应用BitmapShader实现平铺的画布背景和椭圆形的图片

1、布局文件

<?xml version="1.0" encoding="utf-8"?>
<FrameLayout xmlns:android="http://schemas.android.com/apk/res/android"
    android:id="@+id/frameLayout1"
    android:layout_width="fill_parent"
    android:layout_height="fill_parent"
    android:orientation="vertical" >
   
</FrameLayout>

2、MainActivity

public class MainActivity extends Activity {
	
	private int view_width;
	private int view_height;

    @Override
    protected void onCreate(Bundle savedInstanceState) {
        super.onCreate(savedInstanceState);
        setContentView(R.layout.activity_main);
        FrameLayout ll = (FrameLayout)findViewById(R.id.frameLayout1);
        ll.addView(new MyView(this));
    }
    public class MyView extends View{
		public MyView(Context context) {
			super(context);
			view_width = context.getResources().getDisplayMetrics().widthPixels; 		// 获取屏幕的宽度
			view_height = context.getResources().getDisplayMetrics().heightPixels;		// 获取屏幕的高度
		}
		@Override
		protected void onDraw(Canvas canvas) {
			Paint paint = new Paint();//定义一个画笔
			paint.setAntiAlias(true);//使用抗锯齿功能
			Bitmap bitmap_bg = BitmapFactory.decodeResource(MainActivity.this.getResources(),
					R.drawable.android);
			//创建一个在水平和垂直方向都重复的BitmapShader对象
			BitmapShader bitmapshader = new BitmapShader(bitmap_bg, TileMode.REPEAT, TileMode.REPEAT);
			paint.setShader(bitmapshader);//设置渲染对象
			canvas.drawRect(0, 0, view_width, view_height, paint);//绘制一个使用BitmapShader渲染的矩形
			Bitmap bm = BitmapFactory.decodeResource(MainActivity.this.getResources(),
					R.drawable.img02);
			//创建一个在水平方向上重复，在垂直方向上镜像的BitmapShader对象
			BitmapShader bs = new BitmapShader(bm, TileMode.REPEAT, TileMode.MIRROR);
			paint.setShader(bs);//设置渲染对象
			RectF oval = new RectF(0, 0, 280, 180);
			canvas.translate(40, 20);//将画面在X轴上平移40像素，在Y轴上平移20像素
			canvas.drawOval(oval, paint);//绘制一个使用BitmapShader渲染的椭圆形
			super.onDraw(canvas);
		}
    }
}