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Diffstat (limited to 'data/extensions/jsr@javascriptrestrictor/wrappingL-CANVAS.js')
| -rw-r--r-- | data/extensions/jsr@javascriptrestrictor/wrappingL-CANVAS.js | 65 |
1 files changed, 65 insertions, 0 deletions
diff --git a/data/extensions/jsr@javascriptrestrictor/wrappingL-CANVAS.js b/data/extensions/jsr@javascriptrestrictor/wrappingL-CANVAS.js new file mode 100644 index 0000000..0521893 --- /dev/null +++ b/data/extensions/jsr@javascriptrestrictor/wrappingL-CANVAS.js @@ -0,0 +1,65 @@ +/** \file + * \brief Library of functions for the Canvas API wrappers + * + * \see https://www.w3.org/TR/generic-sensor/ + * + * \author Copyright (C) 2022 Libor Polčák + * \author Copyright (C) 2021 Matus Svancar + * + * \license SPDX-License-Identifier: GPL-3.0-or-later + */ + // + // This program is free software: you can redistribute it and/or modify + // it under the terms of the GNU General Public License as published by + // the Free Software Foundation, either version 3 of the License, or + // (at your option) any later version. + // + // This program is distributed in the hope that it will be useful, + // but WITHOUT ANY WARRANTY; without even the implied warranty of + // MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE. See the + // GNU General Public License for more details. + // + // You should have received a copy of the GNU General Public License + // along with this program. If not, see <https://www.gnu.org/licenses/>. + // + /** \file + * \ingroup wrappers + * + * Supporting fuctions for Canvas API Wrappers + */ + +/** + * Farble image data, original Brave implementation-like + * + * \param data RGBA shallow array, (0,0) coordinates are at the top left, + * see CanvasRenderingContext2D.prototype.getImageData for more details on the + * expected format. Note that the data are modified during the call. + * \param height Height of the original canvas. + * \param width Width of the original canvas. + */ +function farbleCanvasDataBrave(rowIterator, width) { + // PRNG function needs to depend on the original canvas, so that the same + // image is farbled the same way but different images are farbled differently + // See https://pagure.io/JShelter/webextension/issue/23 + let crc = new CRC16(); + for (row of rowIterator()) { + crc.next(row); + } + var thiscanvas_prng = alea(domainHash, "CanvasFarbling", crc.crc); + var data_count = BigInt(BigInt(width) * 4n); + + for (row of rowIterator()) { + for (let i = 0n; i < data_count; i++) { + if ((i % 4n) === 3n) { + // Do not modify alpha + continue; + } + if (thiscanvas_prng.get_bits(1)) { // Modify data with probability of 0.5 + // Possible improvements: + // Copy a neighbor pixel (possibly with modifications + // Make bigger canges than xoring with 1 + row[i] ^= 1; + } + } + } +} |