[Android util] [kotlin script] Batch convert Android res from xxxhdpi to *dpi sizes using imagemagick

batch-convert-dpi.kts

/**
 * Batch conversion from one dpi to the others using imagemagick 
 * (got some Windows and personal machine hardcoded stuff, change that)
 *
 * Usage: kotlinc -script batch-convert-dpi.kts <output dir> <paths to input files (pngs)>
 */

import java.io.File
import jdk.nashorn.internal.runtime.ScriptingFunctions.readLine
import java.io.BufferedReader
import java.io.InputStreamReader

val output = File(args[0])
val conversions = arrayOf(File(output, "xxxhdpi") to 1.0, File(output, "xxhdpi") to .75, File(output, "xhdpi") to .5, File(output, "hdpi") to .375, File(output, "mdpi") to .25)

conversions.forEach { it.first.mkdir() }

conversions.forEach { (dir, factor) ->
    args.drop(1).filter{ it.endsWith(".png") }.map{ File(it) }.forEach {
        val dest = "$dir\\${it.name}"
        println("$it $dest $dir $factor")

        println("convert -resize ${Math.round(100.0 * factor)}% ${it.path} $dest")

        val proc = Runtime.getRuntime().exec(arrayOf("C:\\cygwin64\\bin\\convert.exe", "-resize", "${Math.round(100.0 * factor)}%", it.path, dest))

        val stdError = BufferedReader(InputStreamReader(proc.errorStream))
        var s: String?
        val sb = StringBuilder()

        while (true) {
            s = stdError.readLine()
            if(s == null) break
            sb.appendln(s)
        }

        if(sb.isNotEmpty()) System.err.println("\u001B[31m$sb\u001B[0m")
    }
}