[Windows] Allow apps to prefer low power GPUs (flutter#162490)

…and make ANGLE backend to choose low-power GPU when this flag is
provided.

## Pre-launch Checklist

- [ ] I read the [Contributor Guide] and followed the process outlined
there for submitting PRs.
- [ ] I read the [Tree Hygiene] wiki page, which explains my
responsibilities.
- [ ] I read and followed the [Flutter Style Guide], including [Features
we expect every widget to implement].
- [ ] I signed the [CLA].
- [ ] I listed at least one issue that this PR fixes in the description
above.
- [ ] I updated/added relevant documentation (doc comments with `///`).
- [ ] I added new tests to check the change I am making, or this PR is
[test-exempt].
- [ ] I followed the [breaking change policy] and added [Data Driven
Fixes] where supported.
- [ ] All existing and new tests are passing.

If you need help, consider asking for advice on the #hackers-new channel
on [Discord].

<!-- Links -->
[Contributor Guide]:
https://github.com/flutter/flutter/blob/main/docs/contributing/Tree-hygiene.md#overview
[Tree Hygiene]:
https://github.com/flutter/flutter/blob/main/docs/contributing/Tree-hygiene.md
[test-exempt]:
https://github.com/flutter/flutter/blob/main/docs/contributing/Tree-hygiene.md#tests
[Flutter Style Guide]:
https://github.com/flutter/flutter/blob/main/docs/contributing/Style-guide-for-Flutter-repo.md
[Features we expect every widget to implement]:
https://github.com/flutter/flutter/blob/main/docs/contributing/Style-guide-for-Flutter-repo.md#features-we-expect-every-widget-to-implement
[CLA]: https://cla.developers.google.com/
[flutter/tests]: https://github.com/flutter/tests
[breaking change policy]:
https://github.com/flutter/flutter/blob/main/docs/contributing/Tree-hygiene.md#handling-breaking-changes
[Discord]:
https://github.com/flutter/flutter/blob/main/docs/contributing/Chat.md
[Data Driven Fixes]:
https://github.com/flutter/flutter/blob/main/docs/contributing/Data-driven-Fixes.md

Author: zaiste-linganer

engine/src/flutter/shell/platform/windows/client_wrapper/flutter_engine.cc

@@ -17,6 +17,8 @@ FlutterEngine::FlutterEngine(const DartProject& project) {
   c_engine_properties.icu_data_path = project.icu_data_path().c_str();
   c_engine_properties.aot_library_path = project.aot_library_path().c_str();
   c_engine_properties.dart_entrypoint = project.dart_entrypoint().c_str();
+  c_engine_properties.gpu_preference =
+      static_cast<FlutterDesktopGpuPreference>(project.gpu_preference());
 
   const std::vector<std::string>& entrypoint_args =
       project.dart_entrypoint_arguments();

engine/src/flutter/shell/platform/windows/client_wrapper/include/flutter/dart_project.h

@@ -10,6 +10,16 @@
 
 namespace flutter {
 
+// Configures how the Flutter engine selects a GPU.
+enum class GpuPreference {
+  // No preference.
+  NoPreference,
+  // Prefer energy efficiency over performance, such as an integrated GPU.
+  // This falls back to a high performance GPU if no low power GPU is
+  // available.
+  LowPowerPreference,
+};
+
 // A set of Flutter and Dart assets used to initialize a Flutter engine.
 class DartProject {
  public:
@@ -71,6 +81,15 @@ class DartProject {
     return dart_entrypoint_arguments_;
   }
 
+  // Sets the GPU usage preference for flutter engine.
+  void set_gpu_preference(GpuPreference gpu_preference) {
+    gpu_preference_ = gpu_preference;
+  }
+
+  // Returns the project's GPU preference.
+  // Defaults to NoPreference.
+  GpuPreference gpu_preference() const { return gpu_preference_; }
+
  private:
   // Accessors for internals are private, so that they can be changed if more
   // flexible options for project structures are needed later without it
@@ -95,6 +114,8 @@ class DartProject {
   std::string dart_entrypoint_;
   // The list of arguments to pass through to the Dart entrypoint.
   std::vector<std::string> dart_entrypoint_arguments_;
+  // The preference for GPU to be used by flutter engine.
+  GpuPreference gpu_preference_ = GpuPreference::NoPreference;
 };
 
 }  // namespace flutter

engine/src/flutter/shell/platform/windows/egl/manager.cc

@@ -14,19 +14,19 @@ namespace egl {
 
 int Manager::instance_count_ = 0;
 
