c++ - 在qt中获取标签的鼠标点击位置

Question

我用谷歌搜索并找到了 this forum thread其中OP似乎遇到了我遇到的确切问题。问题是，我如何从 QLabel 继承并重新实现 mousepressed 事件？我猜它会是这样的:

class CustomLabel : public QLabel
{
public:
    //what about the constructors?
    void mousePressEvent ( QMouseEvent * ev );
}

void CustomLabel::mousePressEvent ( QMouseEvent * ev )
{
    QPoint = ev->pos();
    //I want to have another function get the event position.
    //How would I achieve this? It's void!
    //Is there perhaps some way to set up a signal and slot with the position?
}

在我成功创建了一个 CustomLabel 类之后，我如何才能将它放入设计 View 中？

Answer 1

是的，您可以在您的 CustomLabel 类上设置一个信号，并让您的覆盖版本的 mousePressEvent 发出它。即

class CustomLabel : public QLabel
{
Q_OBJECT
signals:
    void mousePressed( const QPoint& );

public:
    CustomLabel( QWidget* parent = 0, Qt::WindowFlags f = 0 );
    CustomLabel( const QString& text, QWidget* parent = 0, Qt::WindowFlags f = 0 );

    void mousePressEvent( QMouseEvent* ev );
};

void CustomLabel::mousePressEvent( QMouseEvent* ev )
{
    const QPoint p = ev->pos();
    emit mousePressed( p );
}

CustomLabel::CustomLabel( QWidget * parent, Qt::WindowFlags f )
    : QLabel( parent, f ) {}

CustomLabel::CustomLabel( const QString& text, QWidget* parent, Qt::WindowFlags f )
    : QLabel( text, parent, f ) {}

构造函数只是模仿基本 QLabel 的构造函数，因此只需将它们的参数直接传递给相应的基本构造函数。