pdf-lib/es/core/pdf-structures/factories/PNGXObjectFactory.js

Library for creating and modifying PDF files in JavaScript

import pako from 'pako';
import PNG from 'png-ts';
import { PDFArray, PDFDictionary, PDFName, PDFNumber, PDFRawStream, } from '../../pdf-objects';
import { isInstance, validate } from '../../../utils/validate';
/**
 * A note of thanks to the developers of https://github.com/devongovett/pdfkit,
 * as this class borrows heavily from:
 * https://github.com/devongovett/pdfkit/blob/e71edab0dd4657b5a767804ba86c94c58d01fbca/lib/image/png.coffee
 */
var PNGXObjectFactory = /** @class */ (function () {
    function PNGXObjectFactory(data) {
        var _this = this;
        this.embedImageIn = function (document) {
            _this.document = document;
            _this.xObjDict = PDFDictionary.from({
                Type: PDFName.from('XObject'),
                Subtype: PDFName.from('Image'),
                BitsPerComponent: PDFNumber.fromNumber(_this.image.bits),
                Width: PDFNumber.fromNumber(_this.width),
                Height: PDFNumber.fromNumber(_this.height),
                Filter: PDFName.from('FlateDecode'),
            }, document.index);
            if (!_this.image.hasAlphaChannel) {
                var params = PDFDictionary.from({
                    Predictor: PDFNumber.fromNumber(15),
                    Colors: PDFNumber.fromNumber(_this.image.colors),
                    BitsPerComponent: PDFNumber.fromNumber(_this.image.bits),
                    Columns: PDFNumber.fromNumber(_this.width),
                }, document.index);
                _this.xObjDict.set('DecodeParms', params);
            }
            if (_this.image.palette.length === 0) {
                _this.xObjDict.set('ColorSpace', PDFName.from(_this.image.colorSpace));
            }
            else {
                var paletteStream = document.register(PDFRawStream.from(PDFDictionary.from({
                    Length: PDFNumber.fromNumber(_this.image.palette.length),
                }, document.index), new Uint8Array(_this.image.palette)));
                _this.xObjDict.set('ColorSpace', PDFArray.fromArray([
                    PDFName.from('Indexed'),
                    PDFName.from('DeviceRGB'),
                    PDFNumber.fromNumber(_this.image.palette.length / 3 - 1),
                    paletteStream,
                ], document.index));
            }
            // TODO: Handle the following two transparency types. They don't seem to be
            // fully handled in:
            // https://github.com/devongovett/pdfkit/blob/e71edab0dd4657b5a767804ba86c94c58d01fbca/lib/image/png.coffee
            // if (this.image.transparency.grayscale)
            // if (this.image.transparency.rgb)
            // prettier-ignore
            return (_this.image.transparency.indexed ? _this.loadIndexedAlphaChannel()
                : _this.image.hasAlphaChannel ? _this.splitAlphaChannel()
                    : _this.finalize());
        };
        /** @hidden */
        this.finalize = function () {
            if (_this.alphaChannel) {
                var deflatedAlphaChannel = pako.deflate(_this.alphaChannel);
                var alphaStreamDict = PDFDictionary.from({
                    Type: PDFName.from('XObject'),
                    Subtype: PDFName.from('Image'),
                    Height: PDFNumber.fromNumber(_this.height),
                    Width: PDFNumber.fromNumber(_this.width),
                    BitsPerComponent: PDFNumber.fromNumber(8),
                    Filter: PDFName.from('FlateDecode'),
                    ColorSpace: PDFName.from('DeviceGray'),
                    Decode: PDFArray.fromArray([PDFNumber.fromNumber(0), PDFNumber.fromNumber(1)], _this.document.index),
                    Length: PDFNumber.fromNumber(deflatedAlphaChannel.length),
                }, _this.document.index);
                var smaskStream = _this.document.register(PDFRawStream.from(alphaStreamDict, deflatedAlphaChannel));
                _this.xObjDict.set('SMask', smaskStream);
            }
            _this.xObjDict.set('Length', PDFNumber.fromNumber(_this.imgData.length));
            var xObj = _this.document.register(PDFRawStream.from(_this.xObjDict, _this.imgData));
            return xObj;
        };
        /** @hidden */
        this.splitAlphaChannel = function () {
            var pixels = _this.image.decodePixels();
            var colorByteSize = (_this.image.colors * _this.image.bits) / 8;
            var pixelCount = _this.image.width * _this.image.height;
            _this.imgData = new Uint8Array(pixelCount * colorByteSize);
            _this.alphaChannel = new Uint8Array(pixelCount);
            var i = 0;
            var p = 0;
            var a = 0;
            while (i < pixels.length) {
                _this.imgData[p++] = pixels[i++];
                _this.imgData[p++] = pixels[i++];
                _this.imgData[p++] = pixels[i++];
                _this.alphaChannel[a++] = pixels[i++];
            }
            _this.imgData = pako.deflate(_this.imgData);
            return _this.finalize();
        };
        /** @hidden */
        this.loadIndexedAlphaChannel = function () {
            var transparency = _this.image.transparency.indexed;
            var pixels = _this.image.decodePixels();
            _this.alphaChannel = new Uint8Array(_this.width * _this.height);
            // Can't use forEach here, because it's missing on React Native Android
            for (var idx = 0; idx < pixels.length; idx++) {
                _this.alphaChannel[idx] = transparency[pixels[idx]];
            }
            return _this.finalize();
        };
        validate(data, isInstance(Uint8Array), '"data" must be an instance of Uint8Array');
        this.image = PNG.load(data);
        this.width = this.image.width;
        this.height = this.image.height;
        this.imgData = this.image.imgData;
    }
    PNGXObjectFactory.for = function (data) { return new PNGXObjectFactory(data); };
    return PNGXObjectFactory;
}());
export default PNGXObjectFactory;