自定义imageView圆形

package com.bwie.view;

import android.content.Context;
import android.graphics.Bitmap;
import android.graphics.Bitmap.Config;
import android.graphics.Canvas;
import android.graphics.Color;
import android.graphics.Paint;
import android.graphics.PorterDuff.Mode;
import android.graphics.PorterDuffXfermode;
import android.graphics.Rect;
import android.graphics.drawable.BitmapDrawable;
import android.graphics.drawable.Drawable;
import android.util.AttributeSet;
import android.widget.ImageView;

public class RoundImageView extends ImageView{

    public RoundImageView(Context context, AttributeSet attrs, int defStyle) {
        super(context, attrs, defStyle);
        // TODO Auto-generated constructor stub
    }

    public RoundImageView(Context context, AttributeSet attrs) {
        super(context, attrs);
        // TODO Auto-generated constructor stub
    }

    public RoundImageView(Context context) {
        super(context);
        // TODO Auto-generated constructor stub
    }
    
    @Override
    protected void onDraw(Canvas canvas) {
         Drawable drawable = getDrawable();

            //空值判断，必要步骤，避免由于没有设置src导致的异常错误
            if (drawable == null) {
                return;
            }

            //必要步骤，避免由于初始化之前导致的异常错误
            if (getWidth() == 0 || getHeight() == 0) {
                return;
            }

            if (!(drawable instanceof BitmapDrawable)) {
                return;
            }
            Bitmap b = ((BitmapDrawable) drawable).getBitmap();

            if (null == b) {
                return;
            }

            Bitmap bitmap = b.copy(Bitmap.Config.ARGB_8888, true);

            int w = getWidth();

            Bitmap roundBitmap = getCroppedBitmap(bitmap, w);
            canvas.drawBitmap(roundBitmap, 3.0f, 5.0f, null);
        
    
    }
    
     /**
     * 初始Bitmap对象的缩放裁剪过程
     * @param bmp        初始Bitmap对象
     * @param radius    圆形图片直径大小
     * @return 返回一个圆形的缩放裁剪过后的Bitmap对象
     */
    public static Bitmap getCroppedBitmap(Bitmap bmp, int radius) {
        Bitmap sbmp;
        //比较初始Bitmap宽高和给定的圆形直径，判断是否需要缩放裁剪Bitmap对象
        if (bmp.getWidth() != radius || bmp.getHeight() != radius)
            sbmp = Bitmap.createScaledBitmap(bmp, radius, radius, false);
        else
            sbmp = bmp;
        Bitmap output = Bitmap.createBitmap(sbmp.getWidth(), sbmp.getHeight(),
                Config.ARGB_8888);
        Canvas canvas = new Canvas(output);

        final Paint paint = new Paint();
        final Rect rect = new Rect(0, 0, sbmp.getWidth(), sbmp.getHeight());

        paint.setAntiAlias(true);
        paint.setFilterBitmap(true);
        paint.setDither(true);
        canvas.drawARGB(0, 0, 0, 0);
        paint.setColor(Color.parseColor("#BAB399"));
        canvas.drawCircle(sbmp.getWidth() / 2 + 0.7f,
                sbmp.getHeight() / 2 + 0.7f, sbmp.getWidth() / 2 + 0.1f, paint);
        //核心部分，设置两张图片的相交模式，在这里就是上面绘制的Circle和下面绘制的Bitmap
        paint.setXfermode(new PorterDuffXfermode(Mode.SRC_IN));
        canvas.drawBitmap(sbmp, rect, rect, paint);

        return output;
    }

}