the
// beginning of the run to the beginning of the cluster of glyphs for X
// character.
// For RTL, beginning means the right most side of the cluster.
// Characters may spawn multiple glyphs.
// In the case that multiple characters form a Unicode grapheme cluster, we
// distribute the width of the grapheme cluster among the number of cursor
// positions returned by cursor-based TextBreakIterator.
float ShapeResult::RunInfo::XPositionForOffset(
unsigned offset,
AdjustMidCluster adjust_mid_cluster) const {
DCHECK_LE(offset, num_characters_);
const unsigned num_glyphs = glyph_data_.size();
// In this context, a glyph sequence is a sequence of glyphs that shares the
// same character_index and therefore represent the same interval of source
// characters. glyph_sequence_start marks the character index at the beginning
// of the interval of characters for which this glyph sequence was formed as
// the result of shaping; glyph_sequence_end marks the end of the interval of
// characters for which this glyph sequence was formed. [glyph_sequence_start,
// glyph_sequence_end) is inclusive on the start for the range of characters
// of the current sequence we are visiting.
unsigned glyph_sequence_start = 0;
unsigned glyph_sequence_end = num_characters_;
// the advance of the current glyph sequence.
float glyph_sequence_advance = 0.0;
// the accumulated advance up to the current glyph sequence.
float accumulated_position = 0;
if (!Rtl()) {
for (unsigned i = 0; i < num_glyphs; ++i) {
unsigned current_glyph_char_index = glyph_data_[i].character_index;
// If this glyph is still part of the same glyph sequence for the grapheme
// cluster at character index glyph_sequence_start, add its advance to the
// glyph_sequence's advance.
if (glyph_sequence_start == current_glyph_char_index) {
glyph_sequence_advance += glyph_data_[i].advance;
continue;
}
// We are about to move out of a glyph sequence that contains offset, so
// the current glyph sequence is the one we are looking for.
if (glyph_sequence_start <= offset && offset < current_glyph_char_index) {
glyph_sequence_end = current_glyph_char_index;
break;
}
glyph_sequence_start = current_glyph_char_index;
// Since we always update glyph_sequence_end when we break, set this to
// last_character in case this is the final iteration of the loop.
glyph_sequence_end = num_characters_;
accumulated_position += glyph_sequence_advance;
glyph_sequence_advance = glyph_data_[i].advance;
}
} else {
glyph_sequence_start = glyph_sequence_end = num_characters_;
for (unsigned i = 0; i < num_glyphs; ++i) {
unsigned current_glyph_char_index = glyph_data_[i].character_index;
// If this glyph is still part of the same glyph sequence for the grapheme
// cluster at character index glyph_sequence_start, add its advance to the
// glyph_sequence's advance.
if (glyph_sequence_start == current_glyph_char_index) {
glyph_sequence_advance += glyph_data_[i].advance;
continue;
}
// We are about to move out of a glyph sequence that contains offset, so
// the current glyph sequence is the one we are looking for.
if (glyph_sequence_start <= offset && offset < glyph_sequence_end) {
break;
}
glyph_sequence_end = glyph_sequence_start;
glyph_sequence_start = current_glyph_char_index;
accumulated_position += glyph_sequence_advance;
glyph_sequence_advance = glyph_data_[i].advance;
}
}
// This is the character position inside the glyph sequence.
unsigned pos = offset - glyph_sequence_start;
// We calculate the number of Unicode grapheme clusters (actually cursor
// position stops) on the subset of characters. We use this to divide
// glyph_sequence_advance by the number of unicode grapheme clusters this
// glyph sequence was shaped for, and thus linearly interpolate the cursor
// position based on accumulated position and a fraction of
// glyph_sequence_advance.
unsigned graphemes = NumGraphemes(glyph_sequence_start, glyph_sequence_end);
if (graphemes > 1) {
DCHECK_GE(glyph_sequence_end, glyph_sequence_start);
unsigned size = glyph_sequence_end - glyph_sequence_start;
unsigned place = graphemes * pos / size;
pos -= place;
glyph_sequence_advance = glyph_sequence_advance / graphemes;
if (Rtl()) {
accumulated_position += glyph_sequence_advance * (graphemes - place - 1);
} else {
accumulated_position += glyph_sequence_advance * place;
}
}
// Re-adapt based on adjust_mid_cluster. On LTR, if we want AdjustToEnd and
// offset is not at the beginning, we need to jump to the right side of the
// grapheme. On RTL, if we want AdjustToStart and offset is not at the end, we
// need to jump to the left side of the grapheme.
if (!Rtl() && adjust_mid_cluster == AdjustMidCluster::kToEnd && pos != 0) {
accumulated_position += glyph_sequence_advance;
} else if (Rtl() && adjust_mid_cluster == AdjustMidCluster::kToEnd &&
pos != 0) {
accumulated_position -= glyph_sequence_advance;
}
if (Rtl()) {
// For RTL, we return the right side.
accumulated_position += glyph_sequence_advance;
}
return accumulated_position;
}
// In some ways, CharacterIndexForXPosition is the reverse of
// XPositionForOffset. Given a target pixel distance on screen space, returns a
// character index for the end of the interval that would be included within
// that space. @break_glyphs_option controls wether we use grapheme information
// to break glyphs into grapheme clusters and return character that are a part
// of a glyph.
void ShapeResult::RunInfo::CharacterIndexForXPosition(
float target_x,
BreakGlyphsOption break_glyphs_option,
GlyphIndexResult* result) const {
DCHECK(target_x >= 0 && target_x <= width_);
const unsigned num_glyphs = glyph_data_.size();
result->origin_x = 0;
unsigned glyph_sequence_start = 0;
unsigned glyph_sequence_end = num_characters_;
result->advance = 0.0;
// on RTL, we start on the last index.
if (Rtl()) {
glyph_sequence_start = glyph_sequence_end = num_characters_;
}
for (unsigned i = 0; i < num_glyphs; ++i) {
unsigned current_glyph_char_index = glyph_data_[i].character_index;
// If the glyph is part of the same sequence, we just accumulate the
// advance.
if (glyph_sequence_start == current_glyph_char_index) {
result->advance += glyph_data_[i].advance;
continue;
}
// Since we are about to move to the next sequence of glyphs, check if
// the target falls inside it, if it does, we found our sequence.
if (result->origin_x + result->advance > target_x) {
if (!Rtl()) {
glyph_sequence_end = current_glyph_char_index;
}
break;
}
// Move to the next sequence, update accumulated_x.
