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