初识QT 5项目-爱代码爱编程

main.cpp

#include "widget.h"
#include <QApplication>

int main(int argc, char *argv[])
{
    QApplication a(argc, argv);

    Widget w;
    w.show();

    return a.exec();
}

widget.h

#include <QWidget>

namespace Ui {
class Widget;
}

class Widget : public QWidget
{
	// 为使用 信号槽，必须定义这个宏
    Q_OBJECT

public:
    explicit Widget(QWidget *parent = 0);
    ~Widget();

private:
    Ui::Widget *ui;
};

widget.cpp

#include "widget.h"
#include "ui_widget.h"

Widget::Widget(QWidget *parent) : QWidget(parent), ui(new Ui::Widget)
{
    ui->setupUi(this);
}

Widget::~Widget()
{
    delete ui;
}

widget.ui

添加一个 Label 和 一个 PushButton

ui_widget.h

#include <QtCore/QVariant>
#include <QtWidgets/QAction>
#include <QtWidgets/QApplication>
#include <QtWidgets/QButtonGroup>
#include <QtWidgets/QHeaderView>
#include <QtWidgets/QLabel>
#include <QtWidgets/QPushButton>
#include <QtWidgets/QWidget>

QT_BEGIN_NAMESPACE

class Ui_Widget
{
public:
    QLabel *LabDemo;
    QPushButton *btnClose;

    void setupUi(QWidget *Widget)
    {
        if (Widget->objectName().isEmpty())
            Widget->setObjectName(QStringLiteral("Widget"));
        Widget->resize(400, 300);

        LabDemo = new QLabel(Widget);
        LabDemo->setObjectName(QStringLiteral("LabDemo"));
        // Geometry几何(即大小)
        LabDemo->setGeometry(QRect(70, 92, 81, 20));

        btnClose = new QPushButton(Widget);
        btnClose->setObjectName(QStringLiteral("btnClose"));
        btnClose->setGeometry(QRect(240, 90, 75, 23));

        // 设置 Widget的WindowTitle、LabDemo的Text、btnClose的Text
        retranslateUi(Widget);
        
        // 设置 信号槽
        QObject::connect(btnClose, SIGNAL(clicked()), Widget, SLOT(close()));
        // 设置槽函数的关联方式，用于将UI设计器自动生成的组件信号的槽函数与组件信号相关联
        QMetaObject::connectSlotsByName(Widget);
    } // setupUi

    void retranslateUi(QWidget *Widget)
    {
        Widget->setWindowTitle(QApplication::translate("Widget", "My First Demo", Q_NULLPTR));
        LabDemo->setText(QApplication::translate("Widget", "Hello World", Q_NULLPTR));
        btnClose->setText(QApplication::translate("Widget", "Close", Q_NULLPTR));
    } // retranslateUi

};

namespace Ui {
    class Widget: public Ui_Widget {};
} // namespace Ui

QT_END_NAMESPACE

---

简要说明：

Widget类 继承 QWidget，private包含一个 Ui::Widget* 指针对象 ui

Widget类构造时：
	先调用 父类QWidget的构造函数，
	再 new一个 Ui::Widget对象实例化 ui，
	最后调用 ui->setupUi(this)，实际调用 Ui_Widget::setupUi(QWidget *Widget)
		
	
	Ui_Widget
	

ui_widget.h 中 定义类 Ui::Widget，其继承自 Ui_Widget 

	namespace Ui 
	{
		class Widget: public Ui_Widget {};
	}

继承关系

QLabel : public QFrame
	QFrame : public QWidget
		QWidget : public QObject

对应UI 设计器：

QPushButton : public QAbstractButton
	QAbstractButton : public QWidget
		QWidget : public QObject

对应UI设计器：

信号槽函数

static QMetaObject::Connection connect(
					const QObject *sender, const char *signal,
					const QObject *receiver, const char *member, 
					Qt::ConnectionType = Qt::AutoConnection);

static QMetaObject::Connection connect(
					const QObject *sender, const QMetaMethod &signal,
					const QObject *receiver, const QMetaMethod &method,
					Qt::ConnectionType type = Qt::AutoConnection);

inline QMetaObject::Connection connect(
					const QObject *sender, const char *signal,
					const char *member, 
					Qt::ConnectionType type = Qt::AutoConnection) const;
					
template <typename Func1, typename Func2>
static inline QMetaObject::Connection connect(
					const typename QtPrivate::FunctionPointer<Func1>::Object *sender, Func1 signal,
					const typename QtPrivate::FunctionPointer<Func2>::Object *receiver, Func2 slot,
					Qt::ConnectionType type = Qt::AutoConnection)					
					
					
					
					
//connect to a function pointer  (not a member)
template <typename Func1, typename Func2>
static inline typename std::enable_if<int(QtPrivate::FunctionPointer<Func2>::ArgumentCount) >= 0, QMetaObject::Connection>::type
		connect(
					const typename QtPrivate::FunctionPointer<Func1>::Object *sender, Func1 signal, 
					Func2 slot)					
{       }
				
					
					
//connect to a function pointer  (not a member)
template <typename Func1, typename Func2>
static inline typename std::enable_if<int(QtPrivate::FunctionPointer<Func2>::ArgumentCount) >= 0 &&
									  !QtPrivate::FunctionPointer<Func2>::IsPointerToMemberFunction, QMetaObject::Connection>::type
		connect(
					const typename QtPrivate::FunctionPointer<Func1>::Object *sender, Func1 signal, 
					const QObject *context, Func2 slot,
					Qt::ConnectionType type = Qt::AutoConnection)
{					}
					
	

//connect to a functor
template <typename Func1, typename Func2>
static inline typename std::enable_if<QtPrivate::FunctionPointer<Func2>::ArgumentCount == -1, QMetaObject::Connection>::type
		connect(
					const typename QtPrivate::FunctionPointer<Func1>::Object *sender, Func1 signal, 
					Func2 slot)
{		}



//connect to a functor, with a "context" object defining in which event loop is going to be executed
template <typename Func1, typename Func2>
static inline typename std::enable_if<QtPrivate::FunctionPointer<Func2>::ArgumentCount == -1, QMetaObject::Connection>::type
		connect(
					const typename QtPrivate::FunctionPointer<Func1>::Object *sender, Func1 signal, 
					const QObject *context, Func2 slot,
					Qt::ConnectionType type = Qt::AutoConnection)
{		}





// 实际调用第3个函数
inline QMetaObject::Connection QObject::connect(
					const QObject *asender, const char *asignal,
                    const char *amember, 
					Qt::ConnectionType atype) const
{ return connect(asender, asignal, this, amember, atype); }
	

    // internal slot-name based connect
    static void connectSlotsByName(QObject *o);