-std::unique_ptr<Manager> Manager::Create() {
+std::unique_ptr<Manager> Manager::Create(GpuPreference gpu_preference) {
   std::unique_ptr<Manager> manager;
-  manager.reset(new Manager());
+  manager.reset(new Manager(gpu_preference));
   if (!manager->IsValid()) {
     return nullptr;
   }
   return std::move(manager);
 }
 
-Manager::Manager() {
+Manager::Manager(GpuPreference gpu_preference) {
   ++instance_count_;
 
-  if (!InitializeDisplay()) {
+  if (!InitializeDisplay(gpu_preference)) {
     return;
   }
 
@@ -46,7 +46,40 @@ Manager::~Manager() {
   --instance_count_;
 }
 
-bool Manager::InitializeDisplay() {
+bool Manager::InitializeDisplay(GpuPreference gpu_preference) {
+  // If the request for a low power GPU is provided,
+  // we will attempt to select GPU explicitly, via ANGLE extension
+  // that allows to specify the GPU to use via LUID.
+  std::optional<LUID> luid = std::nullopt;
+  if (gpu_preference == GpuPreference::LowPowerPreference) {
+    luid = GetLowPowerGpuLuid();
+  }
+
+  // These are preferred display attributes and request ANGLE's D3D11
+  // renderer (use only in case of valid LUID returned from above).
+  const EGLint d3d11_display_attributes_with_luid[] = {
+      EGL_PLATFORM_ANGLE_TYPE_ANGLE,
+      EGL_PLATFORM_ANGLE_TYPE_D3D11_ANGLE,
+
+      // EGL_PLATFORM_ANGLE_ENABLE_AUTOMATIC_TRIM_ANGLE is an option that will
+      // enable ANGLE to automatically call the IDXGIDevice3::Trim method on
+      // behalf of the application when it gets suspended.
+      EGL_PLATFORM_ANGLE_ENABLE_AUTOMATIC_TRIM_ANGLE,
+      EGL_TRUE,
+
+      // This extension allows angle to render directly on a D3D swapchain
+      // in the correct orientation on D3D11.
+      EGL_EXPERIMENTAL_PRESENT_PATH_ANGLE,
+      EGL_EXPERIMENTAL_PRESENT_PATH_FAST_ANGLE,
+
+      // Specify the LUID of the GPU to use.
+      EGL_PLATFORM_ANGLE_D3D_LUID_HIGH_ANGLE,
+      static_cast<EGLint>(luid.has_value() ? luid->HighPart : 0),
+      EGL_PLATFORM_ANGLE_D3D_LUID_LOW_ANGLE,
+      static_cast<EGLint>(luid.has_value() ? luid->LowPart : 0),
+      EGL_NONE,
+  };
+
   // These are preferred display attributes and request ANGLE's D3D11
   // renderer. eglInitialize will only succeed with these attributes if the
   // hardware supports D3D11 Feature Level 10_0+.
@@ -92,11 +125,15 @@ bool Manager::InitializeDisplay() {
       EGL_NONE,
   };
 
-  std::vector<const EGLint*> display_attributes_configs = {
-      d3d11_display_attributes,
-      d3d11_fl_9_3_display_attributes,
-      d3d11_warp_display_attributes,
-  };
+  std::vector<const EGLint*> display_attributes_configs;
+
+  if (luid) {
+    // If LUID value is present, obtain an adapter with that luid.
+    display_attributes_configs.push_back(d3d11_display_attributes_with_luid);
+  }
+  display_attributes_configs.push_back(d3d11_display_attributes);
+  display_attributes_configs.push_back(d3d11_fl_9_3_display_attributes);
+  display_attributes_configs.push_back(d3d11_warp_display_attributes);
 
   PFNEGLGETPLATFORMDISPLAYEXTPROC egl_get_platform_display_EXT =
       reinterpret_cast<PFNEGLGETPLATFORMDISPLAYEXTPROC>(
@@ -296,5 +333,33 @@ Context* Manager::resource_context() const {
   return resource_context_.get();
 }
 
