mojo/services/view_manager/interfaces/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.

[DartPackage="mojo_services"]
module mojo;

import "geometry/interfaces/geometry.mojom";
import "input_events/interfaces/input_events.mojom";
import "mojo/public/interfaces/application/service_provider.mojom";
import "native_viewport/interfaces/native_viewport.mojom";
import "surfaces/interfaces/surface_id.mojom";
import "view_manager/interfaces/view_manager_constants.mojom";

struct ViewData {
  uint32 parent_id;
  uint32 view_id;
  mojo.Rect bounds;
  map<string, array<uint8>> properties;
  // True if this view is visible. The view may not be drawn on screen (see
  // drawn for specifics).
  bool visible;
  // True if this view is drawn on screen. A view is drawn if attached to the
  // root and all ancestors (including this view) are visible.
  bool drawn;
  ViewportMetrics viewport_metrics;
};

enum ErrorCode {
  NONE,
  VALUE_IN_USE,
  ILLEGAL_ARGUMENT,
};

// Views are identified by a uint32. The upper 16 bits are the connection id,
// and the lower 16 the id assigned by the client.
//
// The root view is identified with a connection id of 0, and value of 1.
interface ViewManagerService {
  // 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).
  // Additionally the connection id (embedded in |view_id|) must match that of
  // the connection.
  // Errors:
  //   ERROR_CODE_VALUE_IN_USE: a view already exists with the specified id.
  //   ERROR_CODE_ILLEGAL_ARGUMENT: The connection part of |view_id| does not
  //     match the connection id of the client.
  //
  // TODO(erg): Once we have default values in mojo, make this take a map of
  // properties.
  CreateView(uint32 view_id) => (ErrorCode error_code);

  // Deletes a view. This does not recurse. No hierarchy change notifications
  // are sent as a result of this. Only the connection that created the view can
  // delete it.
  DeleteView(uint32 view_id) => (bool success);

  // Sets the specified bounds of the specified view.
  SetViewBounds(uint32 view_id, mojo.Rect bounds) => (bool success);

  // Sets the visibility of the specified view to |visible|. Connections are
  // allowed to change the visibility of any view they have created, as well as
  // any of their roots.
  SetViewVisibility(uint32 view_id, bool visible) => (bool success);

  // Sets an individual named property. Setting an individual property to null
  // deletes the property.
  SetViewProperty(uint32 view_id,
                  string name,
                  array<uint8>? value) => (bool success);

  // Reparents a view.
  // This fails for any of the following reasons:
  // . |parent| or |child| does not identify a valid view.
  // . |child| is an ancestor of |parent|.
  // . |child| is already a child of |parent|.
  //
  // This may result in a connection getting OnViewDeleted(). See
  // RemoveViewFromParent for details.
  AddView(uint32 parent, uint32 child) => (bool success);

  // Removes a view from its current parent. This fails if the view is not
  // valid or the view already has no parent.
  //
  // Removing a view from a parent may result in OnViewDeleted() being sent to
  // other connections. For example, connection A has views 1 and 2, with 2 a
  // child of 1. Connection B has a root 1. If 2 is removed from 1 then B gets
  // OnViewDeleted(). This is done as view 2 is effectively no longer visible to
  // connection B.
  RemoveViewFromParent(uint32 view_id) => (bool success);

  // Reorders a view in its parent, relative to |relative_view_id| according to
  // |direction|.
  // Only the connection that created the view's parent can reorder its
  // children.
  ReorderView(uint32 view_id,
              uint32 relative_view_id,
              OrderDirection direction) => (bool success);

  // Returns the views comprising the tree starting at |view_id|. |view_id| is
  // the first result in the return value, unless |view_id| is invalid, in which
  // case an empty vector is returned. The views are visited using a depth first
  // search (pre-order).
  GetViewTree(uint32 view_id) => (array<ViewData> views);

  // Shows the surface in the specified view.
  SetViewSurfaceId(uint32 view_id, SurfaceId surface_id) => (bool success);

