47 lines
1.2 KiB
JavaScript
47 lines
1.2 KiB
JavaScript
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/* Copyright 2022 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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function applyMaskImageData({
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src,
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srcPos = 0,
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dest,
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destPos = 3,
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width,
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height,
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inverseDecode = false,
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}) {
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const srcLength = src.byteLength;
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const zeroMapping = inverseDecode ? 0 : 255;
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const oneMapping = inverseDecode ? 255 : 0;
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for (let j = 0; j < height; j++) {
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let elem,
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mask = 0;
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for (let k = 0; k < width; k++) {
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if (mask === 0) {
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elem = srcPos < srcLength ? src[srcPos++] : 255;
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mask = 128;
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}
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dest[destPos] = elem & mask ? oneMapping : zeroMapping;
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destPos += 4;
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mask >>= 1;
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}
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}
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return { srcPos, destPos };
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}
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export { applyMaskImageData };
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