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// Copyright (c) 2012 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 <algorithm>
#include <array>
#include <cstring>
#include <memory>
#include <string>
#include <utility>
#include <vector>
#include "base/i18n/rtl.h"
#include "base/macros.h"
#include "base/strings/string16.h"
#include "cc/paint/paint_canvas.h"
#include "cc/paint/paint_flags.h"
#include "third_party/skia/include/core/SkColor.h"
#include "third_party/skia/include/core/SkFont.h"
#include "third_party/skia/include/core/SkRefCnt.h"
#include "ui/gfx/break_list.h"
#include "ui/gfx/font_list.h"
#include "ui/gfx/font_render_params.h"
#include "ui/gfx/geometry/point.h"
#include "ui/gfx/geometry/rect.h"
#include "ui/gfx/geometry/rect_f.h"
#include "ui/gfx/geometry/size_f.h"
#include "ui/gfx/geometry/vector2d.h"
#include "ui/gfx/range/range.h"
#include "ui/gfx/range/range_f.h"
#include "ui/gfx/selection_model.h"
#include "ui/gfx/shadow_value.h"
#include "ui/gfx/text_constants.h"
class SkDrawLooper;
struct SkPoint;
class SkTypeface;
namespace gfx {
namespace test {
class RenderTextTestApi;
class Canvas;
struct DecoratedText;
class Font;
namespace internal {
class TextRunList;
// Internal helper class used by derived classes to draw text through Skia.
class GFX_EXPORT SkiaTextRenderer {
explicit SkiaTextRenderer(Canvas* canvas);
virtual ~SkiaTextRenderer();
void SetDrawLooper(sk_sp<SkDrawLooper> draw_looper);
void SetFontRenderParams(const FontRenderParams& params,
bool subpixel_rendering_suppressed);
void SetTypeface(sk_sp<SkTypeface> typeface);
void SetTextSize(SkScalar size);
void SetForegroundColor(SkColor foreground);
void SetShader(sk_sp<cc::PaintShader> shader);
// TODO(vmpstr): Change this API to mimic SkCanvas::drawTextBlob instead.
virtual void DrawPosText(const SkPoint* pos,
const uint16_t* glyphs,
size_t glyph_count);
void DrawUnderline(int x, int y, int width, SkScalar thickness_factor = 1.0);
void DrawStrike(int x, int y, int width, SkScalar thickness_factor);
friend class test::RenderTextTestApi;
Canvas* canvas_;
cc::PaintCanvas* canvas_skia_;
cc::PaintFlags flags_;
SkFont font_;
struct TextToDisplayIndex {
size_t text_index = 0;
size_t display_index = 0;
using TextToDisplaySequence = std::vector<TextToDisplayIndex>;
using GraphemeIterator = TextToDisplaySequence::const_iterator;
using StyleArray = std::array<BreakList<bool>, TEXT_STYLE_COUNT>;
// Internal helper class used to iterate colors, baselines, and styles.
class StyleIterator {
StyleIterator(const BreakList<SkColor>* colors,
const BreakList<BaselineStyle>* baselines,
const BreakList<int>* font_size_overrides,
const BreakList<Font::Weight>* weights,
const StyleArray* styles);
StyleIterator(const StyleIterator& style);
StyleIterator& operator=(const StyleIterator& style);
// Get the colors and styles at the current iterator position.
SkColor color() const { return color_->second; }
BaselineStyle baseline() const { return baseline_->second; }
int font_size_override() const { return font_size_override_->second; }
bool style(TextStyle s) const { return style_[s]->second; }
Font::Weight weight() const { return weight_->second; }
// Get the intersecting range of the current iterator set.
Range GetRange() const;
// Get the intersecting range of the current iterator set for attributes that
// can break text (e.g. not color).
Range GetTextBreakingRange() const;
// Update the iterator to point to colors and styles applicable at |position|.
void IncrementToPosition(size_t position);
// Pointers to the breaklists to iterate through. These pointers can't be
// nullptr and the breaklists must outlive this object.
const BreakList<SkColor>* colors_;
const BreakList<BaselineStyle>* baselines_;
const BreakList<int>* font_size_overrides_;
const BreakList<Font::Weight>* weights_;
const StyleArray* styles_;
BreakList<SkColor>::const_iterator color_;
BreakList<BaselineStyle>::const_iterator baseline_;
BreakList<int>::const_iterator font_size_override_;
BreakList<Font::Weight>::const_iterator weight_;
std::array<BreakList<bool>::const_iterator, TEXT_STYLE_COUNT> style_;
// Line segments are slices of the display text to be rendered on a single line.
struct LineSegment {
// X coordinates of this line segment in text space.
RangeF x_range;
// The character range this segment corresponds to.
Range char_range;
// Index of the text run that generated this segment.
size_t run;
// Returns the width of this line segment in text space.
float width() const { return x_range.length(); }
// A line of display text, comprised of a line segment list and some metrics.
struct Line {
Line(const Line& other);
// Segments that make up this line in visual order.
std::vector<LineSegment> segments;
// The sum of segment widths and the maximum of segment heights.
