impeller::LineGeometry Class Reference

#include <line_geometry.h>

Inheritance diagram for impeller::LineGeometry:

Public Member Functions
	LineGeometry (Point p0, Point p1, const StrokeParameters &stroke)
	~LineGeometry () override
bool	CoversArea (const Matrix &transform, const IRect &rect) const override
	Determines if this geometry, transformed by the given transform, will completely cover all of the pixels within the given integer rect.
bool	IsAxisAlignedRect () const override
Scalar	ComputeAlphaCoverage (const Matrix &transform) const override
std::optional< Rect >	GetCoverage (const Matrix &transform) const override
	The coverage rectangle of this geometry, transformed by the transform argument.
Point	GetP0 () const
Point	GetP1 () const
Scalar	GetWidth () const
Cap	GetCap () const
Public Member Functions inherited from impeller::Geometry
virtual	~Geometry ()
virtual GeometryResult::Mode	GetResultMode () const
virtual bool	CanApplyMaskFilter () const

Static Public Member Functions
static Scalar	ComputePixelHalfWidth (const Matrix &transform, Scalar width)
static Vector2	ComputeAlongVector (const Matrix &transform, bool allow_zero_length, Point p0, Point p1, Scalar width)
static bool	ComputeCorners (Point corners[4], const Matrix &transform, bool extend_endpoints, Point p0, Point p1, Scalar width)
Static Public Member Functions inherited from impeller::Geometry
static std::unique_ptr< Geometry >	MakeFillPath (const flutter::DlPath &path, std::optional< Rect > inner_rect=std::nullopt)
static std::unique_ptr< Geometry >	MakeStrokePath (const flutter::DlPath &path, const StrokeParameters &stroke={})
static std::unique_ptr< Geometry >	MakeCover ()
static std::unique_ptr< Geometry >	MakeRect (const Rect &rect)
static std::unique_ptr< Geometry >	MakeOval (const Rect &rect)
static std::unique_ptr< Geometry >	MakeLine (const Point &p0, const Point &p1, const StrokeParameters &stroke)
static std::unique_ptr< Geometry >	MakeCircle (const Point &center, Scalar radius)
static std::unique_ptr< Geometry >	MakeStrokedCircle (const Point &center, Scalar radius, Scalar stroke_width)
static std::unique_ptr< Geometry >	MakeFilledArc (const Rect &oval_bounds, Degrees start, Degrees sweep, bool include_center)
static std::unique_ptr< Geometry >	MakeStrokedArc (const Rect &oval_bounds, Degrees start, Degrees sweep, const StrokeParameters &stroke)
static std::unique_ptr< Geometry >	MakeRoundRect (const Rect &rect, const Size &radii)
static std::unique_ptr< Geometry >	MakeRoundSuperellipse (const Rect &rect, Scalar corner_radius)
static Scalar	ComputeStrokeAlphaCoverage (const Matrix &entity, Scalar stroke_width)
	Compute an alpha value to simulate lower coverage of fractional pixel strokes.
static GeometryResult	ComputePositionGeometry (const ContentContext &renderer, const Tessellator::VertexGenerator &generator, const Entity &entity, RenderPass &pass)

Detailed Description

Definition at line 12 of file line_geometry.h.

Constructor & Destructor Documentation

LineGeometry()

impeller::LineGeometry::LineGeometry ( Point  p0, Point  p1, const StrokeParameters &  stroke  )

explicit

Definition at line 11 of file line_geometry.cc.

    : p0_(p0), p1_(p1), width_(stroke.width), cap_(stroke.cap) {
  FML_DCHECK(width_ >= 0);
}

References FML_DCHECK.

~LineGeometry()

impeller::LineGeometry::~LineGeometry ( )

overridedefault

Member Function Documentation

ComputeAlongVector()

Vector2 impeller::LineGeometry::ComputeAlongVector ( const Matrix &  transform, bool  allow_zero_length, Point  p0, Point  p1, Scalar  width  )

static

Definition at line 29 of file line_geometry.cc.

                                                       {
  Scalar stroke_half_width = ComputePixelHalfWidth(transform, width);
  if (stroke_half_width < kEhCloseEnough) {
    return {};
  }
 
  auto along = p1 - p0;
  Scalar length = along.GetLength();
  if (length < kEhCloseEnough) {
    if (!allow_zero_length) {
      // We won't enclose any pixels unless the endpoints are extended
      return {};
    }
    return {stroke_half_width, 0};
  } else {
    return along * stroke_half_width / length;
  }
}

References ComputePixelHalfWidth(), impeller::TPoint< T >::GetLength(), impeller::kEhCloseEnough, length, p1, transform, and width.

Referenced by ComputeCorners().

ComputeAlphaCoverage()

Scalar impeller::LineGeometry::ComputeAlphaCoverage ( const Matrix &  transform ) const

overridevirtual

Reimplemented from impeller::Geometry.

Definition at line 77 of file line_geometry.cc.

