Android 通过onDraw实现在View中绘图操作的示例

public class AndroidTest extends Activity {
    /** Called when the activity is first created. */
    @Override
    public void onCreate(Bundle savedInstanceState) {
        super.onCreate(savedInstanceState);

        MyView mv = new MyView(this);
        setContentView(mv);
    }

    public class MyView extends View {
     MyView(Context context) {
      super(context);
     }

  @Override
  protected void onDraw(Canvas canvas) {
   // TODO Auto-generated method stub
   super.onDraw(canvas);

   // 首先定义一个paint
   Paint paint = new Paint();
   // 绘制矩形区域-实心矩形
   // 设置颜色
   paint.setColor(Color.BLUE);
   // 设置样式-填充
   paint.setStyle(Style.FILL);
   // 绘制一个矩形
   canvas.drawRect(new Rect(0, 0, getWidth(), getHeight()), paint);
   // 绘空心矩形
   // 设置颜色
   paint.setColor(Color.RED);
   // 设置样式-空心矩形
   paint.setStyle(Style.STROKE);
   // 绘制一个矩形
   canvas.drawRect(new Rect(10, 10, 100, 30), paint);
   // 绘文字
   // 设置颜色
   paint.setColor(Color.GREEN);
   // 绘文字
   canvas.drawText("Hello", 10, 50, paint);
   // 绘图
   // 从资源文件中生成位图
   Bitmap bitmap = BitmapFactory.decodeResource(getResources(), R.drawable.icon);
   // 绘图
   canvas.drawBitmap(bitmap, 10, 60, paint);
  }

    }
}