QToolTip

1.文本自动折行显示

// 只处理字符串,在合适的位置插入\n或者 <br/>
QString Widget::dealText(const QString& org)
{
    QString result;
    QFontMetrics fm(fontMetrics());
    int textWidthInPxs = fm.horizontalAdvance(org);  // 获取文本宽度(若Qt5.7则使用width)
    const int rear = org.length();
    int pre = 0, vernier = 1;
    int pickUpWidthPxs = 0;
    QString pickUp;
    unsigned int curLen = 0;
    if (textWidthInPxs <= ui->label->width()) {
        result = org;
        return result;
    }
    while (vernier <= rear) {
        curLen = vernier - pre;
        pickUp = org.mid(pre, curLen);
        pickUpWidthPxs = fm.horizontalAdvance(pickUp);
        if (pickUpWidthPxs >= ui->label->width()) {
            result += pickUp + "\n"; // 插入换行符，或者使用<br/>标签
            pre = vernier;
            pickUpWidthPxs = 0;
        }
        ++vernier;
    }
    if (pickUpWidthPxs < ui->label->width() && !pickUp.isEmpty()) {
        result += pickUp;
    }
    return result;
}

2.使用

常规的使用

QWidget::setToolTip();
// 例如
ui->label->setToolTip("abc");

高级用法

// 使用类型的 QEvent::ToolTip的QHelpEvent事件(注意ignore使用)
bool SortingBox::event(QEvent *event) 
{ 
    if (event->type() == QEvent::ToolTip) { 
        QHelpEvent *helpEvent = static_cast<QHelpEvent *>(event); 
        if (xxxxxx) { 
            QToolTip::showText(helpEvent->globalPos(), "xxxxxxxxx"); 
        } else { 
            QToolTip::hideText(); 
            event->ignore(); 
        } 
        return true; 
    }
 return QWidget::event(event); 
}

立即显示 tooltip，就像上面用的，直接调用 showText()