Android 中的片段与自定义视图

Android中的片段与自定义视图

java
public class MainActivity extends AppCompatActivity {
    @Override
    protected void onCreate(Bundle savedInstanceState) {
        super.onCreate(savedInstanceState);
        setContentView(R.layout.activity_main);
        // 创建一个片段实例
        MyFragment fragment = new MyFragment();
        // 获取FragmentManager
        FragmentManager fragmentManager = getSupportFragmentManager();
        // 开启一个事务
        FragmentTransaction fragmentTransaction = fragmentManager.beginTransaction();
        // 将片段添加到容器中
        fragmentTransaction.add(R.id.fragment_container, fragment);
        // 提交事务
        fragmentTransaction.commit();
    }
}

java
public class CircleButton extends View {
    private Paint mPaint;
    public CircleButton(Context context) {
        super(context);
        init();
    }
    public CircleButton(Context context, @Nullable AttributeSet attrs) {
        super(context, attrs);
        init();
    }
    private void init() {
        mPaint = new Paint();
        mPaint.setColor(Color.RED);
        mPaint.setAntiAlias(true);
    }
    @Override
    protected void onDraw(Canvas canvas) {
        int centerX = getWidth() / 2;
        int centerY = getHeight() / 2;
        int radius = Math.min(centerX, centerY);
        canvas.drawCircle(centerX, centerY, radius, mPaint);
    }
}