[Impeller] add experimental canvas support to screenshotter. (#53751)

Fixes flutter/flutter#150993

This change allows testing the experimental canvas dispatcher in the playgrounds, which is important for golden testing. The plan to enable requires demonstrating that the goldens are the same.

Author: jonahwilliams

impeller/golden_tests/golden_playground_test_mac.cc

@@ -6,6 +6,7 @@
 #include <filesystem>
 #include <memory>
 
+#include "display_list/display_list.h"
 #include "flutter/impeller/golden_tests/golden_playground_test.h"
 
 #include "flutter/impeller/aiks/picture.h"
@@ -14,6 +15,7 @@
 #include "flutter/impeller/golden_tests/vulkan_screenshotter.h"
 #include "flutter/third_party/abseil-cpp/absl/base/no_destructor.h"
 #include "fml/closure.h"
+#include "impeller/aiks/aiks_context.h"
 #include "impeller/display_list/dl_dispatcher.h"
 #include "impeller/display_list/dl_image_impeller.h"
 #include "impeller/typographer/backends/skia/typographer_context_skia.h"
@@ -22,6 +24,8 @@
 #define GLFW_INCLUDE_NONE
 #include "third_party/glfw/include/GLFW/glfw3.h"
 
+#define EXPERIMENTAL_CANVAS false
+
 namespace impeller {
 
 namespace {
@@ -55,6 +59,56 @@ const std::unique_ptr<PlaygroundImpl>& GetSharedVulkanPlayground(
     return *vulkan_playground;
   }
 }
+
+#if EXPERIMENTAL_CANVAS
+std::shared_ptr<Texture> DisplayListToTexture(
+    sk_sp<flutter::DisplayList>& display_list,
+    ISize size,
+    AiksContext& context) {
+  // Do not use the render target cache as the lifecycle of this texture
+  // will outlive a particular frame.
+  impeller::RenderTargetAllocator render_target_allocator =
+      impeller::RenderTargetAllocator(
+          context.GetContext()->GetResourceAllocator());
+  impeller::RenderTarget target;
+  if (context.GetContext()->GetCapabilities()->SupportsOffscreenMSAA()) {
+    target = render_target_allocator.CreateOffscreenMSAA(
+        *context.GetContext(),  // context
+        size,                   // size
+        /*mip_count=*/1,
+        "Picture Snapshot MSAA",  // label
+        impeller::RenderTarget::
+            kDefaultColorAttachmentConfigMSAA  // color_attachment_config
+    );
+  } else {
+    target = render_target_allocator.CreateOffscreen(
+        *context.GetContext(),  // context
+        size,                   // size
+        /*mip_count=*/1,
+        "Picture Snapshot",  // label
+        impeller::RenderTarget::
+            kDefaultColorAttachmentConfig  // color_attachment_config
+    );
+  }
+
+  impeller::TextFrameDispatcher collector(context.GetContentContext(),
+                                          impeller::Matrix());
+  display_list->Dispatch(
+      collector, SkIRect::MakeSize(SkISize::Make(size.width, size.height)));
+  impeller::ExperimentalDlDispatcher impeller_dispatcher(
+      context.GetContentContext(), target,
+      display_list->root_has_backdrop_filter(),
+      display_list->max_root_blend_mode(), impeller::IRect::MakeSize(size));
+  display_list->Dispatch(impeller_dispatcher, SkIRect::MakeSize(SkISize::Make(
+                                                  size.width, size.height)));
+  impeller_dispatcher.FinishRecording();
+
+  context.GetContentContext().GetLazyGlyphAtlas()->ResetTextFrames();
+
+  return target.GetRenderTargetTexture();
+}
+#endif  // EXPERIMENTAL_CANVAS
+
 }  // namespace
 
 #define IMP_AIKSTEST(name)                         \
@@ -214,8 +268,16 @@ bool GoldenPlaygroundTest::OpenPlaygroundHere(
     const AiksDlPlaygroundCallback& callback) {
   AiksContext renderer(GetContext(), typographer_context_);
 
