// Copyright 2023 The Chromium Authors
// Use of this source code is governed by a BSD-style license that can be
// found in the LICENSE file.
module viz.mojom;
import "services/viz/public/mojom/compositing/begin_frame_args.mojom";
import "services/viz/public/mojom/compositing/layer.mojom";
import "services/viz/public/mojom/compositing/local_surface_id.mojom";
import "services/viz/public/mojom/compositing/tiling.mojom";
import "skia/public/mojom/skcolor4f.mojom";
import "ui/gfx/geometry/mojom/geometry.mojom";
// Metadata and contents of a service-side display tree to be updated each time
// the corresponding client layer tree activates.
//
// Note for this structure and its constituent fields: dimensions of viewports,
// layer bounds, clipping rectangles, etc, are used as inputs to a drawing
// subsystem which produces CompositorFrames on behalf of the client. Those
// frames are themselves subjected to authoritative frame hierarchy constraints
// set by the Viz host (i.e. the browser.) Such fields therefore do not require
// additional validation on the service side. Clients are free to describe any
// visual geometry they like, but this does not allow them to escape their
// assigned clipping rectangle on the display, nor their place within the frame
// hierarchy as it pertains to visual layering or input targeting.
//
// TODO(https://crbug.com/40902503): Split less frequently updated fields out
// into an optional substructure to reduce serialization load.
struct LayerTreeUpdate {
// The main frame commit whose tree is driving this update. Incremented over
// time with each client-side commit.
int32 source_frame_number;
// Links trace events on the display side to other events in the client.
uint64 trace_id;
// The device viewport and scale factor set by the tree's client.
gfx.mojom.Rect device_viewport;
float device_scale_factor;
// If a new LocalSurfaceId is assigned by the parent, it's included here.
LocalSurfaceId? local_surface_id_from_parent;
// The background color with which to fill any space not covered by layers
// within the tree's content rect.
skia.mojom.SkColor4f background_color;
// Property tree node indices corresponding to ViewportPropertyIds.
int32 overscroll_elasticity_transform;
int32 page_scale_transform;
int32 inner_scroll;
int32 outer_clip;
int32 outer_scroll;
// Properties of layers added or modified since the last update. Note that the
// ordering of this array is arbitrary and not relevant to the tree's layer
// list order. If any layers were added, removed, or otherwise reordered in
// the client's layer list, `layer_order` will convey the full new layer list
// ordering.
array<Layer> layers;
// The full list of layer IDs in the tree, in layer-list order. If null, the
// layer list has not changed since the last update. For any ID present in
// this list, the display tree must already contain a layer with that ID, or
// there must be such a layer described in `layers` above.
array<int32>? layer_order;
// Miscellaneous transform tree properties, if changed since last update. Does
// not include changes to individual nodes in the tree.
TransformTreeUpdate? transform_tree_update;
// Nodes added or modified on any property tree since the last update.
array<TransformNode> transform_nodes;
array<ClipNode> clip_nodes;
array<EffectNode> effect_nodes;
array<ScrollNode> scroll_nodes;
// The total number of nodes in each property tree.
uint32 num_transform_nodes;
uint32 num_clip_nodes;
uint32 num_effect_nodes;
uint32 num_scroll_nodes;
// Tiling updates for any PictureLayers in the tree.
array<Tiling> tilings;
};
// Drives updates to a GPU-side LayerTreeHostImpl from its corresponding
// client-side (e.g. renderer- or browser-side) LayerTreeHost.
interface LayerContext {
// Globally controls whether the tree contents are visible.
SetVisible(bool visible);
// Flushes pending updates from the client to the service-side display tree.
UpdateDisplayTree(LayerTreeUpdate update);
// Updates one or more tiles in a specific tiling.
UpdateDisplayTiling(Tiling tiling);
};
// Provides feedback from a GPU-side LayerTreeHostImpl to its corresponding
// client-side (e.g. renderer- or browser-side) LayerTreeHost.
interface LayerContextClient {
// Sent by the LayerTreeHostImpl when it needs to produce a new frame soon and
// the client had previously indicated that it wants an opporunity to make
// changes to the tree before that frame is drawn.
OnRequestCommitForFrame(BeginFrameArgs args);
};
// Parameters needed to bind a LayerContext endpoint via a CompositorFrameSink.
struct PendingLayerContext {
// TODO(crbug.com/40902503): De-associate these interfaces from
// CompositorFrameSink.
pending_associated_receiver<LayerContext> receiver;
pending_associated_remote<LayerContextClient> client;
};
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