Qt缩放的QPixmap超出范围时不调整窗口大小

#include <QtWidgets>

int main(int argc, char *argv[])
{
    QApplication app(argc, argv);

    QWidget window;
    QVBoxLayout *layout = new QVBoxLayout(&window);

    QLabel *label = new QLabel(&window);
    layout->addWidget(label);

    QPixmap pixmap("image.png");  // 加载图像文件或创建QPixmap对象
    QPixmap scaledPixmap = pixmap.scaled(label->size(), Qt::KeepAspectRatio);  // 缩放QPixmap

    label->setPixmap(scaledPixmap);  // 设置QLabel的图像

    window.show();

    return app.exec();
}

#include <QtWidgets>

class CustomWidget : public QWidget
{
public:
    CustomWidget(QWidget *parent = nullptr) : QWidget(parent) {}

protected:
    void paintEvent(QPaintEvent *event) override
    {
        QPainter painter(this);

        QPixmap pixmap("image.png");  // 加载图像文件或创建QPixmap对象
        QPixmap scaledPixmap = pixmap.scaled(size(), Qt::KeepAspectRatio);  // 缩放QPixmap

        painter.drawPixmap(rect(), scaledPixmap);  // 绘制QPixmap
    }
};

int main(int argc, char *argv[])
{
    QApplication app(argc, argv);

    CustomWidget window;
    window.show();

    return app.exec();
}