Initial checkin of the new Mozart compositor.

services/gfx/compositor/graph/scene_def.cc

+// Copyright 2015 The Chromium 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 "services/gfx/compositor/graph/scene_def.h"
+
+#include <ostream>
+#include <sstream>
+
+#include "base/bind.h"
+#include "base/logging.h"
+#include "base/message_loop/message_loop.h"
+#include "mojo/services/gfx/composition/cpp/logging.h"
+#include "services/gfx/compositor/graph/snapshot.h"
+#include "services/gfx/compositor/render/render_image.h"
+#include "services/gfx/compositor/render/render_layer.h"
+
+namespace compositor {
+
+// TODO(jeffbrown): Determine and document a more appropriate size limit
+// for transferred images as part of the image pipe abstraction instead.
+static const int32_t kMaxTextureWidth = 65536;
+static const int32_t kMaxTextureHeight = 65536;
+
+static void ReleaseMailboxTexture(
+    mojo::gfx::composition::MailboxTextureCallbackPtr callback) {
+  if (callback)
+    callback->OnMailboxTextureReleased();
+}
+
+SceneDef::SceneDef(mojo::gfx::composition::SceneTokenPtr scene_token,
+                   const std::string& label)
+    : scene_token_(scene_token.Pass()), label_(label) {
+  DCHECK(scene_token_);
+}
+
+SceneDef::~SceneDef() {}
+
+void SceneDef::EnqueueUpdate(mojo::gfx::composition::SceneUpdatePtr update) {
+  DCHECK(update);
+  pending_updates_.push_back(update.Pass());
+}
+
+void SceneDef::EnqueuePublish(
+    mojo::gfx::composition::SceneMetadataPtr metadata) {
+  DCHECK(metadata);
+  pending_publications_.emplace_back(new Publication(metadata.Pass()));
+  pending_updates_.swap(pending_publications_.back()->updates);
+}
+
+SceneDef::Disposition SceneDef::Present(
+    int64_t presentation_time,
+    const SceneResolver& resolver,
+    const SceneUnavailableSender& unavailable_sender,
+    std::ostream& err) {
+  // Walk backwards through the pending publications to find the index
+  // just beyond the last one which is due to be presented at or before the
+  // presentation time.
+  size_t end = pending_publications_.size();
+  for (;;) {
+    if (!end)
+      return Disposition::kUnchanged;
+    if (pending_publications_[end - 1]->is_due(presentation_time))
+      break;  // found last presentable publication
+    end--;
+  }
+
+  // Prepare to apply all publications up to this point.
+  uint32_t version = pending_publications_[end - 1]->metadata->version;
+  if (version_ != version) {
+    version_ = version;
+    formatted_label_cache_.clear();
+  }
+  Invalidate();
+
+  // Apply all updates sequentially.
+  for (size_t index = 0; index < end; ++index) {
+    for (auto& update : pending_publications_[index]->updates) {
+      if (!ApplyUpdate(update.Pass(), resolver, unavailable_sender, err))
+        return Disposition::kFailed;
+    }
+  }
+
+  // Dequeue the publications we processed.
+  pending_publications_.erase(pending_publications_.begin(),
+                              pending_publications_.begin() + end);
+
+  // Ensure the scene is in a valid state.
+  if (!Validate(err))
+    return Disposition::kFailed;
+  return Disposition::kSucceeded;
+}
+
+bool SceneDef::ApplyUpdate(mojo::gfx::composition::SceneUpdatePtr update,
+                           const SceneResolver& resolver,
+                           const SceneUnavailableSender& unavailable_sender,
+                           std::ostream& err) {
+  DCHECK(update);
+
+  // Update resources.
+  if (update->clear_resources) {
+    resources_.clear();
+  }
+  for (auto it = update->resources.begin(); it != update->resources.end();
+       ++it) {
+    uint32_t resource_id = it.GetKey();
+    mojo::gfx::composition::ResourcePtr& resource_decl = it.GetValue();
+    if (resource_decl) {
+      ResourceDef* resource = CreateResource(resource_id, resource_decl.Pass(),
+                                             resolver, unavailable_sender, err);
+      if (!resource)
+        return false;
+      resources_[resource_id].reset(resource);
+    } else {
+      resources_.erase(resource_id);
+    }
+  }
+
+  // Update nodes.
+  if (update->clear_nodes) {
+    nodes_.clear();
+  }
+  for (auto it = update->nodes.begin(); it != update->nodes.end(); ++it) {
+    uint32_t node_id = it.GetKey();
+    mojo::gfx::composition::NodePtr& node_decl = it.GetValue();
+    if (node_decl) {
+      NodeDef* node = CreateNode(node_id, node_decl.Pass(), err);
+      if (!node)
+        return false;
+      nodes_[node_id].reset(node);
+    } else {
+      nodes_.erase(node_id);
+    }
+  }
+  return true;
+}
+
+bool SceneDef::Validate(std::ostream& err) {
+  // Validate all nodes.
+  // TODO(jeffbrown): Figure out how to do this incrementally if it gets
+  // too expensive to process all nodes each time.
+  root_node_ = nullptr;
+  for (auto& pair : nodes_) {
+    uint32_t node_id = pair.first;
+    NodeDef* node = pair.second.get();
+    if (!node->Validate(this, err))
+      return false;
+    if (node_id == mojo::gfx::composition::kSceneRootNodeId)
+      root_node_ = node;
+  }
+  return true;
+}
+
+bool SceneDef::UnlinkReferencedScene(
+    SceneDef* scene,
+    const SceneUnavailableSender& unavailable_sender) {
+  DCHECK(scene);
+
+  bool changed = false;
+  for (auto& pair : resources_) {
+    if (pair.second->type() == ResourceDef::Type::kScene) {
+      auto scene_resource = static_cast<SceneResourceDef*>(pair.second.get());
+      if (scene_resource->referenced_scene() == scene) {
+        scene_resource->clear_referenced_scene();
+        Invalidate();
+        changed = true;
+        unavailable_sender.Run(pair.first);

