[Impeller] Add support to embedder for Impeller on GL (via Angle on Windows).

ci/licenses_golden/licenses_flutter

@@ -2822,6 +2822,8 @@ ORIGIN: ../../../flutter/shell/platform/embedder/embedder_surface.cc + ../../../
 ORIGIN: ../../../flutter/shell/platform/embedder/embedder_surface.h + ../../../flutter/LICENSE
 ORIGIN: ../../../flutter/shell/platform/embedder/embedder_surface_gl.cc + ../../../flutter/LICENSE
 ORIGIN: ../../../flutter/shell/platform/embedder/embedder_surface_gl.h + ../../../flutter/LICENSE
+ORIGIN: ../../../flutter/shell/platform/embedder/embedder_surface_gl_impeller.cc + ../../../flutter/LICENSE
+ORIGIN: ../../../flutter/shell/platform/embedder/embedder_surface_gl_impeller.h + ../../../flutter/LICENSE
 ORIGIN: ../../../flutter/shell/platform/embedder/embedder_surface_metal.h + ../../../flutter/LICENSE
 ORIGIN: ../../../flutter/shell/platform/embedder/embedder_surface_metal.mm + ../../../flutter/LICENSE
 ORIGIN: ../../../flutter/shell/platform/embedder/embedder_surface_metal_impeller.h + ../../../flutter/LICENSE
@@ -5522,6 +5524,8 @@ FILE: ../../../flutter/shell/platform/embedder/embedder_surface.cc
 FILE: ../../../flutter/shell/platform/embedder/embedder_surface.h
 FILE: ../../../flutter/shell/platform/embedder/embedder_surface_gl.cc
 FILE: ../../../flutter/shell/platform/embedder/embedder_surface_gl.h
+FILE: ../../../flutter/shell/platform/embedder/embedder_surface_gl_impeller.cc
+FILE: ../../../flutter/shell/platform/embedder/embedder_surface_gl_impeller.h
 FILE: ../../../flutter/shell/platform/embedder/embedder_surface_metal.h
 FILE: ../../../flutter/shell/platform/embedder/embedder_surface_metal.mm
 FILE: ../../../flutter/shell/platform/embedder/embedder_surface_metal_impeller.h

impeller/renderer/backend/gles/render_pass_gles.cc

@@ -452,6 +452,7 @@ struct RenderPassData {
 
   if (gl.DiscardFramebufferEXT.IsAvailable()) {
     std::vector<GLenum> attachments;
+
     if (pass_data.discard_color_attachment) {
       attachments.push_back(is_default_fbo ? GL_COLOR_EXT
                                            : GL_COLOR_ATTACHMENT0);
@@ -460,7 +461,15 @@ struct RenderPassData {
       attachments.push_back(is_default_fbo ? GL_DEPTH_EXT
                                            : GL_DEPTH_ATTACHMENT);
     }
+
+// TODO(jonahwilliams): discarding the stencil on the default fbo when running
+// on Windows causes Angle to discard the entire render target. Until we know
+// the reason, default to storing.
+#ifdef FML_OS_WIN
+    if (pass_data.discard_stencil_attachment && !is_default_fbo) {
+#else
     if (pass_data.discard_stencil_attachment) {
+#endif
       attachments.push_back(is_default_fbo ? GL_STENCIL_EXT
                                            : GL_STENCIL_ATTACHMENT);
     }

shell/common/rasterizer.cc

@@ -552,7 +552,6 @@ RasterStatus Rasterizer::DrawToSurfaceUnsafe(
 
   auto root_surface_canvas =
       embedder_root_canvas ? embedder_root_canvas : frame->Canvas();
-
   auto compositor_frame = compositor_context_->AcquireFrame(
       surface_->GetContext(),         // skia GrContext
       root_surface_canvas,            // root surface canvas

shell/gpu/gpu_surface_gl_delegate.h

@@ -58,7 +58,7 @@ class GPUSurfaceGLDelegate {
   virtual std::unique_ptr<GLContextResult> GLContextMakeCurrent() = 0;
 
   // Called to clear the current GL context on the thread. This may be called on
-  // either the GPU or IO threads.
+  // either the Raster or IO threads.
   virtual bool GLContextClearCurrent() = 0;
 