                                                                    {
  return Geometry::ComputeStrokeAlphaCoverage(entity, width_);
}

References impeller::Geometry::ComputeStrokeAlphaCoverage().

ComputeCorners()

bool impeller::LineGeometry::ComputeCorners ( Point  corners[4], const Matrix &  transform, bool  extend_endpoints, Point  p0, Point  p1, Scalar  width  )

static

Definition at line 52 of file line_geometry.cc.

                                                {
  auto along = ComputeAlongVector(transform, extend_endpoints, p0, p1, width);
  if (along.IsZero()) {
    return false;
  }
 
  auto across = Vector2(along.y, -along.x);
  corners[0] = p0 - across;
  corners[1] = p1 - across;
  corners[2] = p0 + across;
  corners[3] = p1 + across;
  if (extend_endpoints) {
    corners[0] -= along;
    corners[1] += along;
    corners[2] -= along;
    corners[3] += along;
  }
  return true;
}

References ComputeAlongVector(), p1, transform, and width.

Referenced by impeller::LineContents::CalculatePerVertex(), and GetCoverage().

ComputePixelHalfWidth()

Scalar impeller::LineGeometry::ComputePixelHalfWidth ( const Matrix &  transform, Scalar  width  )

static

Definition at line 18 of file line_geometry.cc.

                                                         {
  Scalar max_basis = transform.GetMaxBasisLengthXY();
  if (max_basis == 0) {
    return {};
  }
 
  Scalar min_size = kMinStrokeSize / max_basis;
  return std::max(width, min_size) * 0.5f;
}

References impeller::kMinStrokeSize, transform, and width.

Referenced by ComputeAlongVector(), and impeller::CircleGeometry::GetPositionBuffer().

CoversArea()

bool impeller::LineGeometry::CoversArea ( const Matrix &  transform, const IRect &  rect  ) const

overridevirtual

Determines if this geometry, transformed by the given transform, will completely cover all of the pixels within the given integer rect.

The integer rect, by definition, will contain all of the area covered by any pixel within its boundary.

The return value can be a conservative estimate which will still be useful for certain optimizations. It may return false for obscure cases that might actually contain all of the pixels if it is too computationally costly to prove containment, but it should never return 'true' unless the implementation can prove that all pixels are fully covered (rendered) by the geometry.

Returns

true if the transformed geometry is guaranteed to cover the given rect. May return false in some cases where the transformed geometry does in fact cover the rect.

Reimplemented from impeller::Geometry.

Definition at line 170 of file line_geometry.cc.

                                                       {
  if (!transform.IsTranslationScaleOnly() || !IsAxisAlignedRect()) {
    return false;
  }
  auto coverage = GetCoverage(transform);
  return coverage.has_value() ? coverage->Contains(rect) : false;
}

References GetCoverage(), IsAxisAlignedRect(), and transform.

GetCap()

Cap impeller::LineGeometry::GetCap ( ) const

inline

Definition at line 34 of file line_geometry.h.

{ return cap_; }

Referenced by impeller::LineContents::CalculatePerVertex().

GetCoverage()

std::optional< Rect > impeller::LineGeometry::GetCoverage ( const Matrix &  transform ) const

overridevirtual

The coverage rectangle of this geometry, transformed by the transform argument.

Implements impeller::Geometry.

Definition at line 156 of file line_geometry.cc.

                                                                         {
  Point corners[4];
  // Note: MSAA boolean doesn't matter for coverage computation.
  if (!ComputeCorners(corners, transform, cap_ != Cap::kButt, p0_, p1_,
                      width_)) {
    return {};
  }
 
  for (int i = 0; i < 4; i++) {
    corners[i] = transform * corners[i];
  }
  return Rect::MakePointBounds(std::begin(corners), std::end(corners));
}

References ComputeCorners(), i, impeller::kButt, impeller::TRect< Scalar >::MakePointBounds(), and transform.

Referenced by CoversArea().

GetP0()

Point impeller::LineGeometry::GetP0 ( ) const

inline

Definition at line 31 of file line_geometry.h.

{ return p0_; }

Referenced by impeller::LineContents::CalculatePerVertex().

GetP1()

Point impeller::LineGeometry::GetP1 ( ) const

inline

Definition at line 32 of file line_geometry.h.

{ return p1_; }

Referenced by impeller::LineContents::CalculatePerVertex().

GetWidth()

Scalar impeller::LineGeometry::GetWidth ( ) const

inline

Definition at line 33 of file line_geometry.h.

{ return width_; }

Referenced by impeller::LineContents::CalculatePerVertex().

IsAxisAlignedRect()

bool impeller::LineGeometry::IsAxisAlignedRect ( ) const

overridevirtual

Reimplemented from impeller::Geometry.

Definition at line 179 of file line_geometry.cc.

                                           {
  return cap_ != Cap::kRound && (p0_.x == p1_.x || p0_.y == p1_.y);
}

References impeller::kRound.

Referenced by CoversArea().

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

• impeller/entity/geometry/line_geometry.h
• impeller/entity/geometry/line_geometry.cc