[Impeller] Refactor KHR swapchains to make it easy to reuse backend agnostic components.

impeller/playground/backend/vulkan/playground_impl_vk.cc

@@ -20,7 +20,7 @@
 #include "impeller/renderer/backend/vulkan/context_vk.h"
 #include "impeller/renderer/backend/vulkan/formats_vk.h"
 #include "impeller/renderer/backend/vulkan/surface_context_vk.h"
-#include "impeller/renderer/backend/vulkan/swapchain/khr/khr_surface_vk.h"
+#include "impeller/renderer/backend/vulkan/swapchain/surface_vk.h"
 #include "impeller/renderer/backend/vulkan/texture_vk.h"
 #include "impeller/renderer/vk/compute_shaders_vk.h"
 #include "impeller/scene/shaders/vk/scene_shaders_vk.h"

impeller/renderer/backend/vulkan/BUILD.gn

@@ -100,14 +100,18 @@ impeller_component("vulkan") {
     "shared_object_vk.h",
     "surface_context_vk.cc",
     "surface_context_vk.h",
-    "swapchain/khr/khr_surface_vk.cc",
-    "swapchain/khr/khr_surface_vk.h",
     "swapchain/khr/khr_swapchain_image_vk.cc",
     "swapchain/khr/khr_swapchain_image_vk.h",
     "swapchain/khr/khr_swapchain_impl_vk.cc",
     "swapchain/khr/khr_swapchain_impl_vk.h",
     "swapchain/khr/khr_swapchain_vk.cc",
     "swapchain/khr/khr_swapchain_vk.h",
+    "swapchain/surface_vk.cc",
+    "swapchain/surface_vk.h",
+    "swapchain/swapchain_transients_vk.cc",
+    "swapchain/swapchain_transients_vk.h",
+    "swapchain/swapchain_vk.cc",
+    "swapchain/swapchain_vk.h",
     "texture_source_vk.cc",
     "texture_source_vk.h",
     "texture_vk.cc",

impeller/renderer/backend/vulkan/surface_context_vk.cc

@@ -64,7 +64,7 @@ void SurfaceContextVK::Shutdown() {
 
 bool SurfaceContextVK::SetWindowSurface(vk::UniqueSurfaceKHR surface,
                                         const ISize& size) {
-  auto swapchain = KHRSwapchainVK::Create(parent_, std::move(surface), size);
+  auto swapchain = SwapchainVK::Create(parent_, std::move(surface), size);
   if (!swapchain) {
     VALIDATION_LOG << "Could not create swapchain.";
     return false;

impeller/renderer/backend/vulkan/surface_context_vk.h

@@ -16,7 +16,7 @@ namespace impeller {
 
 class ContextVK;
 class Surface;
-class KHRSwapchainVK;
+class SwapchainVK;
 
 /// For Vulkan, there is both a ContextVK that implements Context and a
 /// SurfaceContextVK that also implements Context and takes a ContextVK as its
@@ -90,7 +90,7 @@ class SurfaceContextVK : public Context,
 
  private:
   std::shared_ptr<ContextVK> parent_;
-  std::shared_ptr<KHRSwapchainVK> swapchain_;
+  std::shared_ptr<SwapchainVK> swapchain_;
 };
 
 }  // namespace impeller

impeller/renderer/backend/vulkan/swapchain/khr/khr_swapchain_image_vk.cc

@@ -35,31 +35,6 @@ bool KHRSwapchainImageVK::IsValid() const {
   return is_valid_;
 }
 
-std::shared_ptr<Texture> KHRSwapchainImageVK::GetMSAATexture() const {
-  return msaa_texture_;
-}
-
-std::shared_ptr<Texture> KHRSwapchainImageVK::GetDepthStencilTexture() const {
-  return depth_stencil_texture_;
-}
-
-void KHRSwapchainImageVK::SetMSAATexture(std::shared_ptr<Texture> texture) {
-  msaa_texture_ = std::move(texture);
-}
-
-void KHRSwapchainImageVK::SetDepthStencilTexture(
-    std::shared_ptr<Texture> texture) {
-  depth_stencil_texture_ = std::move(texture);
-}
-
-PixelFormat KHRSwapchainImageVK::GetPixelFormat() const {
-  return desc_.format;
-}
-
-ISize KHRSwapchainImageVK::GetSize() const {
-  return desc_.size;
-}
-
 // |TextureSourceVK|
 vk::Image KHRSwapchainImageVK::GetImage() const {
   return image_;
@@ -75,4 +50,9 @@ vk::ImageView KHRSwapchainImageVK::GetRenderTargetView() const {
   return image_view_.get();
 }
 
