| Flutter Impeller |

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_IMPELLER_RENDERER_CONTEXT_H_
6 #define FLUTTER_IMPELLER_RENDERER_CONTEXT_H_
7
8 #include <memory>
9 #include <string>
10
11 #include "fml/closure.h"
12 #include "impeller/core/allocator.h"
13 #include "impeller/core/formats.h"
14 #include "impeller/renderer/capabilities.h"
15 #include "impeller/renderer/command_queue.h"
16 #include "impeller/renderer/sampler_library.h"
17
18 namespace impeller {
19
20 class ShaderLibrary;
21 class CommandBuffer;
22 class PipelineLibrary;
23
24 //------------------------------------------------------------------------------
25 /// @brief To do anything rendering related with Impeller, you need a
26 /// context.
27 ///
28 /// Contexts are expensive to construct and typically you only need
29 /// one in the process. The context represents a connection to a
30 /// graphics or compute accelerator on the device.
31 ///
32 /// If there are multiple context in a process, it would typically
33 /// be for separation of concerns (say, use with multiple engines in
34 /// Flutter), talking to multiple accelerators, or talking to the
35 /// same accelerator using different client APIs (Metal, Vulkan,
36 /// OpenGL ES, etc..).
37 ///
38 /// Contexts are thread-safe. They may be created, used, and
39 /// collected (though not from a thread used by an internal pool) on
40 /// any thread. They may also be accessed simultaneously from
41 /// multiple threads.
42 ///
43 /// Contexts are abstract and a concrete instance must be created
44 /// using one of the subclasses of `Context` in
45 /// `//impeller/renderer/backend`.
46 class Context {
47 public:
48 enum class BackendType {
49 kMetal,
50 kOpenGLES,
51 kVulkan,
52 };
53
54 /// The maximum number of tasks that should ever be stored for
55 /// `StoreTaskForGPU`.
56 ///
57 /// This number was arbitrarily chosen. The idea is that this is a somewhat
58 /// rare situation where tasks happen to get executed in that tiny amount of
59 /// time while an app is being backgrounded but still executing.
60 static constexpr int32_t kMaxTasksAwaitingGPU = 10;
61
62 //----------------------------------------------------------------------------
63 /// @brief Destroys an Impeller context.
64 ///
65 virtual ~Context();
66
67 //----------------------------------------------------------------------------
68 /// @brief Get the graphics backend of an Impeller context.
69 ///
70 /// This is useful for cases where a renderer needs to track and
71 /// lookup backend-specific resources, like shaders or uniform
72 /// layout information.
73 ///
74 /// It's not recommended to use this as a substitute for
75 /// per-backend capability checking. Instead, check for specific
76 /// capabilities via `GetCapabilities()`.
77 ///
78 /// @return The graphics backend of the `Context`.
79 ///
80 virtual BackendType GetBackendType() const = 0;
81
82 // TODO(129920): Refactor and move to capabilities.
83 virtual std::string DescribeGpuModel() const = 0;
84
85 //----------------------------------------------------------------------------
86 /// @brief Determines if a context is valid. If the caller ever receives
87 /// an invalid context, they must discard it and construct a new
88 /// context. There is no recovery mechanism to repair a bad
89 /// context.
90 ///
91 /// It is convention in Impeller to never return an invalid
92 /// context from a call that returns an pointer to a context. The
93 /// call implementation performs validity checks itself and return
94 /// a null context instead of a pointer to an invalid context.
95 ///
96 /// How a context goes invalid is backend specific. It could
97 /// happen due to device loss, or any other unrecoverable error.
98 ///
99 /// @return If the context is valid.
100 ///
101 virtual bool IsValid() const = 0;
102
103 //----------------------------------------------------------------------------
104 /// @brief Get the capabilities of Impeller context. All optionally
105 /// supported feature of the platform, client-rendering API, and
106 /// device can be queried using the `Capabilities`.
