Question

我正在创建一个QLabel子类，它将DoubleClickEvent添加到它。我创建了以下内容，但是我遇到了一些奇怪的链接器错误，也许有人可以指出我做错了什么？

//Header
#ifndef IMAGE_LABEL_H
#define IMAGE_LABEL_H

#include <QLabel>
#include <QMouseEvent>

class image_label : public QLabel
{
    Q_OBJECT
public:
image_label(QWidget* parent = 0);
~image_label();

signals:
    void doubleClicked();

protected:
    void mouseDoubleClickEvent(QMouseEvent * e);

};


#endif


//CPP 

#include "image_label.h"
#include <QMouseEvent>

image_label::image_label(QWidget* parent) : QLabel(parent)
{
}

image_label::~image_label()
{
}

void image_label::mouseDoubleClickEvent(QMouseEvent* e)
{
    if (e->button() == Qt::LeftButton)
    {
        emit doubleClicked();
        QLabel::mouseDoubleClickEvent(e);
    }
}

编译时出现以下链接器错误：

 image_label.obj : error LNK2001: unresolved external symbol "public: virtual struct QMetaObject const * __thiscall image_label::metaObject(void)const " (?metaObject@image_label@@UBEPBUQMetaObject@@XZ)

  image_label.obj : error LNK2001: unresolved external symbol "public: virtual void * __thiscall image_label::qt_metacast(char const *)" (?qt_metacast@image_label@@UAEPAXPBD@Z)

  image_label.obj : error LNK2001: unresolved external symbol "public: virtual int __thiscall image_label::qt_metacall(enum QMetaObject::Call,int,void * *)" (?qt_metacall@image_label@@UAEHW4Call@QMetaObject@@HPAPAX@Z)

  image_label.obj : error LNK2019: unresolved external symbol "protected: void __thiscall image_label::doubleClicked(void)" (?doubleClicked@image_label@@IAEXXZ) referenced in function "protected: virtual void __thiscall image_label::mouseDoubleClickEvent(class QMouseEvent *)" (?mouseDoubleClickEvent@image_label@@MAEXPAVQMouseEvent@@@Z)

有人可以帮我解决这些错误吗？

Answer 1

您必须在文件image_label.h上运行MOC预处理器。这会生成您必须包含在构建中的文件moc_image_label.cpp。错误消息表明您尚未执行此操作。（错误消息中提到的符号image_label::metaObject等在moc_image_label.cpp中定义。）

链接器错误使用doubleclick事件创建QLabel

1 个答案: