components/view_manager/ids.h

   1 // Copyright 2014 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 COMPONENTS_VIEW_MANAGER_IDS_H_
   6 #define COMPONENTS_VIEW_MANAGER_IDS_H_
   7
   8 #include "components/view_manager/public/cpp/types.h"
   9 #include "components/view_manager/public/cpp/util.h"
  10
  11 namespace view_manager {
  12
  13 // Connection id is used to indicate no connection. That is, no ViewTreeImpl
  14 // ever gets this id.
  15 const mojo::ConnectionSpecificId kInvalidConnectionId = 0;
  16
  17 // Adds a bit of type safety to view ids.
  18 struct ViewId {
  19   ViewId(mojo::ConnectionSpecificId connection_id,
  20          mojo::ConnectionSpecificId view_id)
  21       : connection_id(connection_id), view_id(view_id) {}
  22   ViewId() : connection_id(0), view_id(0) {}
  23
  24   bool operator==(const ViewId& other) const {
  25     return other.connection_id == connection_id &&
  26         other.view_id == view_id;
  27   }
  28
  29   bool operator!=(const ViewId& other) const {
  30     return !(*this == other);
  31   }
  32
  33   mojo::ConnectionSpecificId connection_id;
  34   mojo::ConnectionSpecificId view_id;
  35 };
  36
  37 inline ViewId ViewIdFromTransportId(mojo::Id id) {
  38   return ViewId(mojo::HiWord(id), mojo::LoWord(id));
  39 }
  40
  41 inline mojo::Id ViewIdToTransportId(const ViewId& id) {
  42   return (id.connection_id << 16) | id.view_id;
  43 }
  44
  45 // Returns a ViewId that is reserved to indicate no view. That is, no view will
  46 // ever be created with this id.
  47 inline ViewId InvalidViewId() {
  48   return ViewId(kInvalidConnectionId, 0);
  49 }
  50
  51 // Returns a root view id with a given index offset.
  52 inline ViewId RootViewId(uint16_t index) {
  53   return ViewId(kInvalidConnectionId, 2 + index);
  54 }
  55
  56 }  // namespace view_manager
  57
  58 #endif  // COMPONENTS_VIEW_MANAGER_IDS_H_