node-webpmux

A mostly-complete pure Javascript re-implementation of webpmux. Can load "simple" lossy/lossless images as well as animations.

== Basic usage ==

const WebP = require('node-webpmux'); let img = new WebP.Image(); // Load an animation await img.load('img.webp'); // Extract the (unprocessed) fourth frame await img.demuxAnim('.', 3); // Replace the fourth frame with a new image await img.replaceFrame('different.webp', 3); // Save over the old one await img.muxAnim({ path: 'img.webp' });

== Exports ==

TYPE_LOSSY TYPE_LOSSLESS TYPE_EXTENDED Constants for what type of image is loaded

Image The main class

== Class properties ==

.width (read-only) The width of the loaded image

.height (read-only) The height of the loaded image

.type (read-only) The type of image from the TYPE_* constants table.

.hasAnim (read-only) A boolean flag for easily checking if the image is an animation

.frames Returns the array of frames, if any, or undefined

.frameCount (read-only) The number of frames in the image's animation, or 0 if it's not an animation

.anim (read-only) Direct access to the raw animation data (see below)

.iccp (read/write) A Buffer containing the raw ICC profile data stored in the image, or undefined if there isn't any

.exif (read/write) A Buffer containing the raw EXIF data stored in the image, or undefined if there isn't any

.xmp (read/write) A Buffer containing the raw XMP data stored in the image, or undefined if there isn't any

== Class functions ==

async .load(path) Tries to load path as a WebP image

async .demuxAnim(path, frame = -1, prefix = '#FNAME') Dump the individual, unprocessed WebP frames to a directory path The directory to dump the frames to prefix What to prefix the frame names with. Default is the file name of the original image (without .webp). Format is _.webp frame What frame to dump. Defaults to -1, which has it dump all available frames.

async .replaceFrame(path, frame) Replaces a frame in the animation with another image. All other frame settings are preserved. path The new frame image frame Which frame to replace. Frame indexes are 0-based

async .muxAnim(options) A convenience function to remux this image preserving settings. See the static .muxAnim function below for more information Passing true for exif, iccp, or xmp will preserve whichever, if any, of those chunks exist in the original.

async .save(path = this.path) A convenience function to save any modifications made to this image, such as adding EXIF metadata.

== Static functions ==

async Image.muxAnim(options) Mux a WebP image options being an object with the following properties width/height Width/height of the image Range 0-16777216. The product of width*height must NOT exceed (2**32)-1 Passing 0 to either flags it for being set automatically bgColor The background color of the animation Format is [r, g, b, a] Defaults to [255, 255, 255, 255] loops Number of times the animation loops Range is 0-65535, with 0 being an infinite loop Default is 0 x/y/delay/blend/dispose Changes the default frame x/y position where a frame omits it (see below) x/y defaults to 0 delay defaults to 100 blend defaults to true dispose defaults to false frames An array of objects defining each frame of the animation with the following properties x/y x,y offset to place the frame within the animation Range 0-16777215 Default is 0,0 (defined above) delay Length of this frame in miliseconds Range 0-16777215 Default is 100 (defined above) According to the documentation, delays <= 10ms are WebP implementation defined, and many tools/browsers/etc assign their own minimum-allowed delay. blend Boolean flag for whether or not to use alpha blending when drawing the frame Default is true (defined above) dispose Boolean flag to control frame disposal method true causes the background color to be drawn under the frame false draws the new frame directly Default is false (defined above) exif/iccp/xmp Set EXIF/ICCP/XMP chunks in the animation. Note that there is no verification whatsoever that the data passed is valid

async Image.save(path, image) Save the given WebP image to path. Does not currently support animations (use Image.muxAnim above instead).

== Animation object ==

.anim An object with the following properties, or undefined if not an animation raw A Buffer containing the raw data for the ANIM chunk. Mainly for internal use backgroundColor The background color in [r, g, b, a] format loopCount The loop count frames Array in the following format [ { raw, // The raw data for this ANMF chunk type, // The type of image this frame is, from the constants table x, y, // The x,y position width, height, // The frame's width/height duration, // Frame delay blend, dispose, // Blend/dipose flags // Additionally, one or more of the following vp8, // The raw, compressed WebP data for a lossy image vp8l, // The raw, compressed WebP data for a lossless image alph // The raw, compressed WebP data for an alpha map. If this frame is lossy, it might have this }, ... ]

== The full layout for internal Image data == { path, // The path loaded loaded, // Boolean flag for if this object has an image loaded data: { // The loaded data type, // The type of image from the constants table vp8: { // The lossy format image. Only if .type is TYPE_LOSSY or TYPE_EXTENDED raw, // The raw, compressed image data from the VP8 chunk width, height // The width/height, extracted from the VP8 image data }, vp8l: { // The lossless format image. Only if .type is TYPE_LOSSLESS or TYPE_EXTENDED raw, // The raw, compressed image data from the VP8L chunk alpha, // A flag for if this image has alpha data, extracted from the VP8L image data width, height // The width/height, extracted from the VP8L image data }, extended: { // Only if .type is TYPE_EXTENDED raw, // The raw data for the VP8X chunk hasICC, // Flag for if there's an ICC profile chunk defined hasAlpha, // Flag for if any image/frame defined has alpha data hasEXIF, // Flag for if there's an EXIF chunk defined hasXMP, // Flag for if there's an XMP chunk defined hasAnim, // Flag for if this image has an animation defined width, height // Width/height of the image }, anim, // See above alph: { raw // The raw alpha map chunk. Only likely to be here if .vp8 is also defined }, iccp: { raw // The raw ICCP chunk, if defined }, exif: { raw // The raw EXIF chunk, if defined }, xmp: { raw // The raw XMP chunk, if defined } } }