package com.jay.demo.imageviewdemo;

import android.content.Context;

import android.graphics.Bitmap;

import android.graphics.Canvas;

import android.graphics.Paint;

import android.graphics.PaintFlagsDrawFilter;

import android.graphics.Path;

import android.graphics.Rect;

import android.graphics.Region;

import android.util.AttributeSet;

import android.widget.ImageView;

/**

 * Created by coder-pig on 2015/7/18 0018.

 */

public class RoundImageView extends ImageView {

    private Bitmap mBitmap;

    private Rect mRect = new Rect();

    private PaintFlagsDrawFilter pdf = new PaintFlagsDrawFilter(0, Paint.ANTI_ALIAS_FLAG);

    private Paint mPaint = new Paint();

    private Path mPath=new Path();

    public RoundImageView(Context context, AttributeSet attrs) {

        super(context, attrs);

        init();

    }

    //传入一个Bitmap对象

    public void setBitmap(Bitmap bitmap) {

        this.mBitmap = bitmap;

    }

    private void init() {

        mPaint.setStyle(Paint.Style.STROKE);

        mPaint.setFlags(Paint.ANTI_ALIAS_FLAG);

        mPaint.setAntiAlias(true);// 抗锯尺

    }

    @Override

    protected void onDraw(Canvas canvas) {

        super.onDraw(canvas);

        if(mBitmap == null)

        {

            return;

        }

        mRect.set(0,0,getWidth(),getHeight());

        canvas.save();

        canvas.setDrawFilter(pdf);

        mPath.addCircle(getWidth() / 2, getWidth() / 2, getHeight() / 2, Path.Direction.CCW);

        canvas.clipPath(mPath, Region.Op.REPLACE);

        canvas.drawBitmap(mBitmap, null, mRect, mPaint);

        canvas.restore();

    }

}

<com.jay.demo.imageviewdemo.RoundImageView

        android:id="@+id/img_round"

        android:layout_width="200dp"

        android:layout_height="200dp"

        android:layout_margin="5px"/>

package com.jay.demo.imageviewdemo;

import android.graphics.Bitmap;

import android.graphics.BitmapFactory;

import android.os.Bundle;

import android.support.v7.app.AppCompatActivity;

public class MainActivity extends AppCompatActivity {

    private RoundImageView img_round;

    @Override

    protected void onCreate(Bundle savedInstanceState) {

        super.onCreate(savedInstanceState);

        setContentView(R.layout.activity_main);

        img_round = (RoundImageView) findViewById(R.id.img_round);

        Bitmap bitmap = BitmapFactory.decodeResource(getResources(),R.mipmap.meinv);

        img_round.setBitmap(bitmap);

    }

}