Android 阴影，圆形的Button

MainActivity.java

package com.kale.gridlayout;

import android.app.Activity;
import android.graphics.Bitmap;
import android.graphics.drawable.BitmapDrawable;
import android.os.Bundle;
import android.widget.Button;

public class MainActivity extends Activity {

	@Override
	protected void onCreate(Bundle savedInstanceState) {
		super.onCreate(savedInstanceState);
		setContentView(R.layout.activity_main);
		
		Button bt = (Button)findViewById(R.id.button_id);
		Bitmap bitmap = CircleManager.getCircleBitmap(this, R.drawable.kale);
		bt.setBackgroundDrawable(new BitmapDrawable(bitmap));
	}
	
}

CircleManager.java

package com.kale.gridlayout;

import android.content.Context;
import android.graphics.Bitmap;
import android.graphics.BitmapFactory;
import android.graphics.Canvas;
import android.graphics.Paint;
import android.graphics.PorterDuffXfermode;
import android.graphics.Rect;
import android.graphics.RectF;
import android.graphics.Bitmap.Config;
import android.graphics.PorterDuff.Mode;

public class CircleManager {

	/**
	 * 转换图片成圆形
	 * Bitmap bitmap = CircleManager.getCircleBitmap(this, R.drawable.kale);
	 * 
	 *  ImageView ivImageView = (ImageView) findViewById(R.id.imageView1);
		ivImageView.setImageBitmap(bmBitmap);
	 * 	Button bt = (Button)findViewById(R.id.button_id);
		bt.setBackgroundDrawable(new BitmapDrawable(bitmap));
	 * @param bitmap
	 * 传入Bitmap对象
	 * @return
	 */
	public static Bitmap getCircleBitmap(Context context,int resId) {
		Bitmap bitmap = BitmapFactory.decodeResource(context.getResources(), resId);
		int width = bitmap.getWidth();
		int height = bitmap.getHeight();
		float roundPx;
		float left, top, right, bottom, dst_left, dst_top, dst_right, dst_bottom;
		if (width <= height) {
			roundPx = width / 2;
			left = 0;
			top = 0;
			right = width;
			bottom = width;
			height = width;

			dst_left = 0;
			dst_top = 0;
			dst_right = width;
			dst_bottom = width;
		} else {
			roundPx = height / 2;
			float clip = (width - height) / 2;

			left = clip;
			right = width - clip;
			top = 0;
			bottom = height;
			width = height;

			dst_left = 0;
			dst_top = 0;
			dst_right = height;
			dst_bottom = height;
		}

		Bitmap output = Bitmap.createBitmap(width, height, Config.ARGB_8888);
		Canvas canvas = new Canvas(output);

		final Paint paint = new Paint();
		final Rect src = new Rect((int) left, (int) top, (int) right, (int) bottom);
		final Rect dst = new Rect((int) dst_left, (int) dst_top, (int) dst_right, (int) dst_bottom);
		final RectF rectF = new RectF(dst);

		paint.setAntiAlias(true);// 设置画笔无锯齿

		canvas.drawARGB(0, 0, 0, 0); // 填充整个Canvas

		// 以下有两种方法画圆,drawRounRect和drawCircle
		canvas.drawRoundRect(rectF, roundPx, roundPx, paint);// 画圆角矩形，第一个参数为图形显示区域，第二个参数和第三个参数分别是水平圆角半径和垂直圆角半径。
		// canvas.drawCircle(roundPx, roundPx, roundPx, paint);

		paint.setXfermode(new PorterDuffXfermode(Mode.SRC_IN));// 设置两张图片相交时的模式,参考http://trylovecatch.iteye.com/blog/1189452
		canvas.drawBitmap(bitmap, src, dst, paint); // 以Mode.SRC_IN模式合并bitmap和已经draw了的Circle

