LayerTree Domain
Methods
enable#
Enables compositing tree inspection.
disable#
Disables compositing tree inspection.
compositingReasons#
Provides the reasons why the given layer was composited.
Parameters
- layerId
- LayerId 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.
makeSnapshot#
Returns the layer snapshot identifier.
Parameters
- layerId
- LayerId The id of the layer.
Return object
- snapshotId
- SnapshotId The id of the layer snapshot.
loadSnapshot#
Returns the snapshot identifier.
Parameters
- tiles
- array [ PictureTile ] An array of tiles composing the snapshot.
Return object
- snapshotId
- SnapshotId The id of the snapshot.
releaseSnapshot#
Releases layer snapshot captured by the back-end.
Parameters
- snapshotId
- SnapshotId The id of the layer snapshot.
profileSnapshot#
Parameters
- snapshotId
- SnapshotId The id of the layer snapshot.
- minRepeatCount
- integer The maximum number of times to replay the snapshot (1, if not specified).
- minDuration
- number The minimum duration (in seconds) to replay the snapshot.
- clipRect
- DOM.Rect The clip rectangle to apply when replaying the snapshot.
Return object
- timings
- array [ PaintProfile ] The array of paint profiles, one per run.
replaySnapshot#
Replays the layer snapshot and returns the resulting bitmap.
Parameters
- snapshotId
- SnapshotId The id of the layer snapshot.
- fromStep
- integer The first step to replay from (replay from the very start if not specified).
- toStep
- integer The last step to replay to (replay till the end if not specified).
- scale
- number The scale to apply while replaying (defaults to 1).
Return object
- dataURL
- string A data: URL for resulting image.
snapshotCommandLog#
Replays the layer snapshot and returns canvas log.
Parameters
- snapshotId
- SnapshotId The id of the layer snapshot.
Return object
- commandLog
- array [object] The array of canvas function calls.
Events
Types
ScrollRect#
Rectangle where scrolling happens on the main thread.
Type: object
Properties
- rect
- DOM.Rect Rectangle itself.
- type
- string Reason for rectangle to force scrolling on the main thread Allowed values: RepaintsOnScroll, TouchEventHandler, WheelEventHandler.
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.
Layer#
Information about a compositing layer.
Type: object
Properties
- layerId
- LayerId The unique id for this layer.
- parentLayerId
- LayerId The id of parent (not present for root).
- backendNodeId
- 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
- array [number] Transformation matrix for layer, default is identity matrix
- anchorX
- number Transform anchor point X, absent if no transform specified
- anchorY
- number Transform anchor point Y, absent if no transform specified
- anchorZ
- 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
- boolean Set if layer is not visible.
- scrollRects
- array [ ScrollRect ] Rectangles scrolling on main thread only.