Flutter Impeller
impeller::StrokeSegmentsGeometry Class Referenceabstract

An abstract Geometry base class that produces fillable vertices representing the stroked outline of the segments provided by the subclass in the virtual |Dispatch| method. More...

#include <stroke_path_geometry.h>

Inheritance diagram for impeller::StrokeSegmentsGeometry:
impeller::Geometry impeller::ArcStrokeGeometry impeller::StrokePathSourceGeometry impeller::StrokeDashedLineGeometry impeller::StrokeDiffRoundRectGeometry impeller::StrokeEllipseGeometry impeller::StrokePathGeometry impeller::StrokeRoundRectGeometry impeller::StrokeRoundSuperellipseGeometry

Public Member Functions

 ~StrokeSegmentsGeometry () override
 
Scalar GetStrokeWidth () const
 
Scalar GetMiterLimit () const
 
Cap GetStrokeCap () const
 
Join GetStrokeJoin () const
 
Scalar ComputeAlphaCoverage (const Matrix &transform) const override
 
- Public Member Functions inherited from impeller::Geometry
virtual ~Geometry ()
 
virtual std::optional< RectGetCoverage (const Matrix &transform) const =0
 
virtual bool CoversArea (const Matrix &transform, const Rect &rect) const
 Determines if this geometry, transformed by the given transform, will completely cover all surface area of the given rect. More...
 
virtual bool IsAxisAlignedRect () const
 
virtual bool CanApplyMaskFilter () const
 

Protected Member Functions

 StrokeSegmentsGeometry (const StrokeParameters &parameters)
 
virtual void Dispatch (PathAndArcSegmentReceiver &receiver, Tessellator &tessellator, Scalar scale) const =0
 
std::optional< RectGetStrokeCoverage (const Matrix &transform, const Rect &segment_bounds) const
 

Friends

class ImpellerBenchmarkAccessor
 
class ImpellerEntityUnitTestAccessor
 

Additional Inherited Members

- Static Public Member Functions inherited from impeller::Geometry
static std::unique_ptr< GeometryMakeFillPath (const flutter::DlPath &path, std::optional< Rect > inner_rect=std::nullopt)
 
static std::unique_ptr< GeometryMakeStrokePath (const flutter::DlPath &path, const StrokeParameters &stroke={})
 
static std::unique_ptr< GeometryMakeCover ()
 
static std::unique_ptr< GeometryMakeRect (const Rect &rect)
 
static std::unique_ptr< GeometryMakeOval (const Rect &rect)
 
static std::unique_ptr< GeometryMakeLine (const Point &p0, const Point &p1, const StrokeParameters &stroke)
 
static std::unique_ptr< GeometryMakeCircle (const Point &center, Scalar radius)
 
static std::unique_ptr< GeometryMakeStrokedCircle (const Point &center, Scalar radius, Scalar stroke_width)
 
static std::unique_ptr< GeometryMakeFilledArc (const Rect &oval_bounds, Degrees start, Degrees sweep, bool include_center)
 
static std::unique_ptr< GeometryMakeStrokedArc (const Rect &oval_bounds, Degrees start, Degrees sweep, const StrokeParameters &stroke)
 
static std::unique_ptr< GeometryMakeRoundRect (const Rect &rect, const Size &radii)
 
static std::unique_ptr< GeometryMakeRoundSuperellipse (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. More...
 
static GeometryResult ComputePositionGeometry (const ContentContext &renderer, const Tessellator::VertexGenerator &generator, const Entity &entity, RenderPass &pass)
 

Detailed Description

An abstract Geometry base class that produces fillable vertices representing the stroked outline of the segments provided by the subclass in the virtual |Dispatch| method.

Most subclasses will be based on an instance of |PathSource| and use the |StrokePathSourceGeometry| subclass to feed the segments from that path source object, but some subclasses may be able to operate more optimally by talking directly to the |StrokePathSegmentReceiver| (mainly arcs).

Definition at line 35 of file stroke_path_geometry.h.

Constructor & Destructor Documentation

◆ ~StrokeSegmentsGeometry()

impeller::StrokeSegmentsGeometry::~StrokeSegmentsGeometry ( )
overridedefault

◆ StrokeSegmentsGeometry()

impeller::StrokeSegmentsGeometry::StrokeSegmentsGeometry ( const StrokeParameters parameters)
explicitprotected

Definition at line 714 of file stroke_path_geometry.cc.