SizeF size;
// Sum of preceding lines' heights.
int preceding_heights;
// Maximum baseline of all segments on this line.
int baseline;
// The text index of this line in |text_|.
int display_text_index = 0;
// Internal class that contains the results of the text layout and shaping.
class ShapedText {
explicit ShapedText(std::vector<Line> lines);
const std::vector<Line>& lines() const { return lines_; }
std::vector<Line> lines_;
// Creates an SkTypeface from a font, |italic| and a desired |weight|.
// May return null.
sk_sp<SkTypeface> CreateSkiaTypeface(const Font& font,
bool italic,
Font::Weight weight);
// Applies the given FontRenderParams to the SkFont.
void ApplyRenderParams(const FontRenderParams& params,
bool subpixel_rendering_suppressed,
SkFont* font);
} // namespace internal
// RenderText represents an abstract model of styled text and its corresponding
// visual layout. Support is built in for a cursor, selections, simple styling,
// complex scripts, and bi-directional text. Implementations provide mechanisms
// for rendering and translation between logical and visual data.
class GFX_EXPORT RenderText {
#if defined(OS_APPLE)
// On Mac, while selecting text if the cursor is outside the vertical text
// bounds, drag to the end of the text.
static constexpr bool kDragToEndIfOutsideVerticalBounds = true;
// Mac supports a selection that is "undirected". When undirected, the cursor
// doesn't know which end of the selection it's at until it first moves.
static constexpr bool kSelectionIsAlwaysDirected = false;
static constexpr bool kDragToEndIfOutsideVerticalBounds = false;
static constexpr bool kSelectionIsAlwaysDirected = true;
// Default color used for the text and cursor.
static constexpr SkColor kDefaultColor = SK_ColorBLACK;
// Default color used for drawing selection background.
static constexpr SkColor kDefaultSelectionBackgroundColor = SK_ColorGRAY;
// Invalid value of baseline. Assigning this value to |baseline_| causes
// re-calculation of baseline.
static constexpr int kInvalidBaseline = INT_MAX;
// Default fraction of the text size to use for a strike-through or underline.
static constexpr SkScalar kLineThicknessFactor = (SK_Scalar1 / 18);
// The character used for displaying obscured text. Use a bullet character.
// TODO(pbos): This is highly font dependent, consider replacing the character
// with a vector glyph.
static constexpr base::char16 kPasswordReplacementChar = 0x2022;
virtual ~RenderText();
// Creates a RenderText instance.
static std::unique_ptr<RenderText> CreateRenderText();
// Like above but copies all style settings too.
std::unique_ptr<RenderText> CreateInstanceOfSameStyle(
const base::string16& text) const;
const base::string16& text() const { return text_; }
void SetText(const base::string16& text);
void AppendText(const base::string16& text);
HorizontalAlignment horizontal_alignment() const {
return horizontal_alignment_;
void SetHorizontalAlignment(HorizontalAlignment alignment);
VerticalAlignment vertical_alignment() const { return vertical_alignment_; }
void SetVerticalAlignment(VerticalAlignment alignment);
const FontList& font_list() const { return font_list_; }
void SetFontList(const FontList& font_list);
bool cursor_enabled() const { return cursor_enabled_; }
void SetCursorEnabled(bool cursor_enabled);
SkColor selection_color() const { return selection_color_; }
void set_selection_color(SkColor color) { selection_color_ = color; }
SkColor selection_background_focused_color() const {
return selection_background_focused_color_;
void set_selection_background_focused_color(SkColor color) {
selection_background_focused_color_ = color;
bool symmetric_selection_visual_bounds() const {
return symmetric_selection_visual_bounds_;
void set_symmetric_selection_visual_bounds(bool symmetric) {
symmetric_selection_visual_bounds_ = symmetric;
bool focused() const { return focused_; }
void set_focused(bool focused) { focused_ = focused; }
bool clip_to_display_rect() const { return clip_to_display_rect_; }
void set_clip_to_display_rect(bool clip) { clip_to_display_rect_ = clip; }
// In an obscured (password) field, all text is drawn as bullets.
bool obscured() const { return obscured_; }
void SetObscured(bool obscured);
// Makes a char in obscured text at |index| to be revealed. |index| should be
// a UTF16 text index. If there is a previous revealed index, the previous one
// is cleared and only the last set index will be revealed. If |index| is -1
// or out of range, no char will be revealed. The revealed index is also
// cleared when SetText or SetObscured is called.
void SetObscuredRevealIndex(int index);
// For obscured (password) fields, the extra spacing between glyphs.
int obscured_glyph_spacing() const { return obscured_glyph_spacing_; }
void SetObscuredGlyphSpacing(int spacing);
bool multiline() const { return multiline_; }
void SetMultiline(bool multiline);
// If multiline, a non-zero value will cap the number of lines rendered,
// and elide the rest (currently only ELIDE_TAIL supported.)
void SetMaxLines(size_t max_lines);
size_t max_lines() const { return max_lines_; }
// Returns the actual number of lines, broken by |lines_|.
size_t GetNumLines();
// Returns the text index of the given line |line|. Returns the text length
// for any |line| above the number of lines.
size_t GetTextIndexOfLine(size_t line);
// TODO(mukai): ELIDE_LONG_WORDS is not supported.
