Source/WebInspectorUI/UserInterface/Base/BlobUtilities.js

/*
 * Copyright (C) 2019 Apple Inc. All rights reserved.
 *
 * Redistribution and use in source and binary forms, with or without
 * modification, are permitted provided that the following conditions
 * are met:
 * 1. Redistributions of source code must retain the above copyright
 *    notice, this list of conditions and the following disclaimer.
 * 2. Redistributions in binary form must reproduce the above copyright
 *    notice, this list of conditions and the following disclaimer in the
 *    documentation and/or other materials provided with the distribution.
 *
 * THIS SOFTWARE IS PROVIDED BY APPLE INC. AND ITS CONTRIBUTORS ``AS IS''
 * AND ANY EXPRESS OR IMPLIED WARRANTIES, INCLUDING, BUT NOT LIMITED TO,
 * THE IMPLIED WARRANTIES OF MERCHANTABILITY AND FITNESS FOR A PARTICULAR
 * PURPOSE ARE DISCLAIMED. IN NO EVENT SHALL APPLE INC. OR ITS CONTRIBUTORS
 * BE LIABLE FOR ANY DIRECT, INDIRECT, INCIDENTAL, SPECIAL, EXEMPLARY, OR
 * CONSEQUENTIAL DAMAGES (INCLUDING, BUT NOT LIMITED TO, PROCUREMENT OF
 * SUBSTITUTE GOODS OR SERVICES; LOSS OF USE, DATA, OR PROFITS; OR BUSINESS
 * INTERRUPTION) HOWEVER CAUSED AND ON ANY THEORY OF LIABILITY, WHETHER IN
 * CONTRACT, STRICT LIABILITY, OR TORT (INCLUDING NEGLIGENCE OR OTHERWISE)
 * ARISING IN ANY WAY OUT OF THE USE OF THIS SOFTWARE, EVEN IF ADVISED OF
 * THE POSSIBILITY OF SUCH DAMAGE.
 */

WI.BlobUtilities = class BlobUtilities {
    static blobForContent(content, base64Encoded, mimeType)
    {
        if (base64Encoded)
            return BlobUtilities.decodeBase64ToBlob(content, mimeType);
        return BlobUtilities.textToBlob(content, mimeType);
    }

    static decodeBase64ToBlob(base64Data, mimeType)
    {
        mimeType = mimeType || "";

        const sliceSize = 1024;
        let byteCharacters = atob(base64Data);
        let bytesLength = byteCharacters.length;
        let slicesCount = Math.ceil(bytesLength / sliceSize);
        let byteArrays = new Array(slicesCount);

        for (let sliceIndex = 0; sliceIndex < slicesCount; ++sliceIndex) {
            let begin = sliceIndex * sliceSize;
            let end = Math.min(begin + sliceSize, bytesLength);

            let bytes = new Array(end - begin);
            for (let offset = begin, i = 0; offset < end; ++i, ++offset)
                bytes[i] = byteCharacters[offset].charCodeAt(0);

            byteArrays[sliceIndex] = new Uint8Array(bytes);
        }

        return new Blob(byteArrays, {type: mimeType});
    }

    static textToBlob(text, mimeType)
    {
        return new Blob([text], {type: mimeType});
    }

    static blobAsText(blob, callback)
    {
        console.assert(blob instanceof Blob);
        let fileReader = new FileReader;
        fileReader.addEventListener("loadend", () => { callback(fileReader.result); });
        fileReader.readAsText(blob);
    }
};