Optimal use of BitmapFactory.Options.inSampleSize for speed

Question

Thanks to Schermvlieger for asking this question on anddev.org,

I\'m just copying his question to SO as nobody replied on th

Answer 1

Hi try out calculating the inSampleSize using this logic

private fun calculateInSampleSize(options: BitmapFactory.Options, reqWidth: Int, reqHeight: Int): Int {
    val (height: Int, width: Int) = options.run { outHeight to outWidth }
    var inSampleSize = 1

    if (height > reqHeight || width > reqWidth) {
        val halfHeight: Int = height / 2
        val halfWidth: Int = width / 2

        // Calculate the largest inSampleSize value that is a power of 2 and keeps both
        // height and width larger than the requested height and width.
        while (halfHeight / inSampleSize >= reqHeight && halfWidth / inSampleSize >= reqWidth) {
            inSampleSize *= 2
        }
    }

    return inSampleSize
}