看到很多人开发过程中要使用圆角图片时，解决方法有：

1.重新绘制一张图片

2.通过布局来配置

3.通过重写View来实现

其中1，2在这里就不讲了，重点讲讲方法三的实现。

实现一：通过截取画布一个圆形区域与图片的相交部分进行绘制，缺点：锯齿明显，设置Paint,Canvas抗锯齿无效。

package com.open.circleimageview.widget;

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.view.View;

public class CircleImageViewA extends View {

	public CircleImageViewA(Context context, AttributeSet attrs, int defStyle) {

		super(context, attrs, defStyle);

	}

	public CircleImageViewA(Context context, AttributeSet attrs) {

		super(context, attrs);

	}

	public CircleImageViewA(Context context) {

		super(context);

	}

	private Bitmap bitmap;

	private Rect bitmapRect=new Rect();

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

	private Paint paint = new Paint();

    {

	    paint.setStyle(Paint.Style.STROKE);

	    paint.setFlags(Paint.ANTI_ALIAS_FLAG);

	    paint.setAntiAlias(true);// 设置画笔的锯齿效果。 true是去除，大家一看效果就明白了

    }

    private Path mPath=new Path();

	public void setImageBitmap(Bitmap bitmap)

	{

		this.bitmap=bitmap;

	}

	@Override

	protected void onDraw(Canvas canvas) {

		if(null==bitmap)

		{

			return;

		}

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

        canvas.save();

        canvas.setDrawFilter(pdf);

        mPath.reset();

        canvas.clipPath(mPath); // makes the clip empty

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

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

        canvas.drawBitmap(bitmap, null, bitmapRect, paint);

        canvas.restore();

	}

}

实现二：通过PorterDuffXfermode 方式（注意要设置硬件加速，否则部分机子无效），优点：锯齿基本没有

package com.open.circleimageview.widget;

import android.content.Context;

import android.graphics.Bitmap;

import android.graphics.Canvas;

import android.graphics.Color;

import android.graphics.Paint;

import android.graphics.PaintFlagsDrawFilter;

import android.graphics.PorterDuff;

import android.graphics.PorterDuffXfermode;

import android.graphics.Rect;

import android.graphics.RectF;

import android.util.AttributeSet;

import android.view.View;

public class CircleImageViewB extends View {

	public CircleImageViewB(Context context, AttributeSet attrs, int defStyle) {

		super(context, attrs, defStyle);

		init();

	}

	public CircleImageViewB(Context context, AttributeSet attrs) {

		super(context, attrs);

		init();

	}

	public CircleImageViewB(Context context) {

		super(context);

		init();

	}

	private Bitmap bitmap;

	private Rect bitmapRect=new Rect();

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

	private Paint paint = new Paint();

    {

	    paint.setStyle(Paint.Style.STROKE);

	    paint.setFlags(Paint.ANTI_ALIAS_FLAG);

	    paint.setAntiAlias(true);// 设置画笔的锯齿效果。 true是去除，大家一看效果就明白了

    }

    private Bitmap mDstB=null;

    private PorterDuffXfermode xfermode=new PorterDuffXfermode(PorterDuff.Mode.MULTIPLY);

    private void init()

    {

    	try {

			if(android.os.Build.VERSION.SDK_INT>=11)

			{

				setLayerType(LAYER_TYPE_SOFTWARE, null);

			}

		} catch (Exception e) {

			e.printStackTrace();

		}

    }

	public void setImageBitmap(Bitmap bitmap)

	{

		this.bitmap=bitmap;

	}

	private Bitmap makeDst(int w, int h)

    {

        Bitmap bm = Bitmap.createBitmap(w, h, Bitmap.Config.ARGB_8888);

        Canvas c = new Canvas(bm);

        Paint p = new Paint(Paint.ANTI_ALIAS_FLAG);

        p.setColor(Color.parseColor("#ffffffff"));

        c.drawOval(new RectF(0, 0, w, h), p);

        return bm;

    }

	@Override

	protected void onDraw(Canvas canvas) {

		if(null==bitmap)

		{

			return;

		}

		if(null==mDstB)

		{

			mDstB=makeDst(getWidth(), getHeight());

		}

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

        canvas.save();

        canvas.setDrawFilter(pdf);

        canvas.drawBitmap(mDstB, 0, 0, paint);

        paint.setXfermode(xfermode);

        canvas.drawBitmap(bitmap, null, bitmapRect, paint);

        paint.setXfermode(null);

        canvas.restore();

	}

}

效果图如下：

代码地址：http://download.csdn.net/detail/zz7zz7zz/6240225