   // Inform the GL Context that there's going to be no writing beyond

shell/gpu/gpu_surface_gl_impeller.cc

@@ -61,7 +61,7 @@ std::unique_ptr<SurfaceFrame> GPUSurfaceGLImpeller::AcquireFrame(
                         delegate = delegate_]() -> bool {
     if (weak) {
       GLPresentInfo present_info = {
-          .fbo_id = 0,
+          .fbo_id = 0u,
           .frame_damage = std::nullopt,
           // TODO (https://github.com/flutter/flutter/issues/105597): wire-up
           // presentation time to impeller backend.
@@ -80,10 +80,14 @@ std::unique_ptr<SurfaceFrame> GPUSurfaceGLImpeller::AcquireFrame(
     return nullptr;
   }
 
+  GLFrameInfo frame_info = {static_cast<uint32_t>(size.width()),
+                            static_cast<uint32_t>(size.height())};
+  const GLFBOInfo fbo_info = delegate_->GLContextFBO(frame_info);
+
   auto surface = impeller::SurfaceGLES::WrapFBO(
       impeller_context_,                            // context
       swap_callback,                                // swap_callback
-      0u,                                           // fbo
+      fbo_info.fbo_id,                              // fbo
       impeller::PixelFormat::kR8G8B8A8UNormInt,     // color_format
       impeller::ISize{size.width(), size.height()}  // fbo_size
   );
@@ -122,12 +126,12 @@ std::unique_ptr<SurfaceFrame> GPUSurfaceGLImpeller::AcquireFrame(
       });
 
   return std::make_unique<SurfaceFrame>(
-      nullptr,                          // surface
-      SurfaceFrame::FramebufferInfo{},  // framebuffer info
-      submit_callback,                  // submit callback
-      size,                             // frame size
-      std::move(context_switch),        // context result
-      true                              // display list fallback
+      nullptr,                                // surface
+      delegate_->GLContextFramebufferInfo(),  // framebuffer info
+      submit_callback,                        // submit callback
+      size,                                   // frame size
+      std::move(context_switch),              // context result
+      true                                    // display list fallback
   );
 }
 

shell/platform/embedder/BUILD.gn

@@ -95,16 +95,6 @@ template("embedder_source_set") {
     ]
 
     public_deps = [ ":embedder_headers" ]
-
-    if (embedder_enable_gl) {
-      sources += [
-        "embedder_external_texture_gl.cc",
-        "embedder_external_texture_gl.h",
-        "embedder_surface_gl.cc",
-        "embedder_surface_gl.h",
-      ]
-    }
-
     deps = [
       ":embedder_gpu_configuration",
       "//flutter/assets",
@@ -121,13 +111,33 @@ template("embedder_source_set") {
       "//third_party/skia",
     ]
 
+    if (embedder_enable_gl) {
+      sources += [
+        "embedder_external_texture_gl.cc",
+        "embedder_external_texture_gl.h",
+        "embedder_surface_gl.cc",
+        "embedder_surface_gl.h",
+      ]
+
+      if (impeller_supports_rendering) {
+        sources += [
+          "embedder_surface_gl_impeller.cc",
+          "embedder_surface_gl_impeller.h",
+        ]
+        deps += [ "//flutter/impeller/renderer/backend/gles" ]
+      }
+    }
+
     if (impeller_supports_rendering) {
       sources += [
         "embedder_render_target_impeller.cc",
         "embedder_render_target_impeller.h",
       ]
 
-      deps += [ "//flutter/impeller" ]
+      deps += [
+        "//flutter/impeller",
+        "//flutter/impeller/renderer",
+      ]
     }
 
     if (embedder_enable_metal) {
@@ -143,6 +153,7 @@ template("embedder_source_set") {
           "embedder_surface_metal_impeller.h",
           "embedder_surface_metal_impeller.mm",
         ]
+        deps += [ "//flutter/impeller/renderer/backend/metal" ]
       }
 
       cflags_objc = flutter_cflags_objc

shell/platform/embedder/embedder.cc

@@ -64,9 +64,20 @@ extern const intptr_t kPlatformStrongDillSize;
 #include "rapidjson/rapidjson.h"
 #include "rapidjson/writer.h"
 