  // A connection may grant access to a view from another connection by way of
  // the embed functions. There are two variants of this call:
  //
  // . EmbedUrl: the ViewManager connects to the app at the supplied url and
  //   asks it for a ViewManagerClient.
  // . With the second variant a ViewManagerClient is directly supplied.
  //
  // In both cases the new ViewManagerClient is configured with a root of
  // |view_id|.
  //
  // The caller must have created |view_id|. If not the request fails and the
  // response is false.
  //
  // A view may only be a root of one connection at a time. Subsequent calls to
  // Embed() for the same view result in the view being removed from the
  // currently embedded app. The embedded app is told this by way of
  // OnViewDeleted().
  //
  // The embedder can detect when the embedded app disconnects by way of
  // OnEmbeddedAppDisconnected().
  //
  // When a connection embeds an app the connection no longer has priviledges
  // to access or see any of the children of the view. If the view had existing
  // children the children are removed. The one exception is the root
  // connection.
  //
  // |services| encapsulates services offered by the embedder to the embedded
  // app alongside this Embed() call. |exposed_services| provides a means for
  // the embedder to connect to services exposed by the embedded app. Note that
  // if a different app is subsequently embedded at |view_id| the
  // ServiceProvider connections to its client in the embedded app and any
  // services it provided are not broken and continue to be valid.
  EmbedUrl(string url,
           uint32 view_id,
           ServiceProvider&? services,
           ServiceProvider? exposed_services) => (bool success);
  Embed(uint32 view_id, ViewManagerClient client) => (bool success);

  // Requests the WindowManager to perform an action on the specified view.
  // It's up to the WindowManager to decide what |action| is.
  //
  // TODO(sky): nuke this. This is here to guarantee the state of the
  // WindowManager matches that of the ViewManager at the time the client
  // invokes the function. When we can enforce ordering this won't be necessary.
  PerformAction(uint32 view_id, string action) => (bool success);
};

// Changes to views are not sent to the connection that originated the
// change. For example, if connection 1 changes the bounds of a view by calling
// SetBounds(), connection 1 does not receive OnViewBoundsChanged().
interface ViewManagerClient {
  // Invoked when the client application has been embedded at |root|.
  // See Embed() on ViewManagerService for more details. |view_manager_service|
  // will be a handle back to the view manager service, unless the connection is
  // to the WindowManager in which case it will be null.
  // |window_manager_pipe| is a pipe to the WindowManager.
  OnEmbed(uint16 connection_id,
          string embedder_url,
          ViewData root,
          ViewManagerService? view_manager_service,
          ServiceProvider&? services,
          ServiceProvider? exposed_services,
          handle<message_pipe> window_manager_pipe);

  // Invoked when the application embedded at |view| is disconnected.
  OnEmbeddedAppDisconnected(uint32 view);

  // Invoked when a view's bounds have changed.
  OnViewBoundsChanged(uint32 view,
                      mojo.Rect old_bounds,
                      mojo.Rect new_bounds);

  // Invoked when the viewport metrics for the view have changed.
  // Clients are expected to propagate this to the view tree.
  OnViewViewportMetricsChanged(mojo.ViewportMetrics old_metrics,
                               mojo.ViewportMetrics new_metrics);

  // Invoked when a change is done to the hierarchy. A value of 0 is used to
  // identify a null view. For example, if the old_parent is NULL, 0 is
  // supplied.
  // |views| contains any views that are that the client has not been told
  // about. This is not sent for hierarchy changes of views not known to this
  // client or not attached to the tree.
  OnViewHierarchyChanged(uint32 view,
                         uint32 new_parent,
                         uint32 old_parent,
                         array<ViewData> views);

  // Invoked when the order of views within a parent changes.
  OnViewReordered(uint32 view_id,
                  uint32 relative_view_id,
                  OrderDirection direction);

  // Invoked when a view is deleted.
  OnViewDeleted(uint32 view);

  // Invoked when the visibility of the specified view changes.
  OnViewVisibilityChanged(uint32 view, bool visible);

  // Invoked when a change to the visibility of |view| or one if it's ancestors
  // is done such that the drawn state changes. This is only invoked for the
  // top most view of a particular connection. For example, if you have the
  // hierarchy: A -> B1 -> B2 (B2 is a child of B1 and B1 a child of A), B1/B2
  // are from connection 2 and A from connection 1 with all views visible and
  // drawn and the visiblity of A changes to false, then connection 2 is told
  // the drawn state of B1 has changed (to false), but is not told anything
  // about B2 as it's drawn state can be calculated from that of B1.
  //
  // NOTE: This is not invoked if OnViewVisibilityChanged() is invoked.
  OnViewDrawnStateChanged(uint32 view, bool drawn);

  // Invoked when a view property is changed. If this change is a removal,
  // |new_data| is null.
  OnViewSharedPropertyChanged(uint32 view, string name, array<uint8>? new_data);

  // Invoked when an event is targeted at the specified view.
  OnViewInputEvent(uint32 view, mojo.Event event) => ();

  // Invoked solely on the WindowManager. See comments in PerformAction() above
  // for details.
  // TODO(sky): nuke this.
  OnPerformAction(uint32 view_id, string action) => (bool success);
};