GetHighContrastSchemeName.js

/**
 * Child process to get localised high-contrast theme name.
 *
 * Copyright 2018 Raising the Floor - International
 *
 * Licensed under the New BSD license. You may not use this file except in
 * compliance with this License.
 *
 * The R&D leading to these results received funding from the
 * Department of Education - Grant H421A150005 (GPII-APCP). However,
 * these results do not necessarily represent the policy of the
 * Department of Education, and you should not assume endorsement by the
 * Federal Government.
 *
 * You may obtain a copy of the License at
 * https://github.com/GPII/universal/blob/master/LICENSE.txt
 */
"use strict";

var ffi = require("ffi-napi");
var ref = require("ref-napi");

var shlwapi = new ffi.Library("shlwapi", {
    // https://docs.microsoft.com/en-us/windows/desktop/api/shlwapi/nf-shlwapi-shloadindirectstring
    "SHLoadIndirectString": [
        "uint32", [ "char*", "char*", "uint32", "int" ]
    ]
});


// The localised string resources for the built-in theme names.
var stringIds = [
    "2107", // High Contrast #1
    "2108", // High Contrast #2
    "2103", // High Contrast Black
    "2104" // High Contrast White
];

var buf = Buffer.alloc(0xfff);

var localisedNames = stringIds.map(function (stringId) {
    var src = new Buffer("@%SystemRoot%\\System32\\themeui.dll,-" + stringId + "\u0000", "ucs2");
    var togo;
    if (shlwapi.SHLoadIndirectString(src, buf, buf.length, 0) === 0) {
        togo = ref.reinterpretUntilZeros(buf, 2, 0).toString("ucs2");
    } else {
        togo = undefined;
    }

    return togo;
});

process.send(localisedNames);