在qt中获取标签的鼠标单击位置

问题描述

我搜索了一下，发现 QLabel 继承并重新实现mousepressed事件？我猜这将是这样的：

  class CustomLabel：public QLabel 
 {
 public ：
 //构造函数怎么样？ 
 void mousePressEvent（QMouseEvent * ev）; 
} 
 
 void CustomLabel :: mousePressEvent（QMouseEvent * ev）
 {
 QPoint = ev-> pos 
 //我想有另一个函数获取事件位置。 
 //我该如何实现呢？这是无效的！ 
 //有可能有一些方法来设置一个信号和槽位的位置？ 
} 
  

在我成功创建了 CustomLabel 类，我如何能够把它放在设计视图中？

解决方案

您的 CustomLabel 类上的信号，并且您的覆盖版本 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础 QLabel 的构造函数，因此简单地将它们的参数直接传递给相应的基础构造函数。 / p>


I googled around and found this forum thread in which the OP seems to have had the exact problem I am having. The question is, how would I inherit from QLabel and reimplement the mousepressed event? I'm guessing it would be something like this:

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?
}

And after I have successfully created a CustomLabel class, how would I be able to put it in design view?

解决方案

Yes, you can set up a signal on your CustomLabel class and have your overridden version of mousePressEvent emit it. i.e.

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 ) {}

The constructors just mimic those of the base QLabel and therefore simply pass their arguments straight on to the corresponding base constructors.

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