Configure contexts to reduce shader variations. (flutter/engine#27016)

Context creation options for each backend were spread across multiple
translation units. This makes setting options common across all backends hard to
configure. I have moved the creation of such common options into a separate
translation unit.

Fixes https://github.com/flutter/flutter/issues/84213

engine/src/flutter/ci/licenses_golden/licenses_flutter

@@ -671,6 +671,8 @@ FILE: ../../../flutter/shell/common/animator_unittests.cc
 FILE: ../../../flutter/shell/common/canvas_spy.cc
 FILE: ../../../flutter/shell/common/canvas_spy.h
 FILE: ../../../flutter/shell/common/canvas_spy_unittests.cc
+FILE: ../../../flutter/shell/common/context_options.cc
+FILE: ../../../flutter/shell/common/context_options.h
 FILE: ../../../flutter/shell/common/display.h
 FILE: ../../../flutter/shell/common/display_manager.cc
 FILE: ../../../flutter/shell/common/display_manager.h

engine/src/flutter/shell/common/BUILD.gn

@@ -64,6 +64,8 @@ source_set("common") {
     "animator.h",
     "canvas_spy.cc",
     "canvas_spy.h",
+    "context_options.cc",
+    "context_options.h",
     "display.h",
     "display_manager.cc",
     "display_manager.h",

engine/src/flutter/shell/common/context_options.cc

@@ -0,0 +1,39 @@
+// Copyright 2013 The Flutter Authors. All rights reserved.
+// Use of this source code is governed by a BSD-style license that can be
+// found in the LICENSE file.
+
+#include "flutter/shell/common/context_options.h"
+
+#include "flutter/common/graphics/persistent_cache.h"
+
+namespace flutter {
+
+GrContextOptions MakeDefaultContextOptions(ContextType type,
+                                           std::optional<GrBackendApi> api) {
+  GrContextOptions options;
+
+  if (PersistentCache::cache_sksl()) {
+    options.fShaderCacheStrategy = GrContextOptions::ShaderCacheStrategy::kSkSL;
+  }
+  PersistentCache::MarkStrategySet();
+  options.fPersistentCache = PersistentCache::GetCacheForProcess();
+
+  if (api.has_value() && api.value() == GrBackendApi::kOpenGL) {
+    options.fAvoidStencilBuffers = true;
+
+    // To get video playback on the widest range of devices, we limit Skia to
+    // ES2 shading language when the ES3 external image extension is missing.
+    options.fPreferExternalImagesOverES3 = true;
+  }
+
+  // TODO(goderbauer): remove option when skbug.com/7523 is fixed.
+  options.fDisableGpuYUVConversion = true;
+
+  options.fReduceOpsTaskSplitting = GrContextOptions::Enable::kNo;
+
+  options.fReducedShaderVariations = true;
+
+  return options;
+};
+
+}  // namespace flutter

engine/src/flutter/shell/common/context_options.h

@@ -0,0 +1,43 @@
+// Copyright 2013 The Flutter Authors. All rights reserved.
+// Use of this source code is governed by a BSD-style license that can be
+// found in the LICENSE file.
+
+#ifndef FLUTTER_SHELL_COMMON_CONTEXT_OPTIONS_H_
+#define FLUTTER_SHELL_COMMON_CONTEXT_OPTIONS_H_
+
+#include <optional>
+
+#include "flutter/fml/macros.h"
+#include "third_party/skia/include/gpu/GrContextOptions.h"
+
+namespace flutter {
+
+enum class ContextType {
+  /// The context is used to render to a texture or renderbuffer.
+  kRender,
+  /// The context will only be used to transfer resources to and from device
+  /// memory. No rendering will be performed using this context.
+  kResource,
+};
+
+//------------------------------------------------------------------------------
+/// @brief      Initializes GrContextOptions with values suitable for Flutter.
+///             The options can be further tweaked before a GrContext is created
+///             from these options.
+///
+/// @param[in]  type  The type of context that will be created using these
+///                   options.
+/// @param[in]  type  The client rendering API that will be wrapped using a
+///                   context with these options. This argument is only required
+///                   if the context is going to be used with a particular
+///                   client rendering API.
+///
+/// @return     The default graphics context options.
+///
+GrContextOptions MakeDefaultContextOptions(
+    ContextType type,
+    std::optional<GrBackendApi> api = std::nullopt);
+
+}  // namespace flutter
+
+#endif  // FLUTTER_SHELL_COMMON_CONTEXT_OPTIONS_H_

engine/src/flutter/shell/common/platform_view.cc

@@ -11,7 +11,6 @@
 #include "flutter/shell/common/rasterizer.h"
 #include "flutter/shell/common/shell.h"
 #include "flutter/shell/common/vsync_waiter_fallback.h"
-#include "third_party/skia/include/gpu/GrContextOptions.h"
 #include "third_party/skia/include/gpu/gl/GrGLInterface.h"
 
 namespace flutter {

engine/src/flutter/shell/common/shell_io_manager.cc

@@ -7,6 +7,7 @@
 #include "flutter/common/graphics/persistent_cache.h"
 #include "flutter/fml/build_config.h"
 #include "flutter/fml/message_loop.h"
+#include "flutter/shell/common/context_options.h"
 #include "third_party/skia/include/gpu/gl/GrGLInterface.h"
 
 namespace flutter {
@@ -18,30 +19,7 @@ sk_sp<GrDirectContext> ShellIOManager::CreateCompatibleResourceLoadingContext(
     return nullptr;
   }
 
