univ-conv/lib/converters/BlobConverter.js

The universal binary and text converter

import { AbstractConverter, _ } from "./AbstractConverter";
import { getStartEnd, hasNoStartLength, } from "./core";
import { EMPTY_BLOB, handleFileReader, handleReadableStream, hasArrayBufferOnBlob, hasBlob, hasReadAsArrayBufferOnBlob, hasStreamOnBlob, hasTextOnBlob, newBuffer, newBufferFrom, } from "./Environment";
import { dataUrlToBase64, getTextHelper } from "./StringUtil";
export class BlobConverter extends AbstractConverter {
    constructor() {
        super(...arguments);
        this.type = "blob";
    }
    empty() {
        return EMPTY_BLOB;
    }
    is(input) {
        return hasBlob && input instanceof Blob;
    }
    async _from(input, options) {
        if (this.is(input)) {
            if (hasNoStartLength(options)) {
                return input;
            }
            const { start, end } = await this._getStartEnd(input, options);
            return input.slice(start, end);
        }
        const u8 = await _().convert("uint8array", input, options);
        return new Blob([u8]);
    }
    _getStartEnd(input, options) {
        return Promise.resolve(getStartEnd(options, input.size));
    }
    _isEmpty(input) {
        return input.size === 0;
    }
    _merge(chunks) {
        return Promise.resolve(new Blob(chunks));
    }
    _size(input) {
        return Promise.resolve(input.size);
    }
    async _toArrayBuffer(input, options) {
        const u8 = await this._toUint8Array(input, options);
        return u8.buffer.slice(u8.byteOffset, u8.byteOffset + u8.byteLength);
    }
    async _toBase64(input, options) {
        const startEnd = await this._getStartEnd(input, options);
        let start = startEnd.start;
        const end = startEnd.end;
        const chunks = [];
        const bufferSize = options.bufferSize;
        for (; start < end; start += bufferSize) {
            let e = start + bufferSize;
            if (end < e)
                e = end;
            const blobChunk = input.slice(start, e);
            const chunk = await handleFileReader((reader) => reader.readAsDataURL(blobChunk), (data) => dataUrlToBase64(data));
            chunks.push(chunk);
        }
        return chunks.join("");
    }
    async _toText(input, options) {
        if (options.bufferToTextCharset === "utf8") {
            if (hasTextOnBlob) {
                return await input.text();
            }
            return await handleFileReader((reader) => reader.readAsText(input), (data) => data);
        }
        const u8 = await this._toUint8Array(input, options);
        const textHelper = await getTextHelper();
        return await textHelper.bufferToText(u8, options);
    }
    async _toUint8Array(input, options) {
        if (hasArrayBufferOnBlob) {
            const ab = await input.arrayBuffer();
            return newBufferFrom(ab);
        }
        const startEnd = await this._getStartEnd(input, options);
        let start = startEnd.start;
        const end = startEnd.end;
        const bufferSize = options.bufferSize;
        if (hasReadAsArrayBufferOnBlob) {
            const u8 = newBuffer(end - start);
            for (let index = 0; start < end; start += bufferSize) {
                let e = start + bufferSize;
                if (end < e)
                    e = end;
                const blobChunk = input.slice(start, e);
                const chunk = await handleFileReader((reader) => reader.readAsArrayBuffer(blobChunk), (data) => data);
                u8.set(newBufferFrom(chunk), index);
                index += chunk.byteLength;
            }
            return u8;
        }
        const u8ac = _()._of("uint8array");
        if (hasStreamOnBlob) {
            const readable = input.stream();
            const chunks = [];
            let index = 0;
            await handleReadableStream(readable, (u8) => {
                const size = u8.byteLength;
                if (start < index + size) {
                    let e = index + size;
                    if (end < e)
                        e = end;
                    if (index < start && start < e) {
                        chunks.push(u8.subarray(start, e));
                    }
                    else if (start <= index) {
                        chunks.push(u8);
                    }
                }
                index += size;
                return Promise.resolve(end == null || index < end);
            });
            return await u8ac.merge(chunks, options);
        }
        const base64 = await this._toBase64(input, options);
        return await u8ac.from(base64);
    }
}
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