Clips an image by the diagonal, creating just the right-bottom corner

TriangleClipTransformation

import android.graphics.Bitmap;
import android.graphics.Canvas;
import android.graphics.Paint;
import android.graphics.Path;
import android.graphics.PorterDuff;
import android.graphics.PorterDuffXfermode;
import android.graphics.Rect;

import com.squareup.picasso.Transformation;

/**
 * Clips an image by the diagonal, creating just the right-bottom corner
 * 
 * @author Saul Diaz <sefford@gmail.com>
 */
public class TriangleClipTransformation implements Transformation {

    @Override
    public Bitmap transform(Bitmap source) {
        int width = source.getWidth();
        int height = source.getHeight();
        Bitmap output = Bitmap.createBitmap(width, height, Bitmap.Config.ARGB_8888);
        Canvas canvas = new Canvas(output);

        final int color = 0xff424242;
        final Paint paint = new Paint();
        final Rect rect = new Rect(0, 0, width, height);
        final Path path = new Path();
        path.moveTo(0, height);
        path.lineTo(width, height);
        path.lineTo(width, 0);
        path.moveTo(0, height);

        paint.setAntiAlias(true);
        canvas.drawARGB(0, 0, 0, 0);
        paint.setColor(color);
        paint.setStyle(Paint.Style.FILL);
        canvas.drawPath(path, paint);

        paint.setXfermode(new PorterDuffXfermode(PorterDuff.Mode.SRC_IN));
        canvas.drawBitmap(source, rect, rect, paint);
        source.recycle();
        return output;
    }

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