-  GrContextOptions options = {};
-
-  if (PersistentCache::cache_sksl()) {
-    FML_LOG(INFO) << "Cache SkSL";
-    options.fShaderCacheStrategy = GrContextOptions::ShaderCacheStrategy::kSkSL;
-  }
-  PersistentCache::MarkStrategySet();
-
-  options.fPersistentCache = PersistentCache::GetCacheForProcess();
-
-  // There is currently a bug with doing GPU YUV to RGB conversions on the IO
-  // thread. The necessary work isn't being flushed or synchronized with the
-  // other threads correctly, so the textures end up blank.  For now, suppress
-  // that feature, which will cause texture uploads to do CPU YUV conversion.
-  // A similar work-around is also used in shell/gpu/gpu_surface_gl.cc.
-  options.fDisableGpuYUVConversion = true;
-
-  // To get video playback on the widest range of devices, we limit Skia to
-  // ES2 shading language when the ES3 external image extension is missing.
-  options.fPreferExternalImagesOverES3 = true;
-
-  // Enabling this flag can increase VRAM consumption. Turn it off until
-  // further notice.
-  options.fReduceOpsTaskSplitting = GrContextOptions::Enable::kNo;
+  const auto options = MakeDefaultContextOptions(ContextType::kResource);
 
 #if !OS_FUCHSIA
   if (auto context = GrDirectContext::MakeGL(gl_interface, options)) {

engine/src/flutter/shell/common/shell_test_platform_view_vulkan.cc

@@ -5,6 +5,7 @@
 #include "flutter/shell/common/shell_test_platform_view_vulkan.h"
 
 #include "flutter/common/graphics/persistent_cache.h"
+#include "flutter/shell/common/context_options.h"
 #include "flutter/vulkan/vulkan_utilities.h"
 
 namespace flutter {
@@ -113,13 +114,8 @@ bool ShellTestPlatformViewVulkan::OffScreenSurface::CreateSkiaGrContext() {
     return false;
   }
 
-  GrContextOptions options;
-  if (PersistentCache::cache_sksl()) {
-    options.fShaderCacheStrategy = GrContextOptions::ShaderCacheStrategy::kSkSL;
-  }
-  PersistentCache::MarkStrategySet();
-  options.fPersistentCache = PersistentCache::GetCacheForProcess();
-  options.fReduceOpsTaskSplitting = GrContextOptions::Enable::kNo;
+  const auto options =
+      MakeDefaultContextOptions(ContextType::kRender, GrBackendApi::kVulkan);
 
   sk_sp<GrDirectContext> context =
       GrDirectContext::MakeVulkan(backend_context, options);

engine/src/flutter/shell/gpu/gpu_surface_gl.cc

@@ -9,6 +9,7 @@
 #include "flutter/fml/logging.h"
 #include "flutter/fml/size.h"
 #include "flutter/fml/trace_event.h"
+#include "flutter/shell/common/context_options.h"
 #include "third_party/skia/include/core/SkColorFilter.h"
 #include "third_party/skia/include/core/SkSurface.h"
 #include "third_party/skia/include/gpu/GrBackendSurface.h"
@@ -43,26 +44,8 @@ sk_sp<GrDirectContext> GPUSurfaceGL::MakeGLContext(
     return nullptr;
   }
 
-  GrContextOptions options;
-
-  if (PersistentCache::cache_sksl()) {
-    FML_LOG(INFO) << "Cache SkSL";
-    options.fShaderCacheStrategy = GrContextOptions::ShaderCacheStrategy::kSkSL;
-  }
-  PersistentCache::MarkStrategySet();
-  options.fPersistentCache = PersistentCache::GetCacheForProcess();
-
-  options.fAvoidStencilBuffers = true;
-
-  // To get video playback on the widest range of devices, we limit Skia to
-  // ES2 shading language when the ES3 external image extension is missing.
-  options.fPreferExternalImagesOverES3 = true;
-
-  // TODO(goderbauer): remove option when skbug.com/7523 is fixed.
-  // A similar work-around is also used in shell/common/io_manager.cc.
-  options.fDisableGpuYUVConversion = true;
-
-  options.fReduceOpsTaskSplitting = GrContextOptions::Enable::kNo;
+  const auto options =
+      MakeDefaultContextOptions(ContextType::kRender, GrBackendApi::kOpenGL);
 
   auto context = GrDirectContext::MakeGL(delegate->GetGLInterface(), options);
 

engine/src/flutter/shell/platform/darwin/graphics/BUILD.gn

@@ -20,6 +20,7 @@ source_set("graphics") {
   deps = [
     "//flutter/common/graphics",
     "//flutter/fml",
+    "//flutter/shell/common",
     "//flutter/shell/platform/darwin/common:framework_shared",
   ]
 

engine/src/flutter/shell/platform/darwin/graphics/FlutterDarwinContextMetal.mm

@@ -7,21 +7,10 @@
 #include "flutter/common/graphics/persistent_cache.h"
 #include "flutter/fml/logging.h"
 #import "flutter/shell/platform/darwin/common/framework/Headers/FlutterMacros.h"
-#include "third_party/skia/include/gpu/GrContextOptions.h"
+#include "shell/common/context_options.h"
 
