圆形头像

1、MainActivity

public class MainActivity extends AppCompatActivity {
    private ImageView imageView;

    @Override
    protected void onCreate(Bundle savedInstanceState) {
        super.onCreate(savedInstanceState);
        setContentView(R.layout.activity_main);
    }

2、布局

<?xml version="1.0" encoding="utf-8"?>
<LinearLayout xmlns:android="http://schemas.android.com/apk/res/android"
    xmlns:app="http://schemas.android.com/apk/res-auto"
    xmlns:tools="http://schemas.android.com/tools"
    android:id="@+id/activity_main"
    android:layout_width="match_parent"
    android:layout_height="match_parent"
    android:gravity="center"
    android:orientation="vertical"
    tools:context="com.example.administrator.circleview.MainActivity">

    <widget.CircleView
        android:layout_width="wrap_content"
        android:layout_height="240dp"
        android:layout_gravity="center"
        app:is_round="true" />
</LinearLayout>

3、CircleImageVIew

package widget;


import android.content.Context;
import android.content.res.TypedArray;
import android.graphics.Bitmap;
import android.graphics.BitmapFactory;
import android.graphics.Canvas;
import android.graphics.Paint;
import android.graphics.PorterDuff;
import android.graphics.PorterDuffXfermode;
import android.graphics.Rect;
import android.graphics.drawable.BitmapDrawable;
import android.graphics.drawable.Drawable;
import android.util.AttributeSet;
import android.view.View;

import com.example.administrator.circleview.R;

/**
 * Created by Administrator on 2016/12/27.
 */

public class CircleView extends View {
    private boolean isRound;
    Paint paint;

    public CircleView(Context context) {
       this(context,null);

    }

    public CircleView(Context context, AttributeSet attrs) {
        this(context, attrs,0);
    }

    public CircleView(Context context, AttributeSet attrs, int defStyleAttr) {
        super(context, attrs, defStyleAttr);
        paint = new Paint();
        TypedArray typedArray = context.obtainStyledAttributes(attrs, R.styleable.RoundImageView);
        isRound = typedArray.getBoolean(R.styleable.RoundImageView_is_round, true);
    }


    @Override

    protected void onMeasure(int widthMeasureSpec, int heightMeasureSpec) {
        super.onMeasure(widthMeasureSpec, heightMeasureSpec);
    }

    /**
     * 绘制圆形图片
     *
     * @author
     */
    @Override
    protected void onDraw(Canvas canvas) {
        Bitmap newBitmap = BitmapFactory.decodeResource(getResources(), R.mipmap.bg);
        Drawable drawable = new BitmapDrawable(newBitmap);
        // Drawable drawable = getDrawable();
        if (null != drawable) {
            Bitmap bitmap = ((BitmapDrawable) drawable).getBitmap();
            Bitmap b = getCircleBitmap(bitmap, 14);
            final Rect rectSrc = new Rect(0, 0, b.getWidth(), b.getHeight());
            final Rect rectDest = new Rect(0, 0, getWidth(), getHeight());
            paint.reset();
            canvas.drawBitmap(b, rectSrc, rectDest, paint);

        } else {
            super.onDraw(canvas);
        }
    }

    /**
     * 获取圆形图片方法
     *
     * @param bitmap
     * @param pixels
     * @return Bitmap
     * @author
     */
    private Bitmap getCircleBitmap(Bitmap bitmap, int pixels) {
        Bitmap output = Bitmap.createBitmap(bitmap.getWidth(),
                bitmap.getHeight(), Bitmap.Config.ARGB_8888);
        Canvas canvas = new Canvas(output);

        final int color = 0xff424242;

        final Rect rect = new Rect(0, 0, bitmap.getWidth(), bitmap.getHeight());
        paint.setAntiAlias(true);
        canvas.drawARGB(0, 0, 0, 0);
        paint.setColor(color);
        int x = bitmap.getWidth();
        int r = bitmap.getWidth() < bitmap.getHeight() ? bitmap.getWidth() /2: bitmap.getHeight()/2;
        canvas.drawCircle(x / 2, bitmap.getHeight() / 2, r/2 , paint);
        paint.setXfermode(new PorterDuffXfermode(PorterDuff.Mode.SRC_IN));
        canvas.drawBitmap(bitmap, rect, rect, paint);
        return output;

    }

}
效果图：
          
总结：
1.获取图片
2.将图片裁剪
3.在OnDraw（）中显示