+// Note: the IMPELLER_SUPPORTS_RENDERING may be defined even when the
+// embedder/BUILD.gn variable impeller_supports_rendering is disabled.
 #ifdef SHELL_ENABLE_GL
 #include "flutter/shell/platform/embedder/embedder_external_texture_gl.h"
-#endif
+#ifdef IMPELLER_SUPPORTS_RENDERING
+#include "flutter/shell/platform/embedder/embedder_render_target_impeller.h"  // nogncheck
+#include "flutter/shell/platform/embedder/embedder_surface_gl_impeller.h"  // nogncheck
+#include "impeller/core/texture.h"                        // nogncheck
+#include "impeller/renderer/backend/gles/context_gles.h"  // nogncheck
+#include "impeller/renderer/backend/gles/texture_gles.h"  // nogncheck
+#include "impeller/renderer/context.h"                    // nogncheck
+#include "impeller/renderer/render_target.h"              // nogncheck
+#endif  // IMPELLER_SUPPORTS_RENDERING
+#endif  // SHELL_ENABLE_GL
 
 #ifdef SHELL_ENABLE_METAL
 #include "flutter/shell/platform/embedder/embedder_surface_metal.h"
@@ -265,7 +276,8 @@ InferOpenGLPlatformViewCreationCallback(
     const flutter::PlatformViewEmbedder::PlatformDispatchTable&
         platform_dispatch_table,
     std::unique_ptr<flutter::EmbedderExternalViewEmbedder>
-        external_view_embedder) {
+        external_view_embedder,
+    bool enable_impeller) {
 #ifdef SHELL_ENABLE_GL
   if (config->type != kOpenGL) {
     return nullptr;
@@ -441,15 +453,30 @@ InferOpenGLPlatformViewCreationCallback(
 
   return fml::MakeCopyable(
       [gl_dispatch_table, fbo_reset_after_present, platform_dispatch_table,
+       enable_impeller,
        external_view_embedder =
            std::move(external_view_embedder)](flutter::Shell& shell) mutable {
+        std::shared_ptr<flutter::EmbedderExternalViewEmbedder> view_embedder =
+            std::move(external_view_embedder);
+        if (enable_impeller) {
+          return std::make_unique<flutter::PlatformViewEmbedder>(
+              shell,                   // delegate
+              shell.GetTaskRunners(),  // task runners
+              std::make_unique<flutter::EmbedderSurfaceGLImpeller>(
+                  gl_dispatch_table, fbo_reset_after_present,
+                  view_embedder),       // embedder_surface
+              platform_dispatch_table,  // embedder platform dispatch table
+              view_embedder             // external view embedder
+          );
+        }
         return std::make_unique<flutter::PlatformViewEmbedder>(
-            shell,                    // delegate
-            shell.GetTaskRunners(),   // task runners
-            gl_dispatch_table,        // embedder GL dispatch table
-            fbo_reset_after_present,  // fbo reset after present
+            shell,                   // delegate
+            shell.GetTaskRunners(),  // task runners
+            std::make_unique<flutter::EmbedderSurfaceGL>(
+                gl_dispatch_table, fbo_reset_after_present,
+                view_embedder),       // embedder_surface
             platform_dispatch_table,  // embedder platform dispatch table
-            std::move(external_view_embedder)  // external view embedder
+            view_embedder             // external view embedder
         );
       });
 #else
@@ -686,7 +713,7 @@ InferPlatformViewCreationCallback(
     case kOpenGL:
       return InferOpenGLPlatformViewCreationCallback(
           config, user_data, platform_dispatch_table,
-          std::move(external_view_embedder));
+          std::move(external_view_embedder), enable_impeller);
     case kSoftware:
       return InferSoftwarePlatformViewCreationCallback(
           config, user_data, platform_dispatch_table,
@@ -924,6 +951,66 @@ static sk_sp<SkSurface> MakeSkSurfaceFromBackingStore(
 #endif
 }
 
