Flutter Impeller
geometry.cc
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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 
6 
7 #include <memory>
8 #include <optional>
9 
22 #include "impeller/geometry/rect.h"
23 
24 namespace impeller {
25 
27  const ContentContext& renderer,
28  const Tessellator::VertexGenerator& generator,
29  const Entity& entity,
30  RenderPass& pass) {
31  using VT = SolidFillVertexShader::PerVertexData;
32 
33  size_t count = generator.GetVertexCount();
34 
35  return GeometryResult{
36  .type = generator.GetTriangleType(),
37  .vertex_buffer =
38  {
39  .vertex_buffer = renderer.GetTransientsBuffer().Emplace(
40  count * sizeof(VT), alignof(VT),
41  [&generator](uint8_t* buffer) {
42  auto vertices = reinterpret_cast<VT*>(buffer);
43  generator.GenerateVertices([&vertices](const Point& p) {
44  *vertices++ = {
45  .position = p,
46  };
47  });
48  FML_DCHECK(vertices == reinterpret_cast<VT*>(buffer) +
49  generator.GetVertexCount());
50  }),
51  .vertex_count = count,
52  .index_type = IndexType::kNone,
53  },
54  .transform = entity.GetShaderTransform(pass),
55  };
56 }
57 
60 }
61 
62 std::unique_ptr<Geometry> Geometry::MakeFillPath(
63  const flutter::DlPath& path,
64  std::optional<Rect> inner_rect) {
65  return std::make_unique<FillPathGeometry>(path, inner_rect);
66 }
67 
68 std::unique_ptr<Geometry> Geometry::MakeStrokePath(
69  const flutter::DlPath& path,
70  const StrokeParameters& stroke) {
71  // Skia behaves like this.
72  StrokeParameters parameters = stroke;
73  if (parameters.miter_limit < 0) {
74  parameters.miter_limit = 4.0;
75  }
76  return std::make_unique<StrokePathGeometry>(path, parameters);
77 }
78 
79 std::unique_ptr<Geometry> Geometry::MakeCover() {
80  return std::make_unique<CoverGeometry>();
81 }
82 
83 std::unique_ptr<Geometry> Geometry::MakeRect(const Rect& rect) {
84  return std::make_unique<FillRectGeometry>(rect);
85 }
86 
87 std::unique_ptr<Geometry> Geometry::MakeOval(const Rect& rect) {
88  return std::make_unique<EllipseGeometry>(rect);
89 }
90 
91 std::unique_ptr<Geometry> Geometry::MakeLine(const Point& p0,
92  const Point& p1,
93  const StrokeParameters& stroke) {
94  return std::make_unique<LineGeometry>(p0, p1, stroke);
95 }
96 
97 std::unique_ptr<Geometry> Geometry::MakeCircle(const Point& center,
98  Scalar radius) {
99  return std::make_unique<CircleGeometry>(center, radius);
100 }
101 
102 std::unique_ptr<Geometry> Geometry::MakeStrokedCircle(const Point& center,
103  Scalar radius,
104  Scalar stroke_width) {
105  return std::make_unique<CircleGeometry>(center, radius, stroke_width);
106 }
107 
108 std::unique_ptr<Geometry> Geometry::MakeFilledArc(const Rect& oval_bounds,
109  Degrees start,
110  Degrees sweep,
111  bool include_center) {
112  return std::make_unique<ArcGeometry>(
113  Arc(oval_bounds, start, sweep, include_center));
114 }
115 
116 std::unique_ptr<Geometry> Geometry::MakeStrokedArc(
117  const Rect& oval_bounds,
118  Degrees start,
119  Degrees sweep,
120  const StrokeParameters& stroke) {
121  return std::make_unique<ArcGeometry>(Arc(oval_bounds, start, sweep, false),
122  stroke);
123 }
124 
125 std::unique_ptr<Geometry> Geometry::MakeRoundRect(const Rect& rect,
126  const Size& radii) {
127  return std::make_unique<RoundRectGeometry>(rect, radii);
128 }
129 
130 std::unique_ptr<Geometry> Geometry::MakeRoundSuperellipse(
131  const Rect& rect,
132  Scalar corner_radius) {
133  return std::make_unique<RoundSuperellipseGeometry>(rect, corner_radius);
134 }
135 
136 bool Geometry::CoversArea(const Matrix& transform, const Rect& rect) const {
137  return false;
138 }
139 
141  return false;
142 }
143 
145  return true;
146 }
147 
148 // static
150  Scalar stroke_width) {
151  Scalar scaled_stroke_width = transform.GetMaxBasisLengthXY() * stroke_width;
152  if (scaled_stroke_width == 0.0 || scaled_stroke_width >= kMinStrokeSize) {
153  return 1.0;
154  }
155  // This scalling is eyeballed from Skia.