[abarth, 2016/01/10 22:55:36]

This really looks like a weak pointer with a callback.

[jeffbrown, 2016/01/16 03:28:32]

Perhaps, but I don't see a way to set a callback on a base::WeakPtr.  And in any
case, there are side-effects that must be orchestrated by the engine.  I'm going
to leave this one to ponder for later together with whether I want to
encapsulate SceneDef cross-references in some way.

+      }
+    }
+  }
+  return changed;
+}
+
+bool SceneDef::Snapshot(SnapshotBuilder* snapshot_builder,
+                        RenderLayerBuilder* layer_builder) {
+  DCHECK(snapshot_builder);
+  DCHECK(layer_builder);
+
+  // Detect cycles.
+  if (visited_) {
+    if (snapshot_builder->block_log()) {
+      *snapshot_builder->block_log()
+          << "Scene blocked due to recursive cycle: " << FormattedLabel()
+          << std::endl;
+    }
+    return false;
+  }
+
+  // Snapshot the contents of the scene.
+  visited_ = true;
+  bool success = SnapshotInner(snapshot_builder, layer_builder);
+  visited_ = false;
+  return success;
+}
+
+bool SceneDef::SnapshotInner(SnapshotBuilder* snapshot_builder,
+                             RenderLayerBuilder* layer_builder) {
+  // Note the dependency even if blocked.
+  snapshot_builder->AddSceneDependency(this);
+
+  // Ensure we have a root node.
+  if (!root_node_) {
+    if (snapshot_builder->block_log()) {
+      *snapshot_builder->block_log()
+          << "Scene blocked due because it has no root node: "
+          << FormattedLabel() << std::endl;
+    }
+    return false;
+  }
+
+  // Snapshot and draw the layer.
+  std::shared_ptr<RenderLayer> scene_layer = SnapshotLayer(snapshot_builder);
+  if (!scene_layer)
+    return false;
+  layer_builder->DrawLayer(scene_layer);
+  return true;
+}
+
+std::shared_ptr<RenderLayer> SceneDef::SnapshotLayer(
+    SnapshotBuilder* snapshot_builder) {
+  if (cached_layer_)
+    return cached_layer_;
+
+  RenderLayerBuilder scene_layer_builder;
+  scene_layer_builder.PushScene(scene_token_->value, version_);
+  if (!root_node_->Snapshot(snapshot_builder, &scene_layer_builder, this))
+    return nullptr;
+  scene_layer_builder.PopScene();
+
+  // TODO(jeffbrown): Implement caching even when the scene has dependencies.
+  // There are some subtleties to be dealt with to ensure that caches
+  // are properly invalidated and that we don't accidentally cache layers which
+  // bake in decisions which counteract the intended cycle detection and
+  // avoidance behavior.  Basically just need better bookkeeping.

[abarth, 2016/01/10 22:55:36]

The DAG is making this harder for you.  I'm not sure how important it is to have
a DAG rather than a tree.

[jeffbrown, 2016/01/16 03:28:32]

I think the DAG will be quite useful for cross-application transitions, saved
layers, and multi-display support.  That said, I may well change the policy for
handling cycles.

