{
"domain": "Canvas",
"availability": ["web"],
"description": "Canvas domain allows tracking of canvases that have an associated graphics context. Tracks canvases in the DOM and CSS canvases created with -webkit-canvas.",
"types": [
{
"id": "CanvasId",
"type": "string",
"description": "Unique canvas identifier."
},
{
"id": "ProgramId",
"type": "string",
"description": "Unique shader program identifier."
},
{
"id": "ContextType",
"type": "string",
"enum": ["canvas-2d", "bitmaprenderer", "webgl", "webgl2", "webmetal"],
"description": "The type of rendering context backing the canvas element."
},
{
"id": "ShaderType",
"type": "string",
"enum": ["fragment", "vertex"],
"description": "Shader type. WebGL supports vertex and fragment shaders."
},
{
"id": "ContextAttributes",
"type": "object",
"description": "Drawing surface attributes.",
"properties": [
{ "name": "alpha", "type": "boolean", "optional": true },
{ "name": "depth", "type": "boolean", "optional": true },
{ "name": "stencil", "type": "boolean", "optional": true },
{ "name": "antialias", "type": "boolean", "optional": true },
{ "name": "premultipliedAlpha", "type": "boolean", "optional": true },
{ "name": "preserveDrawingBuffer", "type": "boolean", "optional": true },
{ "name": "failIfMajorPerformanceCaveat", "type": "boolean", "optional": true }
]
},
{
"id": "Canvas",
"type": "object",
"description": "Information about a canvas for which a rendering context has been created.",
"properties": [
{ "name": "canvasId", "$ref": "CanvasId", "description": "Canvas identifier." },
{ "name": "contextType", "$ref": "ContextType", "description": "The type of rendering context backing the canvas." },
{ "name": "nodeId", "$ref": "DOM.NodeId", "optional": true, "description": "The corresponding DOM node id." },
{ "name": "cssCanvasName", "type": "string", "optional": true, "description": "The CSS canvas identifier, for canvases created with <code>document.getCSSCanvasContext</code>." },
{ "name": "contextAttributes", "$ref": "ContextAttributes", "optional": true, "description": "Context attributes for rendering contexts." },
{ "name": "memoryCost", "type": "number", "optional": true, "description": "Memory usage of the canvas in bytes." },
{ "name": "backtrace", "type": "array", "items": { "$ref": "Console.CallFrame" }, "optional": true, "description": "Backtrace that was captured when this canvas context was created." }
]
}
],
"commands": [
{
"name": "enable",
"description": "Enables Canvas domain events."
},
{
"name": "disable",
"description": "Disables Canvas domain events."
},
{
"name": "requestNode",
"description": "Gets the NodeId for the canvas node with the given CanvasId.",
"parameters": [
{ "name": "canvasId", "$ref": "CanvasId", "description": "Canvas identifier." }
],
"returns": [
{ "name": "nodeId", "$ref": "DOM.NodeId", "description": "Node identifier for given canvas." }
]
},
{
"name": "requestContent",
"description": "Gets the data for the canvas node with the given CanvasId.",
"parameters": [
{ "name": "canvasId", "$ref": "CanvasId", "description": "Canvas identifier." }
],
"returns": [
{ "name": "content", "type": "string", "description": "Base64-encoded data of the canvas' contents." }
]
},
{
"name": "requestCSSCanvasClientNodes",
"description": "Gets all the nodes that are using this canvas via -webkit-canvas.",
"parameters": [
{ "name": "canvasId", "$ref": "CanvasId" }
],
"returns": [
{ "name": "clientNodeIds", "type": "array", "items": { "$ref": "DOM.NodeId" } }
]
},
{
"name": "resolveCanvasContext",
"description": "Resolves JavaScript canvas context object for given canvasId.",
"parameters": [
{ "name": "canvasId", "$ref": "CanvasId", "description": "Canvas identifier." },
{ "name": "objectGroup", "type": "string", "optional": true, "description": "Symbolic group name that can be used to release multiple objects." }
],
"returns": [
