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view app/src/main/java/com/bartsent/simpleresizer/lib/LanczosKernel.kt @ 35:6607f675a5f7
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author | David Barts <n5jrn@me.com> |
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date | Thu, 11 Mar 2021 22:41:48 -0800 |
parents | 86740f593b6c |
children |
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package com.bartsent.simpleresizer.lib /* * Some code in this file has been adapted from: https://github.com/disintegration/imaging/ . */ import kotlin.math.PI import kotlin.math.abs import kotlin.math.sin class LanczosKernel: ScalingKernel { override val size = 3.0 private val memory = HashMap<Double, Double>() private fun sinc(x: Double): Double { if (x == 0.0) return 1.0 val pix = PI * x return sin(pix) / pix } override fun weight(x: Double): Double { if (abs(x) >= size) return 0.0 val remembered = memory[x] if (remembered != null) return remembered val calculated = sinc(x) * sinc(x/size) memory[x] = calculated return calculated } }