715  : stroke_(stroke) {}

Member Function Documentation

◆ ComputeAlphaCoverage()

Scalar impeller::StrokeSegmentsGeometry::ComputeAlphaCoverage ( const Matrix transform) const
overridevirtual

Reimplemented from impeller::Geometry.

Definition at line 735 of file stroke_path_geometry.cc.

736  {
738 }
static Scalar ComputeStrokeAlphaCoverage(const Matrix &entity, Scalar stroke_width)
Compute an alpha value to simulate lower coverage of fractional pixel strokes.
Definition: geometry.cc:149

References impeller::Geometry::ComputeStrokeAlphaCoverage(), transform, and impeller::StrokeParameters::width.

◆ Dispatch()

virtual void impeller::StrokeSegmentsGeometry::Dispatch ( PathAndArcSegmentReceiver receiver,
Tessellator tessellator,
Scalar  scale 
) const
protectedpure virtual

Dispatch the path segments to the StrokePathSegmentReceiver for the provided transform scale.

Implemented in impeller::ArcStrokeGeometry, and impeller::StrokePathSourceGeometry.

◆ GetMiterLimit()

Scalar impeller::StrokeSegmentsGeometry::GetMiterLimit ( ) const

Definition at line 723 of file stroke_path_geometry.cc.

723  {
724  return stroke_.miter_limit;
725 }

References impeller::StrokeParameters::miter_limit.

◆ GetStrokeCap()

Cap impeller::StrokeSegmentsGeometry::GetStrokeCap ( ) const

Definition at line 727 of file stroke_path_geometry.cc.

727  {
728  return stroke_.cap;
729 }

References impeller::StrokeParameters::cap.

◆ GetStrokeCoverage()

std::optional< Rect > impeller::StrokeSegmentsGeometry::GetStrokeCoverage ( const Matrix transform,
const Rect segment_bounds 
) const
protected

Provide the stroke-padded bounds for the provided bounds of the segments themselves.

Definition at line 815 of file stroke_path_geometry.cc.

817  {
818  if (path_bounds.IsEmpty()) {
819  return std::nullopt;
820  }
821 
822  Scalar max_radius = 0.5;
823  if (stroke_.cap == Cap::kSquare) {
824  max_radius = max_radius * kSqrt2;
825  }
826  if (stroke_.join == Join::kMiter) {
827  max_radius = std::max(max_radius, stroke_.miter_limit * 0.5f);
828  }
829  Scalar max_basis = transform.GetMaxBasisLengthXY();
830  if (max_basis == 0) {
831  return {};
832  }
833  // Use the most conervative coverage setting.
834  Scalar min_size = kMinStrokeSize / max_basis;
835  max_radius *= std::max(stroke_.width, min_size);
836  return path_bounds.Expand(max_radius).TransformBounds(transform);
837 }
float Scalar
Definition: scalar.h:19
constexpr float kSqrt2
Definition: constants.h:47
static constexpr Scalar kMinStrokeSize
Definition: geometry.h:19

References impeller::StrokeParameters::cap, impeller::TRect< T >::Expand(), impeller::TRect< T >::IsEmpty(), impeller::StrokeParameters::join, impeller::kMinStrokeSize, impeller::kMiter, impeller::kSqrt2, impeller::kSquare, impeller::StrokeParameters::miter_limit, transform, impeller::TRect< T >::TransformBounds(), and impeller::StrokeParameters::width.

Referenced by impeller::StrokePathSourceGeometry::GetCoverage(), and impeller::ArcStrokeGeometry::GetCoverage().

◆ GetStrokeJoin()

Join impeller::StrokeSegmentsGeometry::GetStrokeJoin ( ) const

Definition at line 731 of file stroke_path_geometry.cc.

731  {
732  return stroke_.join;
733 }

References impeller::StrokeParameters::join.

◆ GetStrokeWidth()

Scalar impeller::StrokeSegmentsGeometry::GetStrokeWidth ( ) const

Definition at line 719 of file stroke_path_geometry.cc.

719  {
720  return stroke_.width;
721 }

References impeller::StrokeParameters::width.

Friends And Related Function Documentation

◆ ImpellerBenchmarkAccessor

friend class ImpellerBenchmarkAccessor
friend

Definition at line 79 of file stroke_path_geometry.h.

◆ ImpellerEntityUnitTestAccessor

friend class ImpellerEntityUnitTestAccessor
friend

Definition at line 80 of file stroke_path_geometry.h.


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