WordWrapBehavior word_wrap_behavior() const { return word_wrap_behavior_; }
void SetWordWrapBehavior(WordWrapBehavior behavior);
// TODO(ckocagil): Add vertical alignment and line spacing support instead.
int min_line_height() const { return min_line_height_; }
void SetMinLineHeight(int line_height);
// Set the maximum length of the layout text, not the actual text.
// A |length| of 0 forgoes a hard limit, but does not guarantee proper
// functionality of very long strings. Applies to subsequent SetText calls.
// WARNING: Only use this for system limits, it lacks complex text support.
void set_truncate_length(size_t length) { truncate_length_ = length; }
// The display text will be elided to fit |display_rect| using this behavior.
void SetElideBehavior(ElideBehavior elide_behavior);
ElideBehavior elide_behavior() const { return elide_behavior_; }
// When display text is elided, determines how whitespace is handled.
// If base::nullopt is specified, the default elision for the current elide
// behavior will be applied.
void SetWhitespaceElision(base::Optional<bool> elide_whitespace);
base::Optional<bool> whitespace_elision() const {
return whitespace_elision_;
const Rect& display_rect() const { return display_rect_; }
void SetDisplayRect(const Rect& r);
bool subpixel_rendering_suppressed() const {
return subpixel_rendering_suppressed_;
void set_subpixel_rendering_suppressed(bool suppressed) {
subpixel_rendering_suppressed_ = suppressed;
const SelectionModel& selection_model() const { return selection_model_; }
const Range& selection() const { return selection_model_.selection(); }
size_t cursor_position() const { return selection_model_.caret_pos(); }
const std::vector<Range>& secondary_selections() const {
return selection_model_.secondary_selections();
const std::vector<Range> GetAllSelections() const;
// Set the cursor to |position|, with the caret affinity trailing the previous
// grapheme, or if there is no previous grapheme, leading the cursor position.
// See SelectionModel::caret_affinity_ for details.
void SetCursorPosition(size_t position);
// Moves the cursor left or right. Cursor movement is visual, meaning that
// left and right are relative to screen, not the directionality of the text.
// |selection_behavior| determines whether a selection is to be made and it's
// behavior.
void MoveCursor(BreakType break_type,
VisualCursorDirection direction,
SelectionBehavior selection_behavior);
// Set the selection_model_ to the value of |selection|.
// The selection range is clamped to text().length() if out of range.
// Returns true if the cursor position or selection range changed.
// If any index in |selection_model| is not a cursorable position (not on a
// grapheme boundary), it is a no-op and returns false.
bool SetSelection(const SelectionModel& selection);
// Moves the cursor to the text index corresponding to |point|. If |select| is
// true, a selection is made with the current selection start index. If the
// resultant text indices do not lie on valid grapheme boundaries, it is a no-
// op and returns false. If this move is happening because of a drag causing a
// selection change, and |drag_origin| is not the zero point, then
// |drag_origin| overrides the default origin for a select-to-drag
// (usually the existing text insertion cursor).
bool MoveCursorToPoint(const gfx::Point& point,
bool select,
const gfx::Point& drag_origin = gfx::Point());
// Set the |selection_model_| based on |range|. If the |range| start or end is
// greater than text length, it is modified to be the text length. If the
// |range| start or end is not a cursorable position (not on grapheme
// boundary), it is a NO-OP and returns false. Otherwise, returns true. If
// |primary| is true, secondary selections are cleared; otherwise, the range
// will be added as a secondary selection not associated with the cursor. In
// the latter case, |range| should not overlap with existing selections.
bool SelectRange(const Range& range, bool primary = true);
// Returns true if the local point is over selected text.
bool IsPointInSelection(const Point& point);
// Selects no text, keeping the current cursor position and caret affinity.
void ClearSelection();
// Select the entire text range. If |reversed| is true, the range will end at
// the logical beginning of the text; this generally shows the leading portion
// of text that overflows its display area.
void SelectAll(bool reversed);
// Selects the word at the current cursor position. If there is a non-empty
// selection, the selection bounds are extended to their nearest word
// boundaries.
void SelectWord();
void SetCompositionRange(const Range& composition_range);
// Set the text color over the entire text or a logical character range.
// The |range| should be valid, non-reversed, and within [0, text().length()].
void SetColor(SkColor value);
void ApplyColor(SkColor value, const Range& range);
// Set the baseline style over the entire text or a logical character range.
// The |range| should be valid, non-reversed, and within [0, text().length()].
// TODO(tapted): Remove this. The only client is moving to
// ApplyFontSizeOverride.
void SetBaselineStyle(BaselineStyle value);
void ApplyBaselineStyle(BaselineStyle value, const Range& range);
// Alters the font size in |range|.
void ApplyFontSizeOverride(int font_size_override, const Range& range);
// Set various text styles over the entire text or a logical character range.