+// |TextureSourceVK|
+bool KHRSwapchainImageVK::IsSwapchainImage() const {
+  return true;
+}
+
 }  // namespace impeller

impeller/renderer/backend/vulkan/swapchain/khr/khr_swapchain_image_vk.h

@@ -9,7 +9,6 @@
 #include "impeller/renderer/backend/vulkan/formats_vk.h"
 #include "impeller/renderer/backend/vulkan/texture_source_vk.h"
 #include "impeller/renderer/backend/vulkan/vk.h"
-#include "vulkan/vulkan_handles.hpp"
 
 namespace impeller {
 
@@ -24,33 +23,21 @@ class KHRSwapchainImageVK final : public TextureSourceVK {
 
   bool IsValid() const;
 
-  PixelFormat GetPixelFormat() const;
-
-  ISize GetSize() const;
-
   // |TextureSourceVK|
   vk::Image GetImage() const override;
 
-  std::shared_ptr<Texture> GetMSAATexture() const;
-
-  std::shared_ptr<Texture> GetDepthStencilTexture() const;
-
   // |TextureSourceVK|
   vk::ImageView GetImageView() const override;
 
+  // |TextureSourceVK|
   vk::ImageView GetRenderTargetView() const override;
 
-  void SetMSAATexture(std::shared_ptr<Texture> texture);
-
-  void SetDepthStencilTexture(std::shared_ptr<Texture> texture);
-
-  bool IsSwapchainImage() const override { return true; }
+  // |TextureSourceVK|
+  bool IsSwapchainImage() const override;
 
  private:
   vk::Image image_ = VK_NULL_HANDLE;
   vk::UniqueImageView image_view_ = {};
-  std::shared_ptr<Texture> msaa_texture_;
-  std::shared_ptr<Texture> depth_stencil_texture_;
   bool is_valid_ = false;
 
   KHRSwapchainImageVK(const KHRSwapchainImageVK&) = delete;

impeller/renderer/backend/vulkan/swapchain/khr/khr_swapchain_impl_vk.cc

@@ -12,10 +12,9 @@
 #include "impeller/renderer/backend/vulkan/context_vk.h"
 #include "impeller/renderer/backend/vulkan/formats_vk.h"
 #include "impeller/renderer/backend/vulkan/gpu_tracer_vk.h"
-#include "impeller/renderer/backend/vulkan/swapchain/khr/khr_surface_vk.h"
 #include "impeller/renderer/backend/vulkan/swapchain/khr/khr_swapchain_image_vk.h"
+#include "impeller/renderer/backend/vulkan/swapchain/surface_vk.h"
 #include "impeller/renderer/context.h"
-#include "vulkan/vulkan_structs.hpp"
 
 namespace impeller {
 
@@ -228,40 +227,6 @@ KHRSwapchainImplVK::KHRSwapchainImplVK(const std::shared_ptr<Context>& context,
   texture_desc.size = ISize::MakeWH(swapchain_info.imageExtent.width,
                                     swapchain_info.imageExtent.height);
 
-  // Allocate a single onscreen MSAA texture and Depth+Stencil Texture to
-  // be shared by all swapchain images.
-  TextureDescriptor msaa_desc;
-  msaa_desc.storage_mode = StorageMode::kDeviceTransient;
-  msaa_desc.type = TextureType::kTexture2DMultisample;
-  msaa_desc.sample_count = SampleCount::kCount4;
-  msaa_desc.format = texture_desc.format;
-  msaa_desc.size = texture_desc.size;
-  msaa_desc.usage = TextureUsage::kRenderTarget;
-
-  // The depth+stencil configuration matches the configuration used by
-  // RenderTarget::SetupDepthStencilAttachments and matching the swapchain
-  // image dimensions and sample count.
-  TextureDescriptor depth_stencil_desc;
-  depth_stencil_desc.storage_mode = StorageMode::kDeviceTransient;
-  if (enable_msaa) {
-    depth_stencil_desc.type = TextureType::kTexture2DMultisample;
-    depth_stencil_desc.sample_count = SampleCount::kCount4;
-  } else {
-    depth_stencil_desc.type = TextureType::kTexture2D;
-    depth_stencil_desc.sample_count = SampleCount::kCount1;
-  }
-  depth_stencil_desc.format =
-      context->GetCapabilities()->GetDefaultDepthStencilFormat();
-  depth_stencil_desc.size = texture_desc.size;
-  depth_stencil_desc.usage = TextureUsage::kRenderTarget;
-
-  std::shared_ptr<Texture> msaa_texture;
-  if (enable_msaa) {
-    msaa_texture = context->GetResourceAllocator()->CreateTexture(msaa_desc);
-  }
-  std::shared_ptr<Texture> depth_stencil_texture =
-      context->GetResourceAllocator()->CreateTexture(depth_stencil_desc);
-
   std::vector<std::shared_ptr<KHRSwapchainImageVK>> swapchain_images;
   for (const auto& image : images) {
     auto swapchain_image = std::make_shared<KHRSwapchainImageVK>(
@@ -273,9 +238,6 @@ KHRSwapchainImplVK::KHRSwapchainImplVK(const std::shared_ptr<Context>& context,
       VALIDATION_LOG << "Could not create swapchain image.";
       return;
     }
-    swapchain_image->SetMSAATexture(msaa_texture);
-    swapchain_image->SetDepthStencilTexture(depth_stencil_texture);
-
     ContextVK::SetDebugName(
         vk_context.GetDevice(), swapchain_image->GetImage(),
         "SwapchainImage" + std::to_string(swapchain_images.size()));
@@ -302,6 +264,8 @@ KHRSwapchainImplVK::KHRSwapchainImplVK(const std::shared_ptr<Context>& context,
   surface_ = std::move(surface);
   surface_format_ = swapchain_info.imageFormat;
   swapchain_ = std::move(swapchain);
+  transients_ = std::make_shared<SwapchainTransientsVK>(context, texture_desc,
+                                                        enable_msaa);
   images_ = std::move(swapchain_images);
   synchronizers_ = std::move(synchronizers);
   current_frame_ = synchronizers_.size() - 1u;
@@ -403,17 +367,16 @@ KHRSwapchainImplVK::AcquireResult KHRSwapchainImplVK::AcquireNextDrawable() {
 
