slimfits/lib/FitsReader.js

Package for loading data stored in FITS data format

"use strict";
Object.defineProperty(exports, "__esModule", { value: true });
var interfaces_1 = require("./interfaces");
var KeywordsManager_1 = require("./utils/KeywordsManager");
var PromiseUtils_1 = require("./utils/PromiseUtils");
var RegisteredDataReaders_1 = require("./RegisteredDataReaders");
var FitsReader = /** @class */ (function () {
    function FitsReader() {
    }
    FitsReader.readFitsAsync = function (file) {
        var hdus = [];
        var offsetBytes = 0;
        return PromiseUtils_1.PromiseUtils.promiseWhile(function () { return offsetBytes < file.getByteLength(); }, function () {
            return FitsReader.readHduAsync(file, offsetBytes).then(function (hdu) {
                hdus.push(hdu);
                offsetBytes += hdu.bytesRead;
            });
        }).then(function () { return hdus; });
    };
    FitsReader.readHeaderAsync = function (file, offsetBytes) {
        var endLineFound = false;
        var keywords = [];
        var bytesRead = 0;
        return PromiseUtils_1.PromiseUtils.promiseWhile(function () { return !endLineFound; }, function () {
            return file.getStringAsync(offsetBytes + bytesRead, interfaces_1.Constants.blockLength)
                .then(function (block) {
                bytesRead += interfaces_1.Constants.blockLength;
                for (var j = 0; j < interfaces_1.Constants.maxKeywordsInBlock; j++) {
                    var line = block.substring(j * interfaces_1.Constants.lineLength, (j + 1) * interfaces_1.Constants.lineLength);
                    endLineFound = KeywordsManager_1.Keyword.isLastLine(line);
                    if (endLineFound) {
                        break;
                    }
                    var kw = KeywordsManager_1.KeywordsManager.parseKeyword(line);
                    keywords.push(kw);
                }
                return null;
            });
        }).then(function () {
            return {
                header: keywords,
                bytesRead: bytesRead
            };
        });
    };
    FitsReader.readHduAsync = function (file, offsetBytes) {
        return FitsReader.readHeaderAsync(file, offsetBytes).then(function (headerResult) {
            var naxis = KeywordsManager_1.KeywordsManager.getValue(headerResult.header, 'NAXIS', 0);
            var hdu = {
                header: headerResult.header,
                data: function () { return new Promise(function (resolve) {
                    resolve();
                }); },
                bytesRead: 0
            };
            hdu.bytesRead += headerResult.bytesRead;
            hdu.bytesRead += FitsReader.readDataSize(hdu.header);
            if (naxis !== 0) { // has data
                var offset_1 = offsetBytes + headerResult.bytesRead;
                hdu.data = function () { return FitsReader.readDataAsync(file, offset_1, headerResult.header); };
            }
            return hdu;
        });
    };
    FitsReader.readDataAsync = function (file, offsetBytes, header) {
        var readers = RegisteredDataReaders_1.RegisteredDataReaders.filter(function (reader) { return reader.canReadData(header); });
        if (readers.length !== 1) {
            throw new Error('SlimFits was unable to read this file.');
        }
        else {
            return readers[0].readDataAsync(file, offsetBytes, header)
                .then(function (data) { return new interfaces_1.DataResult(data, readers[0].name); });
        }
    };
    FitsReader.readDataSize = function (header) {
        var readers = RegisteredDataReaders_1.RegisteredDataReaders.filter(function (reader) { return reader.canReadData(header); });
        if (readers.length !== 1) {
            throw new Error('SlimFits was unable to read this file.');
        }
        else {
            return readers[0].readDataSize(header);
        }
    };
    return FitsReader;
}());
exports.FitsReader = FitsReader;
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