// The respective |style| is applied if |value| is true, or removed if false.
// The |range| should be valid, non-reversed, and within [0, text().length()].
void SetStyle(TextStyle style, bool value);
void ApplyStyle(TextStyle style, bool value, const Range& range);
void SetWeight(Font::Weight weight);
void ApplyWeight(Font::Weight weight, const Range& range);
// Returns whether this style is enabled consistently across the entire
// RenderText.
bool GetStyle(TextStyle style) const;
// Set or get the text directionality mode and get the text direction yielded.
void SetDirectionalityMode(DirectionalityMode mode);
DirectionalityMode directionality_mode() const {
return directionality_mode_;
base::i18n::TextDirection GetTextDirection() const;
base::i18n::TextDirection GetDisplayTextDirection();
// Returns the visual movement direction corresponding to the logical
// end/beginning of the text, considering only the dominant direction returned
// by |GetDisplayTextDirection()|, not the direction of a particular run.
VisualCursorDirection GetVisualDirectionOfLogicalEnd();
VisualCursorDirection GetVisualDirectionOfLogicalBeginning();
// Returns the text used to display, which may be obscured, truncated or
// elided. The subclass may compute elided text on the fly, or use
// precomputed the elided text.
virtual const base::string16& GetDisplayText() = 0;
// Returns the size required to display the current string (which is the
// wrapped size in multiline mode). The returned size does not include space
// reserved for the cursor or the offset text shadows.
Size GetStringSize();
// This is same as GetStringSize except that fractional size is returned.
// The default implementation is same as GetStringSize. Certain platforms that
// compute the text size as floating-point values, like Mac, will override
// this method.
// See comment in Canvas::GetStringWidthF for its usage.
virtual SizeF GetStringSizeF() = 0;
// Returns the size of the line containing |caret|.
virtual SizeF GetLineSizeF(const SelectionModel& caret) = 0;
// Returns the sum of all the line widths.
float TotalLineWidth();
// Returns the width of the content (which is the wrapped width in multiline
// mode). Reserves room for the cursor if |cursor_enabled_| is true.
float GetContentWidthF();
// Same as GetContentWidthF with the width rounded up.
int GetContentWidth();
// Returns the common baseline of the text. The return value is the vertical
// offset from the top of |display_rect_| to the text baseline, in pixels.
// The baseline is determined from the font list and display rect, and does
// not depend on the text.
int GetBaseline();
// If |select_all| is true, draws as focused with all text selected.
void Draw(Canvas* canvas, bool select_all = false);
// Gets the SelectionModel from a visual point in local coordinates. If
// |drag_origin| is nonzero, it is used as the baseline for
// out-of-vertical-bounds drags on platforms that have them, instead of the
// default origin (the insertion cursor's position).
SelectionModel FindCursorPosition(const Point& point,
const Point& drag_origin = gfx::Point());
// Returns true if the position is a valid logical index into text(). Indices
// amid multi-character graphemes are allowed here, unlike IsValidCursorIndex.
bool IsValidLogicalIndex(size_t index) const;
// Returns true if the position is a valid logical index into text(), and is
// also a valid grapheme boundary, which may be used as a cursor position.
bool IsValidCursorIndex(size_t index) const;
// Get the visual bounds of a cursor at |caret|. These bounds typically
// represent a vertical line if |insert_mode| is true. Pass false for
// |insert_mode| to retrieve the bounds of the associated glyph. These bounds
// are in local coordinates, but may be outside the visible region if the text
// is longer than the textfield. Subsequent text, cursor, or bounds changes
// may invalidate returned values. Note that |caret| must be placed at
// grapheme boundary, i.e. caret.caret_pos() must be a cursorable position.
// TODO( Add multiline support.
Rect GetCursorBounds(const SelectionModel& caret, bool insert_mode);
// Compute the current cursor bounds, panning the text to show the cursor in
// the display rect if necessary. These bounds are in local coordinates.
// Subsequent text, cursor, or bounds changes may invalidate returned values.
const Rect& GetUpdatedCursorBounds();
// Returns a grapheme iterator that contains the codepoint at |index|.
internal::GraphemeIterator GetGraphemeIteratorAtTextIndex(size_t index) const;
internal::GraphemeIterator GetGraphemeIteratorAtDisplayTextIndex(
size_t index) const;
// For a given grapheme iterator, returns its index.
size_t GetTextIndex(internal::GraphemeIterator iter) const;
size_t GetDisplayTextIndex(internal::GraphemeIterator iter) const;
// Returns true of the current index is at the start of a grapheme.
bool IsGraphemeBoundary(size_t index) const;
// Given an |index| in text(), return the next or previous grapheme boundary
// in logical order (i.e. the nearest cursorable index). The return value is
// in the range 0 to text().length() inclusive (the input is clamped if it is
// out of that range). Always moves by at least one character index unless the
// supplied index is already at the boundary of the string.
size_t IndexOfAdjacentGrapheme(size_t index,
LogicalCursorDirection direction) const;
// Return a SelectionModel with the cursor at the current selection's start.