-  std::optional<Picture> picture;
   std::unique_ptr<testing::Screenshot> screenshot;
+#if EXPERIMENTAL_CANVAS
+  for (int i = 0; i < 2; ++i) {
+    auto display_list = callback();
+    auto texture =
+        DisplayListToTexture(display_list, pimpl_->window_size, renderer);
+    screenshot = pimpl_->screenshotter->MakeScreenshot(renderer, texture);
+  }
+#else
+  std::optional<Picture> picture;
   for (int i = 0; i < 2; ++i) {
     auto display_list = callback();
     DlDispatcher dispatcher;
@@ -225,7 +287,7 @@ bool GoldenPlaygroundTest::OpenPlaygroundHere(
     screenshot = pimpl_->screenshotter->MakeScreenshot(renderer, picture,
                                                        pimpl_->window_size);
   }
-
+#endif  // EXPERIMENTAL_CANVAS
   return SaveScreenshot(std::move(screenshot));
 }
 
@@ -250,10 +312,7 @@ bool GoldenPlaygroundTest::OpenPlaygroundHere(
 
 bool GoldenPlaygroundTest::OpenPlaygroundHere(
     const sk_sp<flutter::DisplayList>& list) {
-  DlDispatcher dispatcher;
-  list->Dispatch(dispatcher);
-  Picture picture = dispatcher.EndRecordingAsPicture();
-  return OpenPlaygroundHere(std::move(picture));
+  return OpenPlaygroundHere([&list]() { return list; });
 }
 
 bool GoldenPlaygroundTest::ImGuiBegin(const char* name,

impeller/golden_tests/metal_screenshotter.h

@@ -25,6 +25,10 @@ class MetalScreenshotter : public Screenshotter {
       const ISize& size = {300, 300},
       bool scale_content = true) override;
 
+  std::unique_ptr<Screenshot> MakeScreenshot(
+      AiksContext& aiks_context,
+      const std::shared_ptr<Texture> texture) override;
+
   PlaygroundImpl& GetPlayground() override { return *playground_; }
 
  private:

impeller/golden_tests/metal_screenshotter.mm

@@ -31,6 +31,12 @@
       aiks_context,
       ISize(size.width * content_scale.x, size.height * content_scale.y));
   std::shared_ptr<Texture> texture = image->GetTexture();
+  return MakeScreenshot(aiks_context, texture);
+}
+
+std::unique_ptr<Screenshot> MetalScreenshotter::MakeScreenshot(
+    AiksContext& aiks_context,
+    const std::shared_ptr<Texture> texture) {
   id<MTLTexture> metal_texture =
       std::static_pointer_cast<TextureMTL>(texture)->GetMTLTexture();
 

impeller/golden_tests/screenshotter.h

@@ -24,6 +24,10 @@ class Screenshotter {
       const ISize& size = {300, 300},
       bool scale_content = true) = 0;
 
+  virtual std::unique_ptr<Screenshot> MakeScreenshot(
+      AiksContext& aiks_context,
+      const std::shared_ptr<Texture> texture) = 0;
+
   virtual PlaygroundImpl& GetPlayground() = 0;
 };
 

impeller/golden_tests/vulkan_screenshotter.h

@@ -26,6 +26,10 @@ class VulkanScreenshotter : public Screenshotter {
       const ISize& size = {300, 300},
       bool scale_content = true) override;
 
+  std::unique_ptr<Screenshot> MakeScreenshot(
+      AiksContext& aiks_context,
+      const std::shared_ptr<Texture> texture) override;
+
   PlaygroundImpl& GetPlayground() override { return *playground_; }
 
  private:

impeller/golden_tests/vulkan_screenshotter.mm

@@ -120,5 +120,11 @@ CGImagePtr flipped_image(CGBitmapContextCreateImage(flipped_context.get()),
   return ReadTexture(aiks_context.GetContext(), texture);
 }
 
+std::unique_ptr<Screenshot> VulkanScreenshotter::MakeScreenshot(
+    AiksContext& aiks_context,
+    const std::shared_ptr<Texture> texture) {
+  return ReadTexture(aiks_context.GetContext(), texture);
+}
+
 }  // namespace testing
 }  // namespace impeller