| Flutter Impeller |

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_GEOMETRY_H_
6 #define FLUTTER_IMPELLER_ENTITY_GEOMETRY_GEOMETRY_H_
7
8 #include "impeller/core/formats.h"
9 #include "impeller/core/vertex_buffer.h"
10 #include "impeller/entity/contents/content_context.h"
11 #include "impeller/entity/entity.h"
12 #include "impeller/renderer/render_pass.h"
13 #include "impeller/renderer/vertex_buffer_builder.h"
14
15 namespace impeller {
16
17 class Tessellator;
18
19 static constexpr Scalar kMinStrokeSize = 1.0f;
20
21 struct GeometryResult {
22 enum class Mode {
23 /// The geometry has no overlapping triangles.
24 kNormal,
25 /// The geometry may have overlapping triangles. The geometry should be
26 /// stenciled with the NonZero fill rule.
27 kNonZero,
28 /// The geometry may have overlapping triangles. The geometry should be
29 /// stenciled with the EvenOdd fill rule.
30 kEvenOdd,
31 /// The geometry may have overlapping triangles, but they should not
32 /// overdraw or cancel each other out. This is a special case for stroke
33 /// geometry.
34 kPreventOverdraw,
35 };
36
37 PrimitiveType type = PrimitiveType::kTriangleStrip;
38 VertexBuffer vertex_buffer;
39 Matrix transform;
40 Mode mode = Mode::kNormal;
41 };
42
43 static const GeometryResult kEmptyResult = {
44 .vertex_buffer =
45 {
46 .index_type = IndexType::kNone,
47 },
48 };
49
50 class Geometry {
51 public:
52 virtual ~Geometry() {}
53
54 static std::unique_ptr<Geometry> MakeFillPath(
55 const Path& path,
56 std::optional<Rect> inner_rect = std::nullopt);
57
58 static std::unique_ptr<Geometry> MakeStrokePath(
59 const Path& path,
60 Scalar stroke_width = 0.0,
61 Scalar miter_limit = 4.0,
62 Cap stroke_cap = Cap::kButt,
63 Join stroke_join = Join::kMiter);
64
65 static std::unique_ptr<Geometry> MakeCover();
66
67 static std::unique_ptr<Geometry> MakeRect(const Rect& rect);
68
69 static std::unique_ptr<Geometry> MakeOval(const Rect& rect);
70
71 static std::unique_ptr<Geometry> MakeLine(const Point& p0,
72 const Point& p1,
73 Scalar width,
74 Cap cap);
75
76 static std::unique_ptr<Geometry> MakeCircle(const Point& center,
77 Scalar radius);
78
79 static std::unique_ptr<Geometry> MakeStrokedCircle(const Point& center,
80 Scalar radius,
81 Scalar stroke_width);
82
83 static std::unique_ptr<Geometry> MakeRoundRect(const Rect& rect,
84 const Size& radii);
85
86 virtual GeometryResult GetPositionBuffer(const ContentContext& renderer,
87 const Entity& entity,
88 RenderPass& pass) const = 0;
89
90 virtual GeometryResult::Mode GetResultMode() const;
91
92 virtual std::optional<Rect> GetCoverage(const Matrix& transform) const = 0;
93
94 /// @brief Compute an alpha value to simulate lower coverage of fractional
95 /// pixel strokes.
96 static Scalar ComputeStrokeAlphaCoverage(const Matrix& entity,
97 Scalar stroke_width);
98
99 /// @brief Determines if this geometry, transformed by the given
100 /// `transform`, will completely cover all surface area of the given
101 /// `rect`.
102 ///
103 /// This is a conservative estimate useful for certain
104 /// optimizations.
105 ///
106 /// @returns `true` if the transformed geometry is guaranteed to cover the
107 /// given `rect`. May return `false` in many undetected cases where
108 /// the transformed geometry does in fact cover the `rect`.
109 virtual bool CoversArea(const Matrix& transform, const Rect& rect) const;
110
111 virtual bool IsAxisAlignedRect() const;
112
113 virtual bool CanApplyMaskFilter() const;
114
115 virtual Scalar ComputeAlphaCoverage(const Matrix& transform) const {
116 return 1.0;
117 }
118
119 protected:
120 static GeometryResult ComputePositionGeometry(
121 const ContentContext& renderer,
122 const Tessellator::VertexGenerator& generator,
123 const Entity& entity,
124 RenderPass& pass);
125 };
126
127 } // namespace impeller
128
129 #endif // FLUTTER_IMPELLER_ENTITY_GEOMETRY_GEOMETRY_H_
impeller::GeometryResult::Mode::kNormal
@ kNormal
The geometry has no overlapping triangles.