if (Rtl()) {
// Notice that on RTL, as we move to our next sequence, we already know
// both bounds. Nonetheless, we still need to move forward so we can
// capture all glyphs of this sequence.
glyph_sequence_end = glyph_sequence_start;
}
glyph_sequence_start = current_glyph_char_index;
result->origin_x += result->advance;
result->advance = glyph_data_[i].advance;
}
// At this point, we have [glyph_sequence_start, glyph_sequence_end)
// representing a sequence of glyphs, of size glyph_sequence_advance. We
// linearly interpolate how much space each character takes, and reduce the
// sequence to only match the character size.
if (break_glyphs_option == BreakGlyphs) {
int graphemes = NumGraphemes(glyph_sequence_start, glyph_sequence_end);
if (graphemes > 1) {
float unit_size = result->advance / graphemes;
unsigned step = floor((target_x - result->origin_x) / unit_size);
unsigned glyph_length = glyph_sequence_end - glyph_sequence_start;
unsigned final_size = floor(glyph_length / graphemes);
result->origin_x += unit_size * step;
if (!Rtl()) {
glyph_sequence_start += step;
glyph_sequence_end = glyph_sequence_start + final_size;
} else {
glyph_sequence_end -= step;
glyph_sequence_start = glyph_sequence_end - final_size;
}
result->advance = unit_size;
}
}
if (!Rtl()) {
result->left_character_index = glyph_sequence_start;
result->right_character_index = glyph_sequence_end;
} else {
result->left_character_index = glyph_sequence_end;
result->right_character_index = glyph_sequence_start;
}
}
void HarfBuzzRunGlyphData::SetGlyphAndPositions(uint16_t glyph_id,
uint16_t character_index,
float advance,
const FloatSize& offset,
bool safe_to_break_before) {
glyph = glyph_id;
DCHECK_LE(character_index, kMaxCharacterIndex);
this->character_index = character_index;
this->advance = advance;
this->offset = offset;
this->safe_to_break_before = safe_to_break_before;
}
ShapeResult::ShapeResult(const SimpleFontData* font_data,
unsigned num_characters,
TextDirection direction)
: width_(0),
primary_font_(font_data),
num_characters_(num_characters),
num_glyphs_(0),
direction_(static_cast<unsigned>(direction)),
has_vertical_offsets_(0) {}
ShapeResult::ShapeResult(const Font* font,
unsigned num_characters,
TextDirection direction)
: ShapeResult(font->PrimaryFont(), num_characters, direction) {}
ShapeResult::ShapeResult(const ShapeResult& other)
: width_(other.width_),
glyph_bounding_box_(other.glyph_bounding_box_),
primary_font_(other.primary_font_),
num_characters_(other.num_characters_),
num_glyphs_(other.num_glyphs_),
direction_(other.direction_),
has_vertical_offsets_(other.has_vertical_offsets_) {
runs_.ReserveCapacity(other.runs_.size());
for (const auto& run : other.runs_)
runs_.push_back(std::make_unique<RunInfo>(*run));
}
ShapeResult::~ShapeResult() = default;
size_t ShapeResult::ByteSize() const {
size_t self_byte_size = sizeof(this);
for (unsigned i = 0; i < runs_.size(); ++i) {
self_byte_size += runs_[i]->ByteSize();
}
return self_byte_size;
}
CharacterRange ShapeResult::GetCharacterRange(const StringView& text,
unsigned from,
unsigned to) const {
EnsureGraphemes(text);
return ShapeResultBuffer::GetCharacterRange(this, text, Direction(), Width(),
from, to);
}
unsigned ShapeResult::StartIndexForResult() const {
if (UNLIKELY(runs_.IsEmpty()))
return 0;
const RunInfo& first_run = *runs_.front();
if (!Rtl())
return first_run.start_index_;
unsigned end = first_run.start_index_ + first_run.num_characters_;
DCHECK_GE(end, NumCharacters());
return end - NumCharacters();
}
unsigned ShapeResult::EndIndexForResult() const {
if (UNLIKELY(runs_.IsEmpty()))
return NumCharacters();
const RunInfo& first_run = *runs_.front();
if (!Rtl())
return first_run.start_index_ + NumCharacters();
return first_run.start_index_ + first_run.num_characters_;
}
scoped_refptr<ShapeResult> ShapeResult::MutableUnique() const {
if (HasOneRef())
return const_cast<ShapeResult*>(this);
return ShapeResult::Create(*this);
}
unsigned ShapeResult::NextSafeToBreakOffset(unsigned index) const {
for (auto* it = runs_.begin(); it != runs_.end(); ++it) {
const auto& run = *it;
if (!run)
continue;
unsigned run_start = run->start_index_;
if (index >= run_start) {
unsigned offset = index - run_start;
if (offset <= run->num_characters_) {
return run->NextSafeToBreakOffset(offset) + run_start;
}
if (Rtl()) {
if (it == runs_.begin())
return run_start + run->num_characters_;
const auto& previous_run = *--it;
return previous_run->start_index_;
}
} else if (!Rtl()) {
return run_start;
}
}
return EndIndexForResult();
}
unsigned ShapeResult::PreviousSafeToBreakOffset(unsigned index) const {
for (auto it = runs_.rbegin(); it != runs_.rend(); ++it) {
const auto& run = *it;
if (!run)
continue;
unsigned run_start = run->start_index_;
if (index >= run_start) {
unsigned offset = index - run_start;
if (offset <= run->num_characters_) {
return run->PreviousSafeToBreakOffset(offset) + run_start;
}
if (!Rtl()) {
return run_start + run->num_characters_;
}
} else if (Rtl()) {
if (it == runs_.rbegin())
return run->start_index_;
const auto& previous_run = *--it;
return previous_run->start_index_ + previous_run->num_characters_;
}
}
return StartIndexForResult();
}
// If the position is outside of the result, returns the start or the end offset
// depends on the position.
void ShapeResult::OffsetForPosition(float target_x,
BreakGlyphsOption break_glyphs_option,
GlyphIndexResult* result) const {
if (target_x <= 0) {
if (Rtl()) {
result->left_character_index = result->right_character_index =
NumCharacters();
}
return;
}
unsigned characters_so_far = Rtl() ? NumCharacters() : 0;
float current_x = 0;
for (unsigned i = 0; i < runs_.size(); ++i) {
const RunInfo* run = runs_[i].get();
if (!run)
continue;
if (Rtl())
characters_so_far -= runs_[i]->num_characters_;
float next_x = current_x + run->width_;
float offset_for_run = target_x - current_x;
if (offset_for_run >= 0 && offset_for_run < run->width_) {
// The x value in question is within this script run.