+std::optional<LUID> Manager::GetLowPowerGpuLuid() {
+  Microsoft::WRL::ComPtr<IDXGIFactory1> factory1 = nullptr;
+  Microsoft::WRL::ComPtr<IDXGIFactory6> factory6 = nullptr;
+  Microsoft::WRL::ComPtr<IDXGIAdapter1> adapter = nullptr;
+  HRESULT hr = ::CreateDXGIFactory1(IID_PPV_ARGS(&factory1));
+  if (FAILED(hr)) {
+    return std::nullopt;
+  }
+  hr = factory1->QueryInterface(IID_PPV_ARGS(&factory6));
+  if (FAILED(hr)) {
+    // No support for IDXGIFactory6, so we will not use the selected GPU.
+    // We will follow with the default ANGLE selection.
+    return std::nullopt;
+  }
+  hr = factory6->EnumAdapterByGpuPreference(
+      0, DXGI_GPU_PREFERENCE_MINIMUM_POWER, IID_PPV_ARGS(&adapter));
+  if (FAILED(hr) || adapter == nullptr) {
+    return std::nullopt;
+  }
+  // Get the LUID of the adapter.
+  DXGI_ADAPTER_DESC desc;
+  hr = adapter->GetDesc(&desc);
+  if (FAILED(hr)) {
+    return std::nullopt;
+  }
+  return std::make_optional(desc.AdapterLuid);
+}
+
 }  // namespace egl
 }  // namespace flutter

engine/src/flutter/shell/platform/windows/egl/manager.h

@@ -14,9 +14,12 @@
 
 // Windows platform specific includes
 #include <d3d11.h>
+#include <dxgi.h>
+#include <dxgi1_6.h>
 #include <windows.h>
 #include <wrl/client.h>
 #include <memory>
+#include <optional>
 
 #include "flutter/fml/macros.h"
 #include "flutter/shell/platform/windows/egl/context.h"
@@ -26,11 +29,16 @@
 namespace flutter {
 namespace egl {
 
+enum class GpuPreference {
+  NoPreference,
+  LowPowerPreference,
+};
+
 // A manager for initializing ANGLE correctly and using it to create and
 // destroy surfaces
 class Manager {
  public:
-  static std::unique_ptr<Manager> Create();
+  static std::unique_ptr<Manager> Create(GpuPreference gpu_preference);
 
   virtual ~Manager();
 
@@ -71,17 +79,19 @@ class Manager {
   // Get the EGL context used for async texture uploads.
   virtual Context* resource_context() const;
 
+  static std::optional<LUID> GetLowPowerGpuLuid();
+
  protected:
   // Creates a new surface manager retaining reference to the passed-in target
   // for the lifetime of the manager.
-  explicit Manager();
+  explicit Manager(GpuPreference gpu_preference);
 
  private:
   // Number of active instances of Manager
   static int instance_count_;
 
   // Initialize the EGL display.
-  bool InitializeDisplay();
+  bool InitializeDisplay(GpuPreference gpu_preference);
 
   // Initialize the EGL configs.
   bool InitializeConfig();

engine/src/flutter/shell/platform/windows/flutter_project_bundle.cc

@@ -29,6 +29,9 @@ FlutterProjectBundle::FlutterProjectBundle(
         std::string(properties.dart_entrypoint_argv[i]));
   }
 
+  gpu_preference_ =
+      static_cast<FlutterGpuPreference>(properties.gpu_preference);
+
   // Resolve any relative paths.
   if (assets_path_.is_relative() || icu_path_.is_relative() ||
       (!aot_library_path_.empty() && aot_library_path_.is_relative())) {

engine/src/flutter/shell/platform/windows/flutter_project_bundle.h

@@ -17,6 +17,11 @@ namespace flutter {
 using UniqueAotDataPtr =
     std::unique_ptr<_FlutterEngineAOTData, FlutterEngineCollectAOTDataFnPtr>;
 
+enum class FlutterGpuPreference {
+  NoPreference,
+  LowPowerPreference,
+};
+
 // The data associated with a Flutter project needed to run it in an engine.
 class FlutterProjectBundle {
  public:
@@ -59,6 +64,9 @@ class FlutterProjectBundle {
     return dart_entrypoint_arguments_;
   }
 
+  // Returns the app's GPU preference.
+  FlutterGpuPreference gpu_preference() const { return gpu_preference_; }
+
  private:
   std::filesystem::path assets_path_;
   std::filesystem::path icu_path_;
@@ -74,6 +82,9 @@ class FlutterProjectBundle {
 
   // Engine switches.
   std::vector<std::string> engine_switches_;
+
+  // App's GPU preference.
+  FlutterGpuPreference gpu_preference_;
 };
 
