QTabWidget的每个tab居中显示图标和文本

使用QTabWidget，给每个tab添加了图标之后，文字和图标之间有间距，没有完美居中显示。

遇到此问题，尝试了多种办法，均不理想，最终自定义QTabBar，重绘tab，完美解决。

#include <QTabBar>
#include <QStylePainter>

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

protected:
    void paintEvent(QPaintEvent *) override
    {
        QStylePainter painter(this);
        for (int index = 0; index < this->count(); ++index) {
            QStyleOptionTab opt;
            initStyleOption(&opt, index);
            
            // 计算图标和文字的长度（含间距）
            int iconTextWidth = opt.iconSize.width()
                              + opt.fontMetrics.horizontalAdvance(opt.text)
                              + 4; // 4 是图标和文字的间距

            int x = (opt.rect.width() - iconTextWidth) / 2 + opt.rect.width() * index;

            painter.save();
            
            // 指定各状态下的按钮状态
            if (opt.state & QStyle::State_Selected) { // 按下状态
                painter.setPen(QColor(255, 255, 255));
                painter.fillRect(rect, QColor(31, 68, 133));
            } else if (opt.state & QStyle::State_MouseOver) { // 鼠标停留状态
                painter.setPen(QColor(255, 255, 255));
                painter.fillRect(rect, QColor(33, 72, 141));
            } else if (!(opt.state & QStyle::State_Enabled)) { // 禁止状态
                painter.setPen(QColor(255, 255, 255, 153));
                painter.fillRect(rect, QColor(84, 123, 192));
            } else { // 正常状态（默认）
                painter.setPen(QColor(255, 255, 255));
                painter.fillRect(rect, QColor(41, 90, 176));
            }

            QRect iconRect(x, (opt.rect.height() - opt.iconSize.height()) / 2,
                           opt.iconSize.width(), opt.iconSize.height());
            painter.drawPixmap(iconRect, opt.icon.pixmap(opt.iconSize));

            QRect textRect(iconRect.right() + 4, 0,
                           opt.rect.width() * (index + 1) - iconRect.right() - 4,
                           opt.rect.height());
            painter.drawText(textRect, Qt::AlignVCenter | Qt::AlignLeft, opt.text);
            painter.restore();
        }
    }
};

调用：

ui->tabWidget->setTabBar(new MyTabBar(this));