Path Effects

APIs for path commands and scripted path effects.

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PathCommand

A single drawing instruction inside a Path.

Attributes

command.type

The command type. Type: CommandType (read-only)

Methods

Length (#)

Returns the number of points in the command.

local pointCount = #command

Point counts by type:

Type	Points	Description
moveTo	1	1 Vector (destination)
lineTo	1	1 Vector (endpoint)
quadTo	2	2 Vectors (control, endpoint)
cubicTo	3	3 Vectors (controlOut, controlIn, endpoint)
close	0	No points

Note: Points are Vector objects accessed by index (e.g., cmd[1]), not raw number pairs.

See Also: CommandType, PathData

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PathData

Indexed collection of PathCommand objects. Behaves like an array and supports ipairs iteration.

Methods

Length (#)

Returns the number of commands in the path.

local count = #pathData

pathData:contours()

Returns a ContourMeasure for the first contour. Returns nil if no contours exist.

pathData:contours(): ContourMeasure?

pathData:measure()

Returns a PathMeasure for the entire path.

pathData:measure(): PathMeasure

Example: Iterating Commands

for i, command in ipairs(pathData) do
    print(command.type, #command, "points")
end

See Also: PathCommand, ContourMeasure

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PathEffect

Scripted effect applied to a path. Use for custom path transformations.

Protocol Methods

init(self, context): boolean

Called once when the effect is created.

function init(self: MyEffect, context: Context): boolean
    -- Setup logic
    return true  -- Return true to keep effect active
end

update(self, pathData, node): PathData

Receives the original path data and the host node's read-only data, and returns a modified path.

function update(self: MyEffect, pathData: PathData, node: NodeReadData): PathData
    -- Transform the path using node context
    return modifiedPathData
end

advance(self, seconds): boolean

Optional per-frame update.

function advance(self: MyEffect, seconds: number): boolean
    -- Animation logic
    return true  -- Continue receiving advance calls
end

See Also: PathData, PathMeasure

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CommandType

Enum describing path drawing command types.

Values

Value	Description
none	Placeholder (not normally encountered)
moveTo	Move to a point without drawing
lineTo	Draw a straight line
quadTo	Quadratic Bezier curve
cubicTo	Cubic Bezier curve
close	Close the path

See Also: PathCommand

Next Steps

• Continue to Data Values
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