Source/JavaScriptCore/inspector/protocol/LayerTree.json

{
    "domain": "LayerTree",
    "availability": ["web"],
    "types": [
        {
            "id": "LayerId",
            "type": "string",
            "description": "Unique RenderLayer identifier."
        },
        {
            "id": "PseudoElementId",
            "type": "string",
            "description": "Unique PseudoElement identifier."
        },
        {
            "id": "IntRect",
            "type": "object",
            "description": "A rectangle.",
            "properties": [
                { "name": "x", "type": "integer", "description": "The x position." },
                { "name": "y", "type": "integer", "description": "The y position." },
                { "name": "width", "type": "integer", "description": "The width metric." },
                { "name": "height", "type": "integer", "description": "The height metric." }
            ]
        },
        {
            "id": "Layer",
            "type": "object",
            "description": "Information about a compositing layer.",
            "properties": [
                { "name": "layerId", "$ref": "LayerId", "description": "The unique id for this layer." },
                { "name": "nodeId", "$ref": "DOM.NodeId", "description": "The id for the node associated with this layer." },
                { "name": "bounds", "$ref": "IntRect", "description": "Bounds of the layer in absolute page coordinates." },
                { "name": "paintCount", "type": "integer", "description": "Indicates how many time this layer has painted." },
                { "name": "memory", "type": "integer", "description": "Estimated memory used by this layer." },
                { "name": "compositedBounds", "$ref": "IntRect", "description": "The bounds of the composited layer." },
                { "name": "isInShadowTree", "type": "boolean", "optional": true, "description": "Indicates whether this layer is associated with an element hosted in a shadow tree." },
                { "name": "isReflection", "type": "boolean", "optional": true, "description": "Indicates whether this layer was used to provide a reflection for the element." },
                { "name": "isGeneratedContent", "type": "boolean", "optional": true, "description": "Indicates whether the layer is attached to a pseudo element that is CSS generated content." },
                { "name": "isAnonymous", "type": "boolean", "optional": true, "description": "Indicates whether the layer was created for a CSS anonymous block or box." },
                { "name": "pseudoElementId", "$ref": "PseudoElementId", "optional": true, "description": "The id for the pseudo element associated with this layer." },
                { "name": "pseudoElement", "type": "string", "optional": true, "description": "The name of the CSS pseudo-element that prompted the layer to be generated." }
            ]
        },
        {
            "id": "CompositingReasons",
            "type": "object",
            "description": "An object containing the reasons why the layer was composited as properties.",
            "properties": [
                { "name": "transform3D", "type": "boolean", "optional": true, "description": "Composition due to association with an element with a CSS 3D transform." },
                { "name": "video", "type": "boolean", "optional": true, "description": "Composition due to association with a <video> element." },
                { "name": "canvas", "type": "boolean", "optional": true, "description": "Composition due to the element being a <canvas> element." },
                { "name": "plugin", "type": "boolean", "optional": true, "description": "Composition due to association with a plugin." },
                { "name": "iFrame", "type": "boolean", "optional": true, "description": "Composition due to association with an <iframe> element." },
                { "name": "backfaceVisibilityHidden", "type": "boolean", "optional": true, "description": "Composition due to association with an element with a \"backface-visibility: hidden\" style." },
                { "name": "clipsCompositingDescendants", "type": "boolean", "optional": true, "description": "Composition due to association with an element clipping compositing descendants." },
                { "name": "animation", "type": "boolean", "optional": true, "description": "Composition due to association with an animated element." },
                { "name": "filters", "type": "boolean", "optional": true, "description": "Composition due to association with an element with CSS filters applied." },
                { "name": "positionFixed", "type": "boolean", "optional": true, "description": "Composition due to association with an element with a \"position: fixed\" style." },
                { "name": "positionSticky", "type": "boolean", "optional": true, "description": "Composition due to association with an element with a \"position: sticky\" style." },
                { "name": "overflowScrollingTouch", "type": "boolean", "optional": true, "description": "Composition due to association with an element with a \"overflow-scrolling: touch\" style." },
                { "name": "stacking", "type": "boolean", "optional": true, "description": "Composition due to association with an element establishing a stacking context." },
                { "name": "overlap", "type": "boolean", "optional": true, "description": "Composition due to association with an element overlapping other composited elements." },
                { "name": "negativeZIndexChildren", "type": "boolean", "optional": true, "description": "Composition due to association with an element with descendants that have a negative z-index." },
                { "name": "transformWithCompositedDescendants", "type": "boolean", "optional": true, "description": "Composition due to association with an element with composited descendants." },
                { "name": "opacityWithCompositedDescendants", "type": "boolean", "optional": true, "description": "Composition due to association with an element with opacity applied and composited descendants." },
                { "name": "maskWithCompositedDescendants", "type": "boolean", "optional": true, "description": "Composition due to association with a masked element and composited descendants." },
                { "name": "reflectionWithCompositedDescendants", "type": "boolean", "optional": true, "description": "Composition due to association with an element with a reflection and composited descendants." },
                { "name": "filterWithCompositedDescendants", "type": "boolean", "optional": true, "description": "Composition due to association with an element with CSS filters applied and composited descendants." },
                { "name": "blendingWithCompositedDescendants", "type": "boolean", "optional": true, "description": "Composition due to association with an element with CSS blending applied and composited descendants." },
                { "name": "isolatesCompositedBlendingDescendants", "type": "boolean", "optional": true, "description": "Composition due to association with an element isolating compositing descendants having CSS blending applied." },
                { "name": "perspective", "type": "boolean", "optional": true, "description": "Composition due to association with an element with perspective applied." },
                { "name": "preserve3D", "type": "boolean", "optional": true, "description": "Composition due to association with an element with a \"transform-style: preserve-3d\" style." },
                { "name": "willChange", "type": "boolean", "optional": true, "description": "Composition due to association with an element with a \"will-change\" style." },
                { "name": "root", "type": "boolean", "optional": true, "description": "Composition due to association with the root element." },
                { "name": "blending", "type": "boolean", "optional": true, "description": "Composition due to association with an element with a \"blend-mode\" style." }
            ]
        }
    ],
    "commands": [
        {
            "name": "enable",
            "description": "Enables compositing tree inspection."
        },
        {
            "name": "disable",
            "description": "Disables compositing tree inspection."
        },
        {
            "name": "layersForNode",
            "description": "Returns the layer tree structure of the current page.",
            "parameters": [
                { "name": "nodeId", "$ref": "DOM.NodeId", "description": "Root of the subtree for which we want to gather layers." }
            ],
            "returns": [
                { "name": "layers", "type": "array", "items": { "$ref": "Layer" }, "description": "Child layers." }
            ]
        },
        {
            "name": "reasonsForCompositingLayer",
            "description": "Provides the reasons why the given layer was composited.",
            "parameters": [
                { "name": "layerId", "$ref": "LayerId", "description": "The id of the layer for which we want to get the reasons it was composited." }
            ],
            "returns": [
                { "name": "compositingReasons", "$ref": "CompositingReasons", "description": "An object containing the reasons why the layer was composited as properties." }
            ]
        }
    ],
    "events": [
        {
            "name": "layerTreeDidChange"
        }
    ]
}