Qt中存在StyleSheet时，如何通过Qt::BackgroundRole修改QTableView项背景色

I’ve run into this exact headache before — once you define QTableView::item styles (even just border properties), Qt switches to style sheet-based item painting, which ignores the Qt::BackgroundRole values returned by your model by default. Here’s how to fix it while keeping your shared styles and per-view customization:

Why This Happens #

Qt’s style sheet system takes priority over model-provided roles when you style QTableView::item. The default delegate stops using the model’s background color because the style sheet dictates how the item should be drawn, including its background layer.

Solution 1: Adjust the Target View’s QSS to Respect Model Background #

For your #SecondView that needs custom background colors from the model, update its item style to make the background transparent (so the model’s background shows through) while keeping any other styles you need. Also, restrict the border style to only your standard tables using a specific object name:

/*------------------------------------------*/
/*default*/
QTableView {
    border: 1px solid #cccccc;
    background: #f3f3f3;
    color: #252424;
    font-family: "Segoe UI";
    outline: 0;
}
/* Apply border only to standard tables (give them objectName="DefaultTableView") */
QTableView#DefaultTableView::item {
    border-bottom: 1px solid #cccccc;
}
/*------------------------------------------*/
/*second view*/
QTableView#SecondView {
    background: #99dd99;
    border: 1px solid #cccccc;
    color: #252424;
    font-family: "Segoe UI";
    outline: 0;
}
QTableView#SecondView::item {
    border: none; /* Or your desired border style */
    background-color: transparent; /* Let model's background color show through */
}

This way, only your standard tables get the border style, and #SecondView avoids the style that overrides the model’s background.

Solution 2: Force Delegate to Draw Model Background (If QSS Adjustment Isn’t Enough) #

If adjusting the QSS doesn’t work, create a custom delegate for #SecondView that explicitly draws the model’s background before applying style sheet styles:

class CustomBackgroundDelegate : public QStyledItemDelegate {
protected:
    void paint(QPainter* painter, const QStyleOptionViewItem& option, const QModelIndex& index) const override {
        // First draw the model's background color
        QColor bgColor = index.data(Qt::BackgroundRole).value<QColor>();
        if (bgColor.isValid()) {
            painter->fillRect(option.rect, bgColor);
        }
        // Then let the style sheet handle the rest (border, text, etc.)
        QStyledItemDelegate::paint(painter, option, index);
    }
};

Set this delegate on your second table view:

m_p_table_view2->setItemDelegate(new CustomBackgroundDelegate(m_p_table_view2));

Quick Fix for Your Model Code #

Double-check your data method — the default case doesn’t return a value, which could cause unexpected behavior. Return the default background color to cover all cases:

QVariant MyProxyModel::data(const QModelIndex &in_index, int in_role) const {
    if(Qt::BackgroundRole == in_role) {
        int tmp = QStandardItemModel::data(in_index, Qt::DisplayRole).toInt();
        switch (tmp) {
        case 1:
            return QVariant(QColor(0xBB, 0xFF, 0x99));
        // Add other case logic here...
        default:
            return QStandardItemModel::data(in_index, in_role); // Return default background
        }
    }
    return QStandardItemModel::data(in_index, in_role);
}

These changes should resolve the conflict between your style sheet and model-provided background colors.

内容的提问来源于stack exchange，提问作者M. XX.