Flutter Impeller
line_geometry.h
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1 // Copyright 2013 The Flutter Authors. All rights reserved.
2 // Use of this source code is governed by a BSD-style license that can be
3 // found in the LICENSE file.
4 
5 #ifndef FLUTTER_IMPELLER_ENTITY_GEOMETRY_LINE_GEOMETRY_H_
6 #define FLUTTER_IMPELLER_ENTITY_GEOMETRY_LINE_GEOMETRY_H_
7 
8 #include <type_traits>
10 
11 namespace impeller {
12 
13 class LineGeometry final : public Geometry {
14  public:
15  explicit LineGeometry(Point p0, Point p1, Scalar width, Cap cap);
16 
17  ~LineGeometry() = default;
18 
19  static Scalar ComputePixelHalfWidth(const Matrix& transform, Scalar width);
20 
21  // |Geometry|
22  bool CoversArea(const Matrix& transform, const Rect& rect) const override;
23 
24  // |Geometry|
25  bool IsAxisAlignedRect() const override;
26 
27  private:
28  // Computes the 4 corners of a rectangle that defines the line and
29  // possibly extended endpoints which will be rendered under the given
30  // transform, and returns true if such a rectangle is defined.
31  //
32  // The coordinates will be generated in the original coordinate system
33  // of the line end points and the transform will only be used to determine
34  // the minimum line width.
35  //
36  // For kButt and kSquare end caps the ends should always be exteded as
37  // per that decoration, but for kRound caps the ends might be extended
38  // if the goal is to get a conservative bounds and might not be extended
39  // if the calling code is planning to draw the round caps on the ends.
40  //
41  // @return true if the transform and width were not degenerate
42  bool ComputeCorners(Point corners[4],
43  const Matrix& transform,
44  bool extend_endpoints) const;
45 
46  Vector2 ComputeAlongVector(const Matrix& transform,
47  bool allow_zero_length) const;
48 
49  // |Geometry|
50  GeometryResult GetPositionBuffer(const ContentContext& renderer,
51  const Entity& entity,
52  RenderPass& pass) const override;
53 
54  // |Geometry|
55  GeometryVertexType GetVertexType() const override;
56 
57  // |Geometry|
58  std::optional<Rect> GetCoverage(const Matrix& transform) const override;
59 
60  // |Geometry|
61  GeometryResult GetPositionUVBuffer(Rect texture_coverage,
62  Matrix effect_transform,
63  const ContentContext& renderer,
64  const Entity& entity,
65  RenderPass& pass) const override;
66 
67  Point p0_;
68  Point p1_;
69  Scalar width_;
70  Cap cap_;
71 
72  LineGeometry(const LineGeometry&) = delete;
73 
74  LineGeometry& operator=(const LineGeometry&) = delete;
75 };
76 
77 static_assert(std::is_trivially_destructible<LineGeometry>::value);
78 
79 } // namespace impeller
80 
81 #endif // FLUTTER_IMPELLER_ENTITY_GEOMETRY_LINE_GEOMETRY_H_
impeller::Scalar
float Scalar
Definition: scalar.h:18
impeller::LineGeometry::LineGeometry
LineGeometry(Point p0, Point p1, Scalar width, Cap cap)
Definition: line_geometry.cc:9
impeller::GeometryVertexType
GeometryVertexType
Definition: geometry.h:49
impeller::Entity
Definition: entity.h:21
impeller::LineGeometry::CoversArea
bool CoversArea(const Matrix &transform, const Rect &rect) const override
Determines if this geometry, transformed by the given transform, will completely cover all surface ar...
Definition: line_geometry.cc:179
impeller::LineGeometry
Definition: line_geometry.h:13
geometry.h
impeller::GeometryResult
Definition: geometry.h:20
impeller::LineGeometry::IsAxisAlignedRect
bool IsAxisAlignedRect() const override
Definition: line_geometry.cc:187
impeller::LineGeometry::ComputePixelHalfWidth
static Scalar ComputePixelHalfWidth(const Matrix &transform, Scalar width)
Definition: line_geometry.cc:14
impeller::RenderPass
Render passes encode render commands directed as one specific render target into an underlying comman...
Definition: render_pass.h:33
impeller::Geometry
Definition: geometry.h:83
impeller::TPoint< Scalar >
impeller::LineGeometry::~LineGeometry
~LineGeometry()=default
impeller
Definition: aiks_blur_unittests.cc:20
impeller::ContentContext
Definition: content_context.h:392
impeller::TRect< Scalar >
impeller::Matrix
A 4x4 matrix using column-major storage.
Definition: matrix.h:37
impeller::Cap
Cap
Definition: path.h:17