Class: Layer

(abstract) Rendering.Layer()

Generic layer definition

Constructor

(abstract) new Layer()

Methods

(async, abstract) getExportCanvas()

setTransform(matrix)

Configures ink transformation over underlying layer

Parameters:

Name	Type	Description
matrix	Common.Matrix

(async) toBlob(rectopt, mimeTypeopt, qualityopt) → {Blob}

Exports layer content. Compatible in web environment.

Parameters:

Name	Type	Attributes	Default	Description
rect	Common.Rect	<optional>	bounds	Area to read
mimeType	string	<optional>	image/png	Supported values are image/png, image/jpeg and image/webp.
quality	float	<optional>	0.92	A Number between 0 and 1 indicating image quality if the requested type is image/jpeg or image/webp.If this argument is anything else, the default values 0.92 and 0.80 are used for image/jpeg and image/webp respectively.

Returns:

Layer content

Type

Blob

(async) toBuffer(rectopt, mimeTypeopt, options) → {Buffer}

Exports layer content. Compatible in nodejs environment.

Parameters:

Name	Type	Attributes	Default	Description
rect	Common.Rect	<optional>	bounds	Area to read
mimeType	string	<optional>	image/png	Supported values are image/png and image/jpeg.
options	Rendering.Layer.PNGOptions|Rendering.Layer.JPEGOptions

Returns:

Layer content

Type

Buffer

Type Definitions

JPEGOptions

Defines JPEG options

Properties:

Name	Type	Attributes	Default	Description
quality	float	<optional>	0.75	Specifying the quality (0 to 1)
progressive	boolean	<optional>	false	Enables progressive encoding
chromaSubsampling	boolean	<optional>	true	Enables 2x2 chroma subsampling

PNGFilterType

Enum used in PNGOptions

Properties:

Name	Type	Description
NO	object	Filters are not applied
ALL	object	All filters are applied
NONE	object	The scanline is transmitted unmodified
SUB	object	The Sub filter transmits the difference between each byte and the value of the corresponding byte of the prior pixel
UP	object	The Up filter is just like the Sub filter except that the pixel immediately above the current pixel, rather than just to its left, is used as the predictor
AVG	object	The Average filter uses the average of the two neighboring pixels (left and above) to predict the value of a pixel
PAETH	object	The Paeth filter computes a simple linear function of the three neighboring pixels (left, above, upper left), then chooses as predictor the neighboring pixel closest to the computed value

PNGOptions

Defines PNG options

Properties:

Name	Type	Attributes	Default	Description
compressionLevel	int	<optional>	6	ZLIB compression level (between 0 and 9)
filters	Rendering.Layer.PNGFilterType|Array.<Rendering.Layer.PNGFilterType>	<optional>	ALL	Compression filter(s)
palette	Uint8ClampedArray	<optional>		For creating indexed PNGs. The palette of colors. Entries should be in RGBA order.
backgroundIndex	int	<optional>	0	For creating indexed PNGs. The index of the background color.
resolution	int	<optional>		PPI.Note that the PNG format encodes the resolution in pixels per meter, so if you specify 96, the file will encode 3780 ppm (~96.01 ppi).The resolution is undefined by default to match common browser behavior.

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