Flutter iOS Embedder
ios_context.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_SHELL_PLATFORM_DARWIN_IOS_IOS_CONTEXT_H_
6 #define FLUTTER_SHELL_PLATFORM_DARWIN_IOS_IOS_CONTEXT_H_
7 
8 #include <memory>
9 
10 #include "flutter/common/graphics/gl_context_switch.h"
11 #include "flutter/common/graphics/texture.h"
12 #include "flutter/fml/concurrent_message_loop.h"
13 #include "flutter/fml/macros.h"
14 #include "flutter/fml/platform/darwin/scoped_nsobject.h"
15 #include "flutter/fml/synchronization/sync_switch.h"
18 #include "impeller/display_list/aiks_context.h"
19 #include "third_party/skia/include/gpu/ganesh/GrDirectContext.h"
20 
21 namespace impeller {
22 class Context;
23 } // namespace impeller
24 
25 namespace flutter {
26 
27 //------------------------------------------------------------------------------
28 /// @brief Manages the lifetime of the on-screen and off-screen rendering
29 /// contexts on iOS. On-screen contexts are used by Flutter for
30 /// rendering into the surface. The lifecycle of this context may be
31 /// tied to the lifecycle of the surface. On the other hand, the
32 /// lifecycle of the off-screen context it tied to that of the
33 /// platform view. This one object used to manage both context
34 /// because GPU handles may need to be shared between the two
35 /// context. To achieve this, context may need references to one
36 /// another at creation time. This one object manages the creation,
37 /// use and collection of both contexts in a client rendering API
38 /// agnostic manner.
39 ///
40 class IOSContext {
41  public:
42  //----------------------------------------------------------------------------
43  /// @brief Create an iOS context object capable of creating the on-screen
44  /// and off-screen GPU context for use by Skia.
45  ///
46  /// In case the engine does not support the specified client
47  /// rendering API, this a `nullptr` may be returned.
48  ///
49  /// @param[in] api A client rendering API supported by the
50  /// engine/platform.
51  /// @param[in] backend A client rendering backend supported by the
52  /// engine/platform.
53  ///
54  /// @return A valid context on success. `nullptr` on failure.
55  ///
56  static std::unique_ptr<IOSContext> Create(
57  IOSRenderingAPI api,
58  IOSRenderingBackend backend,
59  const std::shared_ptr<const fml::SyncSwitch>& is_gpu_disabled_sync_switch);
60 
61  //----------------------------------------------------------------------------
62  /// @brief Collects the context object. This must happen on the thread on
63  /// which this object was created.
64  ///
65  virtual ~IOSContext();
66 
67  //----------------------------------------------------------------------------
68  /// @brief Get the rendering backend used by this context.
69  ///
70  /// @return The rendering backend.
71  ///
72  virtual IOSRenderingBackend GetBackend() const;
73 
74  //----------------------------------------------------------------------------
75  /// @brief Create a resource context for use on the IO task runner. This
76  /// resource context is used by Skia to upload texture to
77  /// asynchronously and collect resources that are no longer needed
78  /// on the render task runner.
79  ///
80  /// @attention Client rendering APIs for which a GrDirectContext cannot be realized
81  /// (software rendering), this method will always return null.
82  ///
83  /// @return A non-null Skia context on success. `nullptr` on failure.
84  ///
85  virtual sk_sp<GrDirectContext> CreateResourceContext() = 0;
86 
87  //----------------------------------------------------------------------------
88  /// @brief When using client rendering APIs whose contexts need to be
89  /// bound to a specific thread, the engine will call this method
90  /// to give the on-screen context a chance to bind to the current
91  /// thread.
92  ///
93  /// @attention Client rendering APIs that have no-concept of thread local
94  /// bindings (anything that is not OpenGL) will always return
95  /// `true`.
96  ///
97  /// @attention Client rendering APIs for which a GrDirectContext cannot be created
98  /// (software rendering) will always return `false`.
99  ///
100  /// @attention This binds the on-screen context to the current thread. To
101  /// bind the off-screen context to the thread, use the
102  /// `ResoruceMakeCurrent` method instead.
103  ///
104  /// @attention Only one context may be bound to a thread at any given time.
105  /// Making a binding on a thread, clears the old binding.
106  ///
107  /// @return A GLContextResult that represents the result of the method.
108  /// The GetResult() returns a bool that indicates If the on-screen context could be
109  /// bound to the current
110  /// thread.