107 ///
108 /// @return The capabilities. Can never be `nullptr` for a valid context.
109 ///
110 virtual const std::shared_ptr<const Capabilities>& GetCapabilities()
111 const = 0;
112
113 // TODO(129920): Refactor and move to capabilities.
114 virtual bool UpdateOffscreenLayerPixelFormat(PixelFormat format);
115
116 //----------------------------------------------------------------------------
117 /// @brief Returns the allocator used to create textures and buffers on
118 /// the device.
119 ///
120 /// @return The resource allocator. Can never be `nullptr` for a valid
121 /// context.
122 ///
123 virtual std::shared_ptr<Allocator> GetResourceAllocator() const = 0;
124
125 //----------------------------------------------------------------------------
126 /// @brief Returns the library of shaders used to specify the
127 /// programmable stages of a pipeline.
128 ///
129 /// @return The shader library. Can never be `nullptr` for a valid
130 /// context.
131 ///
132 virtual std::shared_ptr<ShaderLibrary> GetShaderLibrary() const = 0;
133
134 //----------------------------------------------------------------------------
135 /// @brief Returns the library of combined image samplers used in
136 /// shaders.
137 ///
138 /// @return The sampler library. Can never be `nullptr` for a valid
139 /// context.
140 ///
141 virtual std::shared_ptr<SamplerLibrary> GetSamplerLibrary() const = 0;
142
143 //----------------------------------------------------------------------------
144 /// @brief Returns the library of pipelines used by render or compute
145 /// commands.
146 ///
147 /// @return The pipeline library. Can never be `nullptr` for a valid
148 /// context.
149 ///
150 virtual std::shared_ptr<PipelineLibrary> GetPipelineLibrary() const = 0;
151
152 //----------------------------------------------------------------------------
153 /// @brief Create a new command buffer. Command buffers can be used to
154 /// encode graphics, blit, or compute commands to be submitted to
155 /// the device.
156 ///
157 /// A command buffer can only be used on a single thread.
158 /// Multi-threaded render, blit, or compute passes must create a
159 /// new command buffer on each thread.
160 ///
161 /// @return A new command buffer.
162 ///
163 virtual std::shared_ptr<CommandBuffer> CreateCommandBuffer() const = 0;
164
165 /// @brief Return the graphics queue for submitting command buffers.
166 virtual std::shared_ptr<CommandQueue> GetCommandQueue() const = 0;
167
168 //----------------------------------------------------------------------------
169 /// @brief Force all pending asynchronous work to finish. This is
170 /// achieved by deleting all owned concurrent message loops.
171 ///
172 virtual void Shutdown() = 0;
173
174 /// Stores a task on the `ContextMTL` that is awaiting access for the GPU.
175 ///
176 /// The task will be executed in the event that the GPU access has changed to
177 /// being available or that the task has been canceled. The task should
178 /// operate with the `SyncSwitch` to make sure the GPU is accessible.
179 ///
180 /// If the queue of pending tasks is cleared without GPU access, then the
181 /// failure callback will be invoked and the primary task function will not
182 ///
183 /// Threadsafe.
184 ///
185 /// `task` will be executed on the platform thread.
186 virtual void StoreTaskForGPU(const fml::closure& task,
187 const fml::closure& failure) {
188 FML_CHECK(false && "not supported in this context");
189 }
190
191 /// Run backend specific additional setup and create common shader variants.
192 ///
193 /// This bootstrap is intended to improve the performance of several
194 /// first frame benchmarks that are tracked in the flutter device lab.
195 /// The workload includes initializing commonly used but not default
196 /// shader variants, as well as forcing driver initialization.
197 virtual void InitializeCommonlyUsedShadersIfNeeded() const {}
198
199 /// Dispose resources that are cached on behalf of the current thread.
200 ///
201 /// Some backends such as Vulkan may cache resources that can be reused while
202 /// executing a rendering operation. This API can be called after the
203 /// operation completes in order to clear the cache.