run->CharacterIndexForXPosition(offset_for_run, break_glyphs_option,
result);
result->run_index = i;
result->characters_on_left_runs = characters_so_far;
if (Rtl()) {
result->left_character_index =
characters_so_far + result->left_character_index;
result->right_character_index =
characters_so_far + result->right_character_index;
DCHECK_LE(result->left_character_index, NumCharacters() + 1);
DCHECK_LE(result->right_character_index, NumCharacters());
} else {
result->left_character_index += characters_so_far;
result->right_character_index += characters_so_far;
DCHECK_LE(result->left_character_index, NumCharacters());
DCHECK_LE(result->right_character_index, NumCharacters() + 1);
}
result->origin_x += current_x;
return;
}
if (!Rtl())
characters_so_far += run->num_characters_;
current_x = next_x;
}
if (Rtl()) {
result->left_character_index = 0;
result->right_character_index = 0;
} else {
result->left_character_index += characters_so_far;
result->right_character_index += characters_so_far;
}
result->run_index = runs_.size() - 1;
result->characters_on_left_runs = characters_so_far;
DCHECK_LE(result->left_character_index, NumCharacters());
DCHECK_LE(result->right_character_index, NumCharacters() + 1);
}
unsigned ShapeResult::OffsetForPosition(
float x,
BreakGlyphsOption break_glyphs_option) const {
GlyphIndexResult result;
OffsetForPosition(x, break_glyphs_option, &result);
// For LTR, the offset is always the left one.
if (!Rtl())
return result.left_character_index;
// For RTL the offset is the right one, except that the interval is open
// on other side. So in case we are exactly at the boundary, we return the
// left index.
if (x == result.origin_x)
return result.left_character_index;
return result.right_character_index;
}
unsigned ShapeResult::CaretOffsetForHitTest(
float x,
const StringView& text,
BreakGlyphsOption break_glyphs_option) const {
if (break_glyphs_option == BreakGlyphs)
EnsureGraphemes(text);
GlyphIndexResult result;
OffsetForPosition(x, break_glyphs_option, &result);
if (x - result.origin_x <= result.advance / 2)
return result.left_character_index;
return result.right_character_index;
}
unsigned ShapeResult::OffsetToFit(float x, TextDirection line_direction) const {
GlyphIndexResult result;
OffsetForPosition(x, DontBreakGlyphs, &result);
if (IsLtr(line_direction))
return result.left_character_index;
if (x == result.origin_x && IsRtl(Direction()))
return result.left_character_index;
return result.right_character_index;
}
float ShapeResult::PositionForOffset(
unsigned absolute_offset,
AdjustMidCluster adjust_mid_cluster) const {
float x = 0;
float offset_x = 0;
// The absolute_offset argument represents the offset for the entire
// ShapeResult while offset is continuously updated to be relative to the
// current run.
unsigned offset = absolute_offset;
if (Rtl()) {
// Convert logical offsets to visual offsets, because results are in
// logical order while runs are in visual order.
x = width_;
if (offset < NumCharacters())
offset = NumCharacters() - offset - 1;
x -= Width();
}
for (unsigned i = 0; i < runs_.size(); i++) {
if (!runs_[i])
continue;
DCHECK_EQ(Rtl(), runs_[i]->Rtl());
unsigned num_characters = runs_[i]->num_characters_;
if (!offset_x && offset < num_characters) {
offset_x =
runs_[i]->XPositionForVisualOffset(offset, adjust_mid_cluster) + x;
break;
}
offset -= num_characters;
x += runs_[i]->width_;
}
// The position in question might be just after the text.
if (!offset_x && absolute_offset == NumCharacters())
return Rtl() ? 0 : width_;
return offset_x;
}
float ShapeResult::CaretPositionForOffset(
unsigned offset,
const StringView& text,
AdjustMidCluster adjust_mid_cluster) const {
EnsureGraphemes(text);
return PositionForOffset(offset, adjust_mid_cluster);
}
void ShapeResult::FallbackFonts(
HashSet<const SimpleFontData*>* fallback) const {
DCHECK(fallback);
DCHECK(primary_font_);
for (unsigned i = 0; i < runs_.size(); ++i) {
if (runs_[i] && runs_[i]->font_data_ &&
runs_[i]->font_data_ != primary_font_) {
fallback->insert(runs_[i]->font_data_.get());
}
}
}
void ShapeResult::GetRunFontData(Vector<RunFontData>* font_data) const {
for (const auto& run : runs_) {
font_data->push_back(
RunFontData({run->font_data_.get(), run->glyph_data_.size()}));
}
}
// TODO(kojii): VC2015 fails to explicit instantiation of a member function.
// Typed functions + this private function are to instantiate instances.
template <typename TextContainerType>
void ShapeResult::ApplySpacingImpl(
ShapeResultSpacing<TextContainerType>& spacing,
int text_start_offset) {
float offset = 0;
float total_space = 0;
float space = 0;
for (auto& run : runs_) {
if (!run)
continue;
unsigned run_start_index = run->start_index_ + text_start_offset;
float total_space_for_run = 0;
for (size_t i = 0; i < run->glyph_data_.size(); i++) {
HarfBuzzRunGlyphData& glyph_data = run->glyph_data_[i];
// Skip if it's not a grapheme cluster boundary.
if (i + 1 < run->glyph_data_.size() &&
glyph_data.character_index ==
run->glyph_data_[i + 1].character_index) {
continue;
}
space = spacing.ComputeSpacing(
run_start_index + glyph_data.character_index, offset);
glyph_data.advance += space;
total_space_for_run += space;
// |offset| is non-zero only when justifying CJK characters that follow
// non-CJK characters.
if (UNLIKELY(offset)) {
if (run->IsHorizontal()) {
glyph_data.offset.SetWidth(glyph_data.offset.Width() + offset);
} else {
glyph_data.offset.SetHeight(glyph_data.offset.Height() + offset);
has_vertical_offsets_ = true;
}
offset = 0;
}
}
run->width_ += total_space_for_run;
total_space += total_space_for_run;
}
width_ += total_space;
// The spacing on the right of the last glyph does not affect the glyph
// bounding box. Thus, the glyph bounding box becomes smaller than the advance
// if the letter spacing is positve, or larger if negative.
if (space) {
total_space -= space;
// TODO(kojii): crbug.com/768284: There are cases where
// InlineTextBox::LogicalWidth() is round down of ShapeResult::Width() in
// LayoutUnit. Ceiling the width did not help. Add 1px to avoid cut-off.
if (space < 0)
total_space += 1;
}
// Set the width because glyph bounding box is in logical space.
float glyph_bounding_box_width = glyph_bounding_box_.Width() + total_space;
if (width_ >= 0 && glyph_bounding_box_width >= 0) {
glyph_bounding_box_.SetWidth(glyph_bounding_box_width);
return;
}
// Negative word-spacing and/or letter-spacing may cause some glyphs to
// overflow the left boundary and result negative measured width. Adjust glyph
// bounds accordingly to cover the overflow.