{ "name": "object", "$ref": "Runtime.RemoteObject", "description": "JavaScript object wrapper for given canvas context." }
]
},
{
"name": "setRecordingAutoCaptureFrameCount",
"description": "Tells the backend to record `count` frames whenever a new context is created.",
"parameters": [
{ "name": "count", "type": "integer", "description": "Number of frames to record (0 means don't record anything)." }
]
},
{
"name": "startRecording",
"description": "Record the next frame, or up to the given number of bytes of data, for the given canvas.",
"parameters": [
{ "name": "canvasId", "$ref": "CanvasId" },
{ "name": "frameCount", "type": "integer", "optional": true, "description": "Number of frames to record (unlimited when not specified)." },
{ "name": "memoryLimit", "type": "integer", "optional": true, "description": "Memory limit of recorded data (100MB when not specified)." }
]
},
{
"name": "stopRecording",
"description": "Stop recording the given canvas.",
"parameters": [
{ "name": "canvasId", "$ref": "CanvasId" }
]
},
{
"name": "requestShaderSource",
"description": "Requests the source of the shader of the given type from the program with the given id.",
"parameters": [
{ "name": "programId", "$ref": "ProgramId" },
{ "name": "shaderType", "$ref": "ShaderType" }
],
"returns": [
{ "name": "content", "type": "string" }
]
},
{
"name": "updateShader",
"description": "Compiles and links the shader with identifier and type with the given source code.",
"parameters": [
{ "name": "programId", "$ref": "ProgramId" },
{ "name": "shaderType", "$ref": "ShaderType" },
{ "name": "source", "type": "string" }
]
},
{
"name": "setShaderProgramDisabled",
"description": "Enable/disable the visibility of the given shader program.",
"parameters": [
{ "name": "programId", "$ref": "ProgramId" },
{ "name": "disabled", "type": "boolean" }
]
},
{
"name": "setShaderProgramHighlighted",
"description": "Enable/disable highlighting of the given shader program.",
"parameters": [
{ "name": "programId", "$ref": "ProgramId" },
{ "name": "highlighted", "type": "boolean" }
]
}
],
"events": [
{
"name": "canvasAdded",
"parameters": [
{ "name": "canvas", "$ref": "Canvas", "description": "Canvas object." }
]
},
{
"name": "canvasRemoved",
"parameters": [
{ "name": "canvasId", "$ref": "CanvasId", "description": "Removed canvas identifier." }
]
},
{
"name": "canvasMemoryChanged",
"parameters": [
{ "name": "canvasId", "$ref": "CanvasId", "description": "Identifier of canvas that changed." },
{ "name": "memoryCost", "type": "number", "description": "New memory cost value for the canvas in bytes." }
]
},
{
"name": "extensionEnabled",
"parameters": [
{ "name": "canvasId", "$ref": "CanvasId" },
{ "name": "extension", "type": "string", "description": "Name of the extension that was enabled." }
]
},
{
"name": "cssCanvasClientNodesChanged",
"parameters": [
{ "name": "canvasId", "$ref": "CanvasId", "description": "Identifier of canvas that changed." }
]
},
{
"name": "recordingStarted",
"parameters": [
{ "name": "canvasId", "$ref": "CanvasId" },
{ "name": "initiator", "$ref": "Recording.Initiator" }
]
},
{
"name": "recordingProgress",
"parameters": [
{ "name": "canvasId", "$ref": "CanvasId" },
{ "name": "frames", "type": "array", "items": { "$ref": "Recording.Frame" }},
{ "name": "bufferUsed", "type": "integer", "description": "Total memory size in bytes of all data recorded since the recording began." }
]
},
{
"name": "recordingFinished",
"parameters": [
{ "name": "canvasId", "$ref": "CanvasId" },
{ "name": "recording", "$ref": "Recording.Recording", "optional": true }
]
},
{
"name": "programCreated",
"parameters": [
{ "name": "canvasId", "$ref": "CanvasId", "description": "Canvas identifier." },
{ "name": "programId", "$ref": "ProgramId", "description": "Program identifier." }
]
},
{
"name": "programDeleted",
"parameters": [
{ "name": "programId", "$ref": "ProgramId", "description": "Program identifier." }
]
}
]
}