React Native CDP Status

The id of the layer for which we want to get the reasons it was composited.

Return object

compositingReasons

array[ string ]

A list of strings specifying reasons for the given layer to become composited.

compositingReasonIds

array[ string ]

A list of strings specifying reason IDs for the given layer to become composited.

LayerTree.disable #

Disables compositing tree inspection.

LayerTree.enable #

Enables compositing tree inspection.

LayerTree.loadSnapshot #

Returns the snapshot identifier.

Parameters

tiles

array[ PictureTile ]

An array of tiles composing the snapshot.

Return object

snapshotId

The id of the snapshot.

LayerTree.makeSnapshot #

Returns the layer snapshot identifier.

Parameters

layerId

The id of the layer.

Return object

snapshotId

The id of the layer snapshot.

LayerTree.profileSnapshot #

Parameters

snapshotId

The id of the layer snapshot.

minRepeatCount
Optional

integer

The maximum number of times to replay the snapshot (1, if not specified).

minDuration
Optional

number

The minimum duration (in seconds) to replay the snapshot.

clipRect
Optional

The clip rectangle to apply when replaying the snapshot.

Return object

timings

array[ PaintProfile ]

The array of paint profiles, one per run.

LayerTree.releaseSnapshot #

Releases layer snapshot captured by the back-end.

Parameters

snapshotId

The id of the layer snapshot.

LayerTree.replaySnapshot #

Replays the layer snapshot and returns the resulting bitmap.

Parameters

snapshotId

The id of the layer snapshot.

fromStep
Optional

integer

The first step to replay from (replay from the very start if not specified).

toStep
Optional

integer

The last step to replay to (replay till the end if not specified).

scale
Optional

number

The scale to apply while replaying (defaults to 1).

Return object

dataURL

string

A data: URL for resulting image.

LayerTree.snapshotCommandLog #

Replays the layer snapshot and returns canvas log.

Parameters

snapshotId

The id of the layer snapshot.

Return object

commandLog

array[ object ]

The array of canvas function calls.

Events

LayerTree.layerPainted #

Parameters

layerId

The id of the painted layer.

clip

Clip rectangle.

LayerTree.layerTreeDidChange #

Parameters

layers
Optional

array[ Layer ]

Layer tree, absent if not in the compositing mode.

Types

LayerTree.Layer #

Information about a compositing layer.

Type: object

Properties

layerId

The unique id for this layer.

parentLayerId
Optional

The id of parent (not present for root).

backendNodeId
Optional

DOM.BackendNodeId

The backend id for the node associated with this layer.

offsetX

number

Offset from parent layer, X coordinate.

offsetY

number

Offset from parent layer, Y coordinate.

width

number

Layer width.

height

number

Layer height.

transform
Optional

array[ number ]

Transformation matrix for layer, default is identity matrix

anchorX
Optional

number

Transform anchor point X, absent if no transform specified

anchorY
Optional

number

Transform anchor point Y, absent if no transform specified

anchorZ
Optional

number

Transform anchor point Z, absent if no transform specified

paintCount

integer

Indicates how many time this layer has painted.

drawsContent

boolean

Indicates whether this layer hosts any content, rather than being used for transform/scrolling purposes only.

invisible
Optional

boolean

Set if layer is not visible.

scrollRects
Optional

array[ ScrollRect ]

Rectangles scrolling on main thread only.

stickyPositionConstraint
Optional

StickyPositionConstraint

Sticky position constraint information

LayerTree.LayerId #

Unique Layer identifier.

Type: string

LayerTree.PaintProfile #

Array of timings, one per paint step.

Type: array[ number ]

LayerTree.PictureTile #

Serialized fragment of layer picture along with its offset within the layer.

Type: object

Properties

x

number

Offset from owning layer left boundary

y

number

Offset from owning layer top boundary

picture

string

Base64-encoded snapshot data. (Encoded as a base64 string when passed over JSON)

LayerTree.ScrollRect #

Rectangle where scrolling happens on the main thread.

Type: object

Properties

rect

Rectangle itself.

type

string

Reason for rectangle to force scrolling on the main thread

Allowed values: RepaintsOnScroll, TouchEventHandler, WheelEventHandler

LayerTree.SnapshotId #

Unique snapshot identifier.

Type: string

LayerTree.StickyPositionConstraint #

Sticky position constraints.

Type: object

Properties

stickyBoxRect

Layout rectangle of the sticky element before being shifted

containingBlockRect

Layout rectangle of the containing block of the sticky element

nearestLayerShiftingStickyBox
Optional

The nearest sticky layer that shifts the sticky box

nearestLayerShiftingContainingBlock
Optional