Picasso CircleTransformation

CircleTransformation.java

import android.graphics.Bitmap;
import android.graphics.BitmapShader;
import android.graphics.Canvas;
import android.graphics.Matrix;
import android.graphics.Paint;
import android.graphics.Shader;

import com.squareup.picasso.Transformation;

public class CircleTransformation implements Transformation {
    @Override
    public Bitmap transform(Bitmap source) {
        int size = Math.min(source.getWidth(), source.getHeight());

        int left = (source.getWidth() - size) / 2;
        int top = (source.getHeight() - size) / 2;

        final Paint paint = new Paint();
        BitmapShader shader = new BitmapShader(source, Shader.TileMode.CLAMP, Shader.TileMode.CLAMP);
        if (left != 0 || top != 0) {
            // center source
            Matrix translateTransform = new Matrix();
            translateTransform.setTranslate(-left, -top);
            shader.setLocalMatrix(translateTransform);
        }
        paint.setShader(shader);
        paint.setAntiAlias(true);

        Bitmap result = Bitmap.createBitmap(size, size, Bitmap.Config.ARGB_8888);
        Canvas canvas = new Canvas(result);

        float radius = size / 2f;
        canvas.drawCircle(radius, radius, radius, paint);

        source.recycle();

        return result;
    }

    @Override
    public String key() {
        return CircleTransformation.class.getName();
    }
}