// The negative width should be clamped to 0 in CSS box model, but it's up to
// caller's responsibility.
float left = std::min(width_, glyph_bounding_box_width);
if (left < glyph_bounding_box_.X()) {
// The right edge should be the width of the first character in most cases,
// but computing it requires re-measuring bounding box of each glyph. Leave
// it unchanged, which gives an excessive right edge but assures it covers
// all glyphs.
glyph_bounding_box_.ShiftXEdgeTo(left);
} else {
glyph_bounding_box_.SetWidth(glyph_bounding_box_width);
}
}
void ShapeResult::ApplySpacing(ShapeResultSpacing<String>& spacing,
int text_start_offset) {
ApplySpacingImpl(spacing, text_start_offset);
}
scoped_refptr<ShapeResult> ShapeResult::ApplySpacingToCopy(
ShapeResultSpacing<TextRun>& spacing,
const TextRun& run) const {
unsigned index_of_sub_run = spacing.Text().IndexOfSubRun(run);
DCHECK_NE(std::numeric_limits<unsigned>::max(), index_of_sub_run);
scoped_refptr<ShapeResult> result = ShapeResult::Create(*this);
if (index_of_sub_run != std::numeric_limits<unsigned>::max())
result->ApplySpacingImpl(spacing, index_of_sub_run);
return result;
}
namespace {
float HarfBuzzPositionToFloat(hb_position_t value) {
return static_cast<float>(value) / (1 << 16);
}
// This is a helper class to accumulate glyph bounding box.
//
// Glyph positions and bounding boxes from HarfBuzz and fonts are in physical
// coordinate, while ShapeResult::glyph_bounding_box_ is in logical coordinate.
// To minimize the number of conversions, this class accumulates the bounding
// boxes in physical coordinate, and convert the accumulated box to logical.
struct GlyphBoundsAccumulator {
// Construct an accumulator with the logical glyph origin.
explicit GlyphBoundsAccumulator(float origin) : origin(origin) {}
// The accumulated glyph bounding box in physical coordinate, until
// ConvertVerticalRunToLogical().
FloatRect bounds;
// The current origin, in logical coordinate.
float origin;
// Unite a glyph bounding box to |bounds|.
template <bool is_horizontal_run>
void Unite(const HarfBuzzRunGlyphData& glyph_data,
FloatRect bounds_for_glyph) {
if (UNLIKELY(bounds_for_glyph.IsEmpty()))
return;
// Glyphs are drawn at |origin + offset|. Move glyph_bounds to that point.
// All positions in hb_glyph_position_t are relative to the current point.
// https://behdad.github.io/harfbuzz/harfbuzz-Buffers.html#hb-glyph-position-t-struct
if (is_horizontal_run)
bounds_for_glyph.SetX(bounds_for_glyph.X() + origin);
else
bounds_for_glyph.SetY(bounds_for_glyph.Y() + origin);
bounds_for_glyph.Move(glyph_data.offset);
bounds.Unite(bounds_for_glyph);
}
// Non-template version of |Unite()|, see above.
void Unite(bool is_horizontal_run,
const HarfBuzzRunGlyphData& glyph,
FloatRect bounds_for_glyph) {
is_horizontal_run ? Unite<true>(glyph, bounds_for_glyph)
: Unite<false>(glyph, bounds_for_glyph);
}
// Convert vertical run glyph bounding box to logical. Horizontal runs do not
// need conversions because physical and logical are the same.
void ConvertVerticalRunToLogical(const FontMetrics& font_metrics) {
// Convert physical glyph_bounding_box to logical.
bounds = bounds.TransposedRect();
// The glyph bounding box of a vertical run uses ideographic baseline.
// Adjust the box Y position because the bounding box of a ShapeResult uses
// alphabetic baseline.
// See diagrams of base lines at
// https://drafts.csswg.org/css-writing-modes-3/#intro-baselines
int baseline_adjust = font_metrics.Ascent(kIdeographicBaseline) -
font_metrics.Ascent(kAlphabeticBaseline);
bounds.SetY(bounds.Y() + baseline_adjust);
}
};
// Checks whether it's safe to break without reshaping before the given glyph.
bool IsSafeToBreakBefore(const hb_glyph_info_t* glyph_infos,
unsigned num_glyphs,
unsigned i) {
// Before the first glyph is safe to break.
if (!i)
return true;
// Not at a cluster boundary.
if (glyph_infos[i].cluster == glyph_infos[i - 1].cluster)
return false;
// The HB_GLYPH_FLAG_UNSAFE_TO_BREAK flag is set for all glyphs in a
// given cluster so we only need to check the last one.
hb_glyph_flags_t flags = hb_glyph_info_get_glyph_flags(glyph_infos + i);
return (flags & HB_GLYPH_FLAG_UNSAFE_TO_BREAK) == 0;
}
} // anonymous namespace
// Computes glyph positions, sets advance and offset of each glyph to RunInfo.