111  ///
112  virtual std::unique_ptr<GLContextResult> MakeCurrent() = 0;
113 
114  //----------------------------------------------------------------------------
115  /// @brief Creates an external texture proxy of the appropriate client
116  /// rendering API.
117  ///
118  /// @param[in] texture_id The texture identifier
119  /// @param[in] texture The texture
120  ///
121  /// @return The texture proxy if the rendering backend supports embedder
122  /// provided external textures.
123  ///
124  virtual std::unique_ptr<Texture> CreateExternalTexture(
125  int64_t texture_id,
126  fml::scoped_nsobject<NSObject<FlutterTexture>> texture) = 0;
127 
128  //----------------------------------------------------------------------------
129  /// @brief Accessor for the Skia context associated with IOSSurfaces and
130  /// the raster thread.
131  /// @details There can be any number of resource contexts but this is the
132  /// one context that will be used by surfaces to draw to the
133  /// screen from the raster thread.
134  /// @returns `nullptr` on failure.
135  /// @attention The software context doesn't have a Skia context, so this
136  /// value will be nullptr.
137  /// @see For contexts which are used for offscreen work like loading
138  /// textures see IOSContext::CreateResourceContext.
139  ///
140  virtual sk_sp<GrDirectContext> GetMainContext() const = 0;
141 
142  virtual std::shared_ptr<impeller::Context> GetImpellerContext() const;
143 
144  virtual std::shared_ptr<impeller::AiksContext> GetAiksContext() const;
145 
146  protected:
147  explicit IOSContext();
148 
149  private:
150  FML_DISALLOW_COPY_AND_ASSIGN(IOSContext);
151 };
152 
153 } // namespace flutter
154 
155 #endif // FLUTTER_SHELL_PLATFORM_DARWIN_IOS_IOS_CONTEXT_H_
flutter::IOSContext::~IOSContext
virtual ~IOSContext()
Collects the context object. This must happen on the thread on which this object was created.
FlutterTexture.h
flutter::IOSContext
Manages the lifetime of the on-screen and off-screen rendering contexts on iOS. On-screen contexts ar...
Definition: ios_context.h:40
flutter::IOSRenderingBackend
IOSRenderingBackend
Definition: rendering_api_selection.h:19
flutter::IOSContext::GetAiksContext
virtual std::shared_ptr< impeller::AiksContext > GetAiksContext() const
Definition: ios_context.mm:66
flutter
Definition: accessibility_bridge.h:28
flutter::IOSRenderingAPI
IOSRenderingAPI
Definition: rendering_api_selection.h:14
flutter::IOSContext::MakeCurrent
virtual std::unique_ptr< GLContextResult > MakeCurrent()=0
When using client rendering APIs whose contexts need to be bound to a specific thread,...
flutter::IOSContext::GetBackend
virtual IOSRenderingBackend GetBackend() const
Get the rendering backend used by this context.
Definition: ios_context.mm:58
flutter::IOSContext::GetMainContext
virtual sk_sp< GrDirectContext > GetMainContext() const =0
Accessor for the Skia context associated with IOSSurfaces and the raster thread.
rendering_api_selection.h
flutter::IOSContext::CreateResourceContext
virtual sk_sp< GrDirectContext > CreateResourceContext()=0
Create a resource context for use on the IO task runner. This resource context is used by Skia to upl...
flutter::IOSContext::IOSContext
IOSContext()
texture_id
int64_t texture_id
Definition: texture_registrar_unittests.cc:24
impeller
Definition: ios_context.h:21
flutter::IOSContext::Create
static std::unique_ptr< IOSContext > Create(IOSRenderingAPI api, IOSRenderingBackend backend, const std::shared_ptr< const fml::SyncSwitch > &is_gpu_disabled_sync_switch)
Create an iOS context object capable of creating the on-screen and off-screen GPU context for use by ...
Definition: ios_context.mm:23
flutter::IOSContext::CreateExternalTexture
virtual std::unique_ptr< Texture > CreateExternalTexture(int64_t texture_id, fml::scoped_nsobject< NSObject< FlutterTexture >> texture)=0
Creates an external texture proxy of the appropriate client rendering API.
flutter::IOSContext::GetImpellerContext
virtual std::shared_ptr< impeller::Context > GetImpellerContext() const
Definition: ios_context.mm:62