起因

    QTabWidget預設的tabBar在最上端。

改進

    但有時需要將tabBar放置在左側，但是設定後效果如下…

最終

    有時候需要如下效果，則需要自定義style：

附相應程式碼（具體邊框可通過stylesheet進行設定）

#include "mainwindow.h"
#include "ui_mainwindow.h"

#include <QPainter>
#include <QProxyStyle>

class CustomTabStyle : public QProxyStyle
{
public
 
:
    QSize sizeFromContents(ContentsType type, const QStyleOption *option,
        const QSize &size, const QWidget *widget) const
    {
        QSize s = QProxyStyle::sizeFromContents(type, option, size, widget);
        if (type == QStyle::CT_TabBarTab) {
            s.transpose();
            s.rwidth() = 90
 
; // 設定每個tabBar中item的大小
            s.rheight() = 44;
        }
        return s;
    }

    void drawControl(ControlElement element, const QStyleOption *option, QPainter *painter, const QWidget *widget) const
    {
        if (element == CE_TabBarTabLabel) {
            if (const QStyleOptionTab *tab = qstyleoption_cast<const
 
 QStyleOptionTab *>(option)) {
                QRect allRect = tab->rect;

                if (tab->state & QStyle::State_Selected) {
                    painter->save();
                    painter->setPen(0x89cfff);
                    painter->setBrush(QBrush(0x89cfff));
                    painter->drawRect(allRect.adjusted(6, 6, -6, -6));
                    painter->restore();
                }
                QTextOption option;
                option.setAlignment(Qt::AlignCenter);
                if (tab->state & QStyle::State_Selected) {
                    painter->setPen(0xf8fcff);
                }
                else {
                    painter->setPen(0x5d5d5d);
                }

                painter->drawText(allRect, tab->text, option);
                return;
            }
        }

        if (element == CE_TabBarTab) {
            QProxyStyle::drawControl(element, option, painter, widget);
        }
    }
};

MainWindow::MainWindow(QWidget *parent) :
    QMainWindow(parent),
    ui(new Ui::MainWindow)
{
    ui->setupUi(this);
    ui->tabWidget->setTabPosition(QTabWidget::West);
    ui->tabWidget->tabBar()->setStyle(new CustomTabStyle);

#if 0
    ui->tabWidget->setStyleSheet("QTabWidget::pane{ \
            border-left: 1px solid #eeeeee;\
        }");
#endif
}

MainWindow::~MainWindow()
{
    delete ui;
}