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60 lines
1.8 KiB
JavaScript
60 lines
1.8 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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if (!pdfjsImageDecoders.JpegImage) {
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// eslint-disable-next-line no-alert
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alert("Please build the pdfjs-dist library using `gulp dist-install`");
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}
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const JPEG_IMAGE = "fish.jpg";
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const jpegCanvas = document.getElementById("jpegCanvas");
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const 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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const response = await fetch(JPEG_IMAGE);
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if (!response.ok) {
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throw new Error(response.statusText);
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}
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const typedArrayImage = new Uint8Array(await response.arrayBuffer());
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// Parse the image data using `JpegImage`.
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//
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const jpegImage = new pdfjsImageDecoders.JpegImage();
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jpegImage.parse(typedArrayImage);
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const width = jpegImage.width,
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height = jpegImage.height;
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const jpegData = jpegImage.getData({
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width,
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height,
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forceRGB: true,
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});
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// Render the JPEG image on a <canvas>.
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//
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const imageData = jpegCtx.createImageData(width, height);
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const imageBytes = imageData.data;
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for (let j = 0, k = 0, jj = width * height * 4; j < jj; ) {
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imageBytes[j++] = jpegData[k++];
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imageBytes[j++] = jpegData[k++];
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imageBytes[j++] = jpegData[k++];
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imageBytes[j++] = 255;
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}
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jpegCanvas.width = width;
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jpegCanvas.height = height;
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jpegCtx.putImageData(imageData, 0, 0);
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