runtime/flutter_runner/compositor_context.cc

// Copyright 2018 The Fuchsia 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 "compositor_context.h"

#include "flutter/flow/layers/layer_tree.h"

namespace flutter_runner {

class ScopedFrame final : public flutter::CompositorContext::ScopedFrame {
 public:
  ScopedFrame(flutter::CompositorContext& context,
              const SkMatrix& root_surface_transformation,
              bool instrumentation_enabled,
              SessionConnection& session_connection)
      : flutter::CompositorContext::ScopedFrame(context, nullptr, nullptr, nullptr,
                                             root_surface_transformation,
                                             instrumentation_enabled),
        session_connection_(session_connection) {}

 private:
  SessionConnection& session_connection_;

  bool Raster(flutter::LayerTree& layer_tree, bool ignore_raster_cache) override {
    if (!session_connection_.has_metrics()) {
      return true;
    }

    {
      // Preroll the Flutter layer tree. This allows Flutter to perform
      // pre-paint optimizations.
      TRACE_DURATION("flutter", "Preroll");
      layer_tree.Preroll(*this, true /* ignore raster cache */);
    }

    {
      // Traverse the Flutter layer tree so that the necessary session ops to
      // represent the frame are enqueued in the underlying session.
      TRACE_DURATION("flutter", "UpdateScene");
      layer_tree.UpdateScene(session_connection_.scene_update_context(),
                             session_connection_.root_node());
    }

    {
      // Flush all pending session ops.
      TRACE_DURATION("flutter", "SessionPresent");
      session_connection_.Present(*this);
    }

    return true;
  }

  FML_DISALLOW_COPY_AND_ASSIGN(ScopedFrame);
};

CompositorContext::CompositorContext(
    std::string debug_label, fuchsia::ui::views::ViewToken view_token,
    fidl::InterfaceHandle<fuchsia::ui::scenic::Session> session,
    fit::closure session_error_callback, zx_handle_t vsync_event_handle)
    : debug_label_(std::move(debug_label)),
      session_connection_(debug_label_, std::move(view_token),
                          std::move(session), std::move(session_error_callback),
                          vsync_event_handle) {}

void CompositorContext::OnSessionMetricsDidChange(
    const fuchsia::ui::gfx::Metrics& metrics) {
  session_connection_.set_metrics(metrics);
}

void CompositorContext::OnSessionSizeChangeHint(float width_change_factor,
                                                float height_change_factor) {
  session_connection_.OnSessionSizeChangeHint(width_change_factor,
                                              height_change_factor);
}

CompositorContext::~CompositorContext() = default;

std::unique_ptr<flutter::CompositorContext::ScopedFrame>
CompositorContext::AcquireFrame(GrContext* gr_context, SkCanvas* canvas,
                                flutter::ExternalViewEmbedder* view_embedder,
                                const SkMatrix& root_surface_transformation,
                                bool instrumentation_enabled) {
  // TODO: The AcquireFrame interface is too broad and must be refactored to get
  // rid of the context and canvas arguments as those seem to be only used for
  // colorspace correctness purposes on the mobile shells.
  return std::make_unique<flutter_runner::ScopedFrame>(
      *this,                        //
      root_surface_transformation,  //
      instrumentation_enabled,      //
      session_connection_           //
  );
}

}  // namespace flutter_runner