path: root/components/mus/public/interfaces/view_tree.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;

import "components/mus/public/interfaces/compositor_frame.mojom";
import "components/mus/public/interfaces/surface_id.mojom";
import "components/mus/public/interfaces/mus_constants.mojom";
import "mojo/application/public/interfaces/service_provider.mojom";
import "network/public/interfaces/url_loader.mojom";
import "ui/mojo/events/input_events.mojom";
import "ui/mojo/ime/text_input_state.mojom";
import "ui/mojo/geometry/geometry.mojom";

struct ViewportMetrics {
  Size size_in_pixels;
  // A value of 0 indicates the real value is not yet available.
  float device_pixel_ratio = 0.0;
};

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 ViewTree {
  enum AccessPolicy {
    DEFAULT = 0,

    // An embed root has the following abilities:
    // . The app sees all the descendants of the view the app is ebmedded at,
    //   even those from separate connections.
    // . The app is able to Embed() in all the descendants of the view the app
    //   is embedded at, even those from separate connections.
    // Only connections originating from the ViewTreeHostFactory can grant this
    // policy.
    EMBED_ROOT = 1,
  };

  // 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);

  // Requests a Surface for a particular view.
  RequestSurface(uint32 view_id, Surface& surface, SurfaceClient client);

  // 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);

  // A connection may grant access to another connection by way of Embed().
  // Embed() results in the supplied ViewTreeClient being configured with a
  // root view of |view_id|. The supplied ViewTreeClient may create child
  // views and do other various tree operations (including Embed()), but does
  // not see nor have access to any of the views above the embed point.
  //
  // The caller must have created |view_id|. If not the request fails and the
  // response is false.
  //
  // When a connection embeds a ViewTreeClient the originating connection no
  // longer has privileges 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 and any connections with the policy
  // ACCESS_POLICY_EMBED_ROOT.
  //
  // A view may only have one embedding in it at a time. Subsequent calls to
  // Embed() for the same view result in the currently embedded
  // ViewTreeClient being removed. The embedded app is told this by way of
  // OnUnembed(), which is followed by OnViewDeleted() (as the connection no
  // longer has access to the view).
  //
  // The embedder can detect when the embedded app disconnects by way of
  // OnEmbeddedAppDisconnected().
  //
  // The callback returns whether the embedding was successful, and if the
  // embedding was successful and the originating connection is an embed root
  // the resulting id of the new connection.
  //
  // policy_bitmask is a bitmask of the kAccessPolicy constants. See them for
  // details.
  Embed(uint32 view_id,
        ViewTreeClient client,
        uint32 policy_bitmask) => (bool success, uint16 connection_id);

  SetFocus(uint32 view_id);

  // Set text input state for the given view.
  SetViewTextInputState(uint32 view_id, TextInputState state);

  // Set the input method editor UI (software keyboard, etc) visibility.
  // If state is non-null, the specified view's text input state is updated.
  // Otherwise the existing state is used.
  SetImeVisibility(uint32 view_id, bool visible, TextInputState? state);
};

// 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 ViewTreeClient {
  // Invoked when the client application has been embedded at |root|.
  // See Embed() on ViewTree for more details. |tree| will be a handle back to
  // the view manager service, unless the connection is to the root connection
  // in which case it will be null.
  OnEmbed(uint16 connection_id,
          ViewData root,
          ViewTree? tree,
          uint32 focused_view,
          uint32 access_policy);

  // Invoked when the application embedded at |view| is disconnected. In other
  // words the embedded app closes the connection to the server. This is called
  // on the connection that created |view| as well as any ancestors that have
  // the embed root policy.
  OnEmbeddedAppDisconnected(uint32 view);

  // Sent when another connection is embedded in the View this connection was
  // previously embedded in. See Embed() for more information.
  OnUnembed();

  // 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) => ();

  OnViewFocused(uint32 focused_view_id);
};