自定义图文并茂的Button

anroid内置了Button和ImageButton，但是没有提供既能显示图片又能显示文字的button。 
这里我自定义了一个ImageTextButton 
其中了XML文件中使用了自定义属性custom:icon="@drawable/icon" 
下面是ImageTextButton源码： 

import Android.content.Context;
import android.graphics.Bitmap;
import android.graphics.BitmapFactory;
import android.graphics.Canvas;
import android.util.AttributeSet;
import android.widget.Button;

public class ImageTextButton extends Button {
    private final String namespace =  "http://www.javaeye.com/custom";
    private int resourceId =0;
    private Bitmap bitmap;
    public ImageTextButton(Context context, AttributeSet attrs) {
        super(context, attrs);
        // TODO Auto-generated constructor stub
        setClickable(true);
        //默认使用R.drawable.icon这张图片
        resourceId = attrs.getAttributeResourceValue(namespace, "icon", R.drawable.icon);
        bitmap = BitmapFactory.decodeResource(getResources(), resourceId);
    }
    @Override
    protected void onDraw(Canvas canvas) {
        // TODO Auto-generated method stub
        //图片顶部居中显示
        int x=(this.getMeasuredWidth()-bitmap.getWidth())>>1;
        int y=0;
        canvas.drawBitmap(bitmap, x, y, null);
        //坐标需要转换，因为默认情况下Button中的文字居中显示
        //这里需要让文字在底部显示
        canvas.translate(0, (this.getMeasuredHeight()>>1)-(int)this.getTextSize());

        super.onDraw(canvas);
    }

    public void setIcon(Bitmap bitmap){
        this.bitmap=bitmap;
                invalidate();
    }
    public void setIcon(int resourceId){
        this.bitmap=BitmapFactory.decodeResource(getResources(), resourceId);
                invalidate();
    }
}

<?xml version="1.0" encoding="utf-8"?>
<LinearLayout xmlns:android="http://schemas.android.com/apk/res/android"
    xmlns:custom="http://www.javaeye.com/custom"
    android:orientation="vertical"
    android:layout_width="fill_parent"
    android:layout_height="fill_parent"
    >

    <com.wt.app.ImageTextButton
    android:text="OK"
    custom:icon="@drawable/icon"
    android:id="@+id/button_0"
    android:layout_width="80dip"
    android:layout_height="80dip"
    />
    <com.wt.app.ImageTextButton
    android:text="OK"
    custom:icon="@drawable/icon"
    android:id="@+id/button_1"
    android:layout_width="80dip"
    android:layout_height="100dip"
    android:textSize="30dip"
    android:textColor="#ff0000"
    />

    <com.wt.app.ImageTextButton
    android:text="OK"
    custom:icon="@drawable/icon"
    android:id="@+id/button_2"
    android:layout_width="200dip"
    android:layout_height="200dip"
    android:textSize="30dip"
    />

</LinearLayout>