// The returned value represents a cursor/caret position without a selection.
SelectionModel GetSelectionModelForSelectionStart() const;
// Sets shadows to drawn with text.
void set_shadows(const ShadowValues& shadows) { shadows_ = shadows; }
const ShadowValues& shadows() const { return shadows_; }
// Get the visual bounds containing the logical substring within the |range|.
// If |range| is empty, the result is empty. This method rounds internally so
// the returned bounds may be slightly larger than the |range|, but are
// guaranteed not to be smaller. These bounds could be visually discontinuous
// if the substring is split by a LTR/RTL level change. These bounds are in
// local coordinates, but may be outside the visible region if the text is
// larger than the available space. Subsequent text, cursor, or bounds changes
// may invalidate returned values.
virtual std::vector<Rect> GetSubstringBounds(const Range& range) = 0;
// Gets the horizontal span (relative to the left of the text, not the view)
// of the sequence of glyphs in |text_range|, over which the cursor will
// jump when breaking by characters. If the glyphs are RTL then the returned
// Range will have is_reversed() true. (This does not return a Rect because a
// Rect can't have a negative width.)
virtual RangeF GetCursorSpan(const Range& text_range) = 0;
const Vector2d& GetUpdatedDisplayOffset();
void SetDisplayOffset(int horizontal_offset);
// Returns the line offset from the origin after applying the text alignment
// and the display offset.
Vector2d GetLineOffset(size_t line_number);
// Retrieves the word displayed at the given |point| along with its styling
// information. |point| is in the view's coordinates. If no word is displayed
// at the point, returns a nearby word. |baseline_point| should correspond to
// the baseline point of the leftmost glyph of the |word| in the view's
// coordinates. Returns false, if no word can be retrieved.
bool GetWordLookupDataAtPoint(const Point& point,
DecoratedText* decorated_word,
Point* baseline_point);
// Retrieves the text at |range| along with its styling information.
// |baseline_point| should correspond to the baseline point of
// the leftmost glyph of the text in the view's coordinates. If the text
// spans multiple lines, |baseline_point| will correspond with the leftmost
// glyph on the first line in the range. Returns false, if no text can be
// retrieved.
bool GetLookupDataForRange(const Range& range,
DecoratedText* decorated_text,
Point* baseline_point);
// Retrieves the text in the given |range|.
base::string16 GetTextFromRange(const Range& range) const;
void set_strike_thickness_factor(SkScalar f) { strike_thickness_factor_ = f; }
// Return the line index that contains the argument; or the index of the last
// line if the |caret| exceeds the text length.
virtual size_t GetLineContainingCaret(const SelectionModel& caret) = 0;
// Expands |range| to its nearest grapheme boundaries and returns the
// resulting range. Maintains directionality of |range|.
Range ExpandRangeToGraphemeBoundary(const Range& range) const;
// Whether |segment| corresponds to the newline character. This uses |text_|
// to look up the corresponding character.
bool IsNewlineSegment(const internal::LineSegment& segment) const;
// Whether |segment| corresponds to the newline character inside |text|.
bool IsNewlineSegment(const base::string16& text,
const internal::LineSegment& segment) const;
// Returns the character range of segments in |line| excluding the trailing
// newline segment.
Range GetLineRange(const base::string16& text,
const internal::Line& line) const;
// Returns the text used for layout (e.g. after rewriting, eliding and
// obscuring characters).
const base::string16& GetLayoutText() const;
// NOTE: The value of these accessors may be stale. Please make sure
// that these fields are up to date before accessing them.
const base::string16& display_text() const { return display_text_; }
bool text_elided() const { return text_elided_; }
// Returns an iterator over the |text_| attributes.
internal::StyleIterator GetTextStyleIterator() const;
// Returns an iterator over the |layout_text_| attributes.
internal::StyleIterator GetLayoutTextStyleIterator() const;
const BreakList<SkColor>& colors() const { return colors_; }
const BreakList<BaselineStyle>& baselines() const { return baselines_; }
const BreakList<int>& font_size_overrides() const {
return font_size_overrides_;
const BreakList<Font::Weight>& weights() const { return weights_; }
const internal::StyleArray& styles() const { return styles_; }
SkScalar strike_thickness_factor() const { return strike_thickness_factor_; }
const BreakList<SkColor>& layout_colors() const { return layout_colors_; }
// Whether all the BreakLists have only one break.
bool IsHomogeneous() const;
// Returns the shaped text structure. The shaped text contains the visual
// positions of glyphs required to render the text.
bool has_shaped_text() const { return shaped_text_ != nullptr; }
internal::ShapedText* GetShapedText();
void set_shaped_text(std::unique_ptr<internal::ShapedText> shaped_text) {
shaped_text_ = std::move(shaped_text);
// Returns the baseline of the current text. The return value depends on
// the text and its layout while the return value of GetBaseline() doesn't.