//
// Also computes glyph bounding box of the run. In this function, glyph bounding
// box is in physical.
template <bool is_horizontal_run>
void ShapeResult::ComputeGlyphPositions(ShapeResult::RunInfo* run,
unsigned start_glyph,
unsigned num_glyphs,
hb_buffer_t* harfbuzz_buffer) {
DCHECK_EQ(is_horizontal_run, run->IsHorizontal());
const hb_glyph_info_t* glyph_infos =
hb_buffer_get_glyph_infos(harfbuzz_buffer, nullptr);
const hb_glyph_position_t* glyph_positions =
hb_buffer_get_glyph_positions(harfbuzz_buffer, nullptr);
const unsigned start_cluster =
HB_DIRECTION_IS_FORWARD(hb_buffer_get_direction(harfbuzz_buffer))
? glyph_infos[start_glyph].cluster
: glyph_infos[start_glyph + num_glyphs - 1].cluster;
// Compute glyph_origin and glyph_bounding_box in physical, since both offsets
// and boudning box of glyphs are in physical. It's the caller's
// responsibility to convert the united physical bounds to logical.
float total_advance = 0.0f;
bool has_vertical_offsets = !is_horizontal_run;
// HarfBuzz returns result in visual order, no need to flip for RTL.
for (unsigned i = 0; i < num_glyphs; ++i) {
uint16_t glyph = glyph_infos[start_glyph + i].codepoint;
const hb_glyph_position_t& pos = glyph_positions[start_glyph + i];
// Offset is primarily used when painting glyphs. Keep it in physical.
FloatSize offset(HarfBuzzPositionToFloat(pos.x_offset),
-HarfBuzzPositionToFloat(pos.y_offset));
// One out of x_advance and y_advance is zero, depending on
// whether the buffer direction is horizontal or vertical.
// Convert to float and negate to avoid integer-overflow for ULONG_MAX.
float advance = is_horizontal_run ? HarfBuzzPositionToFloat(pos.x_advance)
: -HarfBuzzPositionToFloat(pos.y_advance);
uint16_t character_index =
glyph_infos[start_glyph + i].cluster - start_cluster;
if (UNLIKELY(character_index >= HarfBuzzRunGlyphData::kMaxCharacterIndex)) {
// If the character index exceeds the limit, abort and shrink the run to
// what are actually stored.
run->num_characters_ = character_index;
run->glyph_data_.Shrink(i);
break;
}
HarfBuzzRunGlyphData& glyph_data = run->glyph_data_[i];
glyph_data.SetGlyphAndPositions(
glyph, character_index, advance, offset,
IsSafeToBreakBefore(glyph_infos + start_glyph, num_glyphs, i));
total_advance += advance;
has_vertical_offsets |= (offset.Height() != 0);
}
run->width_ = std::max(0.0f, total_advance);
has_vertical_offsets_ |= has_vertical_offsets;
ComputeGlyphBounds<is_horizontal_run>(*run);
}
template <bool is_horizontal_run>
void ShapeResult::ComputeGlyphBounds(const ShapeResult::RunInfo& run) {
// Skia runs much faster if we give a list of glyph ID rather than calling it
// on each glyph.
const SimpleFontData& current_font_data = *run.font_data_;
unsigned num_glyphs = run.glyph_data_.size();
Vector<Glyph, 256> glyphs(num_glyphs);
for (unsigned i = 0; i < num_glyphs; i++)
glyphs[i] = run.glyph_data_[i].glyph;
Vector<FloatRect, 256> bounds_list(num_glyphs);
current_font_data.BoundsForGlyphs(glyphs, &bounds_list);
GlyphBoundsAccumulator bounds(width_);
for (unsigned i = 0; i < num_glyphs; i++) {
const HarfBuzzRunGlyphData& glyph_data = run.glyph_data_[i];
bounds.Unite<is_horizontal_run>(glyph_data, bounds_list[i]);
bounds.origin += glyph_data.advance;
}
if (!is_horizontal_run)
bounds.ConvertVerticalRunToLogical(current_font_data.GetFontMetrics());
glyph_bounding_box_.Unite(bounds.bounds);
}
void ShapeResult::InsertRun(std::unique_ptr<ShapeResult::RunInfo> run_to_insert,
unsigned start_glyph,
unsigned num_glyphs,
hb_buffer_t* harfbuzz_buffer) {
DCHECK_GT(num_glyphs, 0u);
std::unique_ptr<ShapeResult::RunInfo> run(std::move(run_to_insert));
if (run->IsHorizontal()) {
// Inserting a horizontal run into a horizontal or vertical result. In both
// cases, no adjustments are needed because |glyph_bounding_box_| is in
// logical coordinates and uses alphabetic baseline.
ComputeGlyphPositions<true>(run.get(), start_glyph, num_glyphs,
harfbuzz_buffer);
} else {
// Inserting a vertical run to a vertical result.
ComputeGlyphPositions<false>(run.get(), start_glyph, num_glyphs,
harfbuzz_buffer);
}
width_ += run->width_;
num_glyphs_ += run->NumGlyphs();
DCHECK_GE(num_glyphs_, run->NumGlyphs());
InsertRun(std::move(run));
}
void ShapeResult::InsertRun(std::unique_ptr<ShapeResult::RunInfo> run) {
// The runs are stored in result->m_runs in visual order. For LTR, we place
// the run to be inserted before the next run with a bigger character
// start index. For RTL, we place the run before the next run with a lower
// character index. Otherwise, for both directions, at the end.
if (HB_DIRECTION_IS_FORWARD(run->direction_)) {
for (size_t pos = 0; pos < runs_.size(); ++pos) {
if (runs_.at(pos)->start_index_ > run->start_index_) {
runs_.insert(pos, std::move(run));
break;
}
}
} else {
for (size_t pos = 0; pos < runs_.size(); ++pos) {
if (runs_.at(pos)->start_index_ < run->start_index_) {
runs_.insert(pos, std::move(run));
break;
}
}
}
// If we didn't find an existing slot to place it, append.
if (run)
runs_.push_back(std::move(run));
}
// Insert a |RunInfo| without glyphs. |StartIndexForResult()| needs a run to
// compute the start character index. When all glyphs are missing, this function
// synthesize a run without glyphs.
void ShapeResult::InsertRunForIndex(unsigned start_character_index) {
DCHECK(runs_.IsEmpty());
runs_.push_back(std::make_unique<RunInfo>(
primary_font_.get(), !Rtl() ? HB_DIRECTION_LTR : HB_DIRECTION_RTL,
CanvasRotationInVertical::kRegular, HB_SCRIPT_UNKNOWN,
start_character_index, 0, num_characters_));
}
ShapeResult::RunInfo* ShapeResult::InsertRunForTesting(
unsigned start_index,
unsigned num_characters,
TextDirection direction,
Vector<uint16_t> safe_break_offsets) {
std::unique_ptr<RunInfo> run = std::make_unique<ShapeResult::RunInfo>(
nullptr, IsLtr(direction) ? HB_DIRECTION_LTR : HB_DIRECTION_RTL,
CanvasRotationInVertical::kRegular, HB_SCRIPT_COMMON, start_index,
num_characters, num_characters);
unsigned i = 0;
for (auto& glyph_data : run->glyph_data_)
glyph_data.SetGlyphAndPositions(0, i++, 0, FloatSize(), false);
for (uint16_t offset : safe_break_offsets)
run->glyph_data_[offset].safe_to_break_before = true;
// RTL runs have glyphs in the descending order of character_index.
if (Rtl())
run->glyph_data_.Reverse();
num_glyphs_ += run->NumGlyphs();
RunInfo* run_ptr = run.get();
InsertRun(std::move(run));
return run_ptr;
}
// Moves runs at (run_size_before, end) to the front of |runs_|.
