QT鼠标点击响应事件

Posted 2021-05-18 zieckey

假如我们想在窗口指定区域响应鼠标点击事件，怎么办呢？

比如我们有一个widget窗口，该窗口里有一个PixmapLabel图片，
我们假设想在图片的左上角响应鼠标的点击事件，那么我们可以这样做！

1. 创建一个新类
//mainForm.h
#ifndef MAINFORM_H
#define MAINFORM_H
#include <qevent.h>
#include <qvariant.h>
#include <qwidget.h>
#include <qmessagebox.h>

class QVBoxLayout;
class QHBoxLayout;
class QGridLayout;
class QLabel;

class mainForm : public QWidget
{
    Q_OBJECT

public:
    mainForm( QWidget* parent = 0, const char* name = 0, WFlags fl = 0 );
    ~mainForm();

    QLabel* myPixmapLabel;        
    
signals:
    void clicked();
   
public slots:
    virtual void mousePressEventSlot();

protected:
    void mousePressEvent(QMouseEvent *);
   
protected slots:
    virtual void languageChange();
};

#endif // MAINFORM_H

2. 实现文件

//mainForm.cpp
#include "mainForm.h"

#include <qvariant.h>
#include <qlabel.h>
#include <qlayout.h>
#include <qtooltip.h>
#include <qwhatsthis.h>
#include <qimage.h>
#include <qpixmap.h>

/*
 *  Constructs a mainForm as a child of 'parent', with the
 *  name 'name' and widget flags set to 'f'.
 */
mainForm::mainForm( QWidget* parent, const char* name, WFlags fl )
    : QWidget( parent, name, fl )
{
    if ( !name )
    setName( "mainForm" );
   
    //setCaption("Qt Mouse Click Event Example");

    myPixmapLabel = new QLabel( this, "myPixmapLabel" );
    myPixmapLabel->setGeometry( QRect( 120, 60, 300, 270 ) );
    //放置一个图片，该图片应该在同一文件夹里，否则要指定路径
    myPixmapLabel->setPixmap( QPixmap::fromMimeSource( "about-to-install.png" ) );   
    myPixmapLabel->setScaledContents( TRUE );
    languageChange();
    resize( QSize(600, 480).expandedTo(minimumSizeHint()) );
    connect( this, SIGNAL( clicked() ), this, SLOT( mousePressEventSlot() ) );   //信号连接
}

/*
 *  Destroys the object and frees any allocated resources
 */
mainForm::~mainForm()
{
    // no need to delete child widgets, Qt does it all for us
}
void mainForm::mousePressEvent(QMouseEvent *e)
{ 
    int x = e->x();
    int y = e->y();
    //假如在QRect( 120, 60, 200, 200 ) );这个区域里，就发出信号
    if (x>120 && x<200 && y>60 && y<200)
        emit clicked();
}
void mainForm::mousePressEventSlot()
{
    //该信号响应的曹
    //给出一个提示信息
    QMessageBox::about( this, "Qt Mouse Click Event Example",
                        "You haved clicked the prearranged position /nand the widget will be closed."
                        );
    close();  //关闭程序
}
/*
 *  Sets the strings of the subwidgets using the current
 *  language.
 */
void mainForm::languageChange()
{
    setCaption( tr( "Qt Mouse Click Event Example" ) );
}


3. main 函数
//main.cpp
#include <qapplication.h>
#include "mainForm.h"

int main( int argc, char ** argv )
{
    QApplication a( argc, argv );
    mainForm w;
    w.show();
    a.connect( &a, SIGNAL( lastWindowClosed() ), &a, SLOT( quit() ) );
    return a.exec();
}


将三个上述文件放在同一文件夹里，然后新建 pro 文件：

TEMPLATE = app
INCLUDEPATH += .
# Input
HEADERS += mainForm.h
SOURCES += main.cpp mainForm.cpp

然后：
qmake
make
直接运行，看看效果如何？