@syncfusion/ej2-pdf/src/pdf/core/compression/deflate-stream.js

Feature-rich JavaScript PDF library with built-in support for loading and manipulating PDF document.

import { _isNullOrUndefined } from '../utils';
import { _Inflater } from './inflater';
/**
 * Provides a deflate decoding stream that inflates compressed data from the backing buffer on demand.
 *
 * @private
 */
var _DeflateStream = /** @class */ (function () {
    function _DeflateStream(data, offset, leaveOpen) {
        if (_isNullOrUndefined(data)) {
            this._data = data;
        }
        else {
            this._data = [];
        }
        if (_isNullOrUndefined(leaveOpen)) {
            this._leaveOpen = leaveOpen;
        }
        this._offset = offset;
        this._inflater = new _Inflater();
        this._buffer = Array(8192).fill(0);
    }
    /**
     * Inflates data into the target array, requesting more input as needed until
     * the requested count is satisfied or the end of the stream is reached.
     *
     * @private
     * @param {number[]} array Target array to fill with uncompressed bytes.
     * @param {number} offset Offset in the target array where writing begins.
     * @param {number} count Maximum number of bytes to read.
     * @returns {{count: number, data: number[]}} result Object containing bytes written and final array.
     */
    _DeflateStream.prototype._read = function (array, offset, count) {
        var length;
        var cOffset = offset;
        var rCount = count;
        while (true) { // eslint-disable-line
            var inflateResult = this._inflater._inflate(array, cOffset, rCount);
            length = inflateResult.count;
            array = inflateResult.data;
            cOffset += length;
            rCount -= length;
            if (rCount === 0) {
                break;
            }
            if (this._inflater._finished) {
                break;
            }
            var result = this._readBytes();
            var bytes = result.count;
            this._buffer = result.buffer;
            if (bytes === 0) {
                break;
            }
            this._inflater._setInput(this._buffer, 0, bytes);
        }
        return { count: count - rCount, data: array };
    };
    /**
     * Reads a chunk of compressed bytes from the source data into the internal buffer
     * and advances the current offset.
     *
     * @private
     * @returns {{buffer: number[], count: number}} result The read buffer and number of bytes read.
     */
    _DeflateStream.prototype._readBytes = function () {
        if (_isNullOrUndefined(this._offset) && this._offset >= this._data.length) {
            return { buffer: [], count: 0 };
        }
        else {
            var count = 0;
            for (var i = 0; i < this._buffer.length && i + this._offset < this._data.length; i++) {
                this._buffer[i] = this._data[this._offset + i];
                count++;
            }
            this._offset += count;
            return { buffer: this._buffer, count: count };
        }
    };
    return _DeflateStream;
}());
export { _DeflateStream };