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17 lines
372 B
17 lines
372 B
'use strict'; |
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module.exports = function paethPredictor(left, above, upLeft) { |
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var paeth = left + above - upLeft; |
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var pLeft = Math.abs(paeth - left); |
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var pAbove = Math.abs(paeth - above); |
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var pUpLeft = Math.abs(paeth - upLeft); |
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if (pLeft <= pAbove && pLeft <= pUpLeft) { |
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return left; |
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} |
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if (pAbove <= pUpLeft) { |
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return above; |
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} |
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return upLeft; |
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}; |