qt - Qt：QTreeView：标题上的中心图标

Question

对于来自 QTreeView 小部件的某些列，我使用了一个图标。图标设置为

QVariant headerData (int section, Qt::Orientation orientation, int role) const{
    if(role ==  Qt::DecorationRole)
    {
        QIcon icon;
        if (section == 0) {
            icon.addFile(":/icon1");
        } else if (section == 1){
            icon.addFile(":/icon2");
        }
    }

    if(role ==  Qt::TextAlignmentRole)
    {
        return (Qt::AlignLeft + Qt::AlignVCenter);
    }

标题如下所示：

我想将图标与文本对齐。TextAlignmentRole 仅适用于文本，但不适用于图标。我怎样才能做到这一点？

我还尝试通过设置默认对齐方式：

m_treeview->header()->setDefaultAlignment(Qt::AlignCenter);但没有运气。

Answer 1

为了使图标与文本居中，您必须实现自己的代理样式来创建这种特定的样式行为。

#include <QProxyStyle>
#include <QPainter>

class HeaderProxyStyle : public QProxyStyle
{
public:
    void drawControl(ControlElement oCtrElement, const QStyleOption * poStylrOptionption, QPainter * poPainter, const QWidget * poWidget = 0) const;

};

带有文本实现的中心图标

    void HeaderProxyStyle::drawControl(ControlElement oCtrElement, const QStyleOption *poStylrOptionption, QPainter *poPainter, const QWidget *poWidget) const
    {
        // Header label?
        if (oCtrElement == CE_HeaderLabel) {
            // YES - Allocate style option header
            QStyleOptionHeader *poStyleOptionHeader =
                    (QStyleOptionHeader *) poStylrOptionption;

            // Get header icon
            QIcon oIcon = qvariant_cast<QIcon>(poStyleOptionHeader->icon);

            // Icon is valid?
            if(oIcon.isNull()){
                // No - Draw text header
                QProxyStyle::drawControl(oCtrElement, poStylrOptionption, poPainter, poWidget);
                return;
            }

            // Set icon size 16x16
            QSize oIconSize = QSize(16,16);

            // Get header section rect
            QRect oRect = poStyleOptionHeader->rect;

            // Create header icon pixmap
            QPixmap oIconPixmap = oIcon.pixmap(oIconSize.width(),oIconSize.height());

            // Calculate header text width
            int iTextWidth = poStyleOptionHeader->fontMetrics.width(poStyleOptionHeader->text);

            QRect oCenterRec = QRect(oRect.left(),
                                    oRect.top() + (oRect.height - iTextSize)/2,
                                    oIconPixmap.width(),oIconPixmap.height());


            QRect oTextRect = QRect(oCenterRec.left()+ oIconSize.width(),
                              oCenterRec.top(), oCenterRec.width() + iTextWidth, oCenterRec.height());
            // Draw icon
            poPainter->drawPixmap(oCenterRec, oIconPixmap);
            // Draw text
            poPainter->drawText(oTextRect, poStyleOptionHeader->text);
            return;
        }
        QProxyStyle::drawControl(oCtrElement, poStylrOptionption, poPainter, poWidget);

    }

然后在树视图中应用此标题样式

// Set header style
m_treeview->header()->setStyle(&m_oHeaderStyle);