java 高性能低内存高斯模糊

一、高斯模糊算法都是通用的没什么修改和调整的地方

以下是常用高斯模糊算法

fun blur(context: Context, bitmap: Bitmap?, radius: Int): Bitmap? {
            var radius = radius
            if (bitmap == null) {
                return null
            }
            if (radius >= 25) {
                radius = 24
            }
            //Let's create an empty bitmap with the same size of the bitmap we want to blur
            val outBitmap = Bitmap.createBitmap(bitmap.width, bitmap.height, Bitmap.Config.ARGB_8888)
            //Instantiate a new Renderscript
            val rs = RenderScript.create(context)
            //Create an Intrinsic Blur Script using the Renderscript
            val blurScript = ScriptIntrinsicBlur.create(rs, Element.U8_4(rs))
            //Create the Allocations (in/out) with the Renderscript and the in/out bitmaps
            if (bitmap == null) {
                return null
            }

            val fromBitmap = bitmap.copy(Bitmap.Config.ARGB_8888, true)
            val allIn = Allocation.createFromBitmap(rs, fromBitmap)
            val allOut = Allocation.createFromBitmap(rs, outBitmap)
            //Set the radius of the blur: 0 < radius <= 25
            blurScript.setRadius(radius.toFloat())
            //Perform the Renderscript
            blurScript.setInput(allIn)
            blurScript.forEach(allOut)
            //Copy the final bitmap created by the out