impeller::TextFrame Class Reference

Represents a collection of shaped text runs. More...

#include <text_frame.h>

Public Member Functions
	TextFrame ()
	TextFrame (std::vector< TextRun > &runs, Rect bounds, bool has_color)
	~TextFrame ()
void	CollectUniqueFontGlyphPairs (FontGlyphMap &glyph_map, Scalar scale) const
Rect	GetBounds () const
	The conservative bounding box for this text frame.
size_t	GetRunCount () const
	The number of runs in this text frame.
const std::vector< TextRun > &	GetRuns () const
	Returns a reference to all the text runs in this frame.
bool	MaybeHasOverlapping () const
	Whether any of the glyphs of this run are potentially overlapping.
GlyphAtlas::Type	GetAtlasType () const
	The type of atlas this run should be emplaced in.
TextFrame &	operator= (TextFrame &&other)=default
	TextFrame (const TextFrame &other)=default

Static Public Member Functions
static Scalar	RoundScaledFontSize (Scalar scale, Scalar point_size)

Detailed Description

Represents a collection of shaped text runs.

        This object is typically the entrypoint in the Impeller type
        rendering subsystem.

Definition at line 20 of file text_frame.h.

Constructor & Destructor Documentation

TextFrame() [1/3]

impeller::TextFrame::TextFrame ( )

default

TextFrame() [2/3]

impeller::TextFrame::TextFrame	(	std::vector< TextRun > &	runs,
		Rect	bounds,
		bool	has_color
	)

Definition at line 11 of file text_frame.cc.

    : runs_(std::move(runs)), bounds_(bounds), has_color_(has_color) {}

~TextFrame()

impeller::TextFrame::~TextFrame ( )

default

TextFrame() [3/3]

impeller::TextFrame::TextFrame ( const TextFrame &  other )

default

Member Function Documentation

CollectUniqueFontGlyphPairs()

void impeller::TextFrame::CollectUniqueFontGlyphPairs	(	FontGlyphMap &	glyph_map,
		Scalar	scale
	)		const

Definition at line 70 of file text_frame.cc.

                                                                {
  for (const TextRun& run : GetRuns()) {
    const Font& font = run.GetFont();
    auto rounded_scale =
        RoundScaledFontSize(scale, font.GetMetrics().point_size);
    auto& set = glyph_map[{font, rounded_scale}];
    for (const TextRun::GlyphPosition& glyph_position :
         run.GetGlyphPositions()) {
#if false
// Glyph size error due to RoundScaledFontSize usage above.
if (rounded_scale != scale) {
  auto delta = std::abs(rounded_scale - scale);
  FML_LOG(ERROR) << glyph_position.glyph.bounds.size * delta;
}
#endif
      set.insert(glyph_position.glyph);
    }
  }
}

GetAtlasType()

GlyphAtlas::Type impeller::TextFrame::GetAtlasType

(

)

const

The type of atlas this run should be emplaced in.

Definition at line 28 of file text_frame.cc.

                                             {
  return has_color_ ? GlyphAtlas::Type::kColorBitmap
                    : GlyphAtlas::Type::kAlphaBitmap;
}

GetBounds()

Rect impeller::TextFrame::GetBounds

(

)

const

The conservative bounding box for this text frame.

Returns

The bounds rectangle. If there are no glyphs in this text frame and empty Rectangle is returned instead.

Definition at line 16 of file text_frame.cc.

                                {
  return bounds_;
}

GetRunCount()

size_t impeller::TextFrame::GetRunCount

(

)

const

The number of runs in this text frame.

Returns

The run count.

Definition at line 20 of file text_frame.cc.

                                    {
  return runs_.size();
}

GetRuns()

const std::vector< TextRun > & impeller::TextFrame::GetRuns

(

)

const

Returns a reference to all the text runs in this frame.

Returns

The runs in this frame.

Definition at line 24 of file text_frame.cc.

                                                   {
  return runs_;
}

MaybeHasOverlapping()

bool impeller::TextFrame::MaybeHasOverlapping

(

)

const

Whether any of the glyphs of this run are potentially overlapping.

        It is always safe to return true from this method. Generally,
        any large blobs of text should return true to avoid
        computationally complex calculations. This information is used
        to apply opacity peephole optimizations to text blobs. 

Definition at line 33 of file text_frame.cc.

                                          {
  if (runs_.size() > 1) {
    return true;
  }
  auto glyph_positions = runs_[0].GetGlyphPositions();
  if (glyph_positions.size() > 10) {
    return true;
  }
  if (glyph_positions.size() == 1) {
    return false;
  }
  // To avoid quadradic behavior the overlapping is checked against an
  // accumulated bounds rect. This gives faster but less precise information
  // on text runs.
  auto first_position = glyph_positions[0];
  auto overlapping_rect = Rect::MakeOriginSize(
      first_position.position + first_position.glyph.bounds.GetOrigin(),
      first_position.glyph.bounds.GetSize());
  for (auto i = 1u; i < glyph_positions.size(); i++) {
    auto glyph_position = glyph_positions[i];
    auto glyph_rect = Rect::MakeOriginSize(
        glyph_position.position + glyph_position.glyph.bounds.GetOrigin(),
        glyph_position.glyph.bounds.GetSize());
    auto intersection = glyph_rect.Intersection(overlapping_rect);
    if (intersection.has_value()) {
      return true;
    }
    overlapping_rect = overlapping_rect.Union(glyph_rect);
  }
  return false;
}

operator=()

TextFrame & impeller::TextFrame::operator= ( TextFrame &&  other )

default

RoundScaledFontSize()

Scalar impeller::TextFrame::RoundScaledFontSize ( Scalar  scale, Scalar  point_size  )

static

Definition at line 66 of file text_frame.cc.

                                                                     {
  return std::round(scale * 100) / 100;
}

---

The documentation for this class was generated from the following files:

• impeller/typographer/text_frame.h
• impeller/typographer/text_frame.cc