impeller::VertexBuffer::index_type
IndexType index_type
Definition: vertex_buffer.h:31
impeller::Geometry::ComputeAlphaCoverage
virtual Scalar ComputeAlphaCoverage(const Matrix &transform) const
Definition: geometry.h:115
impeller::Scalar
float Scalar
Definition: scalar.h:18
impeller::Geometry::MakeCircle
static std::unique_ptr< Geometry > MakeCircle(const Point &center, Scalar radius)
Definition: geometry.cc:97
vertex_buffer.h
entity.h
impeller::Geometry::GetCoverage
virtual std::optional< Rect > GetCoverage(const Matrix &transform) const =0
impeller::VertexBuffer
Definition: vertex_buffer.h:15
impeller::Geometry::~Geometry
virtual ~Geometry()
Definition: geometry.h:52
impeller::Geometry::CanApplyMaskFilter
virtual bool CanApplyMaskFilter() const
Definition: geometry.cc:121
formats.h
impeller::Geometry::MakeOval
static std::unique_ptr< Geometry > MakeOval(const Rect &rect)
Definition: geometry.cc:86
impeller::Geometry::IsAxisAlignedRect
virtual bool IsAxisAlignedRect() const
Definition: geometry.cc:117
impeller::Geometry::GetResultMode
virtual GeometryResult::Mode GetResultMode() const
Definition: geometry.cc:55
impeller::Geometry::CoversArea
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:113
impeller::Cap::kButt
@ kButt
impeller::GeometryResult::Mode::kEvenOdd
@ kEvenOdd
stroke_width
const Scalar stroke_width
Definition: stroke_path_geometry.cc:312
impeller::kMinStrokeSize
static constexpr Scalar kMinStrokeSize
Definition: geometry.h:19
impeller::GeometryResult::Mode
Mode
Definition: geometry.h:22
impeller::Join::kMiter
@ kMiter
impeller::Geometry::ComputePositionGeometry
static GeometryResult ComputePositionGeometry(const ContentContext &renderer, const Tessellator::VertexGenerator &generator, const Entity &entity, RenderPass &pass)
Definition: geometry.cc:23
impeller::Entity
Definition: entity.h:20
impeller::TSize< Scalar >
impeller::Tessellator::VertexGenerator
An object which produces a list of vertices as |Point|s that tessellate a previously provided shape a...
Definition: tessellator.h:94
impeller::PrimitiveType::kTriangleStrip
@ kTriangleStrip
impeller::PrimitiveType
PrimitiveType
Decides how backend draws pixels based on input vertices.
Definition: formats.h:352
render_pass.h
impeller::GeometryResult::type
PrimitiveType type
Definition: geometry.h:37
impeller::Geometry::GetPositionBuffer
virtual GeometryResult GetPositionBuffer(const ContentContext &renderer, const Entity &entity, RenderPass &pass) const =0
impeller::Path
Paths are lightweight objects that describe a collection of linear, quadratic, or cubic segments....
Definition: path.h:53
impeller::Geometry::MakeStrokePath
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)
Definition: geometry.cc:65
transform
Matrix transform
Definition: gaussian_blur_filter_contents.cc:214
impeller::Geometry::MakeStrokedCircle
static std::unique_ptr< Geometry > MakeStrokedCircle(const Point &center, Scalar radius, Scalar stroke_width)
Definition: geometry.cc:102
impeller::GeometryResult
Definition: geometry.h:21
impeller::IndexType::kNone
@ kNone
Does not use the index buffer.
impeller::Geometry::MakeRoundRect
static std::unique_ptr< Geometry > MakeRoundRect(const Rect &rect, const Size &radii)
Definition: geometry.cc:108
impeller::Geometry::MakeCover
static std::unique_ptr< Geometry > MakeCover()
Definition: geometry.cc:78
impeller::RenderPass
Render passes encode render commands directed as one specific render target into an underlying comman...
Definition: render_pass.h:30
impeller::Geometry::MakeRect
static std::unique_ptr< Geometry > MakeRect(const Rect &rect)
Definition: geometry.cc:82
impeller::GeometryResult::transform
Matrix transform
Definition: geometry.h:39
content_context.h
impeller::Geometry
Definition: geometry.h:50
impeller::Join
Join
Definition: path.h:25
impeller::kEmptyResult
static const GeometryResult kEmptyResult
Definition: geometry.h:43
impeller::Geometry::MakeLine
static std::unique_ptr< Geometry > MakeLine(const Point &p0, const Point &p1, Scalar width, Cap cap)
Definition: geometry.cc:90
impeller::TPoint
Definition: point.h:27
impeller::Geometry::MakeFillPath
static std::unique_ptr< Geometry > MakeFillPath(const Path &path, std::optional< Rect > inner_rect=std::nullopt)
Definition: geometry.cc:59
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:126
impeller::GeometryResult::Mode::kPreventOverdraw
@ kPreventOverdraw
impeller::GeometryResult::vertex_buffer
VertexBuffer vertex_buffer
Definition: geometry.h:38
impeller
Definition: allocation.cc:12
impeller::ContentContext
Definition: content_context.h:371
impeller::TRect
Definition: rect.h:122
impeller::GeometryResult::mode
Mode mode
Definition: geometry.h:40
impeller::Matrix
A 4x4 matrix using column-major storage.
Definition: matrix.h:37
impeller::Cap
Cap
Definition: path.h:19
impeller::GeometryResult::Mode::kNonZero
@ kNonZero
vertex_buffer_builder.h