// GetAlignmentOffset() takes into account the difference between them.
// We'd like a RenderText to show the text always on the same baseline
// regardless of the text, so the text does not jump up or down depending
// on the text. However, underlying layout engines return different baselines
// depending on the text. In general, layout engines determine the minimum
// bounding box for the text and return the baseline from the top of the
// bounding box. So the baseline changes depending on font metrics used to
// layout the text.
// For example, suppose there are FontA and FontB and the baseline of FontA
// is smaller than the one of FontB. If the text is laid out only with FontA,
// then the baseline of FontA may be returned. If the text includes some
// characters which are laid out with FontB, then the baseline of FontB may
// be returned.
// GetBaseline() returns the fixed baseline regardless of the text.
// GetDisplayTextBaseline() returns the baseline determined by the underlying
// layout engine, and it changes depending on the text. GetAlignmentOffset()
// returns the difference between them.
int GetDisplayTextBaseline();
// Get the selection model that visually neighbors |position| by |break_type|.
// The returned value represents a cursor/caret position without a selection.
SelectionModel GetAdjacentSelectionModel(const SelectionModel& current,
BreakType break_type,
VisualCursorDirection direction);
// Get the selection model visually left/right of |selection| by one grapheme.
// The returned value represents a cursor/caret position without a selection.
virtual SelectionModel AdjacentCharSelectionModel(
const SelectionModel& selection,
VisualCursorDirection direction) = 0;
// Get the selection model visually left/right of |selection| by one word.
// The returned value represents a cursor/caret position without a selection.
virtual SelectionModel AdjacentWordSelectionModel(
const SelectionModel& selection,
VisualCursorDirection direction) = 0;
// Get the selection model visually above/below |selection| by one line.
// The returned value represents a cursor/caret position without a selection.
virtual SelectionModel AdjacentLineSelectionModel(
const SelectionModel& selection,
VisualCursorDirection direction) = 0;
// Get the selection model corresponding to visual text ends.
// The returned value represents a cursor/caret position without a selection.
SelectionModel EdgeSelectionModel(VisualCursorDirection direction);
// Get the selection model corresponding to visual text ends for |line_index|.
// The returned value represents a cursor/caret position without a selection.
SelectionModel LineSelectionModel(size_t line_index,
gfx::VisualCursorDirection direction);
// Sets the selection model. |model| should be valid.
void SetSelectionModel(const SelectionModel& model);
// Adds a secondary selection. |selection| should not overlap with existing
// selections.
void AddSecondarySelection(const Range selection);
// Convert between indices into |text_| and indices into
// GetDisplayText(), which differ when the text is obscured,
// truncated or elided.
size_t TextIndexToDisplayIndex(size_t index) const;
size_t DisplayIndexToTextIndex(size_t index) const;
// Notifies that layout text, or attributes that affect the layout text
// shape have changed. |text_changed| is true if the content of the
// |layout_text_| has changed, not just attributes.
virtual void OnLayoutTextAttributeChanged(bool text_changed);
// Notifies that attributes that affect the display text shape have changed.
virtual void OnDisplayTextAttributeChanged() = 0;
// Ensure the text is laid out, lines are computed, and |lines_| is valid.
virtual void EnsureLayout() = 0;
// Draw all text and make the given ranges appear selected.
virtual void DrawVisualText(internal::SkiaTextRenderer* renderer,
const std::vector<Range>& selections) = 0;
// Update the display text.
void UpdateDisplayText(float text_width);
// Returns display text positions that are suitable for breaking lines.
const BreakList<size_t>& GetLineBreaks();
// Convert points from the text space to the view space. Handles the display
// area, display offset, application LTR/RTL mode and multiline.
Point ToViewPoint(const PointF& point, LogicalCursorDirection caret_affinity);
// Get the alignment, resolving ALIGN_TO_HEAD with the current text direction.
HorizontalAlignment GetCurrentHorizontalAlignment();
// Returns the line offset from the origin, accounts for text alignment only.
Vector2d GetAlignmentOffset(size_t line_number);
// Applies fade effects to |renderer|.
void ApplyFadeEffects(internal::SkiaTextRenderer* renderer);
// Applies text shadows to |renderer|.
void ApplyTextShadows(internal::SkiaTextRenderer* renderer);
// Get the text direction for the current directionality mode and given
// |text|.
base::i18n::TextDirection GetTextDirectionForGivenText(
const base::string16& text) const;
// Adjust ranged styles to accommodate a new |text_| length.
void UpdateStyleLengths();
// Adjust ranged styles to accommodate a new |layout_text_| length.
void UpdateLayoutStyleLengths(size_t max_length) const;
// Returns the line index for the given argument. |text_y| is relative to
// the text bounds. Returns -1 if |text_y| is above the text and
// lines().size() if |text_y| is below it.
int GetLineContainingYCoord(float text_y);
// A convenience function to check whether the glyph attached to the caret
// is within the given range.
