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comparison app/src/main/java/com/bartsent/simpleresizer/lib/Resizer.kt @ 7:9374d044a132 concur

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Concurrency attempt, NOT WORKING.
author David Barts <n5jrn@me.com>
date Wed, 17 Feb 2021 07:24:26 -0800
parents
children 884092efe31a
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6:e8059b166de1 7:9374d044a132
1 package com.bartsent.simpleresizer.lib
2
3 import android.graphics.Bitmap
4 import android.graphics.Color
5 import java.io.Closeable
6 import kotlin.math.ceil
7 import kotlin.math.floor
8
9 class Resizer: Closeable {
10 private val NWORKERS = maxOf(1, Runtime.getRuntime().availableProcessors() - 2)
11 private val workers = Channel<Worker>(NWORKERS)
12 init {
13 for (i in 0 until NWORKERS)
14 workers.write(Worker(workers))
15 }
16
17 override fun close() {
18 for (i in 0 until NWORKERS)
19 workers.read().run {
20 interrupt()
21 join()
22 }
23 }
24
25 private fun drain(): Unit {
26 val saved = Array<Worker>(NWORKERS) { workers.read() }
27 saved.forEach { workers.write(it) }
28 }
29
30 private data class IndexWeight(var index: Int, var weight: Double)
31
32 private fun precomputeWeights(dstSize: Int, srcSize: Int, filter: ScalingKernel): Array<Array<IndexWeight>> {
33 val du = srcSize.toDouble() / dstSize.toDouble()
34 val scale = maxOf(1.0, du)
35 val ru = ceil(scale * filter.size)
36 val TEMPLATE = arrayOf<IndexWeight>()
37 val out = Array<Array<IndexWeight>>(dstSize) { TEMPLATE }
38 val tmp = ArrayList<IndexWeight>((ru.toInt()+2)*2)
39 val emax = srcSize - 1
40
41 for (v in 0 until dstSize) {
42 val fu = (v.toDouble()+0.5)*du - 0.5
43 val begin = maxOf(0, ceil(fu - ru).toInt())
44 val end = minOf(emax, floor(fu + ru).toInt())
45 var sum: Double = 0.0
46 for (u in begin..end) {
47 val w = filter.weight((u.toDouble() - fu) / scale)
48 if (w != 0.0) {
49 sum += w
50 tmp.add(IndexWeight(u, w))
51 }
52 }
53 if (sum != 0.0) {
54 tmp.forEach {
55 it.weight /= sum
56 }
57 }
58 out[v] = tmp.toArray(TEMPLATE)
59 tmp.clear()
60 }
61 return out
62 }
63
64 private data class WorkUnit(val target: Bitmap, val x: Int, val y: Int,
65 val weights: Array<IndexWeight>, val scanLine: IntArray)
66
67 private class Worker(private val workers: Channel<Worker>): Thread() {
68 private val _input = Channel<WorkUnit>(1)
69
70 override fun run() {
71 while (true) {
72 val data = _input.read()
73 if (isInterrupted)
74 return
75 resample(data.target, data.x, data.y, data.weights, data.scanLine)
76 workers.write(this)
77 }
78 }
79
80 fun send(data: WorkUnit) {
81 _input.write(data)
82 }
83
84 private fun clamp(v: Double): Int = minOf(255, maxOf(0, (v + 0.5).toInt()))
85
86 private fun resample(target: Bitmap, x: Int, y: Int, weights: Array<IndexWeight>, scanLine: IntArray): Unit {
87 var r = 0.0; var g = 0.0; var b = 0.0; var a = 0.0
88 weights.forEach {
89 val c = scanLine[it.index]
90 val aw = Color.alpha(c).toDouble() * it.weight
91 r += Color.red(c).toDouble() * aw
92 g += Color.green(c).toDouble() * aw
93 b += Color.blue(c).toDouble() * aw
94 a += aw
95 }
96 if (a == 0.0)
97 return
98 val argb = Color.argb(clamp(a), clamp(r/a), clamp(g/a), clamp(b/a))
99 synchronized(target) {
100 target.setPixel(x, y, argb)
101 }
102 }
103 }
104
105 private fun resample(target: Bitmap, x: Int, y: Int, weights: Array<IndexWeight>, scanLine: IntArray): Unit {
106 workers.read().send(WorkUnit(target, x, y, weights, scanLine))
107 }
108
109 fun horizontal(image: Bitmap, newWidth: Int, kernel: ScalingKernel): Bitmap {
110 val dst = Bitmap.createBitmap(newWidth, image.height, Bitmap.Config.ARGB_8888)
111 val weights = precomputeWeights(newWidth, image.width, kernel)
112 val scanLine = IntArray(image.width)
113 for (y in 0 until image.height) {
114 for (x in 0 until image.width) {
115 scanLine[x] = image.getPixel(x, y)
116 }
117 for (x in weights.indices) {
118 resample(dst, x, y, weights[x], scanLine)
119 }
120 }
121 drain()
122 return dst
123 }
124
125 fun vertical(image: Bitmap, newHeight: Int, kernel: ScalingKernel): Bitmap {
126 val dst = Bitmap.createBitmap(image.width, newHeight, Bitmap.Config.ARGB_8888)
127 val weights = precomputeWeights(newHeight, image.height, kernel)
128 val scanLine = IntArray(image.height)
129 for (x in 0 until image.width) {
130 for (y in 0 until image.height) {
131 scanLine[y] = image.getPixel(x, y)
132 }
133 for (y in weights.indices) {
134 resample(dst, x, y, weights[y], scanLine)
135 }
136 }
137 drain()
138 return dst
139 }
140 }