		return output;
	}
}

circle.xml

<?xml version="1.0" encoding="utf-8"?>
<layer-list xmlns:android="http://schemas.android.com/apk/res/android" >
	<!-- outer circle -->
	<item>
		<shape android:shape="oval" >
			<solid android:color="#FFACB8C3" />
		</shape>
	</item>
	<!-- inner shadow of outer circle -->
	<item 
	    android:bottom="2dp"
	    android:left="2dp"
	    android:right="2dp"
	    android:top="2dp">
		<shape android:shape="oval">
		    <solid android:color="#FFbdcad6" />
		</shape>
	</item>
	<item
		android:bottom="3dp"
		android:left="3dp"
		android:right="3dp"
		android:top="3dp">
		<shape android:shape="oval">
			<solid android:color="#FFc3cfd9" />
		</shape>
	
	</item>
    <item
		android:bottom="4dp"
		android:left="4dp"
		android:right="4dp"
		android:top="4dp">
        <shape android:shape="oval">
            <solid android:color="#FFcbd6df" />
        </shape>
    </item>
    <item
		android:bottom="5dp"
		android:left="5dp"
		android:right="5dp"
		android:top="5dp">
        <shape android:shape="oval">
            <solid android:color="#FFd4dee5" />
        </shape>
    </item>
 
    <!-- gap -->
    <item
		android:bottom="6dp"
		android:left="6dp"
		android:right="6dp"
		android:top="6dp">
        <shape android:shape="oval" >
            <solid android:color="#FFdae2e8" />
        </shape>
    </item>
 
    <!-- outer shadow of center circle -->
    <item
		android:bottom="10dp"
		android:left="10dp"
		android:right="10dp"
		android:top="10dp">
        <shape android:shape="oval">
            <solid android:color="#FFced5dc" />
        </shape>
    </item>
    <item
		android:bottom="12dp"
		android:left="12dp"
		android:right="12dp"
		android:top="12dp">
        <shape android:shape="oval">
            <solid android:color="#FFbcc4c9" />
        </shape>
    </item>
    <item
		android:bottom="13dp"
		android:left="13dp"
		android:right="13dp"
		android:top="13dp">
        <shape android:shape="oval">
            <solid android:color="#FFb4bbc0" />
        </shape>
    </item>
    <item
		android:bottom="14dp"
		android:left="14dp"
		android:right="14dp"
		android:top="14dp">
        <shape android:shape="oval">
            <solid android:color="#FFacb3b8" />
        </shape>
    </item>
 
    <!-- center circle -->
    <item
		android:bottom="15dp"
		android:left="15dp"
		android:right="15dp"
		android:top="15dp">
        <shape android:shape="oval">
            <stroke android:width="1dp" android:color="#FFFCFCFC"/>
            <gradient
				android:angle="270"
				android:endColor="#FFCFD7DD"
				android:startColor="#FFF0F5F9" />
        </shape>
    </item>
 
</layer-list>

xml

<RelativeLayout xmlns:android="http://schemas.android.com/apk/res/android"
    xmlns:tools="http://schemas.android.com/tools"
    android:layout_width="match_parent"
    android:layout_height="match_parent"
    tools:context="${relativePackage}.${activityClass}" >

    <Button
        android:layout_width="match_parent"
        android:layout_height="wrap_content"
        android:shadowColor="#aa5"
        android:shadowDx="5"
        android:shadowDy="5"
        android:shadowRadius="1"
        android:textSize="25sp"
        android:text="shadow" />

    <Button
        android:id="@+id/button2"
        android:layout_width="300dp"
        android:layout_height="300dp"
        android:layout_centerHorizontal="true"
        android:layout_centerVertical="true"
        android:background="@drawable/circle"
        android:textSize="20sp" />

    <Button
        android:id="@+id/button_id"
        android:layout_width="200dp"
        android:layout_height="200dp"
        android:layout_alignBaseline="@+id/button2"
        android:layout_alignBottom="@+id/button2"
        android:layout_centerHorizontal="true" />

</RelativeLayout>