static bool RangeContainsCaret(const Range& range,
size_t caret_pos,
LogicalCursorDirection caret_affinity);
// Returns the baseline, with which the text best appears vertically centered.
static int DetermineBaselineCenteringText(const int display_height,
const FontList& font_list);
// Returns an expanded version of |rect| that is vertically symmetric with
// respect to the center of |display_rect|.
static gfx::Rect ExpandToBeVerticallySymmetric(const gfx::Rect& rect,
const gfx::Rect& display_rect);
// Given |rects|, sort them along the x-axis and merge intersecting rects
// using union. Expects all selections in the text to be from the same line.
static void MergeIntersectingRects(std::vector<Rect>& rects);
// Resets |cached_cursor_x_| to null. When non-null, CURSOR_UP, CURSOR_DOWN
// movements use this value instead of the current cursor x position to
// determine the next cursor x position.
void reset_cached_cursor_x() { cached_cursor_x_.reset(); }
void set_cached_cursor_x(int x) { cached_cursor_x_ = x; }
base::Optional<int> cached_cursor_x() const { return cached_cursor_x_; }
// Fixed width of glyphs. This should only be set in test environments.
float glyph_width_for_test_ = 0;
// Fixed height of glyphs. This should only be set in test environments.
float glyph_height_for_test_ = 0;
friend class test::RenderTextTestApi;
// Resets |layout_text_| and |display_text_| and marks them dirty.
void OnTextAttributeChanged();
// Computes the |layout_text_| by rewriting it from |text_|, if needed.
// Computes the layout break lists, if needed.
void EnsureLayoutTextUpdated() const;
// Elides |text| as needed to fit in the |available_width| using |behavior|.
// |text_width| is the pre-calculated width of the text shaped by this render
// text, or pass 0 if the width is unknown.
base::string16 Elide(const base::string16& text,
float text_width,
float available_width,
ElideBehavior behavior);
// Elides |email| as needed to fit the |available_width|.
base::string16 ElideEmail(const base::string16& email, float available_width);
// Update the cached bounds and display offset to ensure that the current
// cursor is within the visible display area.
void UpdateCachedBoundsAndOffset();
// Draws the specified ranges of text with a selected appearance.
void DrawSelections(Canvas* canvas, const std::vector<Range>& selections);
// Returns a grapheme iterator that contains the codepoint at |index|.
internal::GraphemeIterator GetGraphemeIteratorAtIndex(
const base::string16& text,
const size_t internal::TextToDisplayIndex::*field,
size_t index) const;
// Returns the nearest word start boundary for |index|. First searches in the
// CURSOR_BACKWARD direction, then in the CURSOR_FORWARD direction. Returns
// the text length if no valid boundary is found.
size_t GetNearestWordStartBoundary(size_t index) const;
// Expands |range| to its nearest word boundaries and returns the resulting
// range. Maintains directionality of |range|.
Range ExpandRangeToWordBoundary(const Range& range) const;
// Returns an implementation-specific run list, if implemented.
virtual internal::TextRunList* GetRunList() = 0;
virtual const internal::TextRunList* GetRunList() const = 0;
// Returns the decorated text corresponding to |range|. Returns false if the
// text cannot be retrieved, e.g. if the text is obscured.
virtual bool GetDecoratedTextForRange(const Range& range,
DecoratedText* decorated_text) = 0;
// Specify the width/height of a glyph for test. The width/height of glyphs is
// very platform-dependent and environment-dependent. Otherwise multiline text
// will become really flaky.
void set_glyph_width_for_test(float width) { glyph_width_for_test_ = width; }
void set_glyph_height_for_test(float height) {
glyph_height_for_test_ = height;
// Logical UTF-16 string data to be drawn.
base::string16 text_;
// Horizontal alignment of the text with respect to |display_rect_|. The
// default is to align left if the application UI is LTR and right if RTL.
HorizontalAlignment horizontal_alignment_{base::i18n::IsRTL() ? ALIGN_RIGHT
// Vertical alignment of the text with respect to |display_rect_|. Only
// applicable when |multiline_| is true. The default is to align center.
VerticalAlignment vertical_alignment_ = ALIGN_MIDDLE;
// The text directionality mode, defaults to DIRECTIONALITY_FROM_TEXT.
DirectionalityMode directionality_mode_ = DIRECTIONALITY_FROM_TEXT;
// The cached text direction, potentially computed from the text or UI locale.
// Use GetTextDirection(), do not use this potentially invalid value directly!
mutable base::i18n::TextDirection text_direction_ =
mutable base::i18n::TextDirection display_text_direction_ =
// A list of fonts used to render |text_|.
FontList font_list_;
// Logical selection ranges and visual cursor position.
SelectionModel selection_model_;
// The cached cursor bounds; get these bounds with GetUpdatedCursorBounds.