+static std::unique_ptr<flutter::EmbedderRenderTarget>
+MakeRenderTargetFromBackingStoreImpeller(
+    FlutterBackingStore backing_store,
+    const fml::closure& on_release,
+    const std::shared_ptr<impeller::AiksContext>& aiks_context,
+    const FlutterBackingStoreConfig& config,
+    const FlutterOpenGLFramebuffer* framebuffer) {
+#if defined(SHELL_ENABLE_GL) && defined(IMPELLER_SUPPORTS_RENDERING)
+
+  const auto& gl_context =
+      impeller::ContextGLES::Cast(*aiks_context->GetContext());
+  const auto size = impeller::ISize(config.size.width, config.size.height);
+
+  impeller::TextureDescriptor color0_tex;
+  color0_tex.type = impeller::TextureType::kTexture2D;
+  color0_tex.format = impeller::PixelFormat::kR8G8B8A8UNormInt;
+  color0_tex.size = size;
+  color0_tex.usage = static_cast<impeller::TextureUsageMask>(
+      impeller::TextureUsage::kRenderTarget);
+  color0_tex.sample_count = impeller::SampleCount::kCount1;
+  color0_tex.storage_mode = impeller::StorageMode::kDevicePrivate;
+
+  impeller::ColorAttachment color0;
+  color0.texture = std::make_shared<impeller::TextureGLES>(
+      gl_context.GetReactor(), color0_tex,
+      impeller::TextureGLES::IsWrapped::kWrapped);
+  color0.clear_color = impeller::Color::DarkSlateGray();
+  color0.load_action = impeller::LoadAction::kClear;
+  color0.store_action = impeller::StoreAction::kStore;
+
+  impeller::TextureDescriptor stencil0_tex;
+  stencil0_tex.type = impeller::TextureType::kTexture2D;
+  stencil0_tex.format = impeller::PixelFormat::kR8G8B8A8UNormInt;
+  stencil0_tex.size = size;
+  stencil0_tex.usage = static_cast<impeller::TextureUsageMask>(
+      impeller::TextureUsage::kRenderTarget);
+  stencil0_tex.sample_count = impeller::SampleCount::kCount1;
+
+  impeller::StencilAttachment stencil0;
+  stencil0.clear_stencil = 0;
+  stencil0.texture = std::make_shared<impeller::TextureGLES>(
+      gl_context.GetReactor(), stencil0_tex,
+      impeller::TextureGLES::IsWrapped::kWrapped);
+  stencil0.load_action = impeller::LoadAction::kClear;
+  stencil0.store_action = impeller::StoreAction::kDontCare;
+
+  impeller::RenderTarget render_target_desc;
+
+  render_target_desc.SetColorAttachment(color0, framebuffer->target);
+  render_target_desc.SetStencilAttachment(stencil0);
+
+  return std::make_unique<flutter::EmbedderRenderTargetImpeller>(
+      backing_store, aiks_context,
+      std::make_unique<impeller::RenderTarget>(std::move(render_target_desc)),
+      on_release);
+#else
+  return nullptr;
+#endif
+}
+
 static std::unique_ptr<flutter::EmbedderRenderTarget>
 MakeRenderTargetFromBackingStoreImpeller(
     FlutterBackingStore backing_store,
@@ -1113,12 +1200,19 @@ CreateEmbedderRenderTarget(
           break;
         }
         case kFlutterOpenGLTargetTypeFramebuffer: {
-          auto skia_surface = MakeSkSurfaceFromBackingStore(
-              context, config, &backing_store.open_gl.framebuffer);
-          render_target = MakeRenderTargetFromSkSurface(
-              backing_store, std::move(skia_surface),
-              collect_callback.Release());
-          break;
+          if (enable_impeller) {
+            render_target = MakeRenderTargetFromBackingStoreImpeller(
+                backing_store, collect_callback.Release(), aiks_context, config,
+                &backing_store.open_gl.framebuffer);
+            break;
+          } else {
+            auto skia_surface = MakeSkSurfaceFromBackingStore(
+                context, config, &backing_store.open_gl.framebuffer);
+            render_target = MakeRenderTargetFromSkSurface(
+                backing_store, std::move(skia_surface),
+                collect_callback.Release());
+            break;
+          }
         }
       }
       break;