   auto image = images_[index % images_.size()];
   uint32_t image_index = index;
-  return AcquireResult{KHRSurfaceVK::WrapSwapchainImage(
-      context_strong,  // context
-      image,           // swapchain image
+  return AcquireResult{SurfaceVK::WrapSwapchainImage(
+      transients_,  // transients
+      image,        // swapchain image
       [weak_swapchain = weak_from_this(), image, image_index]() -> bool {
         auto swapchain = weak_swapchain.lock();
         if (!swapchain) {
           return false;
         }
         return swapchain->Present(image, image_index);
-      },            // swap callback
-      enable_msaa_  //
+      }  // swap callback
       )};
 }
 

impeller/renderer/backend/vulkan/swapchain/khr/khr_swapchain_impl_vk.h

@@ -10,8 +10,8 @@
 #include <variant>
 
 #include "impeller/geometry/size.h"
+#include "impeller/renderer/backend/vulkan/swapchain/swapchain_transients_vk.h"
 #include "impeller/renderer/backend/vulkan/vk.h"
-#include "vulkan/vulkan_enums.hpp"
 
 namespace impeller {
 
@@ -68,6 +68,7 @@ class KHRSwapchainImplVK final
   vk::UniqueSurfaceKHR surface_;
   vk::Format surface_format_ = vk::Format::eUndefined;
   vk::UniqueSwapchainKHR swapchain_;
+  std::shared_ptr<SwapchainTransientsVK> transients_;
   std::vector<std::shared_ptr<KHRSwapchainImageVK>> images_;
   std::vector<std::unique_ptr<KHRFrameSynchronizerVK>> synchronizers_;
   size_t current_frame_ = 0u;

impeller/renderer/backend/vulkan/swapchain/khr/khr_swapchain_vk.cc

@@ -10,26 +10,23 @@
 
 namespace impeller {
 
-std::shared_ptr<KHRSwapchainVK> KHRSwapchainVK::Create(
-    const std::shared_ptr<Context>& context,
-    vk::UniqueSurfaceKHR surface,
-    const ISize& size,
-    bool enable_msaa) {
-  auto impl = KHRSwapchainImplVK::Create(context, std::move(surface), size,
-                                         enable_msaa);
+KHRSwapchainVK::KHRSwapchainVK(const std::shared_ptr<Context>& context,
+                               vk::UniqueSurfaceKHR surface,
+                               const ISize& size,
+                               bool enable_msaa)
+    : size_(size), enable_msaa_(enable_msaa) {
+  auto impl = KHRSwapchainImplVK::Create(context,             //
+                                         std::move(surface),  //
+                                         size_,               //
+                                         enable_msaa_         //
+  );
   if (!impl || !impl->IsValid()) {
     VALIDATION_LOG << "Failed to create SwapchainVK implementation.";
-    return nullptr;
+    return;
   }
-  return std::shared_ptr<KHRSwapchainVK>(
-      new KHRSwapchainVK(std::move(impl), size, enable_msaa));
+  impl_ = std::move(impl);
 }
 
-KHRSwapchainVK::KHRSwapchainVK(std::shared_ptr<KHRSwapchainImplVK> impl,
-                               const ISize& size,
-                               bool enable_msaa)
-    : impl_(std::move(impl)), size_(size), enable_msaa_(enable_msaa) {}
-
 KHRSwapchainVK::~KHRSwapchainVK() = default;
 
 bool KHRSwapchainVK::IsValid() const {