impeller::LineGeometry Class Reference

#include <line_geometry.h>

Inheritance diagram for impeller::LineGeometry:

Public Member Functions
	LineGeometry (Point p0, Point p1, Scalar width, Cap cap)
	~LineGeometry ()=default
bool	CoversArea (const Matrix &transform, const Rect &rect) const override
	Determines if this geometry, transformed by the given transform, will completely cover all surface area of the given rect.
bool	IsAxisAlignedRect () const override
Public Member Functions inherited from impeller::Geometry
virtual GeometryResult::Mode	GetResultMode () const
virtual bool	CanApplyMaskFilter () const

Static Public Member Functions
static Scalar	ComputePixelHalfWidth (const Matrix &transform, Scalar width)
Static Public Member Functions inherited from impeller::Geometry
static std::shared_ptr< Geometry >	MakeFillPath (const Path &path, std::optional< Rect > inner_rect=std::nullopt)
static std::shared_ptr< Geometry >	MakeStrokePath (const Path &path, Scalar stroke_width=0.0, Scalar miter_limit=4.0, Cap stroke_cap=Cap::kButt, Join stroke_join=Join::kMiter)
static std::shared_ptr< Geometry >	MakeCover ()
static std::shared_ptr< Geometry >	MakeRect (const Rect &rect)
static std::shared_ptr< Geometry >	MakeOval (const Rect &rect)
static std::shared_ptr< Geometry >	MakeLine (const Point &p0, const Point &p1, Scalar width, Cap cap)
static std::shared_ptr< Geometry >	MakeCircle (const Point &center, Scalar radius)
static std::shared_ptr< Geometry >	MakeStrokedCircle (const Point &center, Scalar radius, Scalar stroke_width)
static std::shared_ptr< Geometry >	MakeRoundRect (const Rect &rect, const Size &radii)
static std::shared_ptr< Geometry >	MakePointField (std::vector< Point > points, Scalar radius, bool round)

Private Member Functions
GeometryResult	GetPositionBuffer (const ContentContext &renderer, const Entity &entity, RenderPass &pass) const override
std::optional< Rect >	GetCoverage (const Matrix &transform) const override

Additional Inherited Members
Static Protected Member Functions inherited from impeller::Geometry
static GeometryResult	ComputePositionGeometry (const ContentContext &renderer, const Tessellator::VertexGenerator &generator, const Entity &entity, RenderPass &pass)

Detailed Description

Definition at line 13 of file line_geometry.h.

Constructor & Destructor Documentation

LineGeometry()

impeller::LineGeometry::LineGeometry ( Point  p0, Point  p1, Scalar  width, Cap  cap  )

explicit

Definition at line 9 of file line_geometry.cc.

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

~LineGeometry()

impeller::LineGeometry::~LineGeometry ( )

default

Member Function Documentation

ComputePixelHalfWidth()

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

static

Definition at line 14 of file line_geometry.cc.

                                                         {
  auto determinant = transform.GetDeterminant();
  if (determinant == 0) {
    return 0.0f;
  }
 
  Scalar min_size = 1.0f / sqrt(std::abs(determinant));
  return std::max(width, min_size) * 0.5f;
}

CoversArea()

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

overridevirtual

Determines if this geometry, transformed by the given transform, will completely cover all surface area of the given rect.

This is a conservative estimate useful for certain optimizations.

Returns

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

Reimplemented from impeller::Geometry.

Definition at line 123 of file line_geometry.cc.

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

GetCoverage()

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

overrideprivatevirtual

Implements impeller::Geometry.

Definition at line 111 of file line_geometry.cc.

                                                                         {
  Point corners[4];
  if (!ComputeCorners(corners, transform, cap_ != Cap::kButt)) {
    return {};
  }
 
  for (int i = 0; i < 4; i++) {
    corners[i] = transform * corners[i];
  }
  return Rect::MakePointBounds(std::begin(corners), std::end(corners));
}

GetPositionBuffer()

GeometryResult impeller::LineGeometry::GetPositionBuffer ( const ContentContext &  renderer, const Entity &  entity, RenderPass &  pass  ) const

overrideprivatevirtual

Implements impeller::Geometry.

Definition at line 67 of file line_geometry.cc.

                                                                       {
  using VT = SolidFillVertexShader::PerVertexData;
 
  auto& transform = entity.GetTransform();
  auto radius = ComputePixelHalfWidth(transform, width_);
 
  if (cap_ == Cap::kRound) {
    std::shared_ptr<Tessellator> tessellator = renderer.GetTessellator();
    auto generator = tessellator->RoundCapLine(transform, p0_, p1_, radius);
    return ComputePositionGeometry(renderer, generator, entity, pass);
  }
 
  Point corners[4];
  if (!ComputeCorners(corners, transform, cap_ == Cap::kSquare)) {
    return kEmptyResult;
  }
 
  auto& host_buffer = renderer.GetTransientsBuffer();
 
  size_t count = 4;
  BufferView vertex_buffer = host_buffer.Emplace(
      count * sizeof(VT), alignof(VT), [&corners](uint8_t* buffer) {
        auto vertices = reinterpret_cast<VT*>(buffer);
        for (auto& corner : corners) {
          *vertices++ = {
              .position = corner,
          };
        }
      });
 
  return GeometryResult{
      .type = PrimitiveType::kTriangleStrip,
      .vertex_buffer =
          {
              .vertex_buffer = vertex_buffer,
              .vertex_count = count,
              .index_type = IndexType::kNone,
          },
      .transform = entity.GetShaderTransform(pass),
  };
}

IsAxisAlignedRect()

bool impeller::LineGeometry::IsAxisAlignedRect ( ) const

overridevirtual

Reimplemented from impeller::Geometry.

Definition at line 131 of file line_geometry.cc.

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

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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