Rect cursor_bounds_;
// Specifies whether the cursor is enabled. If disabled, no space is reserved
// for the cursor when positioning text.
bool cursor_enabled_ = true;
// Whether the current selection has a known direction. That is, whether a
// directional input (e.g. arrow key) has been received for the current
// selection to indicate which end of the selection has the caret. When true,
// directed inputs preserve (rather than replace) the selection affinity.
bool has_directed_selection_ = kSelectionIsAlwaysDirected;
// The color used for drawing selected text.
SkColor selection_color_ = kDefaultColor;
// The background color used for drawing the selection when focused.
SkColor selection_background_focused_color_ =
// Whether the selection visual bounds should be expanded vertically to be
// vertically symmetric with respect to the display rect. Note this flag has
// no effect on multi-line text.
bool symmetric_selection_visual_bounds_ = false;
// The focus state of the text.
bool focused_ = false;
// Composition text range.
Range composition_range_ = Range::InvalidRange();
// Color, baseline, and style breaks, used to modify ranges of text.
// BreakList positions are stored with text indices, not display indices.
// TODO(msw): Expand to support cursor, selection, background, etc. colors.
BreakList<SkColor> colors_{kDefaultColor};
BreakList<BaselineStyle> baselines_{NORMAL_BASELINE};
BreakList<int> font_size_overrides_{0};
BreakList<Font::Weight> weights_{Font::Weight::NORMAL};
internal::StyleArray styles_;
mutable BreakList<SkColor> layout_colors_;
mutable BreakList<BaselineStyle> layout_baselines_;
mutable BreakList<int> layout_font_size_overrides_;
mutable BreakList<Font::Weight> layout_weights_;
mutable internal::StyleArray layout_styles_;
// A mapping from text to display text indices for each grapheme. The vector
// contains an ordered sequence of indice pairs. Both sequence |text_index|
// and |display_index| are sorted.
mutable internal::TextToDisplaySequence text_to_display_indices_;
// A flag to obscure actual text with asterisks for password fields.
bool obscured_ = false;
// The index at which the char should be revealed in the obscured text.
int obscured_reveal_index_ = -1;
// The maximum length of text to display, 0 forgoes a hard limit.
size_t truncate_length_ = 0;
// The obscured and/or truncated text used to layout the text to display.
mutable base::string16 layout_text_;
// The elided text displayed visually. This is empty if the text
// does not have to be elided, or became empty as a result of eliding.
// TODO(oshima): When the text is elided, painting can be done only with
// display text info, so it should be able to clear the |layout_text_| and
// associated information.
mutable base::string16 display_text_;
// The behavior for eliding, fading, or truncating.
ElideBehavior elide_behavior_ = NO_ELIDE;
// The behavior for eliding whitespace when eliding or truncating.
base::Optional<bool> whitespace_elision_;
// True if the text is elided given the current behavior and display area.
bool text_elided_ = false;
// The minimum height a line should have.
int min_line_height_ = 0;
// Whether the text should be broken into multiple lines. Uses the width of
// |display_rect_| as the width cap.
bool multiline_ = false;
// If multiple lines, the maximum number of lines to render, or 0.
size_t max_lines_ = 0;
// The wrap behavior when the text is broken into lines. Do nothing unless
// |multiline_| is set. The default value is IGNORE_LONG_WORDS.
WordWrapBehavior word_wrap_behavior_ = IGNORE_LONG_WORDS;
// Set to true to suppress subpixel rendering due to non-font reasons (eg.
// if the background is transparent). The default value is false.
bool subpixel_rendering_suppressed_ = false;
// The local display area for rendering the text.
Rect display_rect_;
// Flag to work around a Skia bug with the PDF path (
// that results in incorrect clipping when drawing to the document margins.
// This field allows disabling clipping to work around the issue.
// TODO(asvitkine): Remove this when the underlying Skia bug is fixed.
bool clip_to_display_rect_ = true;
// The offset for the text to be drawn, relative to the display area.
// Get this point with GetUpdatedDisplayOffset (or risk using a stale value).
Vector2d display_offset_;
// The baseline of the text. This is determined from the height of the
// display area and the cap height of the font list so the text is vertically
// centered.
int baseline_ = kInvalidBaseline;
// The cached bounds and offset are invalidated by changes to the cursor,
// selection, font, and other operations that adjust the visible text bounds.
bool cached_bounds_and_offset_valid_ = false;
// Text shadows to be drawn.
ShadowValues shadows_;
// A list of valid display text line break positions.
BreakList<size_t> line_breaks_;
// Text shaping computed by EnsureLayout. This should be invalidated upon
// OnLayoutTextAttributeChanged and OnDisplayTextAttributeChanged calls.
std::unique_ptr<internal::ShapedText> shaped_text_;
// The ratio of strike-through line thickness to text height.
SkScalar strike_thickness_factor_ = kLineThicknessFactor;
// Extra spacing placed between glyphs; used only for obscured text styling.
int obscured_glyph_spacing_ = 0;
// The cursor position in view space, used to traverse lines of varied widths.
base::Optional<int> cached_cursor_x_;
// Tell whether or not the |layout_text_| needs an update or is up to date.
mutable bool layout_text_up_to_date_ = false;
} // namespace gfx