Class EscposImage

Readonlyheight

Readonlywidth

ReadonlywidthBytes

center

• center(maxWidth: number): void

  Centre the image within maxWidth pixels by padding each row with white pixels on the left and right. If the image is already as wide as or wider than maxWidth, this is a no-op.

  Parameters

  • maxWidth: number

    Target width in pixels.

  Returns void

  Since

  1.0.0

split

• split(fragmentHeight: number): EscposImage[]

  Split the image into vertical fragments of at most fragmentHeight rows.

  Used by Escpos.image() to avoid printer buffer overruns on large images.

  Parameters

  • fragmentHeight: number

    Maximum number of rows per fragment.

  Returns EscposImage[]

  Array of EscposImage slices (last slice may be shorter).

  Since

  1.0.0

toColumnFormat

• toColumnFormat(highDensity?: boolean): Generator<Buffer<ArrayBufferLike>>

  Yield column data buffers for ESC * column-format printing.

  Each yielded Buffer represents the vertical byte-strip for one pixel column. Bits are packed top-to-bottom, MSB at the top.

  The number of bytes per column depends on highDensity:

  • Low density (8-dot): 1 byte per column.
  • High density (24-dot): 3 bytes per column.

  Escpos.image() wraps these blobs with the ESC * header and line-feed when impl === 'bitImageColumn'.

  Parameters

  • highDensity: boolean = false

    true for 24-dot high-density mode, false for 8-dot low-density mode. Defaults to false.

  Returns Generator<Buffer<ArrayBufferLike>>

  Since

  1.0.0

toRasterFormat

• toRasterFormat(): Buffer

  Encode the image as a raw ESC/POS raster data payload (pixel bytes only, no GS v 0 header).

  Layout: row-major, MSB-first within each byte.

  • Bit 7 of byte 0 in each row → leftmost pixel.
  • Length = widthBytes × height bytes.

  The caller is responsible for prepending the GS v 0 command header. Escpos.image() handles this internally when impl === 'bitImageRaster'.

  Returns Buffer

  Raw pixel data buffer.

  Since

  1.0.0

Staticload

• load(source: string | Buffer<ArrayBufferLike>): Promise<EscposImage>

  Load an image from a file path or raw image Buffer (PNG, BMP, JPEG, GIF, TIFF).

  The image is:

  1. Composited onto a white background to flatten any alpha channel.
  2. Converted to greyscale.
  3. Thresholded at luminance 128 — any pixel darker than 128 is treated as a printed dot.

  Parameters

  • source: string | Buffer<ArrayBufferLike>

    Absolute file path or raw image file Buffer.

  Returns Promise<EscposImage>

  A resolved EscposImage instance.

  Since

  1.0.0