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34 lines
712 B
34 lines
712 B
'use strict'; |
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Object.defineProperty(exports, '__esModule', { |
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value: true |
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}); |
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exports.default = scroll; |
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/** |
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* Copyright (c) Facebook, Inc. and its affiliates. All Rights Reserved. |
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* |
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* This source code is licensed under the MIT license found in the |
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* LICENSE file in the root directory of this source tree. |
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*/ |
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function scroll(size, {offset, max}) { |
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let start = 0; |
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let index = Math.min(offset, size); |
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const halfScreen = max / 2; |
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if (index <= halfScreen) { |
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start = 0; |
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} else { |
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if (size >= max) { |
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start = Math.min(index - halfScreen - 1, size - max); |
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} |
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index = Math.min(index - start, size); |
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} |
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return { |
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end: Math.min(size, start + max), |
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index, |
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start |
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}; |
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}
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