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annotate app/src/main/java/com/bartsent/simpleresizer/lib/LanczosKernel.kt @ 6:e8059b166de1

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Lanczos works, but is painfully slow.
author David Barts <n5jrn@me.com>
date Tue, 16 Feb 2021 17:29:52 -0800
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children 6ae738b8a814
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6
e8059b166de1 Lanczos works, but is painfully slow.
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1 package com.bartsent.simpleresizer.lib
e8059b166de1 Lanczos works, but is painfully slow.
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2
e8059b166de1 Lanczos works, but is painfully slow.
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3 import kotlin.math.PI
e8059b166de1 Lanczos works, but is painfully slow.
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4 import kotlin.math.abs
e8059b166de1 Lanczos works, but is painfully slow.
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5 import kotlin.math.sin
e8059b166de1 Lanczos works, but is painfully slow.
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6
e8059b166de1 Lanczos works, but is painfully slow.
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7 object LanczosKernel: ScalingKernel {
e8059b166de1 Lanczos works, but is painfully slow.
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8 override val size = 3.0
e8059b166de1 Lanczos works, but is painfully slow.
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9
e8059b166de1 Lanczos works, but is painfully slow.
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10 private fun sinc(x: Double): Double {
e8059b166de1 Lanczos works, but is painfully slow.
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11 if (x == 0.0)
e8059b166de1 Lanczos works, but is painfully slow.
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12 return 1.0
e8059b166de1 Lanczos works, but is painfully slow.
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13 val pix = PI * x
e8059b166de1 Lanczos works, but is painfully slow.
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14 return sin(pix) / pix
e8059b166de1 Lanczos works, but is painfully slow.
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15 }
e8059b166de1 Lanczos works, but is painfully slow.
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16
e8059b166de1 Lanczos works, but is painfully slow.
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17 override fun weight(x: Double): Double =
e8059b166de1 Lanczos works, but is painfully slow.
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18 if (abs(x) < size) sinc(x) * sinc(x/size) else 0.0
e8059b166de1 Lanczos works, but is painfully slow.
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19 }