//
// Runs in RTL result are in visual order, and that new runs should be
// prepended. This function adjusts the run order after runs were appended.
void ShapeResult::ReorderRtlRuns(unsigned run_size_before) {
DCHECK(Rtl());
DCHECK_GT(runs_.size(), run_size_before);
if (runs_.size() == run_size_before + 1) {
if (!run_size_before)
return;
std::unique_ptr<RunInfo> new_run(std::move(runs_.back()));
runs_.Shrink(runs_.size() - 1);
runs_.push_front(std::move(new_run));
return;
}
// |push_front| is O(n) that we should not call it multiple times.
// Create a new list in the correct order and swap it.
Vector<std::unique_ptr<RunInfo>> new_runs;
new_runs.ReserveInitialCapacity(runs_.size());
for (unsigned i = run_size_before; i < runs_.size(); i++)
new_runs.push_back(std::move(runs_[i]));
// Then append existing runs.
for (unsigned i = 0; i < run_size_before; i++)
new_runs.push_back(std::move(runs_[i]));
runs_.swap(new_runs);
}
// Returns the left of the glyph bounding box of the left most character.
float ShapeResult::LineLeftBounds() const {
DCHECK(!runs_.IsEmpty());
const RunInfo& run = *runs_.front();
const bool is_horizontal_run = run.IsHorizontal();
const SimpleFontData& font_data = *run.font_data_;
DCHECK(!run.glyph_data_.IsEmpty()) << *this;
const unsigned character_index = run.glyph_data_.front().character_index;
GlyphBoundsAccumulator bounds(0.f);
for (const auto& glyph : run.glyph_data_) {
if (character_index != glyph.character_index)
break;
bounds.Unite(is_horizontal_run, glyph,
font_data.BoundsForGlyph(glyph.glyph));
bounds.origin += glyph.advance;
}
if (UNLIKELY(!is_horizontal_run))
bounds.ConvertVerticalRunToLogical(font_data.GetFontMetrics());
return bounds.bounds.X();
}
// Returns the right of the glyph bounding box of the right most character.
float ShapeResult::LineRightBounds() const {
DCHECK(!runs_.IsEmpty());
const RunInfo& run = *runs_.back();
const bool is_horizontal_run = run.IsHorizontal();
const SimpleFontData& font_data = *run.font_data_;
DCHECK(!run.glyph_data_.IsEmpty()) << *this;
const unsigned character_index = run.glyph_data_.back().character_index;
GlyphBoundsAccumulator bounds(width_);
for (const auto& glyph : base::Reversed(run.glyph_data_)) {
if (character_index != glyph.character_index)
break;
bounds.origin -= glyph.advance;
bounds.Unite(is_horizontal_run, glyph,
font_data.BoundsForGlyph(glyph.glyph));
}
// If the last character has no ink (e.g., space character), assume the
// character before will not overflow more than the width of the space.
if (UNLIKELY(bounds.bounds.IsEmpty()))
return width_;
if (UNLIKELY(!is_horizontal_run))
bounds.ConvertVerticalRunToLogical(font_data.GetFontMetrics());
return bounds.bounds.MaxX();
}
void ShapeResult::CopyRange(unsigned start_offset,
unsigned end_offset,
ShapeResult* target) const {
if (!runs_.size())
return;
#if DCHECK_IS_ON()
unsigned target_num_characters_before = target->num_characters_;
#endif
// When |target| is empty, its character indexes are the specified sub range
// of |this|. Otherwise the character indexes are renumbered to be continuous.
int index_diff = !target->num_characters_
? 0
: target->EndIndexForResult() -
std::max(start_offset, StartIndexForResult());
unsigned target_run_size_before = target->runs_.size();
float total_width = 0;
for (const auto& run : runs_) {
unsigned run_start = run->start_index_;
unsigned run_end = run_start + run->num_characters_;
if (start_offset < run_end && end_offset > run_start) {
unsigned start = start_offset > run_start ? start_offset - run_start : 0;
unsigned end = std::min(end_offset, run_end) - run_start;
DCHECK(end > start);
auto sub_run = run->CreateSubRun(start, end);
sub_run->start_index_ += index_diff;
total_width += sub_run->width_;
target->num_characters_ += sub_run->num_characters_;
target->num_glyphs_ += sub_run->glyph_data_.size();
target->runs_.push_back(std::move(sub_run));
}
}
if (!target->num_glyphs_)
return;
// Runs in RTL result are in visual order, and that new runs should be
// prepended. Reorder appended runs.
DCHECK_EQ(Rtl(), target->Rtl());
if (UNLIKELY(Rtl() && target->runs_.size() != target_run_size_before))
target->ReorderRtlRuns(target_run_size_before);
// Compute new glyph bounding box.
//
// Computing glyph bounding box from Font is one of the most expensive
// operations. If |start_offset| or |end_offset| are the start/end of |this|,
// use the current |glyph_bounding_box_| for the side.
