package liu.roundimagedemo.view;import android.graphics.Bitmap;import android.graphics.BitmapShader;import android.graphics.Canvas;import android.graphics.Paint;import com.squareup.picasso.Transformation;/** * Created by 刘楠 on 2016/8/31 0031.23:09 */public class CircleTransform implements Transformation {    @Override    public Bitmap transform(Bitmap source) {        /**         * 求出宽和高的哪个小         */       int  size = Math.min(source.getWidth(), source.getHeight());        /**         * 求中心点         */        int x = (source.getWidth() - size) / 2;        int y = (source.getHeight() - size) / 2;        /**         * 生成BitMap         */        Bitmap squaredBitmap = Bitmap.createBitmap(source, x, y, size, size);        if (squaredBitmap != source) {            //释放            source.recycle();        }        /**         * 建立新的Bitmap         */        Bitmap bitmap = Bitmap.createBitmap(size, size, source.getConfig());        /**         * 画布画笔         */        Canvas canvas = new Canvas(bitmap);        Paint  paint  = new Paint();                BitmapShader shader = new BitmapShader(squaredBitmap,                BitmapShader.TileMode.CLAMP, BitmapShader.TileMode.CLAMP);        paint.setShader(shader);        paint.setAntiAlias(true);        float r = size / 2f;        /**         * 画圆         */        canvas.drawCircle(r, r, r, paint);        squaredBitmap.recycle();        return bitmap;    }    @Override    public String key() {        return "circle";    }}

Picasso.with(this).load("http://img1.3lian.com/2015/w7/68/d/85.jpg").transform(new CircleTransform())                .into(mNetImageView);