image-in-browser/lib/formats/png-decoder.d.ts

Package for encoding / decoding images, transforming images, applying filters, drawing primitives on images on the client side (no need for server Node.js)

/** @format */
import { InputBuffer } from '../common/input-buffer.js';
import { Decoder, DecoderDecodeOptions } from './decoder.js';
import { PngInfo } from './png/png-info.js';
import { MemoryImage } from '../image/image.js';
import { ImageFormat } from './image-format.js';
/**
 * Decode a PNG encoded image.
 */
export declare class PngDecoder implements Decoder {
    /**
     * The input buffer for the PNG data.
     */
    private _input?;
    /**
     * Get the input buffer.
     */
    get input(): InputBuffer<Uint8Array> | undefined;
    /**
     * Information about the PNG image.
     */
    private _info;
    /**
     * Get the PNG information.
     */
    get info(): PngInfo;
    /**
     * The current progress in the Y direction.
     */
    private _progressY;
    /**
     * Get the current progress in the Y direction.
     */
    get progressY(): number;
    /**
     * The bit buffer used for reading bits.
     */
    private _bitBuffer;
    /**
     * Get the bit buffer.
     */
    get bitBuffer(): number;
    /**
     * The length of the bit buffer.
     */
    private _bitBufferLen;
    /**
     * Get the length of the bit buffer.
     */
    get bitBufferLen(): number;
    /**
     * Get the image format.
     */
    get format(): ImageFormat;
    /**
     * The number of frames that can be decoded.
     */
    get numFrames(): number;
    /**
     * Unfilter a row of pixels.
     * @param {PngFilterType} filterType - The type of filter used.
     * @param {number} bpp - Bytes per pixel.
     * @param {Uint8Array} row - The current row of pixels.
     * @param {Uint8Array} [prevRow] - The previous row of pixels.
     * @throws {LibError} Throws an error if the filter type is invalid.
     */
    private static unfilter;
    /**
     * Return the CRC of the bytes.
     * @param {string} type - The type of the chunk.
     * @param {Uint8Array} bytes - The bytes of the chunk.
     * @returns {number} The CRC value.
     */
    private static crc;
    /**
     * Process a pass of an interlaced image.
     * @param {InputBuffer<Uint8Array>} input - The input buffer.
     * @param {MemoryImage} image - The memory image.
     * @param {number} xOffset - The X offset.
     * @param {number} yOffset - The Y offset.
     * @param {number} xStep - The X step.
     * @param {number} yStep - The Y step.
     * @param {number} passWidth - The width of the pass.
     * @param {number} passHeight - The height of the pass.
     */
    private processPass;
    /**
     * Process the input buffer and decode the image.
     * @param {InputBuffer<Uint8Array>} input - The input buffer.
     * @param {MemoryImage} image - The memory image.
     */
    private process;
    /**
     * Reset the bit buffer.
     */
    private resetBits;
    /**
     * Read a number of bits from the input stream.
     * @param {InputBuffer<Uint8Array>} input - The input buffer.
     * @param {number} numBits - The number of bits to read.
     * @returns {number} The read bits.
     * @throws {LibError} If there is invalid PNG data.
     */
    private readBits;
    /**
     * Read the next pixel from the input stream.
     * @param {InputBuffer<Uint8Array>} input - The input buffer.
     * @param {number[]} pixel - The pixel array to store the read pixel.
     */
    private readPixel;
    /**
     * Set the pixel color.
     * @param {Pixel} p - The pixel object.
     * @param {number[]} raw - The raw pixel data.
     */
    private setPixel;
    /**
     * Is the given file a valid PNG image?
     * @param {Uint8Array} bytes - The bytes of the file.
     * @returns {boolean} True if the file is valid, false otherwise.
     */
    isValidFile(bytes: Uint8Array): boolean;
    /**
     * Start decoding the data as an animation sequence, but don't actually
     * process the frames until they are requested with decodeFrame.
     * @param {Uint8Array} bytes - The bytes of the PNG file.
     * @returns {PngInfo | undefined} The PNG information if successful, undefined otherwise.
     * @throws {LibError} If there is an invalid checksum or invalid chunk.
     */
    startDecode(bytes: Uint8Array): PngInfo | undefined;
    /**
     * Decode the frame (assuming **startDecode** has already been called).
     * @param {number} frameIndex - The index of the frame to decode.
     * @returns {MemoryImage | undefined} The decoded MemoryImage or undefined if input is not defined.
     * @throws {LibError} If an invalid checksum or frame number is encountered.
     */
    decodeFrame(frameIndex: number): MemoryImage | undefined;
    /**
     * Decode the image based on the provided options.
     * @param {DecoderDecodeOptions} opt - The options for decoding the image.
     * @param {Uint8Array} opt.bytes - The byte array of the image to decode.
     * @param {number} [opt.frameIndex] - The index of the frame to decode (optional).
     * @returns {MemoryImage | undefined} The decoded MemoryImage or undefined if decoding fails.
     */
    decode(opt: DecoderDecodeOptions): MemoryImage | undefined;
}