+  std::shared_ptr<RenderLayer> scene_layer = scene_layer_builder.Build();
+  if (!HasSceneResources())
+    cached_layer_ = scene_layer;
+  return scene_layer;
+}
+
+void SceneDef::Invalidate() {
+  cached_layer_.reset();
+}
+
+bool SceneDef::HasSceneResources() {
+  for (auto& pair : resources_) {
+    if (pair.second->type() == ResourceDef::Type::kScene)
+      return true;
+  }
+  return false;
+}
+
+ResourceDef* SceneDef::CreateResource(
+    uint32_t resource_id,
+    mojo::gfx::composition::ResourcePtr resource_decl,
+    const SceneResolver& resolver,
+    const SceneUnavailableSender& unavailable_sender,
+    std::ostream& err) {
+  DCHECK(resource_decl);
+
+  if (resource_decl->is_scene()) {
+    auto& scene_resource_decl = resource_decl->get_scene();
+    DCHECK(scene_resource_decl->scene_token);
+    SceneDef* referenced_scene =
+        resolver.Run(scene_resource_decl->scene_token.get());
+    if (!referenced_scene) {
+      unavailable_sender.Run(resource_id);
+    }
+    return new SceneResourceDef(referenced_scene);
+  }
+
+  if (resource_decl->is_mailbox_texture()) {
+    auto& mailbox_texture_resource_decl = resource_decl->get_mailbox_texture();
+    DCHECK(mailbox_texture_resource_decl->mailbox_name.size() ==
+           GL_MAILBOX_SIZE_CHROMIUM);
+    DCHECK(mailbox_texture_resource_decl->size);
+    int32_t width = mailbox_texture_resource_decl->size->width;
+    int32_t height = mailbox_texture_resource_decl->size->height;
+    if (width < 1 || width > kMaxTextureWidth || height < 1 ||
+        height > kMaxTextureHeight) {
+      err << "MailboxTexture resource has invalid size: "
+          << "resource_id=" << resource_id << ", width=" << width
+          << ", height=" << height;
+      return nullptr;
+    }
+    return new ImageResourceDef(RenderImage::FromMailboxTexture(
+        mailbox_texture_resource_decl->mailbox_name.data(),
+        mailbox_texture_resource_decl->sync_point, width, height,
+        base::MessageLoop::current()->task_runner(),
+        base::Bind(
+            &ReleaseMailboxTexture,
+            base::Passed(mailbox_texture_resource_decl->callback.Pass()))));
+  }
+
+  err << "Unsupported resource type: resource_id=" << resource_id;
+  return nullptr;
+}
+
+NodeDef* SceneDef::CreateNode(uint32_t node_id,
+                              mojo::gfx::composition::NodePtr node_decl,
+                              std::ostream& err) {
+  DCHECK(node_decl);
+
+  NodeOp* op = nullptr;
+  if (node_decl->op) {
+    op = CreateNodeOp(node_id, node_decl->op.Pass(), err);
+    if (!op)
+      return nullptr;
+  }
+
+  return new NodeDef(node_id, node_decl->content_transform.Pass(),
+                     node_decl->content_clip.Pass(), node_decl->hit_id,
+                     node_decl->combinator, node_decl->child_node_ids.storage(),
+                     op);
+}
+
+NodeOp* SceneDef::CreateNodeOp(uint32_t node_id,
+                               mojo::gfx::composition::NodeOpPtr node_op_decl,
+                               std::ostream& err) {
+  DCHECK(node_op_decl);
+
+  if (node_op_decl->is_rect()) {
+    auto& rect_node_op_decl = node_op_decl->get_rect();
+    DCHECK(rect_node_op_decl->content_rect);
+    DCHECK(rect_node_op_decl->color);
+    return new RectNodeOp(*rect_node_op_decl->content_rect,
+                          *rect_node_op_decl->color);
+  }
+
+  if (node_op_decl->is_image()) {
+    auto& image_node_op_decl = node_op_decl->get_image();
+    DCHECK(image_node_op_decl->content_rect);
+    return new ImageNodeOp(*image_node_op_decl->content_rect,
+                           image_node_op_decl->image_rect.Pass(),
+                           image_node_op_decl->image_resource_id,
+                           image_node_op_decl->blend.Pass());
+  }
+
+  if (node_op_decl->is_scene()) {
+    auto& scene_node_op_decl = node_op_decl->get_scene();
+    return new SceneNodeOp(scene_node_op_decl->scene_resource_id,
+                           scene_node_op_decl->scene_version);
+  }
+
+  if (node_op_decl->is_layer()) {
+    auto& layer_node_op_decl = node_op_decl->get_layer();
+    DCHECK(layer_node_op_decl->layer_size);
+    return new LayerNodeOp(*layer_node_op_decl->layer_size,
+                           layer_node_op_decl->blend.Pass());
+  }
+
+  err << "Unsupported node op type: node_id=" << node_id
+      << ", node_op=" << node_op_decl;
+  return nullptr;
+}
+
+NodeDef* SceneDef::FindNode(uint32_t node_id) {
+  auto it = nodes_.find(node_id);
+  return it != nodes_.end() ? it->second.get() : nullptr;
+}
+
+ResourceDef* SceneDef::FindResource(uint32_t resource_id,
+                                    ResourceDef::Type resource_type) {
+  auto it = resources_.find(resource_id);
+  return it != resources_.end() && it->second->type() == resource_type
+             ? it->second.get()
+             : nullptr;
+}
+
+std::string SceneDef::FormattedLabel() {
+  if (formatted_label_cache_.empty()) {
+    std::ostringstream s;
+    s << "<" << scene_token_->value;
+    if (!label_.empty())
+      s << ":" << label_;
+    s << "/" << version_ << ">";
+    formatted_label_cache_ = s.str();
+  }
+  return formatted_label_cache_;
+}
+
+SceneDef::Publication::Publication(
+    mojo::gfx::composition::SceneMetadataPtr metadata)
+    : metadata(metadata.Pass()) {
+  DCHECK(this->metadata);
+}
+
+SceneDef::Publication::~Publication() {}
+
+}  // namespace compositor