Basic BlurTransformer for Square's Picasso

gistfile1.txt

import android.content.Context;
import android.graphics.Bitmap;
import android.renderscript.Allocation;
import android.renderscript.Element;
import android.renderscript.RenderScript;
import android.renderscript.ScriptIntrinsicBlur;

import com.squareup.picasso.Transformation;

public class BlurTransform implements Transformation {

    RenderScript rs;
    public BlurTransform(Context context) {
        super();
        rs = RenderScript.create(context);
    }

    @Override
    public Bitmap transform(Bitmap bitmap) {
        // Create another bitmap that will hold the results of the filter.
        Bitmap blurredBitmap = Bitmap.createBitmap(bitmap);

        // Allocate memory for Renderscript to work with
        Allocation input = Allocation.createFromBitmap(rs, bitmap, Allocation.MipmapControl.MIPMAP_FULL, Allocation.USAGE_SHARED);
        Allocation output = Allocation.createTyped(rs, input.getType());

        // Load up an instance of the specific script that we want to use.
        ScriptIntrinsicBlur script = ScriptIntrinsicBlur.create(rs, Element.U8_4(rs));
        script.setInput(input);

        // Set the blur radius
        script.setRadius(10);

        // Start the ScriptIntrinisicBlur
        script.forEach(output);

        // Copy the output to the blurred bitmap
        output.copyTo(blurredBitmap);

        return blurredBitmap;
    }

    @Override
    public String key() {
        return "blur";
    }

}

You can make this a LOT faster by setting Allocation.USAGE_SHARED and removing the bitmap.recycle() call.

Just a note, most methods in ScriptIntrinsicBlur used in this snippet require API level 17.

Thanks, Tad - noted and updated.

Note that if you don't call bitmap.recycle than the following call will fail:

Picasso.with(getActivity())
.load(mClip.getImageUrl(app))
.resize(width, height)
.centerCrop()
.transform(new BlurTransform(getActivity()))
.into(mImageView);

with the following error: "Transformation blur mutated input Bitmap but failed to recycle the original."

So in this case I've re-added the .recycle() call.

Hmm, so I realize that be re-adding the recycle() call my image is not getting cached. So if I don't want to recycle I get the error mentioned above ("Transformation blur mutated input Bitmap but failed to recycle the original.").

Any idea how I can avoid this? Or is there no way to resize and blur an image at the same time?

Quick note: you shouldn't creating a new RS instance in the constructor, which gets called every time - even when the blurred image is being loaded from memory. Instead, store a WeakReference<Context> and create RenderScript inside of the transform method.

It requires api level 17

Thanks for posting this up.

I had to change one line to get things working in my case:

val blurredBitmap = Bitmap.createBitmap(bitmap)

to

val blurredBitmap = bitmap.copy(Bitmap.Config.ARGB_8888, true)

Problem was that BitMap.createBitmap() doesn't always create a copy - sometimes it reuses the bitmap. Looks like this was confusing Picasso's error checking in terms of whether or not the Transformation object correctly handled recycling.