 FLUTTER_ASSERT_ARC
 
-static GrContextOptions CreateMetalGrContextOptions() {
-  GrContextOptions options = {};
-  if (flutter::PersistentCache::cache_sksl()) {
-    options.fShaderCacheStrategy = GrContextOptions::ShaderCacheStrategy::kSkSL;
-  }
-  flutter::PersistentCache::MarkStrategySet();
-  options.fPersistentCache = flutter::PersistentCache::GetCacheForProcess();
-  options.fReduceOpsTaskSplitting = GrContextOptions::Enable::kNo;
-  return options;
-}
-
 @implementation FlutterDarwinContextMetal
 
 - (instancetype)initWithDefaultMTLDevice {
@@ -77,7 +66,8 @@ static GrContextOptions CreateMetalGrContextOptions() {
 }
 
 - (sk_sp<GrDirectContext>)createGrContext {
-  auto contextOptions = CreateMetalGrContextOptions();
+  const auto contextOptions =
+      flutter::MakeDefaultContextOptions(flutter::ContextType::kRender, GrBackendApi::kMetal);
   id<MTLDevice> device = _device;
   id<MTLCommandQueue> commandQueue = _commandQueue;
   return [FlutterDarwinContextMetal createGrContext:device commandQueue:commandQueue];
@@ -85,7 +75,8 @@ static GrContextOptions CreateMetalGrContextOptions() {
 
 + (sk_sp<GrDirectContext>)createGrContext:(id<MTLDevice>)device
                              commandQueue:(id<MTLCommandQueue>)commandQueue {
-  auto contextOptions = CreateMetalGrContextOptions();
+  const auto contextOptions =
+      flutter::MakeDefaultContextOptions(flutter::ContextType::kRender, GrBackendApi::kMetal);
   // Skia expect arguments to `MakeMetal` transfer ownership of the reference in for release later
   // when the GrDirectContext is collected.
   return GrDirectContext::MakeMetal((__bridge_retained void*)device,

engine/src/flutter/shell/platform/fuchsia/flutter/platform_view_unittest.cc

@@ -20,6 +20,7 @@
 #include "flutter/flow/embedded_views.h"
 #include "flutter/lib/ui/window/platform_message.h"
 #include "flutter/lib/ui/window/viewport_metrics.h"
+#include "flutter/shell/common/context_options.h"
 #include "flutter/shell/platform/fuchsia/flutter/platform_view.h"
 #include "gmock/gmock.h"
 #include "gtest/gtest.h"
@@ -347,8 +348,9 @@ TEST_F(PlatformViewTests, CreateSurfaceTest) {
       );
 
   // Test create surface callback function.
-  sk_sp<GrDirectContext> gr_context =
-      GrDirectContext::MakeMock(nullptr, GrContextOptions());
+  sk_sp<GrDirectContext> gr_context = GrDirectContext::MakeMock(
+      nullptr,
+      flutter::MakeDefaultContextOptions(flutter::ContextType::kRender));
   std::shared_ptr<MockExternalViewEmbedder> view_embedder =
       std::make_shared<MockExternalViewEmbedder>();
   auto CreateSurfaceCallback = [&view_embedder, gr_context]() {

engine/src/flutter/shell/platform/fuchsia/flutter/vulkan_surface_producer.cc

@@ -12,6 +12,7 @@
 #include <vector>
 
 #include "flutter/fml/trace_event.h"
+#include "flutter/shell/common/context_options.h"
 #include "third_party/skia/include/gpu/GrBackendSemaphore.h"
 #include "third_party/skia/include/gpu/GrBackendSurface.h"
 #include "third_party/skia/include/gpu/GrDirectContext.h"
@@ -137,9 +138,8 @@ bool VulkanSurfaceProducer::Initialize(scenic::Session* scenic_session) {
                      backend_context.fPhysicalDevice, 0, nullptr,
                      countof(device_extensions), device_extensions);
   backend_context.fVkExtensions = &vk_extensions;
-  GrContextOptions options;
-  options.fReduceOpsTaskSplitting = GrContextOptions::Enable::kNo;
-
+  const auto options = flutter::MakeDefaultContextOptions(
+      flutter::ContextType::kRender, GrBackendApi::kVulkan);
   context_ = GrDirectContext::MakeVulkan(backend_context, options);
 
   if (context_ == nullptr) {