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// Copyright 2014 The Chromium 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 <stddef.h>
#include <stdint.h>
#include <memory>
#include <string>
#include <vector>
#include "base/macros.h"
#include "third_party/icu/source/common/unicode/ubidi.h"
#include "third_party/icu/source/common/unicode/uscript.h"
#include "ui/gfx/render_text.h"
#include <hb.h>
namespace base {
namespace i18n {
class BreakIterator;
namespace gfx {
class Range;
class RangeF;
class RenderTextHarfBuzz;
namespace internal {
struct GFX_EXPORT TextRunHarfBuzz {
// Construct the run with |template_font| since determining the details of a
// default-constructed gfx::Font is expensive, but it will always be replaced.
explicit TextRunHarfBuzz(const Font& template_font);
// Returns the index of the first glyph that corresponds to the character at
// |pos|.
size_t CharToGlyph(size_t pos) const;
// Returns the corresponding glyph range of the given character range.
// |range| is in text-space (0 corresponds to |GetDisplayText()[0]|). Returned
// value is in run-space (0 corresponds to the first glyph in the run).
Range CharRangeToGlyphRange(const Range& range) const;
// Returns the number of missing glyphs in the shaped text run.
size_t CountMissingGlyphs() const;
// Writes the character and glyph ranges of the cluster containing |pos|.
void GetClusterAt(size_t pos, Range* chars, Range* glyphs) const;
// Returns the grapheme bounds at |text_index|. Handles multi-grapheme glyphs.
// Returned value is the horizontal pixel span in text-space (assumes all runs
// are on the same line). The returned range is never reversed.
RangeF GetGraphemeBounds(RenderTextHarfBuzz* render_text,
size_t text_index) const;
// Returns the horizontal span of the given |char_range| handling grapheme
// boundaries within glyphs. This is a wrapper around one or more calls to
// GetGraphemeBounds(), returning a range in the same coordinate space.
RangeF GetGraphemeSpanForCharRange(RenderTextHarfBuzz* render_text,
const Range& char_range) const;
// Returns the glyph width for the given character range. |char_range| is in
// text-space (0 corresponds to |GetDisplayText()[0]|).
SkScalar GetGlyphWidthForCharRange(const Range& char_range) const;
// Font parameters that may be common to multiple text runs within a text run
// list.
struct GFX_EXPORT FontParams {
// The default constructor for Font is expensive, so always require that a
// Font be provided.
explicit FontParams(const Font& template_font);
FontParams(const FontParams& other);
FontParams& operator=(const FontParams& other);
bool operator==(const FontParams& other) const;
// Populates |render_params|, |font_size| and |baseline_offset| based on
// |font|.
void ComputeRenderParamsFontSizeAndBaselineOffset();
// Populates |font|, |skia_face|, and |render_params|. Returns false if
// |skia_face| is nullptr. Takes |font|'s family name and rematches this
// family and the run's weight and style properties to find a new font.
bool SetRenderParamsRematchFont(const Font& font,
const FontRenderParams& render_params);
// Populates |font|, |skia_face|, and |render_params|. Returns false if
// |skia_face| is nullptr. Does not perform rematching but extracts an
// SkTypeface from the underlying PlatformFont of font. Use this method when
// configuring the |TextRunHarfBuzz| for shaping with fallback fonts, where
// it is important to keep the underlying font handle of platform font and
// not perform rematching as in |SetRenderParamsRematchFont|.
bool SetRenderParamsOverrideSkiaFaceFromFont(
const Font& font,
const FontRenderParams& render_params);
struct Hash {
size_t operator()(const FontParams& key) const;
Font font;
sk_sp<SkTypeface> skia_face;
FontRenderParams render_params;
Font::Weight weight = Font::Weight::NORMAL;
int font_size = 0;
int baseline_offset = 0;
int baseline_type = 0;
bool italic = false;
bool strike = false;
bool underline = false;
bool heavy_underline = false;
bool is_rtl = false;
UBiDiLevel level = 0;
UScriptCode script = USCRIPT_INVALID_CODE;
// Parameters that are set by ShapeRunWithFont.
struct GFX_EXPORT ShapeOutput {
ShapeOutput(const ShapeOutput& other);
ShapeOutput& operator=(const ShapeOutput& other);
ShapeOutput(ShapeOutput&& other);
ShapeOutput& operator=(ShapeOutput&& other);
float width = 0.0;
float preceding_run_widths = 0.0;
std::vector<uint16_t> glyphs;
std::vector<SkPoint> positions;
// Note that in the context of TextRunHarfBuzz, |glyph_to_char| is indexed
// based off of the full string (so it is in the same domain as
// TextRunHarfBuzz::range).
std::vector<uint32_t> glyph_to_char;
size_t glyph_count = 0;
size_t missing_glyph_count = std::numeric_limits<size_t>::max();
// If |new_shape.missing_glyph_count| is less than that of |shape|, set
// |font_params| and |shape| to the specified values.
void UpdateFontParamsAndShape(const FontParams& new_font_params,
const ShapeOutput& new_shape);
Range range;
FontParams font_params;
ShapeOutput shape;
float preceding_run_widths = 0.0;
// Manages the list of TextRunHarfBuzz and its logical <-> visual index mapping.
class TextRunList {
size_t size() const { return runs_.size(); }
// Converts the index between logical and visual index.
size_t visual_to_logical(size_t index) const {
return visual_to_logical_[index];
size_t logical_to_visual(size_t index) const {
return logical_to_visual_[index];
const std::vector<std::unique_ptr<TextRunHarfBuzz>>& runs() const {
return runs_;
// Adds the new |run| to the run list.
void Add(std::unique_ptr<TextRunHarfBuzz> run) {
// Reset the run list.
void Reset();
// Initialize the index mapping.
void InitIndexMap();
// Precomputes the offsets for all runs.
void ComputePrecedingRunWidths();
// Get the total width of runs, as if they were shown on one line.