DCHECK(primary_font_.get() == target->primary_font_.get());
bool know_left_edge = start_offset <= StartIndexForResult();
bool know_right_edge = end_offset >= EndIndexForResult();
if (UNLIKELY(Rtl()))
std::swap(know_left_edge, know_right_edge);
float left = know_left_edge ? target->width_ + glyph_bounding_box_.X()
: target->LineLeftBounds();
target->width_ += total_width;
float right = know_right_edge
? glyph_bounding_box_.MaxX() - width_ + target->width_
: target->LineRightBounds();
FloatRect adjusted_box(left, glyph_bounding_box_.Y(),
std::max(right - left, 0.0f),
glyph_bounding_box_.Height());
target->glyph_bounding_box_.UniteIfNonZero(adjusted_box);
target->has_vertical_offsets_ |= has_vertical_offsets_;
#if DCHECK_IS_ON()
DCHECK_EQ(target->num_characters_ - target_num_characters_before,
std::min(end_offset, EndIndexForResult()) -
std::max(start_offset, StartIndexForResult()));
target->CheckConsistency();
#endif
}
scoped_refptr<ShapeResult> ShapeResult::SubRange(unsigned start_offset,
unsigned end_offset) const {
scoped_refptr<ShapeResult> sub_range =
Create(primary_font_.get(), 0, Direction());
CopyRange(start_offset, end_offset, sub_range.get());
return sub_range;
}
scoped_refptr<ShapeResult> ShapeResult::CopyAdjustedOffset(
unsigned start_index) const {
scoped_refptr<ShapeResult> result = base::AdoptRef(new ShapeResult(*this));
if (start_index > result->StartIndexForResult()) {
unsigned delta = start_index - result->StartIndexForResult();
for (auto& run : result->runs_)
run->start_index_ += delta;
} else {
unsigned delta = result->StartIndexForResult() - start_index;
for (auto& run : result->runs_) {
DCHECK(run->start_index_ >= delta);
run->start_index_ -= delta;
}
}
return result;
}
#if DCHECK_IS_ON()
void ShapeResult::CheckConsistency() const {
if (runs_.IsEmpty()) {
DCHECK_EQ(0u, num_characters_);
DCHECK_EQ(0u, num_glyphs_);
return;
}
const unsigned start_index = StartIndexForResult();
unsigned index = start_index;
unsigned num_glyphs = 0;
if (!Rtl()) {
for (const auto& run : runs_) {
// Characters maybe missing, but must be in increasing order.
DCHECK_GE(run->start_index_, index);
index = run->start_index_ + run->num_characters_;
num_glyphs += run->glyph_data_.size();
}
} else {
// RTL on Mac may not have runs for the all characters. crbug.com/774034
index = runs_.back()->start_index_;
for (const auto& run : base::Reversed(runs_)) {
DCHECK_GE(run->start_index_, index);
index = run->start_index_ + run->num_characters_;
num_glyphs += run->glyph_data_.size();
}
}
const unsigned end_index = EndIndexForResult();
DCHECK_LE(index, end_index);
DCHECK_EQ(end_index - start_index, num_characters_);
DCHECK_EQ(num_glyphs, num_glyphs_);
}
#endif
scoped_refptr<ShapeResult> ShapeResult::CreateForTabulationCharacters(
const Font* font,
const TextRun& text_run,
float position_offset,
unsigned count) {
const SimpleFontData* font_data = font->PrimaryFont();
// Tab characters are always LTR or RTL, not TTB, even when
// isVerticalAnyUpright().
std::unique_ptr<ShapeResult::RunInfo> run = std::make_unique<RunInfo>(
font_data, text_run.Rtl() ? HB_DIRECTION_RTL : HB_DIRECTION_LTR,
CanvasRotationInVertical::kRegular, HB_SCRIPT_COMMON, 0, count, count);
float position = text_run.XPos() + position_offset;
float start_position = position;
for (unsigned i = 0; i < count; i++) {
float advance = font->TabWidth(font_data, text_run.GetTabSize(), position);
HarfBuzzRunGlyphData& glyph_data = run->glyph_data_[i];
glyph_data.SetGlyphAndPositions(font_data->SpaceGlyph(), i, advance,
FloatSize(), true);
position += advance;
}
run->width_ = position - start_position;
scoped_refptr<ShapeResult> result =
ShapeResult::Create(font, count, text_run.Direction());
result->width_ = run->width_;
result->num_glyphs_ = count;
DCHECK_EQ(result->num_glyphs_, count); // no overflow
result->has_vertical_offsets_ =
font_data->PlatformData().IsVerticalAnyUpright();
result->runs_.push_back(std::move(run));
return result;
}
void ShapeResult::ToString(StringBuilder* output) const {
output->Append("#chars=");
output->AppendNumber(num_characters_);
output->Append(", #glyphs=");
output->AppendNumber(num_glyphs_);
output->Append(", dir=");
output->AppendNumber(direction_);
output->Append(", runs[");
output->AppendNumber(runs_.size());
output->Append("]{");
for (unsigned run_index = 0; run_index < runs_.size(); run_index++) {
output->AppendNumber(run_index);
const auto& run = *runs_[run_index];
output->Append(":{start=");
output->AppendNumber(run.start_index_);
output->Append(", #chars=");
output->AppendNumber(run.num_characters_);
output->Append(", dir=");
output->AppendNumber(run.direction_);
output->Append(", glyphs[");
output->AppendNumber(run.glyph_data_.size());
output->Append("]{");
for (unsigned glyph_index = 0; glyph_index < run.glyph_data_.size();
glyph_index++) {
output->AppendNumber(glyph_index);
const auto& glyph_data = run.glyph_data_[glyph_index];
output->Append(":{char=");
output->AppendNumber(glyph_data.character_index);
output->Append(", glyph=");
output->AppendNumber(glyph_data.glyph);
output->Append("}");
}
output->Append("}}");
}
output->Append("}");
}
String ShapeResult::ToString() const {
StringBuilder output;
ToString(&output);
return output.ToString();
}
std::ostream& operator<<(std::ostream& ostream,
const ShapeResult& shape_result) {
return ostream << shape_result.ToString();
}
template <bool rtl>
void ShapeResult::ComputePositionData() const {
auto& data = character_position_->data_;
unsigned start_offset = StartIndexForResult();
unsigned next_character_index = 0;
float run_advance = 0;
// Iterate runs/glyphs in the visual order; i.e., from the left edge
// regardless of the directionality, so that |x_position| is always in
// ascending order.
// TODO(kojii): It does not work when large negative letter-/word-
// spacing is applied.
for (const auto& run : runs_) {
if (!run)
continue;
// Assumes all runs have the same directionality as the ShapeResult so that
// |x_position| is in ascending order.
DCHECK_EQ(Rtl(), run->Rtl());
float total_advance = run_advance;
for (const auto& glyph_data : run->glyph_data_) {
DCHECK_GE(run->start_index_, start_offset);
unsigned character_index =
run->start_index_ + glyph_data.character_index - start_offset;
// Make |character_index| to the visual offset.
DCHECK_LT(character_index, num_characters_);
if (rtl)
character_index = num_characters_ - character_index - 1;
// Multiple glyphs may have the same character index and not all character
// indices may have glyphs.
