@abasb75/jpeg-lossless-decoder/scan-header.js

A JavaScript JPEG Lossless decoder.

var __assign = (this && this.__assign) || function () {
    __assign = Object.assign || function(t) {
        for (var s, i = 1, n = arguments.length; i < n; i++) {
            s = arguments[i];
            for (var p in s) if (Object.prototype.hasOwnProperty.call(s, p))
                t[p] = s[p];
        }
        return t;
    };
    return __assign.apply(this, arguments);
};
import { ScanComponent } from './scan-component';
var ScanHeader = /** @class */ (function () {
    function ScanHeader() {
        Object.defineProperty(this, "ah", {
            enumerable: true,
            configurable: true,
            writable: true,
            value: 0
        });
        Object.defineProperty(this, "al", {
            enumerable: true,
            configurable: true,
            writable: true,
            value: 0
        });
        Object.defineProperty(this, "numComp", {
            enumerable: true,
            configurable: true,
            writable: true,
            value: 0
        }); // Number of components in the scan
        Object.defineProperty(this, "selection", {
            enumerable: true,
            configurable: true,
            writable: true,
            value: 0
        }); // Start of spectral or predictor selection
        Object.defineProperty(this, "spectralEnd", {
            enumerable: true,
            configurable: true,
            writable: true,
            value: 0
        }); // End of spectral selection
        Object.defineProperty(this, "components", {
            enumerable: true,
            configurable: true,
            writable: true,
            value: []
        });
    }
    Object.defineProperty(ScanHeader.prototype, "read", {
        enumerable: false,
        configurable: true,
        writable: true,
        value: function (data) {
            var count = 0;
            var i;
            var temp;
            var length = data.get16();
            count += 2;
            this.numComp = data.get8();
            count += 1;
            for (i = 0; i < this.numComp; i += 1) {
                this.components[i] = __assign({}, ScanComponent);
                if (count > length) {
                    throw new Error('ERROR: scan header format error');
                }
                this.components[i].scanCompSel = data.get8();
                count += 1;
                temp = data.get8();
                count += 1;
                this.components[i].dcTabSel = temp >> 4;
                this.components[i].acTabSel = temp & 0x0f;
            }
            this.selection = data.get8();
            count += 1;
            this.spectralEnd = data.get8();
            count += 1;
            temp = data.get8();
            this.ah = temp >> 4;
            this.al = temp & 0x0f;
            count += 1;
            if (count !== length) {
                throw new Error('ERROR: scan header format error [count!=Ns]');
            }
            return 1;
        }
    });
    return ScanHeader;
}());
export { ScanHeader };