// Do not use this when multiline is enabled.
float width() const { return width_; }
// Get the run index applicable to |position| (at or preceeding |position|).
size_t GetRunIndexAt(size_t position) const;
// Text runs in logical order.
std::vector<std::unique_ptr<TextRunHarfBuzz>> runs_;
// Maps visual run indices to logical run indices and vice versa.
std::vector<int32_t> visual_to_logical_;
std::vector<int32_t> logical_to_visual_;
float width_;
} // namespace internal
class GFX_EXPORT RenderTextHarfBuzz : public RenderText {
~RenderTextHarfBuzz() override;
// RenderText:
const base::string16& GetDisplayText() override;
Size GetStringSize() override;
SizeF GetStringSizeF() override;
Size GetLineSize(const SelectionModel& caret) override;
float TotalLineWidth() override;
SelectionModel FindCursorPosition(const Point& point,
const Point& drag_origin) override;
bool IsSelectionSupported() const override;
std::vector<Rect> GetSubstringBounds(const Range& range) override;
RangeF GetCursorSpan(const Range& text_range) override;
size_t GetLineContainingCaret(const SelectionModel& caret) override;
// ICU grapheme iterator for the layout text. Can be null in case of an error.
base::i18n::BreakIterator* GetGraphemeIterator();
// RenderText:
int GetDisplayTextBaseline() override;
SelectionModel AdjacentCharSelectionModel(
const SelectionModel& selection,
VisualCursorDirection direction) override;
SelectionModel AdjacentWordSelectionModel(
const SelectionModel& selection,
VisualCursorDirection direction) override;
SelectionModel AdjacentLineSelectionModel(
const SelectionModel& selection,
VisualCursorDirection direction) override;
bool IsValidCursorIndex(size_t index) override;
void OnLayoutTextAttributeChanged(bool text_changed) override;
void OnDisplayTextAttributeChanged() override;
void EnsureLayout() override;
void DrawVisualText(internal::SkiaTextRenderer* renderer,
const Range& selection) override;
friend class test::RenderTextTestApi;
friend class RenderTextTest;
// Return the run index that contains the argument; or the length of the
// |runs_| vector if argument exceeds the text length or width.
size_t GetRunContainingCaret(const SelectionModel& caret);
// Given a |run|, returns the SelectionModel that contains the logical first
// or last caret position inside (not at a boundary of) the run.
// The returned value represents a cursor/caret position without a selection.
SelectionModel FirstSelectionModelInsideRun(
const internal::TextRunHarfBuzz* run);
SelectionModel LastSelectionModelInsideRun(
const internal::TextRunHarfBuzz* run);
using CommonizedRunsMap =
// Break the text into logical runs in |out_run_list|. Populate
// |out_commonized_run_map| such that each run is present in the vector
// corresponding to its FontParams.
void ItemizeTextToRuns(const base::string16& string,
internal::TextRunList* out_run_list,
CommonizedRunsMap* out_commonized_run_map);
// Shape the glyphs needed for each run in |runs| within |text|. This method
// will apply a number of fonts to |base_font_params| and assign to each
// run's FontParams and ShapeOutput the parameters and resulting shape that
// had the smallest number of missing glyphs.
void ShapeRuns(const base::string16& text,
const internal::TextRunHarfBuzz::FontParams& base_font_params,
std::vector<internal::TextRunHarfBuzz*> runs);
// Shape the glyphs for |in_out_runs| within |text| using the parameters
// specified by |font_params|. If, for any run in |*in_out_runs|, the
// resulting shaping has fewer missing glyphs than the existing shape, then
// write |font_params| and the resulting ShapeOutput to that run. Remove all
// runs with no missing glyphs from |in_out_runs| (the caller, ShapeRuns, will
// terminate when no runs with missing glyphs remain).
void ShapeRunsWithFont(
const base::string16& text,
const internal::TextRunHarfBuzz::FontParams& font_params,
std::vector<internal::TextRunHarfBuzz*>* in_out_runs);
// Itemize |text| into runs in |out_run_list|, shape the runs, and populate
// |out_run_list|'s visual <-> logical maps.
void ItemizeAndShapeText(const base::string16& text,
internal::TextRunList* out_run_list);
// Makes sure that text runs for layout text are shaped.
void EnsureLayoutRunList();
// RenderText:
internal::TextRunList* GetRunList() override;
const internal::TextRunList* GetRunList() const override;
bool GetDecoratedTextForRange(const Range& range,
DecoratedText* decorated_text) override;
// Text run list for |layout_text_| and |display_text_|.
// |display_run_list_| is created only when the text is elided.
internal::TextRunList layout_run_list_;
std::unique_ptr<internal::TextRunList> display_run_list_;
bool update_layout_run_list_ : 1;
bool update_display_run_list_ : 1;
bool update_grapheme_iterator_ : 1;
bool update_display_text_ : 1;
// ICU grapheme iterator for the layout text. Use GetGraphemeIterator()
// to access the iterator.
std::unique_ptr<base::i18n::BreakIterator> grapheme_iterator_;
// The total size of the layouted text.
SizeF total_size_;
// The process application locale used to configure text rendering.
std::string locale_;
} // namespace gfx