试图在矩形内绘制文本，但在android中却在矩形上方绘制文本

public class MyTextView extends View {
    private Paint mPaint;

    public MyTextView(Context context) {
        super(context);
        init();
    }

    public MyTextView(Context context, @Nullable AttributeSet attrs) {
        super(context, attrs);
        init();
    }

    private void init() {
        mPaint = new Paint();
        mPaint.setTextAlign(Paint.Align.CENTER);
        mPaint.setTextSize(30);
        mPaint.setColor(Color.BLACK);
    }

    @Override
    protected void onDraw(Canvas canvas) {
        super.onDraw(canvas);
        
        String text = "Hello, World!";
        int x = getWidth() / 2;
        int y = getHeight() / 2;
        
        canvas.drawText(text, x, y, mPaint);
    }
}