cc/resources/returned_resource.h

   1 // Copyright 2013 The Chromium Authors. All rights reserved.
   2 // Use of this source code is governed by a BSD-style license that can be
   3 // found in the LICENSE file.
   4
   5 #ifndef CC_RESOURCES_RETURNED_RESOURCE_H_
   6 #define CC_RESOURCES_RETURNED_RESOURCE_H_
   7
   8 #include <vector>
   9
  10 #include "base/basictypes.h"
  11 #include "cc/base/cc_export.h"
  12 #include "cc/base/resource_id.h"
  13
  14 namespace cc {
  15
  16 // A ReturnedResource is a struct passed along to a child compositor from a
  17 // parent compositor that corresponds to a TransferableResource that was
  18 // first passed to the parent compositor.
  19 struct CC_EXPORT ReturnedResource {
  20   ReturnedResource() : id(0), sync_point(0), count(0), lost(false) {}
  21   // |id| is an identifier generated by the child compositor that uniquely
  22   // identifies a resource. This is the same ID space as TransferableResource.
  23   ResourceId id;
  24
  25   // A |sync_point| is an identifier for a point in the parent compositor's
  26   // command buffer. The child compositor then issues a WaitSyncPointCHROMIUM
  27   // command with this |sync_point| as a parameter into its own command buffer.
  28   // This ensures that uses of the resource submitted by the parent compositor
  29   // are executed before commands submitted by the child.
  30   unsigned sync_point;
  31
  32   // |count| is a reference count for this resource. A resource may be used
  33   // by mulitple compositor frames submitted to the parent compositor. |count|
  34   // is the number of references being returned back to the child compositor.
  35   int count;
  36
  37   // If the resource is lost, then the returner cannot give a sync point for it,
  38   // and so it has taken ownership of the resource. The receiver cannot do
  39   // anything with the resource except delete it.
  40   bool lost;
  41 };
  42
  43 typedef std::vector<ReturnedResource> ReturnedResourceArray;
  44
  45 }  // namespace cc
  46
  47 #endif  // CC_RESOURCES_RETURNED_RESOURCE_H_