// For character indices without glyps set the x-position to that of the
// nearest preceding glyph.
for (unsigned i = next_character_index; i < character_index; i++) {
DCHECK_LT(i, num_characters_);
data[i] = {total_advance, false};
}
// For glyphs with the same character index the last logical one wins.
// This is the last visual one in LTR, no need to do anything speical.
// For glyphs with the same character index in LTR take the advance from
// the last one but the safe to break flag from the first.
DCHECK_LT(character_index, num_characters_);
bool safe_to_break =
next_character_index > character_index
? data[next_character_index - 1].safe_to_break_before
: glyph_data.safe_to_break_before;
data[character_index] = {total_advance, safe_to_break};
total_advance += glyph_data.advance;
next_character_index = character_index + 1;
}
run_advance += run->width_;
}
// Fill |x_position| for the rest of characters, when they don't have
// corresponding glyphs.
for (unsigned i = next_character_index; i < num_characters_; i++) {
data[i] = {run_advance, false};
}
character_position_->start_offset_ = start_offset;
}
void ShapeResult::EnsurePositionData() const {
if (character_position_)
return;
character_position_ =
std::make_unique<CharacterPositionData>(num_characters_, width_);
if (Direction() == TextDirection::kLtr)
ComputePositionData<false>();
else
ComputePositionData<true>();
}
unsigned ShapeResult::CachedOffsetForPosition(float x) const {
DCHECK(character_position_);
unsigned offset;
// At or before start, return offset *of* the first character.
// At or beyond the end, return offset *after* the last character.
if (!Rtl()) {
if (x <= 0) {
offset = 0;
} else if (x >= width_) {
offset = num_characters_;
} else {
offset = character_position_->OffsetForPosition(x);
DCHECK_LE(offset, num_characters_);
}
#if 0
// TODO(kojii): This DCHECK fails in ~10 tests. Needs investigations.
DCHECK_EQ(OffsetForPosition(x, BreakGlyphsOption::DontBreakGlyphs), offset);
#endif
} else {
if (x <= 0) {
offset = num_characters_;
} else if (x >= width_) {
offset = 0;
} else {
unsigned visual_offset = character_position_->OffsetForPosition(x);
DCHECK_LT(visual_offset, num_characters_);
if (visual_offset &&
x == character_position_->data_[visual_offset].x_position)
--visual_offset;
offset = num_characters_ - visual_offset - 1;
}
DCHECK_EQ(OffsetForPosition(x, BreakGlyphsOption::DontBreakGlyphs), offset);
}
return offset;
}
float ShapeResult::CachedPositionForOffset(unsigned offset) const {
DCHECK_GE(offset, 0u);
DCHECK_LE(offset, num_characters_);
DCHECK(character_position_);
float position;
if (!Rtl()) {
position = character_position_->PositionForOffset(offset);
#if 0
// TODO(kojii): This DCHECK fails in several tests. Needs investigations.
DCHECK_EQ(PositionForOffset(offset), position);
#endif
} else {
if (offset >= num_characters_) {
position = 0;
} else {
unsigned visual_offset = num_characters_ - offset;
position = character_position_->PositionForOffset(visual_offset);
}
#if DCHECK_IS_ON()
if (!offset && !runs_.back()->glyph_data_.IsEmpty() &&
runs_.back()->glyph_data_.front().character_index) {
// TODO(kojii): |PositionForOffset| incorrectly returns 0 if offset == 0
// and the glyph is missing.
} else {
DCHECK_EQ(PositionForOffset(offset), position);
}
#endif
}
return position;
}
unsigned ShapeResult::CachedNextSafeToBreakOffset(unsigned offset) const {
if (Rtl())
return NextSafeToBreakOffset(offset);
DCHECK(character_position_);
return character_position_->NextSafeToBreakOffset(offset);
}
unsigned ShapeResult::CachedPreviousSafeToBreakOffset(unsigned offset) const {
if (Rtl())
return PreviousSafeToBreakOffset(offset);
DCHECK(character_position_);
return character_position_->PreviousSafeToBreakOffset(offset);
}
// TODO(eae): Might be worth trying to set midpoint to ~50% more than the number
// of characters in the previous line for the first try. Would cut the number
// of tries in the majority of cases for long strings.
unsigned ShapeResult::CharacterPositionData::OffsetForPosition(float x) const {
// Caller should handle before-start and beyond-end because their results are
// not symmetric for LTR and RTL.
DCHECK_GT(x, 0);
DCHECK_LT(x, width_);
// Do a binary search to find the largest x-position that is less than or
// equal to the supplied x value.
unsigned length = data_.size();
unsigned low = 0;
unsigned high = length - 1;
while (low <= high) {
unsigned midpoint = low + (high - low) / 2;
if (data_[midpoint].x_position <= x &&
(midpoint + 1 == length || data_[midpoint + 1].x_position > x)) {
return midpoint;
}
if (x < data_[midpoint].x_position)
high = midpoint - 1;
else
low = midpoint + 1;
}
return 0;
}
float ShapeResult::CharacterPositionData::PositionForOffset(
unsigned offset) const {
DCHECK_GT(data_.size(), 0u);
if (offset >= data_.size())
return width_;
return data_[offset].x_position;
}
unsigned ShapeResult::CharacterPositionData::NextSafeToBreakOffset(
unsigned offset) const {
DCHECK_LE(start_offset_, offset);
unsigned adjusted_offset = offset - start_offset_;
DCHECK_LT(adjusted_offset, data_.size());
// Assume it is always safe to break at the start. While not strictly correct
// the text has already been segmented at that offset. This also matches the
// non-CharacterPositionData implementation.
if (adjusted_offset == 0)
return start_offset_;
unsigned length = data_.size();
for (unsigned i = adjusted_offset; i < length; i++) {
if (data_[i].safe_to_break_before)
return start_offset_ + i;
}
// Next safe break is at the end of the run.
return start_offset_ + length;
}
unsigned ShapeResult::CharacterPositionData::PreviousSafeToBreakOffset(
unsigned offset) const {
DCHECK_LE(start_offset_, offset);
unsigned adjusted_offset = offset - start_offset_;
DCHECK_LT(adjusted_offset, data_.size());
// Assume it is always safe to break at the end of the run.
if (adjusted_offset >= data_.size())
return start_offset_ + data_.size();
for (unsigned i = adjusted_offset + 1; i > 0; i--) {
if (data_[i - 1].safe_to_break_before)
return start_offset_ + (i - 1);
}
// Previous safe break is at the start of the run.
return 0;
}
} // namespace blink