| Flutter Impeller |

Public Member Functions | Static Public Member Functions | List of all members
impeller::LineGeometry Class Referencefinal

`#include <line_geometry.h>`

Inheritance diagram for impeller::LineGeometry:

## Public Member Functions
| LineGeometry (Point p0, Point p1, Scalar width, Cap cap)
| ~LineGeometry () override
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`. More...
bool | IsAxisAlignedRect () const override
Scalar | ComputeAlphaCoverage (const Matrix &transform) const override
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, bool msaa)
Static Public Member Functions inherited from impeller::Geometry
static std::unique_ptr< Geometry > | MakeFillPath (const Path &path, std::optional< Rect > inner_rect=std::nullopt)
static std::unique_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::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, Scalar width, Cap cap)
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 > | MakeRoundRect (const Rect &rect, const Size &radii)
static std::unique_ptr< Geometry > | MakePointField (std::vector< Point > points, Scalar radius, bool round)
static Scalar | ComputeStrokeAlphaCoverage (const Matrix &entity, Scalar stroke_width)
| Compute an alpha value to simulate lower coverage of fractional pixel strokes. More...

## 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 12 of file line_geometry.h.

## Constructor & Destructor Documentation

## ◆ LineGeometry()

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

Definition at line 10 of file line_geometry.cc.

11 : p0_(p0), p1_(p1), width_(width), cap_(cap) {
12 FML_DCHECK(width >= 0);
13 }

## ◆ ~LineGeometry()

impeller::LineGeometry::~LineGeometry | ( |  | ) |
| overridedefault

## Member Function Documentation

## ◆ ComputeAlphaCoverage()

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

Reimplemented from impeller::Geometry.

Definition at line 73 of file line_geometry.cc.

73 {
74 return Geometry::ComputeStrokeAlphaCoverage(entity, width_);
75 }

References impeller::Geometry::ComputeStrokeAlphaCoverage().

## ◆ ComputePixelHalfWidth()

Scalar impeller::LineGeometry::ComputePixelHalfWidth | ( | const Matrix & | transform,
|  | Scalar | width,
|  | bool | msaa
| ) |  |
| static

Definition at line 17 of file line_geometry.cc.

19 {
20 Scalar max_basis = transform.GetMaxBasisLengthXY();
21 if (max_basis == 0) {
22 return {};
23 }
24
25 Scalar min_size = (msaa ? kMinStrokeSize : kMinStrokeSizeMSAA) / max_basis;
26 return std::max(width, min_size) * 0.5f;
27 }

References impeller::kMinStrokeSize, impeller::kMinStrokeSizeMSAA, and transform.

## ◆ 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 136 of file line_geometry.cc.

136 {
137 if (!transform.IsTranslationScaleOnly() || !IsAxisAlignedRect()) {
138 return false;
139 }
140 auto coverage = GetCoverage(transform);
141 return coverage.has_value() ? coverage->Contains(rect) : false;
142 }

References IsAxisAlignedRect(), and transform.

## ◆ IsAxisAlignedRect()

bool impeller::LineGeometry::IsAxisAlignedRect | ( |  | ) | const
| overridevirtual

Reimplemented from impeller::Geometry.

Definition at line 144 of file line_geometry.cc.

144 {
145 return cap_ != Cap::kRound && (p0_.x == p1_.x || p0_.y == p1_.y);
146 }

References impeller::kRound, impeller::TPoint< T >::x, and impeller::TPoint< T >::y.

Referenced by CoversArea().

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

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

impeller::Cap::kRound
@ kRound
impeller::TPoint::y
Type y
Definition: point.h:31
impeller::Scalar
float Scalar
Definition: scalar.h:18
impeller::kMinStrokeSizeMSAA
static constexpr Scalar kMinStrokeSizeMSAA
The minimum stroke size can be less than one physical pixel because of MSAA, but no less that half a ...
Definition: geometry.h:22
impeller::kMinStrokeSize
static constexpr Scalar kMinStrokeSize
Definition: geometry.h:24
transform
Matrix transform
Definition: gaussian_blur_filter_contents.cc:213
impeller::LineGeometry::IsAxisAlignedRect
bool IsAxisAlignedRect() const override
Definition: line_geometry.cc:144
impeller::TPoint::x
Type x
Definition: point.h:30
impeller::Geometry::ComputeStrokeAlphaCoverage
static Scalar ComputeStrokeAlphaCoverage(const Matrix &entity, Scalar stroke_width)
Compute an alpha value to simulate lower coverage of fractional pixel strokes.
Definition: geometry.cc:133