image-in-browser/lib/formats/jpeg/jpeg-utils.js

Package for encoding / decoding images, transforming images, applying filters, drawing primitives on images on the client side (no need for server Node.js)

import { InputBuffer } from '../../common/input-buffer.js';
import { OutputBuffer } from '../../common/output-buffer.js';
import { ExifData } from '../../exif/exif-data.js';
import { JpegMarker } from './jpeg-marker.js';
export class JpegUtils {
    readExifData(block) {
        if (block === undefined) {
            return undefined;
        }
        const signature = block.readUint32();
        if (signature !== JpegUtils._exifSignature) {
            return undefined;
        }
        if (block.readUint16() !== 0) {
            return undefined;
        }
        return ExifData.fromInputBuffer(block);
    }
    writeAPP1(out, exif) {
        if (exif.isEmpty) {
            return;
        }
        const exifData = new OutputBuffer();
        exif.write(exifData);
        const exifBytes = exifData.getBytes();
        out.writeUint16(exifBytes.length + 8);
        out.writeUint32(JpegUtils._exifSignature);
        out.writeUint16(0);
        out.writeBytes(exifBytes);
    }
    readBlock(input) {
        const length = input.readUint16();
        if (length < 2) {
            return undefined;
        }
        return input.readRange(length - 2);
    }
    skipBlock(input, output) {
        const length = input.readUint16();
        output === null || output === void 0 ? void 0 : output.writeUint16(length);
        if (length < 2) {
            return false;
        }
        if (output !== undefined) {
            output.writeBuffer(input.readRange(length - 2));
        }
        else {
            input.skip(length - 2);
        }
        return true;
    }
    nextMarker(input, output) {
        let c = 0;
        if (input.isEOS) {
            return c;
        }
        do {
            do {
                c = input.read();
                output === null || output === void 0 ? void 0 : output.writeByte(c);
            } while (c !== 0xff && !input.isEOS);
            if (input.isEOS) {
                return c;
            }
            do {
                c = input.read();
                output === null || output === void 0 ? void 0 : output.writeByte(c);
            } while (c === 0xff && !input.isEOS);
        } while (c === 0 && !input.isEOS);
        return c;
    }
    decodeExif(data) {
        const input = new InputBuffer({
            buffer: data,
            bigEndian: true,
        });
        const soiCheck = input.peek(2);
        if (soiCheck.get(0) !== 0xff || soiCheck.get(1) !== 0xd8) {
            return undefined;
        }
        let marker = this.nextMarker(input);
        if (marker !== JpegMarker.soi) {
            return undefined;
        }
        let exif = undefined;
        marker = this.nextMarker(input);
        while (marker !== JpegMarker.eoi && !input.isEOS) {
            switch (marker) {
                case JpegMarker.app1:
                    exif = this.readExifData(this.readBlock(input));
                    if (exif !== undefined) {
                        return exif;
                    }
                    break;
                default:
                    this.skipBlock(input);
                    break;
            }
            marker = this.nextMarker(input);
        }
        return undefined;
    }
    injectExif(exif, data) {
        const input = new InputBuffer({
            buffer: data,
            bigEndian: true,
        });
        const soiCheck = input.peek(2);
        if (soiCheck.get(0) !== 0xff || soiCheck.get(1) !== 0xd8) {
            return undefined;
        }
        const output = new OutputBuffer({
            size: data.length,
            bigEndian: true,
        });
        let marker = this.nextMarker(input, output);
        if (marker !== JpegMarker.soi) {
            return undefined;
        }
        let hasExifBlock = false;
        const startOffset = input.offset;
        marker = this.nextMarker(input);
        while (!hasExifBlock && marker !== JpegMarker.eoi && !input.isEOS) {
            if (marker === JpegMarker.app1) {
                const block = this.readBlock(input);
                const signature = block === null || block === void 0 ? void 0 : block.readUint32();
                if (signature === JpegUtils._exifSignature) {
                    hasExifBlock = true;
                    break;
                }
            }
            else {
                this.skipBlock(input);
            }
            marker = this.nextMarker(input);
        }
        input.offset = startOffset;
        if (!hasExifBlock) {
            this.writeAPP1(output, exif);
            output.writeBuffer(input.readRange(input.length));
            return output.getBytes();
        }
        marker = this.nextMarker(input, output);
        while (marker !== JpegMarker.eoi && !input.isEOS) {
            if (marker === JpegMarker.app1) {
                const saveOffset = input.offset;
                input.skip(2);
                const signature = input.readUint32();
                input.offset = saveOffset;
                if (signature === JpegUtils._exifSignature) {
                    this.skipBlock(input);
                    this.writeAPP1(output, exif);
                    output.writeBuffer(input.readRange(input.length));
                    return output.getBytes();
                }
            }
            this.skipBlock(input, output);
            marker = this.nextMarker(input, output);
        }
        return output.getBytes();
    }
}
JpegUtils._exifSignature = 0x45786966;
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