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tessellator_libtess.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_TESSELLATOR_TESSELLATOR_LIBTESS_H_
6 #define FLUTTER_IMPELLER_TESSELLATOR_TESSELLATOR_LIBTESS_H_
7
8 #include <functional>
9 #include <memory>
10
11 #include "flutter/impeller/geometry/path_source.h"
12
13 struct TESStesselator;
14
15 namespace impeller {
16
17 void DestroyTessellator(TESStesselator* tessellator);
18
19 using CTessellator =
20 std::unique_ptr<TESStesselator, decltype(&DestroyTessellator)>;
21
22 //------------------------------------------------------------------------------
23 /// @brief An extended tessellator that offers arbitrary/concave
24 /// tessellation via the libtess2 library.
25 ///
26 /// This object is not thread safe, and its methods must not be
27 /// called from multiple threads.
28 ///
29 class TessellatorLibtess {
30 public:
31 TessellatorLibtess();
32
33 ~TessellatorLibtess();
34
35 enum class Result {
36 kSuccess,
37 kInputError,
38 kTessellationError,
39 };
40
41 /// @brief A callback that returns the results of the tessellation.
42 ///
43 /// The index buffer may not be populated, in which case [indices] will
44 /// be nullptr and indices_count will be 0.
45 using BuilderCallback = std::function<bool(const float* vertices,
46 size_t vertices_count,
47 const uint16_t* indices,
48 size_t indices_count)>;
49
50 //----------------------------------------------------------------------------
51 /// @brief Generates filled triangles from the path. A callback is
52 /// invoked once for the entire tessellation.
53 ///
54 /// @param[in] source The path source to tessellate.
55 /// @param[in] tolerance The tolerance value for conversion of the path to
56 /// a polyline. This value is often derived from the
57 /// Matrix::GetMaxBasisLength of the CTM applied to the
58 /// path for rendering.
59 /// @param[in] callback The callback, return false to indicate failure.
60 ///
61 /// @return The result status of the tessellation.
62 ///
63 TessellatorLibtess::Result Tessellate(const PathSource& source,
64 Scalar tolerance,
65 const BuilderCallback& callback);
66
67 private:
68 CTessellator c_tessellator_;
69
70 TessellatorLibtess(const TessellatorLibtess&) = delete;
71
72 TessellatorLibtess& operator=(const TessellatorLibtess&) = delete;
73 };
74
75 } // namespace impeller
76
77 #endif // FLUTTER_IMPELLER_TESSELLATOR_TESSELLATOR_LIBTESS_H_
impeller::PathSource
Definition: path_source.h:55
impeller::TessellatorLibtess
An extended tessellator that offers arbitrary/concave tessellation via the libtess2 library.
Definition: tessellator_libtess.h:29
impeller::TessellatorLibtess::BuilderCallback
std::function< bool(const float *vertices, size_t vertices_count, const uint16_t *indices, size_t indices_count)> BuilderCallback
A callback that returns the results of the tessellation.
Definition: tessellator_libtess.h:48
impeller::TessellatorLibtess::Result
Result
Definition: tessellator_libtess.h:35
impeller::TessellatorLibtess::Result::kSuccess
@ kSuccess
impeller::TessellatorLibtess::Result::kInputError
@ kInputError
impeller::TessellatorLibtess::Result::kTessellationError
@ kTessellationError
impeller::TessellatorLibtess::Tessellate
TessellatorLibtess::Result Tessellate(const PathSource &source, Scalar tolerance, const BuilderCallback &callback)
Generates filled triangles from the path. A callback is invoked once for the entire tessellation.
Definition: tessellator_libtess.cc:85
impeller::TessellatorLibtess::TessellatorLibtess
TessellatorLibtess()
Definition: tessellator_libtess.cc:35
impeller::TessellatorLibtess::~TessellatorLibtess
~TessellatorLibtess()
impeller
Definition: allocation.cc:12
impeller::Scalar
float Scalar
Definition: scalar.h:19
impeller::DestroyTessellator
void DestroyTessellator(TESStesselator *tessellator)
Definition: tessellator_libtess.cc:186
impeller::CTessellator
std::unique_ptr< TESStesselator, decltype(&DestroyTessellator)> CTessellator
Definition: tessellator_libtess.h:20
path_source.h