mojo/services/public/interfaces/view_manager/view_manager.mojom

// Copyright 2014 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.

module mojo.services.view_manager {

struct INode {
  uint32 parent_id;
  uint32 node_id;
  uint32 view_id;
};

// Functions that mutate the hierarchy take a |change_id|. |change_id| is an
// arbitrary value assigned by the client originating the change. It may be
// used by the client originating the change to later identify the change in
// an OnNodeHierarchyChanged callback. |change_id| is only passed to the client
// that originated the change; all other clients get a value of 0.
//
// Nodes are identified by a uint32. The upper 16 bits are the connection id,
// and the lower 16 the id assigned by the client. CreateNode() only takes a
// uint16 as the connection id of the originating connection is used.
//
// The root node is identified with a connection id of 0, and value of 1.
[Peer=IViewManagerClient]
interface IViewManager {
  // Creates a new node with the specified id. It is up to the client to ensure
  // the id is unique to the connection (the id need not be globally unique).
  CreateNode(uint16 node_id) => (bool success);

  // Deletes a node. This does not recurse. Children are removed from the node
  // before it is destroyed.
  DeleteNode(uint32 node_id, uint32 change_id) => (bool success);

  // Reparents a node. See description above class for details of |change_id|.
  AddNode(uint32 parent, uint32 child, uint32 change_id) => (bool success);

  // Removes a view from its current parent.  See description above class for
  // details of |change_id|.
  RemoveNodeFromParent(uint32 node_id, uint32 change_id) => (bool success);

  // Returns the nodes comprising the tree starting at |node_id|. |node_id| is 
  // the first result in the return value, unless |node_id| is invalid, in which
  // case an empty vector is returned. The nodes are visited using a depth first
  // search (pre-order).
  GetNodeTree(uint32 node_id) => (INode[] nodes);

  // Creates a new view with the specified id. It is up to the client to ensure
  // the id is unique to the connection (the id need not be globally unique).
  CreateView(uint16 view_id) => (bool success);

  // Deletes the view with the specified id.
  DeleteView(uint32 view_id, uint32 change_id) => (bool success);

  // Sets the view a node is showing.
  SetView(uint32 node_id, uint32 view_id, uint32 change_id) => (bool success);
};

[Peer=IViewManager]
interface IViewManagerClient {
  // Invoked once the connection has been established. |connection_id| is the id
  // used to uniquely identify the connection.
  OnConnectionEstablished(uint16 connection_id);

  // Invoked when a change is done to the hierarchy. A value of 0 is used to
  // identify a null node. For example, if the old_parent is NULL, 0 is
  // supplied. See description above ViewManager for details on |change_id|.
  OnNodeHierarchyChanged(uint32 node,
                         uint32 new_parent,
                         uint32 old_parent,
                         uint32 change_id);

  // Invoked when the view associated with a node is replaced by another view.
  // 0 is used to identify a null view.
  OnNodeViewReplaced(uint32 node,
                     uint32 new_view_id,
                     uint32 old_view_id,
                     uint32 change_id);
};

}