自定义view imageviw

新建一个类继承imageview

package com.exaple.myselfview;

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.PorterDuffXfermode;
import android.graphics.Rect;
import android.graphics.drawable.BitmapDrawable;
import android.graphics.drawable.Drawable;
import android.util.AttributeSet;
import android.view.View;
import android.widget.ImageView;

public class MyView extends ImageView {

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

	public MyView(Context context) {
		super(context);
		// TODO Auto-generated constructor stub
	}

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

	@Override
	protected void onDraw(Canvas canvas) {
		// TODO Auto-generated method stub
		Drawable drawable = getDrawable();

		if (drawable == null) {

			return;

		}

		if (getWidth() == 0 || getHeight() == 0) {

			return;

		}

		Bitmap b = ((BitmapDrawable) drawable).getBitmap();

		if (null == b)

		{

			return;

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

		// //获取图片的宽 高

		int w = getWidth(), h = getHeight();

		// 通过getCroppedBitmap函数，返回一个圆形图片

		Bitmap roundBitmap = getCroppedBitmap(bitmap, w);

		// 在自定义的CircleImageEx上展现

		canvas.drawBitmap(roundBitmap, 0, 0, null);
		/* super.onDraw(canvas); */

	}

	public static Bitmap getCroppedBitmap(Bitmap bmp, int radius) {
		Bitmap p;
		// 判断图片的大小与传入radius是否相等，如果不相等，那么

		// 将图片设置成长 宽都是radius的图片

		if (bmp.getWidth() != radius || bmp.getHeight() != radius)

			p = Bitmap.createScaledBitmap(bmp, radius, radius, false);

		else

			p = bmp;

		// 最后输出的图片信息

		Bitmap output = Bitmap.createBitmap(p.getWidth(),

		p.getHeight(), Config.ARGB_8888);

		Canvas canvas = new Canvas(output);

		final int color = 0xffa19774;

		final Paint paint = new Paint();

		final Rect rect = new Rect(0, 0, p.getWidth(), p.getHeight());

		// 画笔加上 抗锯齿标志，图像更加平滑

		paint.setAntiAlias(true);

		// 如果该项设置为true,则图像在动画进行中会滤掉对Bitmap图像的优化操作,加快显示

		paint.setFilterBitmap(true);

		// 防抖动

		paint.setDither(true);

		// 透明色

		canvas.drawARGB(0, 0, 0, 0);

		// 画笔的颜色

		paint.setColor(Color.parseColor("#BAB399"));

		// 画出一个圆形

		canvas.drawCircle(p.getWidth() / 2, p.getHeight() / 2,

		p.getWidth() / 2 + 0.1f, paint);

		// 设置两张图片相交时的模式 ，就是在画布上遮上圆形的图片信息

		paint.setXfermode(new PorterDuffXfermode(
				android.graphics.PorterDuff.Mode.SRC_IN));

		canvas.drawBitmap(p, rect, rect, paint);

		return output;

	}

}

　　在xml中一定要src而不是background