5984c24415
The image was "borrowed" from one of the examples found at https://github.com/notmasteryet/jpgjs/tree/master/images
76 lines
2.3 KiB
JavaScript
76 lines
2.3 KiB
JavaScript
/* Copyright 2018 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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'use strict';
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if (!pdfjsImageDecoders.JpegImage) {
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alert('Please build the pdfjs-dist library using `gulp dist-install`');
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}
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var JPEG_IMAGE = 'fish.jpg';
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var jpegCanvas = document.getElementById('jpegCanvas');
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var jpegCtx = jpegCanvas.getContext('2d');
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// Load the image data, and convert it to a Uint8Array.
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//
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var nonBinaryRequest = false;
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var request = new XMLHttpRequest();
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request.open('GET', JPEG_IMAGE, false);
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try {
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request.responseType = 'arraybuffer';
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nonBinaryRequest = request.responseType !== 'arraybuffer';
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} catch (e) {
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nonBinaryRequest = true;
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}
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if (nonBinaryRequest && request.overrideMimeType) {
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request.overrideMimeType('text/plain; charset=x-user-defined');
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}
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request.send(null);
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var typedArrayImage;
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if (nonBinaryRequest) {
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var str = request.responseText, length = str.length;
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var bytes = new Uint8Array(length);
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for (var i = 0; i < length; ++i) {
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bytes[i] = str.charCodeAt(i) & 0xFF;
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}
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typedArrayImage = bytes;
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} else {
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typedArrayImage = new Uint8Array(request.response);
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}
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// Parse the image data using `JpegImage`.
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//
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var jpegImage = new pdfjsImageDecoders.JpegImage();
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jpegImage.parse(typedArrayImage);
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var width = jpegImage.width, height = jpegImage.height;
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var jpegData = jpegImage.getData(width, height, /* forceRGB = */ true);
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// Render the JPEG image on a <canvas>.
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//
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var imageData = jpegCtx.createImageData(width, height);
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var imageBytes = imageData.data;
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for (var i = 0, j = 0, ii = width * height * 4; i < ii;) {
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imageBytes[i++] = jpegData[j++];
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imageBytes[i++] = jpegData[j++];
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imageBytes[i++] = jpegData[j++];
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imageBytes[i++] = 255;
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}
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jpegCanvas.width = width, jpegCanvas.height = height;
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jpegCtx.putImageData(imageData, 0, 0);
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