src/cobalt/loader/loader_factory.h

// Copyright 2016 Google Inc. All Rights Reserved.
//
// Licensed under the Apache License, Version 2.0 (the "License");
// you may not use this file except in compliance with the License.
// You may obtain a copy of the License at
//
//     http://www.apache.org/licenses/LICENSE-2.0
//
// Unless required by applicable law or agreed to in writing, software
// distributed under the License is distributed on an "AS IS" BASIS,
// WITHOUT WARRANTIES OR CONDITIONS OF ANY KIND, either express or implied.
// See the License for the specific language governing permissions and
// limitations under the License.

#ifndef COBALT_LOADER_LOADER_FACTORY_H_
#define COBALT_LOADER_LOADER_FACTORY_H_

#include <set>

#include "base/threading/thread.h"
#include "cobalt/csp/content_security_policy.h"
#include "cobalt/loader/fetcher_factory.h"
#include "cobalt/loader/font/typeface_decoder.h"
#include "cobalt/loader/image/image_decoder.h"
#include "cobalt/loader/loader.h"
#include "cobalt/loader/mesh/mesh_decoder.h"
#include "cobalt/render_tree/resource_provider.h"
#include "googleurl/src/gurl.h"

namespace cobalt {
namespace loader {

// The LoaderFactory provides a central loader creator object from which clients
// can request the creation of loaders of various types.  The LoaderFactory
// maintains all context necessary to create the various resource types.
class LoaderFactory {
 public:
  LoaderFactory(FetcherFactory* fetcher_factory,
                render_tree::ResourceProvider* resource_provider,
                base::ThreadPriority loader_thread_priority);

  // Creates a loader that fetches and decodes an image.
  scoped_ptr<Loader> CreateImageLoader(
      const GURL& url, const csp::SecurityCallback& url_security_callback,
      const image::ImageDecoder::SuccessCallback& success_callback,
      const image::ImageDecoder::ErrorCallback& error_callback,
      const Origin& origin);

  // Creates a loader that fetches and decodes a render_tree::Typeface.
  scoped_ptr<Loader> CreateTypefaceLoader(
      const GURL& url, const csp::SecurityCallback& url_security_callback,
      const font::TypefaceDecoder::SuccessCallback& success_callback,
      const font::TypefaceDecoder::ErrorCallback& error_callback,
      const Origin& orgin);

  // Creates a loader that fetches and decodes a Mesh.
  scoped_ptr<Loader> CreateMeshLoader(
      const GURL& url, const csp::SecurityCallback& url_security_callback,
      const mesh::MeshDecoder::SuccessCallback& success_callback,
      const mesh::MeshDecoder::ErrorCallback& error_callback,
      const Origin& origin);

  // Clears out the loader factory's resource provider, aborting any in-progress
  // loads.
  void Suspend();
  // Resets a new resource provider for this loader factory to use.  The
  // previous resource provider must have been cleared before this method is
  // called.
  void Resume(render_tree::ResourceProvider* resource_provider);

 private:
  void OnLoaderCreated(Loader* loader);
  void OnLoaderDestroyed(Loader* loader);

  Loader::FetcherCreator MakeFetcherCreator(
      const GURL& url, const csp::SecurityCallback& url_security_callback,
      RequestMode request_mode, const Origin& origin);

  // Ensures that the LoaderFactory methods are only called from the same
  // thread.
  base::ThreadChecker thread_checker_;

  // Used to create the Fetcher component of the loaders.
  FetcherFactory* fetcher_factory_;

  // Used to create render_tree resources.
  render_tree::ResourceProvider* resource_provider_;

  // Keeps track of all active loaders so that if a suspend event occurs they
  // can be aborted.
  typedef std::set<Loader*> LoaderSet;
  LoaderSet active_loaders_;

  // Thread to run asynchronous fetchers and decoders on.  At the moment,
  // image decoding is the only thing done on this thread.
  base::Thread load_thread_;

  // Whether or not the LoaderFactory is currently suspended. While it is, all
  // loaders created by it begin in a suspended state.
  bool is_suspended_;
};

}  // namespace loader
}  // namespace cobalt

#endif  // COBALT_LOADER_LOADER_FACTORY_H_