86 lines
3.0 KiB
JavaScript
86 lines
3.0 KiB
JavaScript
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/* Copyright 2019 Mozilla Foundation
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*
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* Licensed under the Apache License, Version 2.0 (the "License");
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* you may not use this file except in compliance with the License.
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* You may obtain a copy of the License at
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*
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* http://www.apache.org/licenses/LICENSE-2.0
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*
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* Unless required by applicable law or agreed to in writing, software
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* distributed under the License is distributed on an "AS IS" BASIS,
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* WITHOUT WARRANTIES OR CONDITIONS OF ANY KIND, either express or implied.
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* See the License for the specific language governing permissions and
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* limitations under the License.
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*/
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/* eslint no-var: error */
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import { ColorSpace } from './colorspace';
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import { JpegStream } from './jpeg_stream';
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import { Stream } from './stream';
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class NativeImageDecoder {
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constructor({ xref, resources, handler, forceDataSchema = false,
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pdfFunctionFactory, }) {
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this.xref = xref;
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this.resources = resources;
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this.handler = handler;
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this.forceDataSchema = forceDataSchema;
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this.pdfFunctionFactory = pdfFunctionFactory;
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}
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canDecode(image) {
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return image instanceof JpegStream &&
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NativeImageDecoder.isDecodable(image, this.xref, this.resources,
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this.pdfFunctionFactory);
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}
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decode(image) {
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// For natively supported JPEGs send them to the main thread for decoding.
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const dict = image.dict;
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let colorSpace = dict.get('ColorSpace', 'CS');
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colorSpace = ColorSpace.parse(colorSpace, this.xref, this.resources,
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this.pdfFunctionFactory);
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return this.handler.sendWithPromise('JpegDecode', [
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image.getIR(this.forceDataSchema), colorSpace.numComps
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]).then(function({ data, width, height, }) {
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return new Stream(data, 0, data.length, dict);
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});
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}
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/**
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* Checks if the image can be decoded and displayed by the browser without any
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* further processing such as color space conversions.
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*/
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static isSupported(image, xref, res, pdfFunctionFactory) {
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const dict = image.dict;
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if (dict.has('DecodeParms') || dict.has('DP')) {
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return false;
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}
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const cs = ColorSpace.parse(dict.get('ColorSpace', 'CS'), xref, res,
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pdfFunctionFactory);
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// isDefaultDecode() of DeviceGray and DeviceRGB needs no `bpc` argument.
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return (cs.name === 'DeviceGray' || cs.name === 'DeviceRGB') &&
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cs.isDefaultDecode(dict.getArray('Decode', 'D'));
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}
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/**
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* Checks if the image can be decoded by the browser.
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*/
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static isDecodable(image, xref, res, pdfFunctionFactory) {
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const dict = image.dict;
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if (dict.has('DecodeParms') || dict.has('DP')) {
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return false;
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}
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const cs = ColorSpace.parse(dict.get('ColorSpace', 'CS'), xref, res,
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pdfFunctionFactory);
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const bpc = dict.get('BitsPerComponent', 'BPC') || 1;
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return (cs.numComps === 1 || cs.numComps === 3) &&
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cs.isDefaultDecode(dict.getArray('Decode', 'D'), bpc);
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}
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}
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export {
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NativeImageDecoder,
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};
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