204 virtual void DisposeThreadLocalCachedResources() {}
205
206 protected:
207 Context();
208
209 std::vector<std::function<void()>> per_frame_task_;
210
211 private:
212 Context(const Context&) = delete;
213
214 Context& operator=(const Context&) = delete;
215 };
216
217 } // namespace impeller
218
219 #endif // FLUTTER_IMPELLER_RENDERER_CONTEXT_H_
impeller::Context::GetPipelineLibrary
virtual std::shared_ptr< PipelineLibrary > GetPipelineLibrary() const =0
Returns the library of pipelines used by render or compute commands.
impeller::Context::~Context
virtual ~Context()
Destroys an Impeller context.
impeller::Context::BackendType
BackendType
Definition: context.h:48
sampler_library.h
impeller::Context::GetCapabilities
virtual const std::shared_ptr< const Capabilities > & GetCapabilities() const =0
Get the capabilities of Impeller context. All optionally supported feature of the platform,...
command_queue.h
impeller::Context::GetShaderLibrary
virtual std::shared_ptr< ShaderLibrary > GetShaderLibrary() const =0
Returns the library of shaders used to specify the programmable stages of a pipeline.
formats.h
impeller::PixelFormat
PixelFormat
The Pixel formats supported by Impeller. The naming convention denotes the usage of the component,...
Definition: formats.h:99
impeller::Context::GetBackendType
virtual BackendType GetBackendType() const =0
Get the graphics backend of an Impeller context.
impeller::Context::StoreTaskForGPU
virtual void StoreTaskForGPU(const fml::closure &task, const fml::closure &failure)
Definition: context.h:186
impeller::Context::BackendType::kOpenGLES
@ kOpenGLES
impeller::Context::InitializeCommonlyUsedShadersIfNeeded
virtual void InitializeCommonlyUsedShadersIfNeeded() const
Definition: context.h:197
impeller::Context::Context
Context()
capabilities.h
impeller::Context::GetSamplerLibrary
virtual std::shared_ptr< SamplerLibrary > GetSamplerLibrary() const =0
Returns the library of combined image samplers used in shaders.
impeller::Context::CreateCommandBuffer
virtual std::shared_ptr< CommandBuffer > CreateCommandBuffer() const =0
Create a new command buffer. Command buffers can be used to encode graphics, blit,...
impeller::Context::GetCommandQueue
virtual std::shared_ptr< CommandQueue > GetCommandQueue() const =0
Return the graphics queue for submitting command buffers.
impeller::Context::IsValid
virtual bool IsValid() const =0
Determines if a context is valid. If the caller ever receives an invalid context, they must discard i...
allocator.h
impeller::Context::BackendType::kVulkan
@ kVulkan
impeller::Context::BackendType::kMetal
@ kMetal
impeller::Context
To do anything rendering related with Impeller, you need a context.
Definition: context.h:46
impeller::Context::DisposeThreadLocalCachedResources
virtual void DisposeThreadLocalCachedResources()
Definition: context.h:204
impeller::Context::Shutdown
virtual void Shutdown()=0
Force all pending asynchronous work to finish. This is achieved by deleting all owned concurrent mess...
impeller::Context::per_frame_task_
std::vector< std::function< void()> > per_frame_task_
Definition: context.h:209
impeller::Context::DescribeGpuModel
virtual std::string DescribeGpuModel() const =0
impeller
Definition: allocation.cc:12
impeller::Context::GetResourceAllocator
virtual std::shared_ptr< Allocator > GetResourceAllocator() const =0
Returns the allocator used to create textures and buffers on the device.
impeller::Context::UpdateOffscreenLayerPixelFormat
virtual bool UpdateOffscreenLayerPixelFormat(PixelFormat format)
Definition: context.cc:13
impeller::Context::kMaxTasksAwaitingGPU
static constexpr int32_t kMaxTasksAwaitingGPU
Definition: context.h:60