 }  // namespace flutter

engine/src/flutter/shell/platform/windows/flutter_windows_engine.cc

@@ -194,7 +194,8 @@ FlutterWindowsEngine::FlutterWindowsEngine(
   enable_impeller_ = std::find(switches.begin(), switches.end(),
                                "--enable-impeller=true") != switches.end();
 
-  egl_manager_ = egl::Manager::Create();
+  egl_manager_ = egl::Manager::Create(
+      static_cast<egl::GpuPreference>(project_->gpu_preference()));
   window_proc_delegate_manager_ = std::make_unique<WindowProcDelegateManager>();
   window_proc_delegate_manager_->RegisterTopLevelWindowProcDelegate(
       [](HWND hwnd, UINT msg, WPARAM wpar, LPARAM lpar, void* user_data,

engine/src/flutter/shell/platform/windows/flutter_windows_unittests.cc

@@ -31,7 +31,7 @@ namespace {
 // An EGL manager that initializes EGL but fails to create surfaces.
 class HalfBrokenEGLManager : public egl::Manager {
  public:
-  HalfBrokenEGLManager() : egl::Manager() {}
+  HalfBrokenEGLManager() : egl::Manager(egl::GpuPreference::NoPreference) {}
 
   std::unique_ptr<egl::WindowSurface>
   CreateWindowSurface(HWND hwnd, size_t width, size_t height) override {
@@ -422,6 +422,28 @@ TEST_F(WindowsTest, GetGraphicsAdapter) {
   ASSERT_TRUE(SUCCEEDED(dxgi_adapter->GetDesc(&desc)));
 }
 
+TEST_F(WindowsTest, GetGraphicsAdapterWithLowPowerPreference) {
+  std::optional<LUID> luid = egl::Manager::GetLowPowerGpuLuid();
+  if (!luid) {
+    GTEST_SKIP() << "Not able to find low power GPU, nothing to check.";
+  }
+
+  auto& context = GetContext();
+  WindowsConfigBuilder builder(context);
+  builder.SetGpuPreference(FlutterDesktopGpuPreference::LowPowerPreference);
+  ViewControllerPtr controller{builder.Run()};
+  ASSERT_NE(controller, nullptr);
+  auto view = FlutterDesktopViewControllerGetView(controller.get());
+
+  Microsoft::WRL::ComPtr<IDXGIAdapter> dxgi_adapter;
+  dxgi_adapter = FlutterDesktopViewGetGraphicsAdapter(view);
+  ASSERT_NE(dxgi_adapter, nullptr);
+  DXGI_ADAPTER_DESC desc{};
+  ASSERT_TRUE(SUCCEEDED(dxgi_adapter->GetDesc(&desc)));
+  ASSERT_EQ(desc.AdapterLuid.HighPart, luid->HighPart);
+  ASSERT_EQ(desc.AdapterLuid.LowPart, luid->LowPart);
+}
+
 // Implicit view has the implicit view ID.
 TEST_F(WindowsTest, PluginRegistrarGetImplicitView) {
   auto& context = GetContext();

engine/src/flutter/shell/platform/windows/public/flutter_windows.h

@@ -35,6 +35,16 @@ typedef struct FlutterDesktopEngine* FlutterDesktopEngineRef;
 // The unique identifier for a view.
 typedef int64_t FlutterDesktopViewId;
 
+// Configures how the Flutter engine selects a GPU.
+typedef enum {
+  // No preference.
+  NoPreference,
+  // Prefer energy efficiency over performance, such as an integrated GPU.
+  // This falls back to a high performance GPU if no low power GPU is
+  // available.
+  LowPowerPreference,
+} FlutterDesktopGpuPreference;
+
 // Properties for configuring a Flutter engine instance.
 typedef struct {
   // The path to the flutter_assets folder for the application to be run.
@@ -68,6 +78,8 @@ typedef struct {
   // to FlutterDesktopEngineCreate.
   const char** dart_entrypoint_argv;
 
+  // GPU choice preference
+  FlutterDesktopGpuPreference gpu_preference;
 } FlutterDesktopEngineProperties;
 
 // ========== View Controller ==========

engine/src/flutter/shell/platform/windows/testing/egl/mock_manager.h

@@ -16,7 +16,7 @@ namespace egl {
 /// Mock for the |Manager| base class.
 class MockManager : public flutter::egl::Manager {
  public:
-  MockManager() : Manager() {}
+  MockManager() : Manager(flutter::egl::GpuPreference::NoPreference) {}
 
   MOCK_METHOD(std::unique_ptr<flutter::egl::WindowSurface>,
               CreateWindowSurface,