Paint类（画笔）

线性渐变、径向渐变和角度渐变的画笔

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 {

	@Override
	public 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);
		}

		@Override
		protected void onDraw(Canvas canvas) {
			Paint paint = new Paint(); // 定义一个默认的画笔
			// 线性渐变
			Shader shader = new LinearGradient(0, 0, 50, 50, Color.RED,
					Color.GREEN, Shader.TileMode.MIRROR);
			paint.setShader(shader); // 为画笔设置渐变器
			canvas.drawRect(10, 70, 100, 150, paint); // 绘制矩形
			// 径向渐变
			shader = new RadialGradient(160, 110, 50, Color.RED, Color.GREEN,
					Shader.TileMode.MIRROR);
			paint.setShader(shader); // 为画笔设置渐变器
			canvas.drawRect(115, 70, 205, 150, paint); // 绘制矩形
			// 角度渐变
			shader = new SweepGradient(265, 110, new int[] { Color.RED,
					Color.GREEN, Color.BLUE }, null);
			paint.setShader(shader);
			canvas.drawRect(220, 70, 310, 150, paint); // 绘制矩形

			super.onDraw(canvas);
		}

	}
}