156  return std::clamp(scaled_stroke_width * 2.0f, 0.f, 1.f);
157 }
158 
159 } // namespace impeller
HostBuffer & GetTransientsBuffer() const
Retrieve the currnent host buffer for transient storage.
Matrix GetShaderTransform(const RenderPass &pass) const
Definition: entity.cc:48
static std::unique_ptr< Geometry > MakeFillPath(const flutter::DlPath &path, std::optional< Rect > inner_rect=std::nullopt)
Definition: geometry.cc:62
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
virtual GeometryResult::Mode GetResultMode() const
Definition: geometry.cc:58
static std::unique_ptr< Geometry > MakeRect(const Rect &rect)
Definition: geometry.cc:83
static std::unique_ptr< Geometry > MakeFilledArc(const Rect &oval_bounds, Degrees start, Degrees sweep, bool include_center)
Definition: geometry.cc:108
static std::unique_ptr< Geometry > MakeStrokePath(const flutter::DlPath &path, const StrokeParameters &stroke={})
Definition: geometry.cc:68
static std::unique_ptr< Geometry > MakeCircle(const Point &center, Scalar radius)
Definition: geometry.cc:97
virtual bool CanApplyMaskFilter() const
Definition: geometry.cc:144
static std::unique_ptr< Geometry > MakeRoundRect(const Rect &rect, const Size &radii)
Definition: geometry.cc:125
static GeometryResult ComputePositionGeometry(const ContentContext &renderer, const Tessellator::VertexGenerator &generator, const Entity &entity, RenderPass &pass)
Definition: geometry.cc:26
virtual bool CoversArea(const Matrix &transform, const Rect &rect) const
Determines if this geometry, transformed by the given transform, will completely cover all surface ar...
Definition: geometry.cc:136
static std::unique_ptr< Geometry > MakeLine(const Point &p0, const Point &p1, const StrokeParameters &stroke)
Definition: geometry.cc:91
static std::unique_ptr< Geometry > MakeOval(const Rect &rect)
Definition: geometry.cc:87
static std::unique_ptr< Geometry > MakeStrokedCircle(const Point &center, Scalar radius, Scalar stroke_width)
Definition: geometry.cc:102
static std::unique_ptr< Geometry > MakeRoundSuperellipse(const Rect &rect, Scalar corner_radius)
Definition: geometry.cc:130
static std::unique_ptr< Geometry > MakeCover()
Definition: geometry.cc:79
static std::unique_ptr< Geometry > MakeStrokedArc(const Rect &oval_bounds, Degrees start, Degrees sweep, const StrokeParameters &stroke)
Definition: geometry.cc:116
virtual bool IsAxisAlignedRect() const
Definition: geometry.cc:140
BufferView Emplace(const BufferType &buffer, size_t alignment=0)
Emplace non-uniform data (like contiguous vertices) onto the host buffer.
Definition: host_buffer.h:92
Render passes encode render commands directed as one specific render target into an underlying comman...
Definition: render_pass.h:30
An object which produces a list of vertices as |Point|s that tessellate a previously provided shape a...
Definition: tessellator.h:110
virtual size_t GetVertexCount() const =0
Returns the number of vertices that the generator plans to produce, if known.
virtual PrimitiveType GetTriangleType() const =0
Returns the |PrimitiveType| that describes the relationship among the list of vertices produced by th...
virtual void GenerateVertices(const TessellatedVertexProc &proc) const =0
Generate the vertices and deliver them in the necessary order (as required by the PrimitiveType) to t...
@ kNone
Does not use the index buffer.
float Scalar
Definition: scalar.h:19
flutter::DlPath DlPath
Definition: dl_dispatcher.h:29
static constexpr Scalar kMinStrokeSize
Definition: geometry.h:19
PrimitiveType type
Definition: geometry.h:37
@ kNormal
The geometry has no overlapping triangles.
A 4x4 matrix using column-major storage.
Definition: matrix.h:37
A structure to store all of the parameters related to stroking a path or basic geometry object.
const size_t start