RenderScriptBox3x3Blur.java

package at.favre.lib.dali.blur.algorithms;

import android.graphics.Bitmap;
import android.support.v8.renderscript.Allocation;
import android.support.v8.renderscript.Element;
import android.support.v8.renderscript.RenderScript;
import android.support.v8.renderscript.ScriptIntrinsicConvolve3x3;

import at.favre.lib.dali.blur.BlurKernels;
import at.favre.lib.dali.blur.IBlur;


/**
 * This is a convolve matrix based blur algorithms powered by Renderscript's ScriptIntrinsicConvolve class. This uses a box kernel.
 * Instead of radius it uses passes, so a radius parameter of 16 makes the convolve algorithm applied 16 times onto the image.
 */
public class RenderScriptBox3x3Blur implements IBlur {
    private RenderScript rs;

    public RenderScriptBox3x3Blur(RenderScript rs) {
        this.rs = rs;
    }

    @Override
    public Bitmap blur(int radius, Bitmap bitmapOriginal) {
        Allocation input = Allocation.createFromBitmap(rs, bitmapOriginal);
        final Allocation output = Allocation.createTyped(rs, input.getType());
        final ScriptIntrinsicConvolve3x3 script = ScriptIntrinsicConvolve3x3.create(rs, Element.U8_4(rs));
        script.setCoefficients(BlurKernels.BOX_3x3);
        for (int i = 0; i < radius; i++) {
            script.setInput(input);
            script.forEach(output);
            input = output;
        }
        output.copyTo(bitmapOriginal);
        return bitmapOriginal;
    }
}